o Parasites obtain their food either ready-made or partially prepared from their hosts .... Q: What happen if Green plants cultivated in a soil free from iron? ..... (2) Plasma membrane allows passage of water through it, and prevents passage of sugar .... pressure) through a semi-permeable membrane, by osmotic pressure. اﻧïºïº·ïº.
BIOLOGY Unit I
Unit II
Structure and function Inheritance of in Living organisms livings organisms الزشمٍت والىظٍفخ فً النبئٌبد الحٍخ
الىساثخ فً النبئٌبد الحٍخ
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Unit III Molecular biology الجٍىلىخٍخ الدزٌئٍخ
Unit (I)
Structure and function of living organisms
الزشمٍت والىظٍفخ فً النبئٌبد الحٍخ
In Plants
In man
Chapter (1): Nutrition and Digestion الزغزٌخ والهضن فً النبئٌبد الحٍخ Chapter 2: Transport الٌقل Chapter 3: Respiration الزٌفش Chapter 4: Excretion in living organism اإلخشاج Chapter 5: Sensitivity اإلحضبس Chapter 6: Hormonal Co- ordination in living organisms ًًالزٌضٍق الهشهى Chapter 7: Support and movement الذعبهخ والحشمخ Chapter 8: Reproduction in Living Organisms الزنبثش
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In Plants
In Man (دعبء قجل الوزامشح)
ال اله إال اهلل الحلٍن النشٌن -ال اله إال اهلل العلى العظٍن -ال اله إال اهلل سة العشط العظٍن ،اللهن أًى اصبلل فهن الٌجٍٍي ،وحفظ الوشصلٍي ،وألهبم الوالئنخ الوقشثٍي ،واى ردعل لضبًً عبهشاً ثزمشك، وقلجً هلٍئ ًب ثخشٍزل ،وأصشاسًب لطبعزل ،فأًذ حضجً وًعن الىمٍل ،اًل على مل شٌئ قذٌش.
(دػجء دؼذ ثُٔزثًشر) ثُِ ْٜأٗ ٠ثعضٞدػضي ٓج هشأسٓٝ ،ج كٜٔشٓٝ ،ج فلظش ،كشدر إُ ٠ػ٘ذ فجؽض ٢إُ،ٚ٤ ثٗي ػِ ًَ ٠شب هذ٣ش ٝفغذ٘ج ثهلل ٗٝؼْ ثُ.َ٤ًٞ
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Chapter 1 Nutrition and Digestion ز٤ ثٌُجة٘جس ثُق٢ؼْ كُٜثٝ ز٣ثُضـز
I- Nutrition in living organisms: II- Nutrition in green plants: Absorption of water and salts The process of photosynthesis III- Nutrition in man: Concept Digestion. Absorption. Metabolism. Excretion.
1- Nutrition الزغزٌخ Definition - Food: - The importance of food -Types of nutrition
Definition of Nutrition: ز٣ثُضـز Nutrition is scientific study of food and various methods of feeding in living organisms. Nutrition is one of the most important characteristics of the living organism. ٢جر ك٤ش ثُقْٛ ٓظجٛثفذ ٖٓ أٝ ز٣صؼضذش ثُضـز. ز٤ج ثٌُجة٘جس ثُقٜثعـضٞ دٟ صضـز٢ثُـشم ثُٔخضِلز ثُضٝ ز ُِـزثء٤ِٔ ثُذسثعز ثُؼ:ز٣ثُضـز ز٤ثٌُجة٘جس ثُق Food: -ّثُـؼج
Food is the source of energy required for all vital processes of the body and the materials needed for growth and repair of worn- out tissues. ٠ِذ٣ غ ٓج٣ٞصؼٝ ُِٞٔ٘ ثد ثُالصٓزُٞٔثٝ ،ْز ُِؾغ٣ٞ٤جس ثُق٤ِٔغ ثُؼ٤ٔ ثُـجهز ثُالصٓز ُؾ٢ ثٌُجةٖ ثُقٚ٘ٓ غضٔذ٣ ١ ثُٔظذس ثُزٞٛ ثُـزثء .ْٖٓ ٓجدر ثُؾغ The importance of food :ز ثُـزثء٤ٔٛأ
1- The source from which the living organism obtains the energy required for all the vital processes of the body. ز٣ٞ٤جس ثُق٤ِٔغ ثُؼ٤ٔٓظذس ثُـجهز ثُالصٓز ُؾ. 2- Food contains the material needed for growth. ُِٞٔ٘ ثُٔجدر ثُخجّ ثُالصٓزٟٞق٣. 3- Food contains the material needed to repair the worn- out tissues. ز٤ُج ثُؾغْ ثُذج٣غ خال٣ٞ ثُٔجدر ثُخجّ ثُالصٓز ُضؼٟٞق٣
4- Protection from diseases.
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Types of nutrition ز٣ع ثُضـزٞٗأ Living organisms are divided into 2 types on the base of nutrition: ز٣ أعجط ثُضـز٠ِز ػ٤ػجٕ ٖٓ ثٌُجة٘جس ثُقٞٗ ؽذٞ٣
1-Autrotrophic nutrition:- ز٣ز صـز٤رثص Definition – example - types
Definition: Autotrophs are living organisms that can make their food (organic materials) by themselves , from simple inorganic materials, ex. green plants which can synthesize their food by photosynthesis or chemosynthesis from simple inorganic materials (water and CO2). .ج ٓغجٍ ثُ٘ذجصجس ثُخؼشثءٜج د٘لغٜغ إٔ صظ٘غ ؿزثة٤ صغضـ٢ز ثُض٤ ثٌُجة٘جس ثُق٢ٛ ز٣ز ثُضـز٤ثٌُجة٘جس رثص
Ex of autotrophic nutrition: Nutrition in green plants. Types of autotrophic nutrition: A. Photosynthesis: o It is the process by which green plants can manufacture the high-energy organic food compound substances ز ثُـجهز٤ُز ػج٣ٞز ثُؼؼ٤( ثُٔشًذجس ثُـزثةwhich is needed for building its body جٜٔج ُذ٘جء ؽغٜ صقضجؽ٢ )ثُضas carbohydrates (as sugars and starch), fats, and proteins inside its cells from inorganic simple, raw, and low-energy materials (carbon dioxide, water, and mineral salts). These materials are obtained from the surrounding habitat. By using these materials together with light energy that is absorbed by chlorophyll, green plants can carry out certain chemical reactions which are collectively called photosynthesis. جٜ صقضجؽ٢ز ثُـجهز ثُض٤ُز ػج٣ٞز ثُؼؼ٤ظ صظ٘غ ثُٔشًذجس ثُـزثة٤ ف،جٜج د٘لغٛغ ثُ٘ذجصجس ثُخؼشثء صظ٘غ ؿزثء٤ج صغضـٜثعـضٞز د٤ِٔػ ز٤ُٝـز أ٤ز دغ٣ٞش ػؼ٤ثد ؿٞٓ ٖٓ جٛج٣جس دثخَ خال٤٘٤صٝثُذشٝ ٕٞٛ ثُذٝ ) ٗشج-ز (عٌش٤ذسثص٤ٛٞثد ثٌُشدُٞٔ ٓغَ ث، جُٜٔذ٘جء ؽغ َّ ألصٔج٤كٝسٌُِٞز ثُٔٔضظز دج٤ةٞج ٓغ ثعضخذثّ ثُـجهز ثُؼٜتض٤ج ٖٓ دٜ٤ِز) صقظَ ػ٤ٗثألٓالؿ ثُٔؼذ- CO2- ثُـجهز (ثُٔجء٢ٓ٘خلؼز ك .٢ةٞز ثُذ٘جء ثُؼ٤ِـِن ػ٣ ز دٔج٤جة٤ٔ٤ٌُثُضلجػالس ث
B. Chemosynthesis: o Some bacteria use chemical energy to manufacture its food. 2-Heterotrophic nutrition:- ز٤ش رثص٤ز ؿ٣صـز Definition – example - types
Definition: Heterotrophs are living organisms that obtain food from bodies of other organisms. They obtain high-energy food substances either from green plants or from animals that were feeding on plants. ز٤ ثُٔشًذجس ثُـزثة٠ِ صقظَ ػ٢ٜ كٟج ٖٓ أؽغجّ ثٌُجة٘جس ثألخشٜ ؿزثة٢ِ صقظَ ػ٢ز ثُض٤ ثٌُجة٘جس ثُق٢ٛ ز٣ز ثُضـز٤ش رثص٤ثٌُجة٘جس ؿ . ثُ٘ذجصجس٢ِ صـزس ػ٢ثٗجس ثُضٞ٤ ثُقٝز ثُـجهز ٖٓ ثُ٘ذجصجس ثُخؼشثء أ٤ُػج
Ex of heterotrophic nutrition: Nutrition in man. Types of heterotrophic nutrition: 3 types 1) Holozoic nutrition: - ز٤ز أعجع٤ش رثص٤ ؿIt includes 3 subtypes: a) Carnivores: ّٞآًالس ثُِق- which feed on animals flesh ثٗجسٞ٤ّ ثُقٞ( ُقcats – doges – eagles). b) Herbivores: آًالس ثُؼشخ- which feed on plants (rabbits – cattle – horses). c) Omnivores:ػز ثُـزثءٞ٘ ٓض- which feed on plants and animals (Man). 2) Parasitic nutrition: ز٤ِ٤ؿل- As Bilharzias worms 5
o Parasites are livings that live either as ectoparasites ٢َ خجسؽ٤ ؿلor as endoparasites َ٤ؿل ْ دثخَ ثُؾغon or in other living organisms (which are called hosts َ) ثُؼجة. o Parasites obtain their food either ready-made or partially prepared from their hosts that will be harmed. o Examples for parasites: fleas, mosquitoes, bilharzias worms, tape worms, and some kinds of bacteria and fungi. 3) Saprophytic nutrition: ز٤ٓس-As some fungi and saprophytic bacteria. o Saprophytes are livings that obtain their food in a liquid form from decayed remains ج ثُٔضقِِز٣ ثُذوجof dead organisms. o Examples for saprophytes: many kinds of fungi and saprophytic bacteria. Comparison between Autotrophs and Heterotrophs: Autrotrophs Heterotrophs Definition Living organisms that can make their food by Living organisms that obtain food themselves ex. green plants which can synthesize from bodies of other organisms. They their food by photosynthesis or chemosynthesis. obtain high-energy food substances either from green plants or from animals that were feeding on plants. A. Photosynthesis: 1) Holozoic nutrition:- It includes: Method o It is the process by which green plants can a) Carnivores. manufacture the high-energy organic food b) Herbivores. compound substances as carbohydrates, fats, and c) Omnivores. proteins inside its cells from inorganic simple, 2) Parasitic nutrition As Bilharzias raw, and low-energy materials (carbon dioxide, worms. water, and mineral salts). 3) Saprophytic nutrition: ز٤ٓس-As o These materials are obtained from the some fungi and saprophytic bacteria. surrounding habitat. o By using these materials together with light energy that is absorbed by chlorophyll, green plants can carry out certain chemical reactions which are collectively called photosynthesis. B. Chemosynthesis: o Some bacteria use chemical energy to manufacture its food.
Q- G.R. All living organisms feed continuously? A- Because: Nutrition is one of the most important characteristics of the living organism. As Food is the sours to obtain energy required for all vital processes of the body and the materials needed for growth and repair of worn- out tissues. Q- G.R. Nutrition is considered the base for differentiate living organisms? A- Because: Nutrition is the scientific study of food and various methods of feeding in living organisms. Living organisms are divided into 2 types on the base of nutrition: 6
II- Nutrition in green plants (Autotrophic Nutrition) الزغزٌخ فً الٌجبربد الخضشاء:الزغزٌخ الزارٍخ Autotrophic nutrition carried out by green plants includes 2 main processes: 1. Absorption of water, mineral salts, and carbon dioxide. 2. The process of photosynthesis. ٢ةٞز ثُذ٘جء ثُؼ٤ِٔ ػ- ثألٓالؿٝ ز ثٓضظجص ثُٔجء٤ِٔػ: ٔجٛ ٖ٤ض٤ِٔ ثُ٘ذجصجس ثُخؼشثء صضْ ٖٓ خالٍ ػ٢ز ك٤ز ثُزثص٣ثُضـز
1-Absorption of water and salts ثألٓالؿٝ ز ثٓضظجص ثُٔجء٤ِٔ ػ:ًالٝأ Essential nutrients for green plants - Root - Water absorption - Salt absorption.
Essential elements and nutrients for green plants: ز ُِ٘ذجصجس ثُخؼشثء٣سٝز ثُؼش٤ثُؼ٘جطش ثُـزثة Types – importance - deficiencies
Plants need essential elements (Carbon, Hydrogen, and Oxygen) and essential nutrients. Plants absorb these elements through the root. ٕٞش ثٌُشد٤ز ؿ٣سٝ ػ٘جطش ػش٠ٛٝ ز٤جس أعجع٣ٓـزٝ ) ٖ٤ثألًغؾٝ ٖ٤ؽٝذس٤ُٜثٝ ٕٞز (ثٌُشد٣سٝ ػ٘جطش ػش٠ُقضجػ إ٣ ثُ٘ذجس سٝن ثُؾز٣ج ػٖ ؿشٜٔضظ٣ ٖ٤ثألًغؾٝ ٖ٤ؽٝذس٤ُٜثٝ
Types of essential elements and nutrients: 1) Essential elements: o Carbon, Hydrogen and Oxygen (CO2 and water).
.ٖ٤ثألًغؾ- ٖ٤ؽٝذس٤ُٜ ث-ٕٞثٌُشد: ز٤ثُؼ٘جطش ثألعجع
2) Essential Nutrients: جس٣ثُٔـز These elements are divided into 2 groups: A ) Macro – nutrients :- ٟجس ثٌُذش٣ثُٔـز o The plants need to these elements in large quantities. o Absorbed as anions. o They are 7 elements: [Potassium– Calcium – Magnesium –Sculpture –Phosphorous Nitrogen– Iron]. ٠٘دٌجّ عل N-P- K- Ca- Mg- S- Fe.َشر ٓغ٤جس ًذ٤ٌٔج ثُ٘ذجس دٜقضجؽ٣
B) Micro – nutrients: - ٟجس ثُظـش٣ثُٔـز o The plants need to these elements in very small quantities not more than few milligrams/ liter. So they are called " Trace elements " o They are 8 elements (Manganese, Zinc, Boron, Aluminum, chlorine, Copper, Molybdenum, and Iodine}. Zn- B- Cu- Mn- Al- Cl- I. :٢ٛٝ ز٣ دجُؼ٘جطش ثألعش٠ٔ ثُِضش ُزث صغ٢ؾشثٓجس ك٤ِِٓ دؼغ٠ِذ ػ٣ِز ال صض٤جس ػت٤ٌٔج ثُ٘ذجس دٜقضجؽ٣
Importance of essential elements and nutrients:
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o Some of macronutrients share in the synthesis of chlorophyll (Mg), and ATP (P). .٠ د٠ صٚ٣د٘جء ثٝ َ٤كٝسٌُِٞ د٘جء ث٢ذخَ ك٣ جٜدؼؼٝ ٔجس٣ؼَٔ ًٔ٘شـجس ُإلٗض٣ ثُؼ٘جطشٙزٛ دؼغ
o Magnesium is an important element in the synthesis of chlorophyll; Magnesium atom occupies the center of the chlorophyll molecule. The molecular formula of chlorophyll A is . There is a relationship between the presence of Mg in the chlorophyll and the ability of chlorophyll to absorb light energy required for o Phosphorus required to form energy transferee compounds (ATP) during photosynthesis. o Iron required to form some enzymes which help in photosynthesis. o Nitrates, Phosphates, and sulfates: Are required to convert carbohydrates into proteins. o Some of micronutrients act as enzymes activator. Deficiencies of these elements lead to:٠ُ ثُؼ٘جطش إٙزٛ ٗوض١ؤد٣ : 1. Disturbances in plant growth. ١ ثُخؼشُٞٔ٘ثخضالٍ ث. 2. The growth may stop completely. ١ ثُخؼشُٞٔ٘هق ثٞص 3. Flowers or fruits may not produce. ثُغٔجسٝجس إٔٛ ثألصٌٞ ػذّ ص. Q: What happen if Green plants cultivated in a soil free from iron? A- The plant can not complete photosynthesis, because Iron: is an important element in building up of some enzymes that help to complete photosynthesis. Q: What happens if Plant grows in a soil rich is Calcium? A- The plant get red off excess calcium by its collection in leafs which fall at the end. Q: What happen if a Magnesium atom disappears from chlorophyll molecules? A- Molecular formula of chlorophyll change ( ) and become unable to absorb light. So photosynthesis stop and plant die. Q What happen if C; H2 and O2 are present for a plant without other elements? A- Deficiencies of these elements lead to: (1) Disturbances in plant growth. (2)The growth may stop completely.(3) Flowers or fruits may not produce. Because some of these elements acts as enzymes activator, and others share in the synthesis of chlorophyll, and ATP. Amount needed It includes
Importance
Macro – nutrients Micro – nutrients (Trace elements) The plants need to these elements in The plants need to these elements in very small large quantities. quantities not more than few milligrams/ liter. So they are called Trace elements They are 7 elements : Potassium – They are 8 elements (Manganese, Zinc, Calcium – Magnesium – [Nitrogen Aluminum, chlorine, Iodine, Molybdenum, – Phosphorous – Sulphur – Iron]. Copper and, Boron,} ذ٣دٌْ ٗلي ثُقذ )ٞ د- ّ– ٗقجط-ٞ٣ -ًَ -ُٞ -(ٖٓ– خج: 1- Share in the synthesis of 1- Some of these elements act as enzymes chlorophyll (Mg), and ATP (P). activator. 2- Required fror growth of plants.
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Deficiencies
Q- G.R. Magnesium plays an important role in photosynthesis? A- Because: Magnesium is an important element in the synthesis of chlorophyll, Magnesium atom occupies the center of the chlorophyll molecule. The molecular formula of chlorophyll A is . There is a relationship between the presence of Mg in the chlorophyll and the ability of chlorophyll to absorb light energy required for Q- G.R. Iron and phosphorus play an important role in photosynthesis? A- Iron required forming some enzymes which help in photosynthesis. Phosphorus required forming energy transferee compounds (ATP) during photosynthesis. Q- G.R. Some Micro – nutrients are important for plants? o The plants need micronutrients (Trace elements) in very small quantities, not more than few milligrams/ liter. o They are 8 elements (Manganese, Zinc, Boron, Aluminum, chlorine, Copper, Molybdenum, and Iodine} o Some of these elements act as enzymes activator. Q- G.R.Autotrophic plants do not means that plant need CO2 and water only? A- Experiments proved that plants need : 1- Essential elements: o Carbon, Hydrogen, and Oxygen (CO2 and water). 2- Essential Nutrients: الوغزٌبد Essential elements (other than Carbon, Hydrogen, and Oxygen). Plants absorb these elements through the root. Deficiencies of these elements lead to: Disturbances in plant growth. The growth may stop completely. Flowers or fruits may not produce. And Stop reactions in which these elements help to activate its enzymes. These elements are divided into 2 groups: ٍ ثُغجدنٝزًش ثُؾذ٣
Structure of Root A plant has two organ systems: 1- The shoot system: above ground and includes leaves, buds, stems, flowers, and fruits. 2- The root system: includes those parts of the plant below ground, such as the roots, tubers, and rhizomes. The arrangement of the cells in a root is root hair, epidermis, cortex, endodermis, pericycle and lastly the vascular tissue in the centre of a root to transport 9
the water absorbed by the root to other places of the plant. 1- Epidermis; Epidermis of the root is known as piliferous layer ةز٣دشُٞثُـذوةز ث, because root hairs exit from it as a tubular outgrowth of an epidermal cell which may reach 4mm. long. Root hair lined internally with a thin layer of cytoplasm which contains the nucleus and large cell vacuole. 2- Cortex: The exodermis represents an unicellular cell layer located at the outer surface of the root directly below the root epidermis. It replace the cortex. It is called external cortex or exodermis. There are intercellular spaces between cells of root cortex : (a)- It helps in passage of absorbed water through root cells, where water flows by imbibitions through cell walls and intercellular spaces. (b) Help in aeration of inner tissues of root by Gas exchange. 3 – Endodermis: The endodermis represents an unicellular cell layer separating the central cylinder of the root from the cortex The endodermis (the innermost row of cells of the cortex) controls the passage of water and solutes inwards to xylem vessels. A- The endodermal cells facing phloem:ػز ثُِقجءٞٔز ُٔؾٜثؽُٞٔدسٓظ ثٝج ثالٗذ٣خال o Their cell walls completely thickened with suberin. So these cells prevent the passage of water inwards by imbibitions which are not under the control of the cell. B- While the endodermal cells facing xylem vessels: ز ثُخشخ٤ػٝز ألٜثؽُٞٔدسٓظ ثٝج ثالٗذ٣خال o Called Passage cells because their cell walls thickened with suberin only as a strip called Caspian Strip that runs as a ribbon around the middle region of both the radial walls and the transverse walls. 4- Pericycle: o The pericycle is a cylinder of parenchyma cells that lies just inside the endodermis and is the outer most part of the vascular cambium of plants. o Funcrtion : (1) It has the capacity to produce secondary lateral roots. (2) allow passage of water and salts.
5- Vascular tissues (cambium): A- Phloem:ثُِقجء Placed toward the pericycle and endodermis. 10
Formed of 4 types of cells: 1- Sieve tubes ٚ٤ُخ ؿشدج٤أٗجد = Cylindrical. = Arranged in a vertical row = Their transverse walls having tiny pores forming sieve plates which allow cytoplasm to flow from one cell to another in the form of cytoplasmic strands, carrying the ready made food to reach the plant’s parts. = Nucleus disappears during cell formation. 2- Companion cells ج ٓشثكوز٣خال = Small nucleated cell beside each sieve cell to control its activities and provide it with energy. 3- Phloem parenchyma: parenchymatous cells ; Present between sieve tubes ; connected phloes vessels with each other. 4- Scherenchyma fibers: Present between sieve tubes. Function: = From conductive tissue. = Transport the soluble organic foodstuffs that are formed in the leaf during photosynthesis to all the plant parts.
Q: What happen if Phloem tissue disappears from plant? A- Phloem transports the soluble organic foodstuffs that are formed in the leaf to all the plant parts. When disappeared: the plant can not transport the soluble organic foodstuffs that are formed in the leaf during photosynthesis to all the plant parts, so the plant dies. Q- G.R. Epidermis of the root is known as piliferous layer? A- Because root hairs exit from it as a tubular outgrowth of an epidermal cell which may reach 4mm. long. Root hair lined internally with a thin layer of cytoplasm which contains the nucleus and large cell vacuole. ز ؟٣دشُٞصؼشف دششر ثُؾزس دجُـذوز ث ٖٓ شر٤ْٓ صذـٖ ثُشؼ4 ٢ُج إُٜٞظَ ؿ٣ٝ ج ثُذششر٣ثفذر ٖٓ خالٝ ز٤ِشر ثٓضذثد خ٤ز كٌَ شؼ٣شثس ثُؾزس٤ج صخشػ ثُشؼٜ٘ٓ ٕ ال- ػ شر٤ز ًذ٣ر ػظجسٞ كؾٝ ثرٞٗ جٜدالصّ دٞض٤وز ٖٓ ثُغ٤ثُذثخَ دـذوز سه
B- Xylem: ثُخشخ Compound tissue formed of 3 types of cells: 11
1- Xylem cells: * Wall: thick with lignin ; lignified secondary walls, deposited on their primary walls. * Both cytoplasm and nucleus of each cell degenerate forming thick walled hollow elongated cell. * It forms: A- Tracheids ذجس٤ثُوظ: =Formed by super imposed cells over each other. B-Vessels = Formed by disappearance of transverse walls between adjacent cells of tracheids, to form a long wide tube called vessel through which water and salts can pass easily and quickly. 2- Xylem parenchyma: = Paeanchyma cells having thickened walls. = May be present among tracheids and vessels in the form of rays. 3- Sclerenchyma: = Among xylem vessels and tracheids. Function: = Xylem: support the plant and transport water and salts absorbed from the root to the leafs. = It supports the plant, due to the deposition of thick lignified secondary walls on the primary walls of the tracheids and vessels which makes them strong and hard. = Xylem is a dead tissue because its cells have no nuclei or cytoplasm. Q: What happen if Xylem tissue disappears from plant? A- Xylem support the plant and transport water and salts absorbed from the root to the leafs. When disappeared: the plant loss its support and water and salts absorbed from the root can not reach to the leafs, so the plant die.
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Root hairs (Function - Structure – adaptation – factors)
Function: * Higher green plants absorb H2O and salts from the soil through roots hairs present in the root system of the plant. ُِ٘ذجس١ع ثُؾزسٞٔ ثُٔؾ٢ز ك٣شثس ثُؾزس٤ن ثُشؼ٣ثألٓالؿ ٖٓ ثُضشدز ػٖ ؿشٝ ّ ثُ٘ذجس دجٓضظجص ثُٔجءٞو٣ ز٤ ثُ٘ذجصجس ثُخؼشثء ثُشثه٢ك
* Then the soil solution transported from one cell to anther until they reach ascending vessels (xylem vessels) which transport water and salts to the leafs. .ز ثُ٘جهِز٤ػٝ ثألٙ ثصؾج٢ كٟ أخش٠ُز إ٤ِثةَ ثُضشدز ٖٓ خٞعْ ص٘ضوَ ع The structure of the root hair:-ز٣شر ثُؾزس٤خ ثُشؼ٤ًصش
Root hair is tubular outgrowth of an epidermal cell (piliferous layer) which may reach 4mm. long. ْٓ 4 ٢ُٞج فُٜٞظَ ؿ٣ ز) هذ٣دشُٞج ثُذششر (ثُـذوز ث٣ثفذر ٖٓ خالٝ ز٤ِ ُخ٢دٞ ثٓضذثد أٗذ٢ٛ Root hair lined internally with a thin layer of cytoplasm which contains the nucleus and large cell vacuole (formed of plasma membrane wall , contains high osmotic pressure solution). شر٤ز ًذ٣ر ػظجسٞكؾٝ ثرُٞ٘ج ثٜدالصّ دٞض٤وز ٖٓ ثُغ٤ٓذـ٘ز ٖٓ ثُذثخَ دـذوز سه The outer surface of root hairs are covered with a thin colloidal layer (the cell wall that is made up of cellulose), that will imbibe water from the soil solution. Root hair don’t exist for more than few days or weeks (G.R.) , since epidermal cells are lost from time to time and continuously regenerated from zone of elongation in root. ع دجعضٔشثس ٖٓ ٓ٘ـوزٞصؼٝ آخشٝ ٖ٤ٖ ف٤ ثُؾزس صضٔضم د٢غ ألٕ ثُذششر ك٤ أعجدٝجّ أ٣ص دؼؼز أٝضؾج٣ ز ال٣شر ثُؾزس٤ػٔش ثُشؼ. ثُؾزس٢ثالعضـجُز ك
Epidermis (piliferous layer) Cortex Nucleus Large vacuole Root hair Thin cytoplasm
Adaptation of the root hairs:-جٜلض٤ظُٞ ز٣شثس ثُؾزس٤ٓالءٓز ثُشؼ 1-They have thin walls to permit the passage of water and salts through them. جُٜثألٓالؿ خالٝ وز ُضغٔـ د٘لجر ثُٔجء٤ج سهٛؽذس
2-Their large number and protruding to the outside of root (G.R.) to increase the area of absorbing surface. جدر ٓغجفز عــ ثالٓضظجص٣ج خجسػ ثُؾزس ُضٛثٓضذثدٝ ش٤ج ثٌُذٛػذد
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3-The solution inside the root hair vacuole is more concentrated than that of the soil solution to help water to pass from the soil to the root hair by osmosis. .جٜ٤ُ ثٗضوجٍ ثُٔجء ٖٓ ثُضشدز إ٢ِغجػذ ػ٣ ٓٔج- ٍ ثُضشدزِٞض ٓق٤ً ٖٓ صش٢ِز أػ٣ج ثُؼظجسٜصٍٞ دثخَ كؾِٞض ثُٔق٤ًصش
4- The wall of the vacuole is semi permeable (plasma membrane) to allow passage of water from outside to inside the vacuole by osmosis. 5-They secrete a viscous substance to help this hair to find their way easily among soil particles and to stick to them which helps to fix the plant in the soil. . ثُضشدز٢ش ثُ٘ذجس ك٤ صغذ٢ِذجس ثُضشدز كضؼَٔ ػ٤ ثالُضظجم دقذٝ ذجس ثُضشدز٤ٖ فذ٤ ثالٗضالم د٢ِصلشص ٓجدر ُضؽز صغجػذ ػ
Factors help root of plants to absorb water by imbibitions? ن ثُضششح٣ ثٓضظجص ثُٔجء ػٖ ؿش٠ِ ثُ٘ذجس ػ٢ صغجػذ ثُؾزس ك٢ثَٓ ثُضٞٓج ثُؼ
A- Root hairs are covered with a thin colloidal layer, stick to soil particles with its water and soil solution. B- The cell wall (that is made up of cellulose) possesses strong affinity for water in the adjacent soil particles. C- Plasma membrane allows passage of water freely. Q: What happen if all root hairs are removed from a plant? A- It will die because it can not absorb water and salts from soil, so cannot do photosynthesis. Q- G. R. Root hair doesn't exist for more than few days or weeks? A- Because epidermal cells of the root are lost from time to time and continuously regenerated from zone of elongation in root. ) َِغ( ػ٤ أعجدٝجّ أ٣ أٟضؼذ٣ ز ال٣شر ثُؾزس٤ػٔش ثُشؼ ع ٖٓ ٓ٘ـوز ثالعضـجُزٞصؼٝ ذجس ثُضشدز٤ج دقذًٜؾز الفضٌج٤ٖ ألخش ٗض٤ج ثُذششر صضٔضم ٖٓ ف٣ ألٕ خال- ػ
Q- G.R. Adaptation of the root hairs with its function? 1-They have thin walls to permit the passage of water and salts through them. 2-Their large number and protruding to the outside of root increase the area of absorbing surface. 3-The solution inside the root hair vacuole is more concentrated than that of the soil solution to help water to pass from the soil to the root hair by osmosis.
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4-They secrete a viscous substance to help this hair to find their way easily among soil particles and to stick to them which helps to fix the plant in the soil. Q- G.R. Root hair adapted to water transfer by osmosis? A- Because: (1) It is surrounded by cellulose cell wall which imbibes water and allows water to pass through it. (2) Plasma membrane allows passage of water through it, and prevents passage of sugar and amino acids. (3) the solution inside the root hair vacuole is more concentrated than that of the soil solution (due to soluble sugar in it which increase its osmotic pressure ) i.e. water concentration less than soil, so water pass from the soil to the root hair by osmosis. : ٚ٣رٞٔلز ٗوَ ثُٔجء ٖٓ ثُضشدز دجالع٤ظٝ ْز صالة٣شثس ثُؾزس٤ثُشؼ ، ُٚغٔـ د٘لجر ثُٔجء خال٣ ٢ٓؽذ ؿشجء دالصٞ٣ ًٔج، ٙغٔـ د٘لجر٣ٝ ضششح ثُٔجء٣ ١ص ثُزِٞ٤ِ ٖٓ ٓجدر ثُغ١ِٞج صقجؽ دؾذثس خٜٗ أل/ػ ٢ٍُ ثُٔجء أٞ دخ٠ِؼَٔ ػ٣ ١ ثُزٟصٞٔذ ٖٓ ثُؼـؾ ثالع٣ض٣ د ثُغٌش ثُزثةخٞؽُٞ ز٣ر ثُؼظجسٞ ثُلؾ٢ٍ كِٞض ثُٔق٤ًؼج ثسصلجع صش٣أٝ رٞدثخَ ثُلؾ
Q- G.R. Root hair not covered by cutin? A- To allow water and salts to pass through it, because cutin is impermeable to water and salts. ٖ ؟٤صٞ٤ٌُ دششر ثُؾزس دج٠ػَِ الصضــ ش ٓ٘لز ُِٔجء٤ٖ ؿ٤صٞ٤ٌُثألٓالؿ كجٝ ضٌٖٔ ثُؾزس ٖٓ أثٓضظجص ثُٔجء٣ ٠ فض- ػ
Plant cell: Cell
Protoplasm
Cytoplasm
Living constituents (organelles)
Plasma membrane
Nucleus
Non living
Cell wall ١ِٞثُؾذثس ثُخ: Site: = In plant cell only. = Externally surrounds the plant cell Shape: = Inflexible wall. Structure: 15
Cell wall
= Composed of cellulose which imbibe water and allows water and other substance to pass through it Function: = Protects, support the plant cell and gives it its final shape. = it is fully permeable membrane. Comparison between cell wall and cell membrane: Points of comparison 1- Site 2- Chemical composition
3- Permeability 4- Function
Cell wall = In plant cell only = Mainly cellulose
Cell membrane = In both plant and animal cells = Fluid Mosaic structure, = Consists of Molecules of protein embedded in double layers of phospholipids = Fully permeable = Selectively permeable = Protects, encloses, support 1- Encloses and protect the cell the plant cell and gives it its contents. final shape. 2- Control what enters and leaves the cell according to the need of the cell.
Water absorption: Mechanism of water absorption - Absorption of water by root- Path ways of water through root cells to xylem
Mechanism of water absorption:ز ثٓضظجص ثُٔجء٤ُآ Mechanism of water absorption depends on 4 physical phenomena: :-٢ٛ ز٤جة٣ض٤ش كٛثٞ أسدؼز ظ٠ِز ػ٤ُ٥ ثٙزٛ صؼضٔذ
1 – Diffusion: - ز ثالٗضشجس٤خجط * It is the movement of molecules or ions from high concentrated medium to low concentrated one, due to the continuous free motion of the molecules of the diffused substance in the medium of diffusion. تجس ثُٔجدر ثُٔ٘ضششر٣ز ثُٔغضٔشر ُؾض٤دغذخ ثُقشًز ثُزثص
* Diffusion requires kinetic energy from the environment but does not require cellular energy. Hence diffusion is a form of passive transport. * Example: a- Diffusion of water vapor and CO2 from high to low concentrated zone in mesophyll of plant leaf. b- Diffusion of a drop of ink when it falls into a beaker containing water. ٓجءٚح دًٞ ٢ٓغَ ثٗضشجس ٗوـز فذش عوـش ك
c - Diffusion of salts from the soil solution (high concentrated medium) and pass through the wet cellulose walls to the cell (less concentrated medium). Because ions are present in continuous free motion. 16
2 – Permeability: - خبصٍخ الٌفبرٌخ * It is the ability of membranes to allow water and ions to pass through them. * Membranes may be: a) Permeable membranes: Allow water and salts ions to pass through them. Ex: Cellulose cell walls: as they allow both water and mineral ions to pass through. b) Impermeable membranes: Don’t allow water and salt to pass through them. Ex: Cell walls covered with lignin, suberin, or cutin: are impermeable to water and salts. ز٤ٗٗجس ثألٓالؿ ثُٔؼذٞ٣أٝ ش ٓ٘لزر ُِٔجء٤ؿ: ٖ٤٘ثُِؾٝ ٖ٤صٞ٤ٌُثٝ ٖ٣دشٞ٤ثُؾذس ثُٔــجر دجُغ
c) Semi-permeable membranes: A membrane that prevents the passage of some substances but allows the passage of others based on differences in the size, charge, or lipid-solubility of the substances. Ex: Plasma membrane which is thin, with tiny pores, that allow free passage of water , slow passage of some salts, and prevents the sugars, amino acids (large size molecules). Plasma membranes: are selectively permeable, i.e. can control the passage of substances through them: 1. Some substances: May be allowed to pass freely through the pores. 2. Some other substances: May pass but slowly. 3. Other substances: Are not allowed to pass at all. صٔ٘غٝ - ثد صٔش دذؾءُٞٔدؼغ ثٝ - سر فشرٞج دظُٜس ثُٔجء خالٝوز ؽذًث صغٔـ دٔش٤ح دهٞج عوٜوز د٤ز سه٤ أؿش٢ٛ: ز٤ٓز ثُذالص٤ثألؿش .)ز٣جس٤ز ثالخض٣ (ثُ٘لجرٟثد أخشٞٓ ٗلجر Selective permeability:- ز٣جس٤ز ثالخض٣ثُ٘لجر
o It is the ability of plasma membrane to allow passage of some substance, control passage of some substance, and prevent passage of other substance according to the cell needs. Regardless of their size, concentrations or charges. o Plasma membranes has a selective permeability as it allow the passage of water, and control the permeability of many salts, but it prevents the permeability of sugars and amino acids because they are of large-sized molecules.
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شر٤تجس ًذ٣ز رثس ثُؾض٤٘٤ٓثألفٔجع ثألٝ صٔ٘غ ٗلجر ثُغٌشٝ ش ٖٓ ثألٓالؿ٤٘ٔج صقذد ٗلجر ًغ٤زً صغٔـ د٘لجر ثُٔجء د٤ٓز ثُذالص٤كْ ثألؿش .ْثُقؾ
Permeability
Swlective permeability
3 – Osmosis :- ز٣صٞٔز ثالع٤ثُخجط * It is the diffusion of water molecules from a medium with high concentration of water (low osmotic pressure) to another with low concentration of water (high osmotic pressure) through a semi-permeable membrane, by osmotic pressure. )ض ػجٍ ُألٓالؿ٤ًض ٓ٘خلغ ُِٔجء (صش٤ً ٓ٘ـوز رثس صش٢ُض ٓ٘خلغ ُألٓالؿ) إ٤ًض ػجٍ ُِٔجء (صش٤ًثٗضشجس ثُٔجء ٖٓ ٓ٘ـوز رثس صش ١صٞٔ ثُٔ٘لزر دجُؼـؾ ثألعٚز شذ٤خالٍ ثألؿش * Osmotic pressure: - ١صٞٔثُؼـؾ ثالع
o It is the pressure due to concentration of solute in water that causes the diffusion of water through semi-permeable membranes from high concentration of water to low concentration of water. َض ثأله٤ً ثُضش٢ُ إ٠ِض ثألػ٤ً ثُٔ٘لزر ٖٓ ثُضشٚز شذ٤ ثٗضشجس ثُٔجء خالٍ ثألؿش٢ُ إ١ؤد٣ٝ ثُٔجء٢ثد ثُٔزثدز كُٞٔض ث٤ً٘شؤ ػٖ صش٣ ػـؾٞٛ
o Osmotic pressure increases by increase in concentration of solutes (salts) in the solution. i.e. Osmotic pressure is directly proportional to concentration of solutes (salts) in the solution. Os P.
Solute conc. High water conc.
Low water conc.
* Its importance for the plant: A- Help in water absorption from the soil: as the solution inside the root hair vacuole is more concentrated than that of the soil solution (due to the presence of sugar solution in the vascular sap) so water concentration in soil solution is more than vacuoles so water pass from the soil to the root hair by osmosis. B- One of the 3 ways by which absorbed water pass from epidermis through cortex root cells to xylem vessels. Through cells sap: - which needs a gradual fall of osmotic pressure along the root cells. C- Root hairs of desert plants (Xero-phytes) and those of plants living in salt marshes ( ثُٔغةض٘وؼجسHalo-phytes) are characterized by their high osmotic pressure ( ranges from 50 18
up to 200 atmosphere ) compared to the osmotic pressure of root hairs of ordinary plants (Meso-phytes) ( that ranges from 5 up to 20 atmosphere ). This is to help to absorb as much water as possible from the very difficult surrounding medium. 4 – Imbibitions:- ز ثُضششح٤خجط * It is the ability of Solid particles epically colloidal solid particles to absorb liquids (water), swell, and increase in volume. .ص٘ضلخٝ ْ ثُقؾ٢ ثٓضظجص ثُٔجء كضضدثد ك٢ِز ػ٣ٝخجطز ثُذهجةن ثُـشٝ هذسر ثُذهجةن ثُظِذز * Plant cell walls absorb water by imbibition. ز ثُضششح٤ج ثُ٘ذجس ثُٔجء دخجط٣صٔضض ؽذثس خال * From colloidal hydrophilic ثُٔقذةز ُِٔةجءsubstances in plants that show this property: -
Cellulose – Pectin – Proteins of the protoplasm. ّدالصٞصٝجس ثُذش٤٘٤صٝدشٝ - ز٤٘٤ثد ثُذٌضُٞٔ ث-صِٞ٤ِ ثُغ: ز٤ ثُخجطٙزٛ جٜ٤صضؼـ كٝ ثُ٘ذجس٢ز ثُٔقذز ُِٔجء ك٣ٝثد ثُـشُٖٞٔٓ ث
* Ex: When a piece of wood is placed in water, it imbibes water. Imbibition extends through the piece of wood till it reaches the parts which are not submerged in water.
Q- G.R. Plasma membranes: are semi-permeable and selectively permeable? A- Because: Semi-permeable: means they prevent the passage of some substances but allows the passage of others based on differences in the size, charge, or lipid-solubility of the substances. Selectively permeable: means it is able to control passage of some substance according to the cell needs. Plasma membranes are thin with tiny pores that can control the passage of substances through them: 1. Some substances allowed passing freely (as water). 2. Some other substances: May pass but slowly (Controls the salts). 3. Other substances: are not allowed to pass at all (Prevents the sugars, amino acids (large size molecules) Q- G.R. Water transport from soil to root cells by osmosis ? A- Because : The concentration of cell sap of the vacuole of root hairs, is more than the concentration of the soil solution due to the presence of sugar solution in the vascular sap (i.e. water concentration is higher in soil solution than its concentration in the cell sap) So water pass to inside of epidermal cells by osmosis.
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The water concentration in the epidermal cells becomes higher than that in the neighboring cells of the cortex, so absorption and movement of water continues from one cell to another inwards until it reaches the xylem vessels in the center of the root. Q- G.R. There are several ways for water absorbed through root cells? A- Absorbed water passes across the root cells, until it reaches xylem vessels in 3 pathways: 1- Through cells sap: By osmosis which needs a gradual fall of osmotic pressure along the root cells? 2- Through the cytoplasm: Where water rushes from one cell to another through plasmodesmata that connect the protoplasm of plant cells together. 3- Through cell walls and intercellular spaces: Water passes through the cell wall by imbibitions, and the small intercellular spaces where the imbibed water flows. ش ثٓضظجص ثُؾزس ُِٔجء٤ صلغ:
Absorption of water by root:
1-Root hairs cell walls imbibe water from soil solution: o Root hairs are covered with a thin colloidal layer (the cell wall that is made up of cellulose), stick to soil particles with its water and soil solution, o So they possess strong affinity for water in the adjacent soil particles. o So, the outer surface of root hairs (cell wall) will imbibe water from the soil solution. ز٤ز دجُٔجء (خجط٣صِٞ٤ِرثةذجس كضضششح ثُؾذس ثُغٝ ج ٖٓ ٓجءٜ٤ذجس ثُضشدز دٔج ك٤ج فذٜز صِضظن د٣ٝز ؿذوز ؿش٣شثس ثُؾزس٤ؾ دجُشؼ٤صق )ثُضششح
2-Imbibed water passes to inside of epidermal cells by osmosis: o The imbibed water is then withdrawn to the inside of epidermal cells by osmosis, because the concentration of cell sap of the vacuole of root hairs, is more than the concentration of the soil solution due to the presence of sugar solution in the vascular sap (i.e. water concentration is higher in soil solution than its concentration in the cell sap). شر٤ز ُِشؼ٣ر ثُؼظجسٞ ثُلؾ٢ ك١ِٞش ثُخ٤ض ثُؼظ٤ًز ألٕ صش٣صٞٔز ثألع٤ج ثُذششر دجُخجط٣ دثخَ خال٠ُ٘ضوَ ثُٔجء ثُٔضششح ٖٓ ثُضشدز إ٣ ٚ٘ٓ ٠ٍِ ثُضشدز أػِٞ ٓق٢ض ثُٔجء ك٤ً إٔ صش١ أ، ١ِٞش ثُخ٤ ثُؼظ٢د ثُغٌش رثةذج كٞؽُٞ ٍ ثُضشدز ٗظشثِٞض ٓق٤ً ٖٓ صش٠ِز أػ٣ثُؾزس ز٣ر ثُؼظجسٞ ثُلؾ٢ك
3-Water movement continues from cell to anther until xylem vessels by osmosis: o The water concentration in the epidermal cells becomes higher than that in the neighboring cells of the cortex .ثُوششر o So absorption and movement of water continues from one cell to another inwards until it reaches the xylem vessels in the center of the root by osmosis. .ز٣صٞٔز ثالع٤ز ثُخشخ دجُخجط٤ػٝ أ٢ُج ثُوششر عْ إ٣ خال٠ُ٘ضشش ثُٔجء ٖٓ ثُذششر إ٣
4- Water moves through xylem vessels needs a graduation of osmotic pressure. Xylem transport water and salts absorbed from the root to the leafs.
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Xylem خشخ
Phloem ُقجء
Pericycle َ٤ٌغ٣دش
Endodermis دسٓظٝثٗذ
Cortex ثُوششر
Epidermi s ثُذششر
Root hair ز٣شثس ؽزس٤شؼ
Passage of water throuth the root’s cells
N.B. 1: Root hairs of desert plants (Xero-phytes) and those of plants living in salt marshes ( ثُٔغةض٘وؼجسHalo-phytes) are characterized by their high osmotic pressure (ranges from 50 up to 200 atmosphere) compared to the osmotic pressure of root hairs of ordinary plants (Meso-phytes) (that ranges from 5 up to 20 atmosphere ), (G.R.) to help to absorb as much water as possible from the very difficult surrounding medium. ؿ ثُؼـؾٝضشث٣ ظ٤ز ف٤ُز ػج٣صٞٔؽ أعٞز دؼـ٤ ثُِٔق٢ ثألسثػ٢ػز كٝثُٔضسٝ ز٣ٝ ثُ٘ذجصجس ثُظقشث٢ز ك٣شثس ثُؾزس٤ض ثُشؼ٤ٔصض ُضغٔـ دجٓضظجص.ٞ ع ؽ05-5 ز٣ ثُ٘ذجصجس ثُؼجد٢ ك١صٞٔ٘ٔج ثُؼـؾ ثالع٤ د.ٞ ع ؽ055-55 ز٣ٝ ثُ٘ذجصجس ثُظقشث٢ ك١صٞٔثالع .أًذش هذس ٖٓ ثُٔجء
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2: Continuous movement of water from soil to root need: Graduation of osmotic pressure. Live and active leaf. High atmospheric temperature and humidity. Q- G.R. Root hairs of desert plants and salt marshes are characterized by high osmotic pressure (50 –200 atmosphere)? A- Due to increase solute (salts and sugar) concentration in its vacuoles. To allow to absorb as much water as possible from the very difficult surrounding medium. Their osmotic pressure ranges from 50 up to 200 atmospheres, while osmotic pressure of root hairs of ordinary plants ranges from 5 up to 20 atmospheres. ػَِ ؟.....١ٞ ػـؾ ؽ055 ٢ُ إ55 ٖ٤ؿ دٝز صضشث٤ُز ػج٣صٞٔؽ أعٞز دؼـ٣ج ثُؾزسٜشثص٤ض شؼ٤ٔصض ٢٘ٔج ك٤ـز د٤تز ثُٔق٤ُضغٔـ دجٓضظجص أًذش هذس ٖٓ ثُٔجء ٖٓ ثُذٝ ز٣ج ثُؼظجسٜثصٞ كؾ٢ثألٓالؿ ) كٝ ض ثُزثةذجس ( ثُغٌش٤ًجدر صش٣ُض . ١ٞ ػـؾ ؽ05 ٢ُ إ5 ٖ٤ د١صٞٔؿ ثُؼـؾ ثألعٝضشث٣ ز٣ثُ٘ذجس ثُؼجد
Q: What happen if Normal plant cultivated in salt marshes or desert? A- It will die because : the osmotic pressure in its root hair about 5 – 20 atmosphere which is very lower than the osmotic pressure of soil solution , so it can not absorb water and salts from soil, so cannot do photosynthesis. Q- G.R. There are intercellular spaces between cells of root cortex: A- (1)- It help in passage of absorbed water through root cells, where water flows by imbibitions through cell walls and intercellular spaces. (2) Help in aeration of inner tissues of root by Gas exchange. Q- G.R. Root hair acts as osmotic apparatus: A- Because: Root hair contains large cell vacuole [formed of semi permeable (plasma membrane) wall and contains high osmotic pressure solution] that allows passage of water from outside to inside the vacuole by osmosis. because the osmotic pressure outside the root hair vacuole usually is less than inside the vacuole. Q: What happen if Desert plant (cactus ( طذجسcultivated in normal culture? A- It will grow and continue in life because it can absorb water and salts from soil, as the concentration of the vacuolar solution is more than the concentration of the soil solution. Q: What happen if Concentration of soil solution become more than root hair vacuolar solution? A- It will die because it can not absorb water and salts from soil, so cannot do photosynthesis.
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Path ways of water through root cells to xylem: - ج ثُوششر٣ج ثُٔجء ػذش خالٜ٤ٔش ك٣ ٢ثُـشم ثُض There are 3 ways by which absorbed water pass through root cells to xylem. :٢ٛ ز٤ز ثُخشذ٤ػٝ ثأل٠ُظَ إ٣ ٠ج ثُؾزس فض٣ج ثُٔجء ثُٔٔضض ػذش خالٜ٤ٔش ك٣ ؽذ عالط ؿشمٞأعذضش أدقجط ثُؼِٔجء أٗز ص 1- Through cells sap:- ز٣ثس ثُؼظجسٞن ثُلؾ٣ؿش
o By osmosis which needs a gradual fall of osmotic pressure along the root cells. ج ثُؾزس (ٓ٘قذس٣ خال٢ض ثألٓالؿ) ك٤ً ( ثٗقذثس صشٟصٞٔ ثالٗقذثس ثُٔضذسػ ُِؼـؾ ثألع٢ِؼضٔذ ثٗضوجٍ ثُٔجء ػ٣ٝ ز٣صٞٔز ثألع٤دجُخجط )١صٞٔثع 2- Through the cytoplasm :- ّدالصٞض٤ن ثُغ٣ؿش
o Where water rushes from one cell to another through plasmodesmata (Fine strands of cytoplasm that connect the protoplasm of plant cells together). .)جٜدؼؼٝ ج٣ٖ ثُخال٤ز صظَ د٤ٓدالصٞض٤ؽ عٞ٤ضٓج (ػذجسر ػٖ خ٣دٞٓؽ ثُذالصٞ٤ خالٍ خٟ أخش٠ُز إ٤ِضذكن ثُٔجء ٖٓ خ٣ ظ٤ف
Water passes through cytoplasm and cell walls
3- Through cell walls and intercellular spaces: -ج٣ٖ ثُخال٤ز د٤٘٤ثُٔغجكجس ثُذٝ ج٣ن ؽذسثٕ ثُخال٣ؿش Water passes through the cell wall and the small intercellular spaces by imbibitions. There are intercellular spaces between cells of root cortex : because: 1- It helps in passage of absorbed water through root cells, where water flows by imbibitions through cell walls and intercellular spaces. 2- Help in aeration of inner tissues of root by Gas exchange. ضذكن ثُٔجء٣ ظ٤ج ثُؾزس ف٣س ثُٔجء ثُٔٔضض ػذش خالٝ ٓش٢ٔز كٛ ُِٔغج: ثُؾزس٢ج ؿذوز ثُوششر ك٣ٖ خال٤ز) د٤٘٤ؽذ كشثؿجس (ٓغجكجس دٞ٣ .ز ُِؾذثس دضذجدٍ ثُـجصثس٤ِز ثألٗغؾز ثُذثخ٣ٜٞ ص٢ْ كٛغج٣ ًٔج، ز٤٘٤خالٍ ثُٔغجكجس ثُذٝ ج٣ ؽذسثٕ ثُخال٠ِز ثُضششح ػ٤دخجط
2 3 2
Osmoses
++++
+++
++
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+
Absorbed water pass through cortex by the 3 pathways, till the endodermis: it pass through cell saps and cytoplasm only. The role of endodermis in controlling the passage of water and salts ثُزثةذجسٝ س ثُٔجءْٝ ٓش٤ ص٘ظ٢دسٓظ كٝس ثالٗذٝد
The endodermis (the innermost row of cells of the cortex) control the passage of water and solutes inwards to xylem vessels as (G.R.): :ظ٤ز ثُخشخ ف٤ػٝ أ٠ُس ثُٔجء إٝ ٓش٢دسٓظ كٝج ثألٗذ٣صضقٌْ خال 1- The endodermal cells facing phloem:ػز ثُِقجءٞٔز ُٔؾٜثؽُٞٔدسٓظ ثٝج ثالٗذ٣خال
o Their cell walls completely thickened with suberin. So these cells prevent the passage of water inwards by imbibition which is not under the control of the cell. ج دجُضششحُٜس ثُٔجء ٖٓ خالٖٝ كال صغٔـ دٔش٣دشٞ٤ظ دٔجدر ثُغ٤ِج صجٓز ثُضـٜٕٗ ؽذسثٌٞص 2- While the endodermal cells facing xylem vessels: ز ثُخشخ٤ػٝز ألٜثؽُٞٔدسٓظ ثٝج ثالٗذ٣خال
o Called Passage cells because their cell walls thickened with suberin only as a strip called Caspian Strip that runs as a ribbon around the middle region of both the radial walls and the transverse walls. ٔش٣ ١ ثُز١ؾ ًجعذش٣ شش٠ٔغ٣ ؾ كوؾ٣ شٌَ شش٠ِٖ ػ٣دشٞ٤ٕ ٓـِـز دجُغٌٞ٣ جٛس ألٕ ؽذثسٝج ثُٔش٣ج ثعْ خال٣ ثُخالٙزٛ ٠ِـِن ػ٣ٝ ٢ثُؼشػٝ ٢ٖ ثُٔٔجع٣ ُِؾذثس٠عـٍُٞ ثُٔ٘ـوز ثًٞقضثّ ف
o So, passage of water by imbibitions is prevented because suberin is impermeable for water. But water is allowed to pass inwards only through unthickened walls which face both the root hairs and xylem vessels, through plasma membrane by osmosis and salts by active transport under the control of the protoplasm of these cells. ٜٚثؽٞ ص٢ش ٓـِظز ثُض٤ٔش ثُٔجء ُِذثخَ كوؾ خالٍ ثُؾذس ثُـ٣ ٘ٔج٤ش ٓ٘لز ُِٔجء د٤ٖ ؿ٣ذش٤س ثُٔجء دجُضششح ألٕ ثُغٝٔ٘غ ٓش٣ ُزث .ز٤ِدالصّ ثُخٞصٝـشر دش٤ٕ صقش عٌٞ٣ٝ ثُ٘وَ ثُ٘شؾٝ ز٣صٞٔز ثالع٤ دجُخجط٢ٓز ثُخشخ خالٍ ثُـشجء ثُذالص٤ػٝأٝ ز٣شثس ثُؾزس٤ثُشؼ Endodermal cell facing phloem Endodermal cell facing xylem
Phloem Xylem
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NB ٖ كوؾ٣ُِـِذز ثُٔٔضجص Caspian strip: ٟؾ ًجعذش٣شش Is a band of suberin material (impermeable waxy layer) lined the 4 sides of the radial and transverse walls of the endodermis. It is used to block the passive flow of water and solutes into the xylem (i.e. prevents water and minerals from passing between the cells), In order to get to the xylem vessels, water and minerals must pass through the cell membrane of adjacent cells (i.e. forces water to enter the endodermal cells before passing through to the xylem vessels) and in such a way regulates the amount of water getting to the xylem. Only when water concentrations inside the endodermal cell fall below that of the cortex parenchyma cells, water flow into the endodermis and on into the xylem. So the endodermis helps to increase the osmotic pressure of the xylem vessel in the root. Without the casparian strip, water and minerals would be able to enter the xylem vessels by going between cells.
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Q: What happen if Endodermis does not contain Caspian Strip? A- The endodermis can not control the passage of water and solutes from cortex to xylem vessels, so water and minerals would be able to enter the xylem vessels by going between cells by imbibitions of water, without control of the cell. This threatened the life of the plant. NB: Xylem: support the plant and transport water and salts absorbed from the root to the leafs. Phloem : transport the soluble organic foodstuffs that are formed in the leaf during photosynthesis to all the plant parts. Q G.R. The endodermis controls the passage of water and solutes to xylem vessels? A- 1- The endodermal cells facing phloem: are completely thickened with suberin. So these cells prevent the passage of water inwards by imbibition which is not under the control of the cell. 2- While the endodermal cells facing xylem vessels: Called Passage cells because their cell walls thickened with suberin only as a strip called Caspian Strip. So, passage of water by imbibitions is prevented because suberin is impermeable for water. But water is allowed to pass inwards only through unthickened walls which face both the root hairs and xylem vessels, through plasma membrane by osmosis and active transport under the control of the protoplasm of these cells. Q- G.R. Water can not pass through endodermis by imbibition? A- Due to presence of suberin in the form of a strip called Caspian Strip prevent passage of water by imbibitions. Q: What happen if Plant cell does not contain cell vacuole ? A- It will die because: (1) it can not absorb water and salts from soil, so cannot do photosynthesis. (2) It can not store important substance or harmful substance that can not get red of it.
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Salt absorption: Mechanism of salts absorption - Absorption of salts by root- Experiment to show that absorption of salts is done against conc. gradient
Mechanism of absorption of Minerals آلٍخ اهزصبص األهالذ الوعذًٍخ It depends on the following 3 phenomena:ز٤ُش ثُضجٛثٞز فغخ ثُظ٤ٗضْ ثٓضظجص ثألٓالؿ ثُٔؼذ٣ 1. Diffusion: االٗضشجس * It is the passage of ions from high concentrated medium to low concentration medium due to its continuous free motion. * Salts are present in the soil in the form of ions dissolved in water: a) Positive ions called Cations, as : (Ca++ , k+ , Na+ ). b) Negative ions called Anions as : (SO4 )-- - ( NO3)- - ( Cl)ٗجسٞ٣ ثألٝأ
َٗجس) ٓغٞ٤ٗٗجس ثُغجُذز (ثألٞ٣ثأل. ثُٔجء٢ٗجس رثةذز كٞ٣ شٌَ أ٠ِ ثُضشدز ػ٢ؽذ ثألٓالؿ كٞص َٗجس) ٓغٞ٤ؽذز (ثٌُجصُٞٔث
* These ions spread independently of each other and of water itself . .ػٖ ثُٔجءٝ ج ثُذؼغٜٗجس ٓغضوِز ػٖ دؼؼٞ٣ص٘ضشش ثأل
* Salt ions move by diffusion from soil solution through cellulose wall to inside cells by: A- Diffusion from the soil solution (high concentrated medium) and pass through the wet cellulosic walls to the cell (less concentrated medium). Because ions are present in continuous free motion. Or ز٤ِ ثُخ٠ُز ثُشؿذز إ٣صٞ٤ِ٤ص٘لز دثخَ ثُؾذسثٕ ثُغٝ )ض٤ً صش٠ِعؾ ثألػٍُٞ ثُضشدز (ثِٞٗجس دجالٗضشجس ٖٓ ٓقٞ٣ ثألٙزٛ صضقشى دؼغ ، ثُٔغضٔشرٝ ٗجس ثُقشرٞ٣ؾز فشًز ثأل٤ ٗض، )ض٤ًعؾ ثألهَ صشُٞ(ث
B- Cation exchange may take place : exchange Na+ (gets out of the cell) and is replaced by a K+ ion (enters the cell). .ٚ٘ٓ ّ دذالٞ٤صجعٕٞ ثُذٞ٣ذخَ أ٣ٝ ز٤ِّ ٖٓ ثُخٞ٣دٕٞ ثُظٞ٣خشػ أ٣ ٗجس كٔغالٞ٤قذط صذجدٍ ٌُِجص٣ هذ 2. Selective permeability:- ز٣جس٤ز ثالخض٣ثُ٘لجر
* When ions reach the semi- permeable plasma membrane, some of the ions are selected and allowed to pass inwards according to the plant’s requirement. * Other ions are not allowed to pass regardless of their size, concentrations or charges. ٘ٔج٤ د،ز صذؼج ُقجؽز ثُ٘ذجس٤ِس دثخَ ثُخٝج دجُٔشُٜ غٔـ٣ٝ ٗجس صخضجسٞ٣ ثُٔ٘لز دؼغ ثألٚ شذ٢ٓ ثُـشجء ثُذالص٠ُٗجس إٞ٣ػ٘ذٓج صظَ ثأل .ٗجسٞ٣ ثألٙزٛ شق٘زٝض أ٤ً صشٝ فؾْ أ٢ِهق رُي ػٞض٣ الٝ ، جُٜ غٔـ٣ الٟٗجس ثألخشٞ٣ثأل 3.Active transport ثُ٘وَ ثُ٘شؾ
* It is the passage of any substance through the cell membrane against the concentration gradient, by using chemical energy. *Ex: Passage of ions from the soil solution where the concentration is low to the inside of the cell where the concentration is high. Energy is needed to force these ions to move against the concentration gradient. -ٗجسٞ٣ ثألٙزٛ َضـِخ رُي ؿجهز ُ٘و٣ٝ ،ض٤ًضًث) ػذ كشم ثُضش٤ً صش٠ِج ثُ٘ذجس )ثألػ٣ خال٠ُضًث) إ٤ًٗجس ٖٓ ثُضشدز (ثألهَ صشٞ٣ثٗضوجٍ ثأل .ض٤ً ٗوَ ػذ صذسػ ثُضشٚٗأل
* The cell obtains energy from aerobic respiration (Cellular respiration) of root cells. * Plants need sugar and oxygen in its cells to produce energy (from aerobic respiration) 27
required for active transport of salts. * It increase under aerobic conditions and decrease unber anaerobic conditions. Comparison between Diffusion and active transport? Definition
Direction of ions transfer Energy Semi permeable membrane Example
Diffusion It is the movement of molecules or ions from high concentrated medium to low concentrated one, due to the continuous free motion of the molecules of the diffused substance in the medium of diffusion. From high concentrated medium to low concentrated one. Does not required energy Does not need Semi permeable membrane, as it can pass through cellulose walls. - Diffusion of salts from the soil solution (high concentrated medium) and pass through the wet cellulose walls to the cell (less concentrated medium).
Active transport It is the passage of ions through the cell membrane, from the soil solution where the concentration is low to the inside of the cell where the concentration is high. Energy is needed to force these ions to move against the concentration gradient. From low concentration medium to the high concentration one. Energy is needed to force these ions to move against the concentration gradient. Need Semi permeable membrane.
Passage of ions from the soil solution where the concentration is low to the inside of the cell where the concentration is high.
Absorption of Minerals ز٤ٗثٓضظجص ثألٓالؿ ثُٔؼذ * After salts dissolved in water of soil, its particles spread independently of each other and of water itself in the form of: a) Positive ions called Cations (as k+ ). b) Negative ions called Anions , as ( NO3)* Salt ions move by : 1- Diffusion from the soil solution ( high concentrated medium) and pass through the wet cellulose walls to the cell (less concentrated medium). Because ions are present in continuous free motion. Or 2- Cation exchange may take place: exchange Na+ (gets out of the cell) and is replaced by a K+ ion (enters the cell). 3- Selective permeability: * When ions reach the semi- permeable plasma membrane, some of the ions are selected and allowed to pass inwards according to the plant’s requirement. Other ions are not allowed to pass regardless of their size, concentrations or charges. 4- Active transport: * As salts needed by the plant although its concentration inside the plant in more than its concentration in soil so it is absorbed by active transport which the passage of any substance through the cell membrane against the concentration gradient , by using chemical energy to force these ions to move against the concentration gradient. From aerobic respiration. ) +
k ، Ca+ +( َٓغة )ٗةجسٞ٤ؽذةز ( ًجصٞٓ ٗةجسٞ٣سر أٞ طة٢ػةٖ ثُٔةجء كةٝ جٜ ص٘ضشش دهةجةن ثُةزثةذجس ٓغةضوِز ػةٖ دؼؼة: ثالٗضشجس-1 ز ثُٔذضِةز٣صِٞ٤ِص٘لز دثخَ ثُؾذسثٕ ثُغٝ ثُزثةذجس دجالٗضشجسٙزٛ صضقشىٝ ( CL- ،NO3- ( َٗجس ) ٓغٞ٤ٗٗجس عجُذز ( أٞ٣سر أٞ ط٢كٝأ
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َ ػ٘ةذٓج صظة: ةز٣جس٤ةز ثالخض٣ ثُ٘لجر-0 k+ ّٞ٤صجعةٕٞ ثُذٞة٣ةذخَ أ٣ٝ Na+ ّٞ٣دٕٞ ثُظةٞة٣خةشػ أ٣ ٕٗةجس ًةؤٞ٤قةذط صذةجدٍ ٌُِجص٣ هذ. ٝةج أٛض٤ً صشٝٗةجس أٞ٣ ثُ٘ذةجس كوةؾ دظةشف ثُ٘ظةش ػةٖ فؾةْ ثألٚقضجؽة٣ غةٔـ د٘لةجر ٓةج٣ ٚ ثُٔ٘لةز كجٗةٚ شةذ٢ ثُـشةجء ثُذالصٓة٠ٗجس إُةٞ٣ثأل ٙةةزٛ ِةضّ ؿجهةةز ؽذةجس٣ٝ ةةض٤ً صش٠ ثُ٘ذةجس ثألػِة٢ةض إُةة٤ًةز ٓةةٖ ثُضشدةز ثألهةةَ صش٤ِٗةةجس دثخةَ ثُخٞ٣ صضةشث ًْ ثأل: ثُ٘وةَ ثُ٘شةةؾ-3 جٜشةق٘ض ٕج٣سٖٝ ػةش٤ثألًغةؾٝ ( ُةزُي كةجٕ ثُغةٌش ثُـجهز ص٘ةضؼ ٓةٖ صة٘لظ أٗغةؾز ثُؾةزسٙزٛٝ ض٤ً ثالٗضشجس ػذ صذسػ ثُضش٢ِٗجس ػٞ٣ثأل )ز ثُ٘وَ ثُ٘شؾ٤ِٔ ػ٢ ك٢ُدجُضجٝ ز ثُض٘لظ٤ِٔ ػ٢ك
Plants can absorb fertilizers Potassium nitrate (Kno3), although its concentration in plant is high? * After KNO3 dissolved in water of soil, its particles spread independently of each other and of water itself in the form of: a) Positive ions called Cations (k+ ). b) Negative ions called Anions ( NO3)* Salt ions move by : 1- Simple diffusion from the soil solution (high concentrated medium) and pass through the wet cellulose walls to the cell (less concentrated medium). Because ions are present in continuous free motion. Or 2- Cation exchange may take place: exchange Na+ (gets out of the cell) and is replaced by a K+ ion (enters the cell). * When ions reach the semi- permeable plasma membrane, some of the ions are selected and allowed to pass inwards according to the plant’s requirement. Other ions are not allowed to pass regardless of their size, concentrations or charges. * As KNO3 needed by the plant although its concentration inside the plant in more than its concentration in soil so it is absorbed by active transport which the passage of any substance through the cell membrane against the concentration gradient , by using chemical energy to force these ions to move against the concentration gradient. Q- G.R. Respiratory rate may increase in root hairs during salt absorption? A- To produce more energy from aerobic respiration required for active transport of salts. Q- G.R. Movement of salts ions from soil to root cells against concentration gradient? A- Because Active transport: which is the passage of any substance through the cell membrane against the concentration gradient, by using chemical energy. * Where ions pass from the soil solution where the concentration is low to the inside of the cell where the concentration is high. Energy is needed to force these ions to move against the concentration gradient. * The cell obtains energy from aerobic respiration.
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Processes of mineral absorption from the soil by active transport. - Any fertile soil contains some clay particles carry a negative electrical charge to which the mineral ions (K+, Na+, Ca2+) attach. - This attachment effectively prevents the leaching of the mineral ions from the soil. 1. Unlike animal cell there are no potassium-sodium pumps in the cell membranes of plant cells. Rather there are proton pumps (Hydrogen pumps) which pump ( H+) outside of the cell. This creates an electro-negative charge within the cell. 2. When the root cells secrete protons into the surrounding soil water the hydrogen ions displace the mineral ions from the clay particle, freeing them into solution. 3. The mineral ions in the soil water are free to be absorbed by plasma membrane of the plant cell by two different energy demanding processes: A- Indirect processes (hydrogen pumps): 1. Plasma membrane actively pump hydrogen ions out into the soil water. This creates a membrane potential of -120 mV. 2. Hydrogen ions combine with anions such as Cl- in W or membrane carriers allow the uptake of the ion against the electrochemical gradient. 3 H+ displace cations (e.g. K+) from the clay particles so that they are free to move down an electrochemical gradient by facilitated diffusion .
B- Direct method of active mineral absorption: The cations such as K+ which are free and in solution in the soil water can be taken up actively by active transport membrane pumps.
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Q- G.R. Concentration of some ions accumulated in the algal cells is higher than the concentration of other ions? A- Because: the absorption of salts is selective according to cell requirement. Q- G. R. Plants needs sugar and oxygen to absorb salts from soil? A- Because: Plants needs sugar and oxygen in its cells to produce large energy (through aerobic respiration) required for active transport of salts. Q- G.R. Salts absorption by plants decreased in anaerobic conditions? A- Because salt absorption occurs by active transport which need energy taken from chemical energy produced from aerobic respiration? In Anaerobic conditions the chemical energy produced is very low so absorption decreased. Experiment to show that absorption of salts is done against conc. gradient ٗجس ثألٓالؿ دجُ٘وَ ثُ٘شؾٞ٣صؾجسح إعذجس ٗوَ أ
Steps: * Measure salt concentration in Nitella alga طحلت الٌٍزلالand in swamps water ثُذشىٙج٤ٓ in which it live. And draw a graph between concentration of salts ions in cells of Nitella alga طحلت الٌٍزلالand in swamps water ثُذشىٙج٤ٓ in which the alga live. .ٖ٣ض٤ًٖ ثُضش٤ د٢ٗج٤ٗشعْ سعْ دٝ ، زث ثُـقِخٛ جٜ٤ش ك٤ؼ٣ ٢ ٓجء ثُذشًز ثُض٠كٝ ضِال٤ُ٘ ؿقِخ ث٢ض ثألٓالؿ ك٤ًظ صش٤ٗو
Results: * The Concentration of different ions accumulated in the cell sap of the algal cells is more than their concentration in the swamp water. That means salts pass against concentration gradient and. This proves that the cell must use up energy to absorb these ions. ٗجسٞ٣ذٍ إٓ ثأل٣ زثٛٝ ٓجء ثُذشًز٢ج كٛض٤ًج ٖٓ صش٤ ٗغذ٠ِج ثُـقِخ أػ٣ ُخال١ِٞش ثُخ٤ ثُؼظ٢ٗجس ثُٔخضِلز ثُٔضشثًٔز كٞ٣ض ثأل٤ًصش .ٗجسٞ٣ ثألٙزٛ ز ؿجهز الٓضظجص٤ِِي ثُخٜ إٔ صغض٠غضذػ٣ ض ٓٔج٤ًز ػذ كشم ثُضش٤ِٓشس دثخَ ثُخ
* Concentration of some ions accumulated in the algal cells is higher than the concentration of other ions. That means the absorption of salts is selective according to cell requirement. ز٤ِج فغخ فجؽز ثُخ٣جس٤ٗجس صٔضض ثخضٞ٣ إٔ ثأل٠ِذٍ ػ٣ ٓٔجٟ ٖٓ ثألخش٠ِج ثُـقِخ أػ٣ خال٢ٗجس ثُٔضشثًٔز كٞ٣ض دؼغ ثأل٤ًصش
Conclusion: * Absorption of salts is an active process, required energy, supplied during respiration of root tissues.
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Q- Importance of experiments on Nitella alga? A- On measure salt concentration in Nitella alga and in swamps water in which it live, it was found that (1) The Concentration of ions in the algal cells is more than their concentration in the swamp water. Which means that salts pass against concentration gradient, and need energy? (2) Concentration of some ions in the algal cells is higher than the concentration of other ions. That means the absorption of salts is selective according to cell requirement. Experiment proves that sugar and oxygen are important for both respiration and absorption. ضال ؟٤ُ٘ ؿقِخ ث٠ِز ثُضؾجسح ػ٤ٔٛأ -:ٕؽذ أٝٝ جٜ٤ش ك٤ؼ٣ ٢ ٓجء ثُذشًز ثُض٢ج كٛض٤ًصشٝ ج ثُـقِخ٣ خال٢ض دؼغ ثألٓالؿ ك٤ًجط صش٤صْ ه ٙزٛ ِي ؿجهز الٓضظجصٜز صغض٤ِ إٔ ثُخ٠ِذٍ ػ٣ ٓجء ثُذشًز ٓٔج٢ج كٛض٤ً ٖٓ صش٢ِج ثُـقِخ أػ٣ٗجس دثخَ خالٞ٣ض ثأل٤ً(أ) صش َق ثُ٘و٣ج فغخ فجؽز ثُ٘ذجس صؼش٣جس٤ٗجس صٔضض ثخضٞ٣ إٔ ثأل٠ِذٍ ػ٣ ٓٔجٟٗجس ػٖ ثألخشٞ٣ض دؼغ ثأل٤ًجدر صش٣ٗجس (ح) صٞ٣ثأل ٖٓ ص٘لظ أٗغؾز ثُؾزس-: ٓظذس ؿجهز ثُ٘وَ ثُ٘شؾ.ز٤جة٤ٔ٤ً ج ؿجهزِٜٓض٣ ز ػ٘ذٓج٤ِ ٓجدر خالٍ ؿشجء ثُخٟ فشًز ث٠ِـِن ػ٣ : ثُ٘شؾ . ثالٓضظجص ٓؼجٝ ثُض٘لظ٢ض٤ِٔ ػ٢ٖ ك٤ثألًغؾٝ ز ثُغٌش٤ٔٛػقش أٝأٝ هذ أعذضش ثُضؾجسح طقز رُيٝ
Experiment to show that active transport need aerobic respiration (O2) Aim: Show the effect of Oxygen presence (aerobic respiration) on the absorption of sulphate ions (SO4--) ions by the Barley plant. ش٣ٗجس ثٌُذشٞ٣ش أل٤ ثٓضظجص ٗذجس ثُشؼ٠ِٖ ػ٤جح ثألًغؾ٤ش ؿ٤جٕ صؤع٤د
Steps: Supplied the Barley plant with sulphate salts containing radioactive ions S35 . ش ٓشغ٣ج ًذشٜضجس د٣ش أٓالؿ ثٌُذش٤إػـجء دجدسثس ٗذجس ثُشؼ
Plants are divided into two groups: o 1st group : the root is exposed to aerobic conditions. o 2nd group : the root is exposed to anaerobic conditions. ٢ػؼش كٝ ٟػز ثألخشٞٔثُٔؾٝ )ٖ٤ثكش ثألًغؾٞز (ص٤ثةٞٛ فٝ ظش٢ ك٠ُٝػز ثألٞٔػؼش ثُٔؾٝ ،ٖ٤ػضٞٔ ٓؾ٢ُ"هغٔش ثُذجدسثس إ )ٖ٤جح ثألًغؾ٤ز (ؿ٤ثةٞٛ ف الٝظش
The quantity of absorbed salt is estimated using Geiger counter. ؾش٤ثعـز ػذثد ؽٞز ثألٓالؿ ثُٔٔضظز د٤ًٔ ٗقذد
Draw a graph between rate of absorption of sulphate ions (SO4--) ions by the Barley plant per minute and time . .وز٤ثُضٖٓ دجُذهٝ وز٤ ده٢ٖ ٓؼذٍ ثالٓضظجص ك٤ د٢ٗج٤ٗشعْ سعْ د
Observation: o When root is exposed to aerobic conditions the quantity of ( 35S) is twice when the root is exposed to anaerobic condition. o Absorption of sulfate ions ( 35S) is less in the case of anaerobic conditions. طٝ فذ٠َِ ػ٤ُزث دٛٝ ٢ثةٞٛ فجُز ثُض٘لظ ثُال٢ز ثُٔٔضظز ك٤ٌُٔ أًذش ٖٓ ث٢ثةُٜٞ فجُز ثُض٘لظ ث٢ ثألٓالؿ كٙزٛ ٖٓ ز ثُٔٔضظز٤ٌُٔث ثُ٘وَ ثُ٘شؾ
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Conclusion: o Occurrence of aerobic respiration is essential for active transport of ions (absorption of salts) using energy from aerobic respiration. .٢ثةُٜٞج ثُض٘لظ ثٛكشٞ٣ ضـِخ ؿجهز٣ ١ٗجس ثُزٞ٣ط ثُ٘وَ ثُ٘شؾ ُألٝ ُقذ١سٝ ػش٢ثةُٜٞط ثُض٘لظ ثٝفذ
o Salt ions accumulate in the plant cells due to energy that is released during aerobic respiration. o Since the process of aerobic respiration ٢ثةٞةُٜ ثُضة٘لظ ثrequire ضـِةخ٣ the presence of sugar and Oxygen to produce energy , both of them are essential for absorption of salts by the plant ٢ثةُٜٞثعـز ثُـجهز ثُٔ٘ـِوز خالٍ ثُض٘لظ ثٞج ثُ٘ذجس د٣ خال٢ٗجس ثألٓالؿ صضشثًْ كٞ٣أ
Q- Importance of experiments on Barley plant? A- Show the effect of Oxygen presence (aerobic respiration) on the absorption of sulphate ions (SO4--) ions by the Barley plant………. ش ؟٤ز صؾشدز ٗذجس ثُشؼ٤ٔٛث جٜدٝ ضجس٣ش أٓالؿ ثٌُذش٤ش ُ٘ذجس ثُشؼ٤ أػـ-1 ضجس٣ٗجس ثٌُذشٞ٣ش ال٤ ثٓضظجص ٗذجس ثُشؼ٠ِٖ ػ٤ش ثُقشٓجٕ ٖٓ ثألًغؾ٤جٕ صؤع٤ُذ ز٤ثةُٜٞ شث٤ف ؿٝز عْ ُِظش٤ثةُٜٞف ثٝ فجُز صؼشع ثُؾزس ُِظش٢ؾش ك٤ثعـز ػذثد ؽٞز ثُٔٔضظز د٤ٌُٔ هذسس ث-0 S35 ش ٓشغ٣ًذش ٕ رُي كج٠ِػٝ ط ثُ٘وَ ثُ٘شؾٝط ثُض٘لظ ُقذٝسر فذٝ ػش٠ُش إ٤ش٣ ز ٓٔج٤ثةٞٛف ثُالٝ ثُظش٢ـ ثالٓضظجص هَ ك:ٕؽذ أٝ هذٝ ٢ثةُٜٞالى ثُـجهز ثُٔ٘ـِوز ٖٓ ثُض٘لظ ثٜثعـز ثعضٞج ثُ٘ذجس د٣ خال٢ٗجس ثألٓالؿ صضشثًْ كٞ٣ث
Comparison between Photosynthesis and cellular respiration?
Products Type of Reactions
Photosynthesis Chloroplast CO2 + water+ chlorophyll + light + some salts as nitrate, magnesium, iron, and phosphorus Carbohydrates + O2 Light and dark reactions
Coenzymes needed
NADP
Site of occurrence Raw materials required
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cellular respiration Mitochondria Glucose + O2
CO2 + water + energy released Aerobic respiration (splitting + Crab’s cycle + electron transfer chain) NAD + FAD + Cytochrome.
( 2 ) Photosynthesis in green plants الجٌبء الضىئً فً الٌجبربد الخضشاء Importance of photosynthesis- Raw materials for photosynthesis - The products of photosynthesis- The rate of photosynthesis - Where does photosynthesis take place- Structure of chloroplasts in higher plants - Leaf structure and its Adaptation to photosynthesis - The Mechanism of photosynthesis - Melvin Calvin Experiment
Importance of photosynthesis: Photosynthesis is the most important chemical process to all living organisms, as it produces chemical energy stored in food required to live, grow and reproduce: Photosynthesis is the most important chemical process to Man, as it produces: 6 فجؽجس : ص٘ضؼ٢ٜز دجُ٘غذز ُإلٗغجٕ ك٤جة٤ٔ٤ٌُجس ث٤ِْٔ ثُؼٛ ٖٓ أ٢ةٞز ثُذ٘جء ثُؼ٤ِٔصؼضذش ػ
1) Man's food such as carbohydrates, proteins, fats and vitamins: 2) O2 : Oxygen which is 21% of volume of the atmospheric air that surrounds Earth is a product of photosynthesis process, that accumulates during the past ages. ز٤س ثُٔجػٞثُؼظ 3) Industrial products based on direct products for photosynthesis, as Plants and animals fibers for textile ؼ٤ ثُ٘غfibrils, wood, and paper: Man's economic life ز٣ ث ٗغةجٕ ثالهضظةجدٙج٤ فdepends on photosynthesis, as it produces plant and animal fibers ةز٤ٗثٞ٤ثُقٝ ةز٤ةجف ثُ٘ذجص٤ُ ثألthat are used as textile fabrics طة٘جػز ثألٗغةؾزas well as wood, and paper. 4) Industrial products based on indirect products for photosynthesis as fats, alcohol, vinegar, are indirect products for photosynthesis after various chemical changes done on final or intermediate product of photosynthesis. ٠ِ ػٟز ٓخضِلز صؾش٤جة٤ٔ٤ً شثس٤ دؼذ صـ٢ةٞز ثُذ٘جء ثُؼ٤ِٔ إال ٗضجػ ُؼ٢ٛ ج ٓجٛش٤ؿٝ َثُخٝ ٍٞثٌُقٝ ٕٞٛز ًجُذ٤ثُٔ٘ضؾجس ثُظ٘جػ .ز٤ِٔ ثُؼٙزُٜ ز٤جةُٜ٘ ثٝـز أ٤عُٞثد ثُٞٔث
5) Source of chemical energy stored in food : Living organisms require energy in order to grow, reproduce, and survive. They obtain their energy requirements from the chemical energy stored in food that has been originally produced in plant during the process of photosynthesis. 6) Source of fuels ١ٞد ثُؼؼةٞهةُٞ ٓظةذس ثsuch as cool, petroleum and natural gas which from plants which stored solar energy: Fuels of engines الس٥ ثand means of transport ثطةالسُٞٔعةجةَ ثٝٝ as coal, petroleum, and natural gas have originated from plants that stored the solar energy inside their tissues as fuels while they were performing photosynthesis in the ancient geological ages. سٞ ثُؼظة٢ك ٔز٣ز ثُوذ٤ؽُٞٞ٤ثُؾ
So life is a photochemical phenomena : as solar energy is absorbed and transformed into chemical energy in green plants during photosynthesis which produce food, oxygen, fuel...etc Photosynthesis is main life principal ز٤ ثألعجعةٙةج٤ هجػةذر ثُق:Without photosynthesis, life would have come to an end. It produce food and energy and liberate O2 to maintain life on the earth. ز٤ِٔ ثُ٘ذجصجس ثُخؼشثء أع٘جء ػ٢ز ك٤جة٤ٔ٤ً ؿجهز٢ُج إِٜ٣ٞصقٝ ز٤ةٞضْ ثٓضظجص ثُـجهز ثُؼ٣ ظ٤ف: ز٤جة٤ٔ٤ً ءٞشر ػٛجر ظج٤ُزث كجُق
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. عــ ثألسع٠ِجر ػ٤ج ُٔج ثعضٔشس ثُقٛالِٖٞ ك٤ضقشس ثألًغؾ٣ٝ ٘ضؼ ثُـزثء٤ ك٢ةٞثُذ٘جء ثُؼ
Q- G.R. Life is a photochemical phenomenon? A- Because solar energy is absorbed and transformed into chemical energy stored in glucose formed in green plants during photosynthesis which produce food, oxygen, fuel...etc. Without photosynthesis, life would have come to an end. ٢ةٞز ثُذ٘جء ثُؼ٤ِٔثد ثُخجّ ثُالصٓز ُؼُٞٔث
Raw materials for photosynthesis
1. Water: is the only source of Hydrogen needed by green plants to reduce Carbon dioxide, which is the first step in the production of carbohydrates. ٢ر كٍٞ خـٝ أ٠ٛٝ ٕٞذ ثٌُشد٤ أًغ٢ٖٗ ثُالصّ الخضضثٍ ؿجص عج٤ؽٝذس٤ُٜ ث٠ِذ ُِ٘ذجصجس ثُخؼشثء ُضقظَ ػ٤فُٞ ثُٔظذس ثٞٛ : ثُٔجء .ذسثس٤ٛٞد٘جء ثٌُشد
2. Carbon dioxide: is the only source from which green plants obtain Carbon (the essential element in carbohydrates). )ذسثس٤ٛٞ ثٌُشد٢ ك٢ٕ (ثُؼ٘ظش ثألعجعٞج ثُ٘ذجس ثٌُشدٜ٘ٓ غضٔذ٣ ٢ذر ثُض٤فُٞسر ثٞ ثُظٞٛ ٕٞذ ثٌُشد٤ ًغٝ أ٢ٗعج
3. Mineral salts: a. Nitrates, Phosphates, and sulfates: Are required to convert carbohydrates into proteins. .ٖ٤صٝ دش٢ُذسثس إ٤َٛٞ ثٌُشد٣ٞدز ُضقِٞش ٓـ٣ثٌُذشٝ علجسٞثُلٝ ٘ضشثس٤ُث
b. Phosphorus: is an important element in the structure of compounds that carry energy during photosynthesis (ATP) (Adenine Tri-Phosphate). .٢ةٞز ثُذ٘جء ثُؼ٤ِٔ( أع٘جء ػATP) خ ثُٔشًذجس ثُ٘جهِز ُِـجهز٤ً صش٢ذخَ ك٣ ْٜٓ س ػ٘ظشٞعلٞثُل
a. Magnesium: is an important element in the synthesis of chlorophyll. َ٤كٝسٌُِٞخ ؽضا ث٤ً صش٢ذخَ ك٣ ّٞ٤غ٤٘ثُٔـ
d. Iron: is an important element in building up of some enzymes that help to complete photosynthesis. ..٢ةٞز ثُذ٘جء ثُؼ٤ِٔٔجس ثُٔغجػذر ألصٔجّ ػ٣ د٘جء ث ٗض٢ذخَ ك٣ ذ٣ثُقذ
4- Solar energy: Sun is the source of energy required for photosynthesis. ٢ةٞثصؼ ثُذ٘جء ثُؼٞٗ
The products of photosynthesis
1. The main product ٢غ٤ ثُ٘جصؼ ثُشةof Photosynthesis is a mono-saccharide صنش أحبدي الزضنش. This sugar can be used in: a. Building up of proteins needed for growth. ُِٞٔ٘ جس ثُالصٓز٤٘٤صٝ ثُذشٚ٘ٓ ٠٘ذ٣ b. Oxidized (broken down) during the respiration process to produce energy. ز ثُض٘لظ ألٗضجػ ثُـجهز٤ِٔ ػ٢ذّ كٜ٣
c. Transformed into starch ٗشجin order to be stored ٖ٣ ٗشج ُِضخض٠ٍُ إٞق٣. 2. The bi-product (second product) ١ٞٗ ٗجصؼ عجof Photosynthesis is Oxygen. Q- G.R. Roots of beet ثُذ٘ؾشplant become small, if present in bad aerated medium? A- Because: Bad aerated medium leads to decrease O2 required for aerobic respiration which produce high energy required for active transport of salts used by plants in photosynthesis which produce carbohydrates stored in beet roots, so decrease O 2 causes decrease active transport , decrease photosynthesis , and decrease size of roots. 35
ز ثُ٘وَ ثُ٘شؾ٤ِٔ ػ٢جً ٖٓ ثُـجهز صغضخذّ ك٤ُ٘ضؼ ٓوذثس ػج٣ ١ثُزٝ ٢ثةُٜٖٞ ثُالصّ ُِض٘لظ ث٤ج ٗغذز ثألًغؾٜ٤وَ ك٣ ز٣ٜٞتز ثُض٣تز سد٤ألٕ ثُذ ٕ كج٢ُدجُضجٝ س ٗذجس ثُذ٘ؾشٝ ؽز٢ صخضٕ ك٢ز ثُض٣ثد ثُغٌشُٞٔج ثٜ٘٘ضؼ ػ٣ٝ ٢ةٞ ثُذ٘جء ثُؼ٢ج ثُ٘ذجس كٜٓغضخذ٣ ٢ز ثُض٤ُٗألٓالؿ ثُٔؼذ .سٝوَ فؾْ ثُؾز٤ ك٢ةٞوَ ثُذ٘جء ثُؼ٤غذخ ٗوض ثُ٘وَ ثُ٘شؾ ك٣ ٖ٤ٗوض ثألًغؾ
The rate of photosynthesis ٢ةٞٓؼذٍ ثُذ٘جء ثُؼ Rate of Photosynthesis depends on: 1- CO2 2- Water, light, and temperature Rate of Photosynthesis can be determined by: 1. Estimating فغةجحthe amount of carbohydrates formed in unit time in unit surface area of leaf: Under good conditions of illumination, the rate of Photosynthesis would be 1 gm of carbohydrates in an hour per each meter square of the leaf surface area (i.e. 1gm/hr/m2) 2. Counting the number of Oxygen bubbles evolved in the unit time. Or 3. Measuring the volume of Oxygen gas formed in the unit time. Where does photosynthesis take place?
٢ةٞز ثُذ٘جء ثُؼ٤ِٖٔ صقذط ػ٣أ
It occurs in green parts of plants, as: َ ثألؽضثء ثُخؼشثء ٖٓ ثُ٘ذجس ٓغ٢قذط ك٣ 1. Green leaves: is the main sites for Photosynthesis (G.R.) as they contain chloroplasts (in which dark and light reactions occurs) in their cells in higher plants. .ز٤ ثُ٘ذجصجس ثُشثه٢ذثس ثُخؼشثء ك٤ ثُذالعض٠ِ ػٟٞج صقضٜٗ أل٢ةٞز ثُذ٘جء ثُؼ٤ِٔز ُؼ٤ صؼضذش ثألٓجًٖ ثألعجع: سثم ثُخؼشثءٝثأل
2. Green Herbaceous stems: Take part in Photosynthesis, as they contain chlorenchymatous tissues contain chloroplasts in their cells. ذثس ثُخؼشثء٤ج ثُذالعضٜز د٤ٔ٤سشًِٞ أٗغؾز٢ِج ػٜثةٞ الفض٢ةٞ ثُذ٘جء ثُؼ٢ْ دوذس كٛ صغج: ز ثُخؼشثء٤وجٕ ثُؼشذ٤ثُغ
Chloroplast
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Structure of chloroplasts in higher plants.
رشمٍت الجالصزٍذح الخضشاء فً الٌجبربد الشاقٍخ
1) Under light microscope: Chloroplast appears as homogeneous mass having the shape of a convex lens. شٌَ ػذعز ٓقذدز٢ِذثس ثُخؼشثء ًٌضَ ٓضؾجٗغز ػ٤ش ثُذالعضٜ صظ٢ةٞح ثُؼٌٞعٌٝش٤ُٔصقش ث
2) Under electron microscope it is formed of 6 parts: 1- Outer double membrane: ٢ػ خجسؽٝ ؿشجء ٓضدthat enclosed the chloroplast ذر٤ـِق ثُذالعض٣, thin (about 10 nanometer thick) ٓضشٞٗ ٗج15 ٢ُثٞن ف٤ سه. 2- Matrix or Stroma: )ٓجٝ ثألعةضشٝذر (ثُ٘خةجع أ٤ز ثُذالعةض٤ أسػةwhich is a colorless proteinic substance, inside the chloroplast. ُِٕٞٔز ث٣ز ػذ٤٘٤صٝصضشًخ ٖٓ ٓجدر دش. 3- Grana : أهشثص ثُؾشثٗجٝذجس أ٤فذ o Granules embedded in the stroma of chloroplast ثُ٘خجع٢عز كٞٔٓـ. o Discoid shape and arranged as clusters دٞ ػوةalong the body of plastid and linked together by thin membrane (grana lamellae). ذر٤د صٔضذ دثخَ ؽغْ ثُذالعضٞ ػو٢ ص٘ظْ ك٠ٛٝ o Each granum ذةز٤ فذis 0.5 micron in diameter and 0.7 micron thick, ٢ُثٞذةز فة٤ذِةؾ هـةش ثُقذ٣ 5 ٕٝ ٓذٌةش.ٝ7 ٢ُثٞج فةٌٜٔعةٝ ٕٝ ٓذٌةش.ٝ5 , formed of a pile ٓةزًٞ of 15 or more discs هةشصarranged over each other. o Each disc قرشص, is hollow from the inside, while its margin extends outside the granum to meat the margin of another disc in a neighboring granum . This structure increase the exposed surface area of the disc greatly, which carrying the pigments that absorb light energy (chlorophyll) . o Function of grana :Light reactions take place in grana. carrying the pigments that absorb light energy (chlorophyll) ٢ُثٞج فٌٜٔعٝ ٕٝ ٓذٌش.ٝ5 ٢ُثٞذز ف٤ذِؾ هـش ثُقذ٣ .ن٤ثعـز ؿشجء سهٞج ثُذؼغ دٜٓشصذـز ٓغ دؼؼٝ دٞ ػو٢ٓز كٞٓ٘ظٝ ثُ٘خجع٢عز كٞٔذجس ٓـ٤ؽذ ثُقذٞص ثف هشصٞ دق٢ذز ُضِضو٤د ثُقذٝ خجسػ فذٚثكٞصٔضذ فٝ َف ٖٓ ثُذثخٞ ًَ هشص ٓؾ. جٜم دؼؼٞ أًغش ٓضشثطز كٝ هشص أ15 ٢ُثٕٞ ٖٓ فٌٞصضٝ ٕٝ ٓذٌش.ٝ7 .ءٞ صٔضض ثُؼ٢ صخضض دقَٔ ثألطذجؽ ثُض٢ ثُض٠ٛٝ جدر ٓغجفز عــ ثألهشثص ثُٔؼشػز٣ ص٠ِسر كضؼَٔ دزُي ػٝذز ٓؾج٤ فذ٢آخش ك
Q- G.R. Margin of granum discs extends outside the granum? A- Disc margin extends outside the granum to meat the margin of another disc in a neighboring granum to increase the exposed surface area of the disc greatly, which carrying the pigments that absorb light energy . Q: What happen if Grana disappears from chloroplast? A- Grana carrying the chlorophyll that absorb light energy and in which light reactions take place. So when disappeared plant can not do light reaction, so ATP & NADPH2 not formed , so dark reactions also stopped, so plant die. 4- Starch granules : ذجس ثُ٘شج٤فذ o Starch grains are produced inside the chloroplast by large number. o They are the temporary product of photosynthesis, they will soon change back to soluble sugar . o They are small in size because they are change to soluble sugar to be transport to other organs of the plant under certain circumstance. ٢ كٟج أخش٣ خال٢ُ إِٚضْ ٗو٣ٝ عٌش٠ُج صضقَِ إٜٗشر ثُقؾْ أل٤ٕ طـٌٞصٝ شر٤ذر ثُخؼشثء دؤػذثد ًذ٤ذجس ثُ٘شج دثخَ ثُذالعض٤ٕ فذٌٞص . ٘ز٤ف ٓؼٝثُ٘ذجس صقش ظش
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Q- G.R. Starch grains inside the chloroplast are small in size and produced in large number ? A- They are small in size because they are change to soluble sugar to be transport to other organs of the plant under certain circumstance. Q- G.R. Starch granules in stroma of chloroplast is small? A- They are small in size because they are hydrolyzed to soluble sugar to be transport to other organs of the plant under certain circumstance. 5- DNA:
6- The chloroplast contains 4 main pigments; as in the following table: The pigment Chlorophyll A Chlorophyll B Xanthophylls Carotene
Formula C55H72O5N4Mg
The color Blue green Yellow green Lemon yellow Orange yellow
The percentage About 70% 25% 5%
o As Chlorophyll A and B which has a green colour represent about 70%, while Xanthophylls and Carotene which has a yellow colour represent about 30% , so Green color is the dominates colors of other pigments in the plastid. ذر٤ ثُذالعض٢ كٟثٕ ثألطذجؽ ثألخشُٞ أ٠ِٕ ثألخؼش ػُِٞـِخ ث٣ ُزث
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o Chlorophyll is conceder with خةضض٣ absorption of light energy required for plants to carry out photosynthesis. o The structure of chlorophyll molecule: The structure of the chlorophyll molecule is complex ٓؼوذ. The molecular formula of chlorophyll – A is : C55H72O5N4Mg. The Magnesium atom occupies the centre of the molecule. There is a relationship between the presence of Mg in the chlorophyll and the ability of chlorophyll to absorb light. Q- G.R. Chloroplast appears green instead of its content of yellow pigments? A- The chloroplast contains 4 main pigments, as in the following table: As Chlorophyll A and B which has a green colour represent 70%, while Xanthophylls and Carotene which has a yellow colour represent 30% , so Green color is the dominates colors of other pigments in the plastid. Q: What happen if the stored energy in chlorophyll is released? A- The electrons of its atoms fall once more to the lower energy levels. So, the chlorophyll will returns to the stable state, ready to receive another influx صذكنof light, to become excited once more. Leaf structure and its Adaptation to photosynthesis: - ًرشمٍت الىسقخ وهالئوزهب للجٌبء الضىئ The structure of the plant leaf: رشمٍت وسقخ الٌجبد Examination of transverse section of leaf of dicotyledonous plant passing through the midrib, show that the leaf is composed of three main tissues: :٢ٛ ز٤سهز صضشًخ ٖٓ عالط أٗغؾز أعجعُٞ ٗؾذ إٔ ث٠عـُٞٔش دجُؼشم ث٣ ٖ٤ثس ثُلِوضٝسهز ٗذجس ٖٓ رُٞ إرث كقظ٘ج ٓوـؼج ٓغضؼشػج
Structure of the leaf
Upper and lower epidermis
Mesophyll
Vascular tissue
Palisade layer
Xylem
Spongy layer
Phloe m
1. The upper and the lower epidermis: ٢ِثُغلٝ ج٤ِثُذششصجٕ ثُؼ Each of them consists of one row of parenchyma cells: adjacent, barrel- shaped , with no chlorophyll . Stomata سٞ( ثُغـةsmall tiny opening وز٤ ػةٙش٤ح طةلٞ )عوةspread in the lower epidermis more than the upper epidermis . The external wall of epidermis (except stomata) is covered with cutin to reduce water lass.
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٠ٛٝ سٞج ثُغـِِٜ صضخ،)َ٤كٝسٌُِٞز ٖٓ ث٤ُ خج- ٓضالطوز- ٌَز ثُش٤ِٓ (دش: ز٤ٔ٤ج ثُذجسثٗش٣ثفذ ٖٓ ثُخالٝ ٕ ًَ دششر ٖٓ طقٌٞصض (سٖٞ (ػذث ثُغـ٤صٞ٤ٌُج ٓــجر دـذوز ٖٓ ثُٜ ٢ثُؾذثس ثُخجسؽٝ ،ج٤ِ أًغش ٖٓ ثُؼ٢ِ ثُذششر ثُغل٢وز ص٘ضشش ك٤شر ػ٤ح طـٞعو Stoma: لألرمٍبء فقط
o Situated on the underside of the leaf to decrease water loss, as in light stomata open and would thus lose much water and the plant dying. o Surrounded by guard cells ج فجسعز٣ خال: In light the guard cells : causing the pore to be widest, to allow CO2 diffuses into the leaf to be used in photosynthesis. In the dark the stomata are closed and no photosynthesis takes place. o Opening of the stomata allows CO2 to diffuse into the leaf, and water vapor to diffuse out of the leaf (By diffusion). 2. The mesophyll tissue: الٌضٍح الوزىصط Lie between the upper and the lower epidermis and it is transversed by veins. It consists of two main layers:ٖ٤ٕ ٖٓ ؿذوضٌٞض٣ٝ مٝ ثُؼشٚصخضشهٝ ٢ِثُغلٝ ج٤ِٖ ثُؼ٤ٖ ثُذششص٤وغ د٣ a. The Palisade layer:الطجقخ العوبدٌخ It lies below the upper epidermis. It consists of one row of parenchymatous cells which is : cylindrical, elongated , arranged in a columnar form, perpendicular to leaf surface, and contains many chloroplasts (that are arranged at the upper parts of these cells to receive as much sunrays as possible, and can move freely upper and low according to the light intensity) With intercellular spaces between them for gas exchange . CO2 and O2 pass to and from the leaf cells by diffusion. Water vapor transport from high concentration zone to low concentration zone in leaf mesophyll , (by diffusion). ز٤٘ؿٝ ج٤ِ عــ ثُذششر ثُؼ٠ِز ػ٣دِٞٔز ثُشٌَ ػ٤ز ٓغضـ٤ٔ٤ج ثُذجسثٗش٣ثفذ ٖٓ ثُخالٝ ٕ ٖٓ طقٌٞ صض- ج٤ِصوغ أعلَ ثُذششر ثُؼ .ز٤ةٞج ُضغضوذَ أًذش هذس ٖٓ ثألشؼز ثُؼ٣ ٖٓ ثُخال١ِٞ ثُؾضء ثُؼ٢ج كٜ صشصخ ٗلغ٢ثُض.ذثس ثُخؼشثء٤دجُذالعض b. The spongy layer:ز٤ثُـذوز ث عل٘ؾ
It lies below the palisade layer. Consists of parenchymal cells which are: irregularly - shaped, loosely- arranged , contain less number of chloroplasts than the palisade cells. with large intercellular spaces between them for gas exchange ذثس٤ ٗغذز أهَ ٖٓ ثُذالعض٠ِ ػ١ٞ صقض- ٓلٌٌز-ٌَش ٓ٘ضظٔز ثُش٤ز ؿ٤ٔ٤ج دجسثٗش٣ٕ ٖٓ خالٌٞز – صض٣ؽذ أعق ثُـذوز ثُؼٔجدٞص .ثعؼز ُضذجدٍ ثُـجصثسٝ ز٤٘٤ج ٓغجكجس دِٜ صلظ-ثُخؼشثء 3. The vascular tissue: ٢ػجةُٞؼ ث٤ثُ٘غ
It consist of many vascular bundles which extend through mid rib , veins and venules. - وجس٣ثُؼشٝ مٝذر ٓٔضذر دثخَ ثُؼش٣ز ػذ٤ػجةٝ ّٕ ٖٓ فضٌٞض٣ The mid rib of the leaf contains the main vascular bundle of the leaf , while veins and venules contain many smaller secondary vascular bundles. ٙش٤ز ثُظل٣ٞٗز ثُغج٤ػجةُٞذ ٖٓ ثُقضّ ث٣ ثُؼذٟٞوجس صقض٣ثُؼشٝ مٝ٘ٔج ثُؼش٤ز د٤غ٤ز ثُشة٤ػجةُٞ ثُقضٓز ث٠ِ ػ٢عـُٞ ثُؼشم ثٟٞقض٣
Inside the vascular bundle there are: 1- Xylem vessels: Towards the upper surface of the leaf , arranged in several vertical rows , separated from each other by xylem parenchyma cells (thin – walled cells).It transmit water and salts from root to leafs ٖٓ ثألٓالؿٝ ّ د٘وَ ثُٔجءٞو٣ٝ ْ ثُخشخ٤ج دجسثٗش٣ج خالِٜز صلظ٤ف سأعٞ ػذر طل٢ز ثُخشخ ٓشصذز ك٤ػٝؽذ أٞز ص٤ػجةُٞدثخَ ثُقضٓز ث سثمٝ ثأل٠ُثُؾزس إ
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2- The phloem ثُِقةةجء: Next to xylem, towards the lower epidermis of the leaf, it translocates the soluble organic foodstuffs that are formed in the mesophyll to all the plant parts. . أؽضثء ثُ٘ذجس٠ُعؾ إٞؼ ثُٔض٤ ثُ٘غ٢ٗش كٌٞ ص٢ز ثُزثةذز ثُض٣ٞز ثُؼؼ٤ثد ثُـزثةَُٞٔ ث٤طّٞ دضٞو٣ ٞٛٝ سهز ثُِقجءُِٞ ٢ِز ثُغــ ثُغلٜ ثُخشخ ؽ٢ِ٣
The vascular tissue is surrounded by large parenchyma cells, (which help to support the leaf by their turgidity) and collenchyma cells (consists of living cells with additional cellulose thickening in their walls, providing support and protection for young leaves.)
T . S in the leaf in dicotyledonous plant 41
Adaptation of leaf to photosynthesis : ٢ةٞسثم ُِذ٘جء ثُؼٝصالةْ ثأل A- External shape: 1-Leaves are arranged on the stem and branches of the plant in a way which expose them to largest amount of sunlight. .ج ألًذش هذس ٖٓ أشؼز ثُشٔظٜوز صؼشػ٣ع ثُ٘ذجس دـشٝكشٝ ثُغجم٠ِصػز ػٞٓ سثمٝثأل
2-Leaf blade is the thin and flattened to increase surface area to receive as much light as possible. .ءٞء العضوذجٍ أًذش هذس ٖٓ ثُؼٞجدر ٓغجفز ثُغــ ثُٔؼشع ُِؼ٣ٓلِــ ُضٝ ن٤سثم دهٝٗظَ ثأل
3-The leaf blade is supported by midrib ٠عـٝ ػشمwhich branched into lateral veins and venules forming a network that spreads all over the leaf blade , to supply the leaf with water and salts absorbed form root and helps to transport food from leaf to other parts of the plant. The midrib contains xylem (transfer water and salts) and phloem (transfer food) ثألٓالؿٝ سهز دجُٔجءُٞذ ث٣ٝٗج شذٌز صضخَِ ثُ٘ظَ ُضضٌٞٓ أكشع أطـش كؤطـش٢ُضلشع أ٣ ١ ثُز٢عـُٞسهز ٓذػْ دجُؼشم ثُٞٗظَ ث ٢عـُٞ ثُؼشم ث١ٞقض٣ ظ٤غ أؽضثء ثُ٘ذجس ف٤ٔ ؽ٠ُسهز إُٞج ثٛضٜ صؾ٢ز ثُـجهز ثُض٤ُز ػج٤ثد ثُـزثةُٞٔٗوَ ثٝ ن ثُؾزس٣ثُٔٔضظز ػٖ ؿش .)ثُِقجء (ُ٘وَ ثُـزثءٝ )ثألٓالؿٝ ز خشخ (ُ٘وَ ثُٔجء٤ػٝ أ٢ِػ
4- The plant leafs control the rate of water evaporation from the plant, by the following: Both the upper and lower surfaces of the leaf are covered with a layer of cutin, except for stomata, to decreases water loss by evaporation. .ن ثُذخش٣د ػٖ ؿشَٞ ثُٔجء ثُٔلو٤ِس) ُضوٖٞ (ػذث ثُغـ٤صٞ٤ٌُ دـذوز ٖٓ ث٠ ٓــ٢ِثُغلٝ ١ِٞعــ ثُشهز ثُؼ
Stomata (narrow tiny pores) which are the main sites for gas exchange, between the atmosphere and the interior of the leaf present mainly on the lower leaf surface. . سهزُِٞ ٢ِ ثُغــ ثُغل٠ِسهز أعجعج ػُٞدثخَ ثٝ ٟٞثء ثُؾُٜٖٞ ث٤ ُضذجدٍ ثُـجصثس د٢غ٤ ثٌُٔجٕ ثُشة٠ٛٝ سٞؽذ ثُغـٞص
Stomata often open in the light and close in the dark. Opening of stomata is affected also by the degree of humidity in air. .دزٞصضؤعش دذسؽز ثُشؿٝ - ّ ثُظال٢صـِن كٝ ءٞ ثُؼ٢س كٞصلضـ ثُغـ
Blade
Midrib
Veins
B- Leaf structure: Epidermis: consists of one row of parenchyma cells: adjacent, barrel- shaped, covered with cutin, with no chlorophyll, contains Stomata which control gas exchange and water evaporation. / سٞج ثُغـٜدٝ / ذثس خؼشثء٤ج دالعضٜظ د٤ُ / ٖ٤صٌُٞ ٓــجر دج/ ٚ٤ٔ٤ دجسٗشٚ٤ِ٤ٓج دش٣ثفذ ٖٓ خالٝ طق: ثُ٘ذجسٚسهٝ ٙدشش صذجدٍ ثُـجصثسٚ٤ِٔػٝ ثُضذخشٚ٤ًٔ ٢ُضضقٌْ ك
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The Palisade layer: contains many chloroplasts ……………. The spongy layer:…… The vascular tissue………. Q- G.R. Most of plant leaf appears green? A- Because it contains green plastids which contains Chlorophyll A and B which has a green colour represent 70% of pigments , while Xanthophylls and Carotene which has a yellow colour represent 30% , so Green color is the dominates colors of other pigments in the plastid. Q- G.R. Green leaves represent a carbohydrate factory? A- Because their cells contain chloroplasts (in which all dark and light reaction of photosynthesis occurs) which produce glucose that transformed to starch, fat or proteins. Q- G.R. Green leaves represent a carbohydrate factory? A- Because their cells contain chloroplasts (in which all dark and light reaction of photosynthesis occurs) which produce glucose that transformed to starch, fat or proteins. Q- G.R. Leaf is adapted for photosynthesis? 1-Leaves are arranged on the stem and branches of the plant in a way which expose them to largest amount of sunlight. 2-Leaf blade is the thin and flattened to increase surface area to receive as much light as possible. 3-The leaf blade is supported by midrib ٠عـٝ ػشمwhich branched into lateral veins and venules forming a network that spreads all over the leaf blade , to supply the leaf with water and salts absorbed form root and helps to transport food from leaf to other parts of the plant. The midrib contains xylem (transfer water and salts) and phloem (transfer food) 4- Leaves control the rate of water evaporation from the plant by the following: Both the upper and lower surfaces of the leaf are covered with a layer of cutin, except for stomata, to decreases water loss by evaporation. Stomata (narrow tiny pores) which are the main sites for gas exchange, between the atmosphere and the interior of the leaf present mainly on the lower leaf surface. Stomata often open in the light and close in the dark. Opening of stomata is affected also by the degree of humidity in air. Q- G.R. The Palisade layer of leaf adapted for photosynthesis? A Because: It consists of one row of parenchymatous cells which is : cylindrical, elongated , arranged in a columnar form, perpendicular to leaf surface, and contains many chloroplasts that are arranged at the upper parts of these cells to receive as much sunrays as possible. They can move freely upper and low according to the light intensity. With intercellular spaces between them for gas exchange. Q- G.R. The spongy layer of leaf adapted for photosynthesis? A- Because: It lies below the palisade layer. Consists of parenchymal cells which are: irregularly - shaped, loosely- arranged, contain less number of chloroplasts than the palisade cells. 43
With large intercellular spaces between them for gas exchange Q- G.R. The upper surface of the leaf is more greener than the lower surface? A- Because the upper surface is near to the palisade layer which contains large number of chloroplasts, while the lower surface is near the spongy layer which contain less number of chloroplasts than the palisade cells. Q- G.R. The upper surface of the leaf is greener in early morning than midday? A- Because: In the early morning : Chloroplasts move up in the palisade layer to absorb as mush light as possible so the upper surface appears more greener , while In the midday : Chloroplasts move down in the palisade layer to escape from intense light so the upper surface appears less greener. Q- G.R. Both the upper and lower surface of the leaf may be of the same degree of green colour ? ٕ ثألخؼشُِٞ دسؽز ث٢سهز كُٞ ث٠ عـقٟٝضغج٣ هذ A- This occurs when the leaf is in vertical position, and the palisade layer lies behind each epidermis, and equal percent of light fall on both surfaces of the leaf. . سهزُٞ ث٢ عـق٠ِز ػ٣ٝغوؾ د٘غخ ٓضغج٣ ءٞ ثُؼٝ خِق ًَ دششرٚ٣ؽذ ؿذوز ػٔجدٞ٣ ٝ ػغُٞز ث٤سهز سأعُٕٞ ثٌٞػ٘ذٓج ص
Q- G.R. Light reactions in photosynthesis depend on light ? A- Because the reaction need energy, taken from light energy. When light falls on chlorophyll of the grana inside the chloroplast, some electrons in the atoms of chlorophyll molecule gain light energy.…………… Q- G.R. Dark reactions in photosynthesis can occur in both dark and light? A- Because the reaction depends mainly on the enzymes + raw materials ( ATP as a source of energy + CO2 + NADPH2). Q- G.R. Dark reactions in photosynthesis depend on light by indirect way ? A- Because the reaction depends mainly on the enzymes + raw materials ( ATP as a source of energy + CO2 + NADPH2). As light energy transformed in the grana to chemical energy used in: (1) Split water into O2 (released) and H2 fixed to NADP forming NADPH2 required in dark reactions and (2) Form ATP required in dark reactions, So Dark reactions in photosynthesis depend on light by indirect way. Q- Some organisms can do photosynthesis without using water? A- By using hydrogen sulfide instead of water itself. As Sulphur bacteria (green and purple bacteria) they contain bacteriochlorophyll (simpler in structure than ordinary chlorophyll). They live in swamps and pounds where hydrogen sulphide (which is the source of hydrogen used by these bacteria to reduce CO2 to build up carbohydrates and release of sulphur) is abundant. . ٕ ثعضخذثّ ثُٔجءٝ د٢ةٞ ثُذ٘جء ثُؼٚ٤ِّٔ دؼٞ صوٚ٤دؼغ ثٌُجة٘جس ثُق
Q: What happen if NADP disappears from plant cells? A- NADP acts as a Hydrogen receptor i.e. fix (store) Hydrogen produced during light reaction and transformed to NADPH2 which use to fix CO2 in dark reactions to form carbohydrates. When disappears: Both light and dark reactions of photosynthesis stop as (1) H2 produced from water splitting escape and reunite with O2 to form water again. (2) Plant can not fix H2 required to fix CO2 in dark reactions to form carbohydrates required for plant so the plant die. 44
The Mechanism of photosynthesis ٢ةٞز ثُذ٘جء ثُؼ٤ُآ 1- The source of oxygen evolved during photosynthesis: ٢ةٖٞ ثُٔ٘ـِن أع٘جء ثُذ٘جء ثُؼ٤ٓظذس ثألًغؾ A- Van Neil experiment: َ٤ٗ ٕ كج٢ٌ٣ز ثُؼجُْ ثألٓش٣ٗظش * Van Neil: American scientist was the first person who pointed out ػةـٝ the role of light in photosynthesis. Aim: * Pointed out the role of light and the source of O2 evolved during photosynthesis. Steps: * He study photosynthesis in sulphur bacteria (green and purple bacteria), because: ش٣ج ثٌُذش٣ش٤ دٌض٢ ك٢ةٞهذ هجّ دذسثعز ثُذ٘جء ثُؼٝ :جٜٗز أل٤ٗثٞثألسؽٝ ثُخؼشثء 1) These bacteria are autotrophic because they contain bacteriochlorophyll (simpler in structure than ordinary chlorophyll). 2) They live in swamps and pounds where hydrogen sulphide (which is the source of hydrogen used by these bacteria to reduce CO2 to build up carbohydrates and release of sulphur) is abundant. ٖ ثُذشى٤ ؿ٢ش ك٤ صؼ٠ٛٝ )١َ ثُؼجد٤كٝسٌُِٞذج ٖٓ ث٤ً (أدغؾ صش١ش٤َ دٌض٤كٝسًِٞ ٠ِ ػٟٞج صقضٜٗز أل٣ز ثُضـز٤ج رثص٣ش٤ ثُذٌضٙزٛ ثدُٕٞٔ ُذ٘جء ثٞذ ثٌُشد٤ أًغ٢ٗ ثخضضثٍ عج٢ كِٚٔ صغضؼ١ٖ ثُز٤ؽٝذس٤ُٜ ٓظذس ثٞٛٝ ٖ٤ؽٝذس٤ُٜذ ث٤ض٣كش ًذشٞض٣ ظ٤ثُٔغض٘وؼجس فٝ .ش٣ش ثٌُذش٣ز ٓغ صقش٤ذسثص٤ٛٞثٌُشد Results: (assumption of Van Neil َ٤ٗ ٕع كجٝكش
1- He assumed that light decomposed hydrogen sulphide into hydrogen and sulphur. Then hydrogen used in dark reactions to reduce CO2 into carbohydrates . As in the following equation: َٔغضؼ٣ ْش ع٣ًذشٝ ٖ٤ؽٝذس٤ٛ ٢ُٖ أ٤ؽٝذس٤ُٜذ ث٤ض٣َ ًذش٤ِ صق٠ِؼَٔ ػ٣ ءَٞ إٔ ثُؼ٤ٗ ٕهذ أكضشع كجٝ : ثُٔؼجدُز٢ٕ ًٔج كٞذ ثٌُشد٤ أًغ٢ٗز الخضضثٍ عج٤ةٞ صلجػالس ال ػ٢ٖ ك٤ؽٝذس٤ُٜث Light energy
6CO2 + 12H2S
C6H12O6 + 6 H2O + 12S
Bacteriochlorophyll
2- He assumed that : Light reactions in green plants are similar to that happening in sulfur bacteria, except that in green plants water is decomposed by light into Hydrogen and Oxygen. Hydrogen is then used to reduce Carbon dioxide in a series of reactions that don’t require light to produce carbohydrates, and Oxygen releases. ٌُٖٝ ش٣ج ثٌُذش٣ش٤ دٌض٢قذط ك٣ ز ُٔجٜٕ ٓشجدٌٞ ثُ٘ذجصجس ثُخؼشثء ص٢ز ك٤ةَٞ إٔ ثُضلجػالس ثُؼ٤ٗ ٕزث ثألعجط أكضشع كجٛ ٠ِػ ٠ُ عِغِز ٖٓ ثُضلجػالس ال صقضجػ إ٢ٕ كٞذ ثٌُشد٤ أًغ٢ٖٗ الخضضثٍ عج٤ؽٝذس٤ُٜغضؼَٔ ث٣ ْٖ ع٤أًغؾٝ ٖ٤ؽٝذس٤ٛ ٠ُقَِ ثُٔجء إ٣ ءٞثُؼ .ٖ٤ضقشس ثألًغؾ٣ٝ ذسثس٤ٛٞء ألٗضجػ ثٌُشدٞد ثُؼٞؽٝ
3- He assumed that: Released Oxygen comes from water, a case which is similar to Sulfur that is released from Hydrogen Sulfide by sulphur bacteria. Conclusion: * So the general chemical equation that represents Photosynthesis in green plants is: رُي٠ِػٝ ، ٖ٤ؽٝذس٤ُٜذ ث٤ض٣ضقشس ٖٓ ًذش٣ ١ش ثُز٣ فجٍ ثٌُذشٞٛ ٖٓ ثُٔجء ًٔج٢ؤص٣ ٖ ثُٔضقشس٤َ إٔ ثألًغؾ٤ٗ ُٕزُي أكضشع كج :٢ِ٣ ثُ٘ذجصجس ثُخؼشثء ًٔج٢ ك٢ةٞز ثُذ٘جء ثُؼ٤ِٔز ثُؼجٓز ُؼ٤جة٤ٔ٤ٌٌُٖٔ ًضجدز ثُٔؼجدٍ ث٣
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6CO2 + 12H2O
Light energy Chlorophyll
C6H12O6 + 6 H2O + 6O2
B- Scientists of California University (1941) Verifying the theory of Van Neil experimentally: َ٤ٗ ٕز كج٣ج دضؾجسح عذجس طقز ٗظش٤ٗسٞل٤ُن ٖٓ ػِٔجء ؽجٓؼز ًج٣ هجّ كش1941 ّ ػج٢ك
Aim: * Prove the correctness of Van Neil theory experimentally, i.e. prove that Oxygen released during Photosynthesis comes from water, not CO2. ظ٤ُٝ
ٞٛ ٢ةٞز ثُذ٘جء ثُؼ٤ِٖٔ ثُٔضظجػذ ٖٓ ػ٤ إٔ ٓظذس ثألًغؾ، ج٤ٗ ٕز كج٣أعذجس طقز ٗظش
Steps: * They used the green alga called (Chlorella) and provided it with all conditions favorable for photosynthesis. But they used water containing the Oxygen isotope 18 (O18) instead of the ordinary Oxygen 16 (O16) and CO2 contained ordinary oxygen ( O16). ش٤ ٗظٌُٚجٕ ثُٔجء ثُٔغضخذّ دٝ ٢ةٞز ثُذ٘جء ثُؼ٤ِٔف ثُٔ٘جعذز ُؼٝغ ثُظش٤ٔ ؽُٚ ثٝكشٝٝ ال ثألخؼش٣سٌُِٞثعضخذّ ثُؼِٔجء ؿقِخ ث ٢ٖ ك٤ثألًغؾٝ ٖ٤ثألًغؾ
Result: * They found that the Oxygen evolved during photosynthesis of the alga was the isotope Oxygen 18 (O18), and not Oxygen 16 (O16). This proves that the source of Oxygen evolved is water and not Carbon dioxide. . ثُٔجءٞٛ ٙ إٕ ٓظذس٠َِ ػ٤ُ دO16ظ٤ُٝ 16
6CO2 + 12H2O
18
Light energy
ٞٛ ٢ةٞز ثُذ٘جء ثُؼ٤ِٖٔ ثُٔضظجػذ ٖٓ ػ٤ث إٔ ثألًغؾٝؽذٝ 16
6H12O6
Chlorophyll
16
18
+ 6 H2O + 6O2
* In order to confirm this result, they repeated the experiment using ordinary water containing the ordinary Oxygen 16 (O16), and Carbon dioxide containing the isotope Oxygen 18 (O18). The Oxygen evolved was ordinary Oxygen 16. The ordinary Oxygen 16 (O16) comes from the ordinary water. َ٤ُد
١ آ١ٖ ػجد٤كضقشس أًغؾ
18
6CO2 + 12H2O
16
٠ِ ػٟٞقض٣ ٕٞذ ثٌُشد٤ أًغ٢ٗٓغ عج
١ٞقض٣ ١ػ٘ذ صٌشثس ثُضؾشدز دجعضخذثّ ٓجء ػجدٝ .ٕٞذ ثٌُشد٤ أًغ٢ٗظ ٖٓ عج٤ُٝ ٖٓ ثُٔجءٙ صقشس٠ِػ 18
Light energy
18
16
C6H12O6 + 6 H2O + 6O2
Chlorophyll
Q- G.R. Van Neil selects sulfur bacteria for his experiments on Photosynthesis? A- To shows the role of light and the source of O2 evolved during photosynthesis. He studies photosynthesis in sulfur bacteria, because: 1- These bacteria are autotrophic because they contain bacteriochlorophyll (simpler in structure than ordinary chlorophyll).
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2- They live in swamps and pounds where hydrogen sulphide (which is the source of hydrogen used by these bacteria to reduce CO2 to build up carbohydrates and release of sulphur) is abundant. So he concluded that: In green plants released Oxygen comes from water, a case which is similar to Sulfur that is released from Hydrogen Sulfide by sulphur bacteria. Q- G.R. Van Neil does not select Chlorella alga to study the source of O2 released during Photosynthesis? A- Because Chlorella alga is similar to green plants in using water during photosynthesis, so he could not know the source of O2 released (water or CO2) as both of them contain O2. Q- G.R. Sulphur bacteria are autotrophic? A- Because they contain bacteriochlorophyll (simpler in structure than ordinary chlorophyll). And live in swamps and pounds where hydrogen sulphide (which is the source of hydrogen used by these bacteria to reduce CO2 to build up carbohydrates and release of sulphur) is abundant. : ٚ٣ ثُضـزٚ٤ رثصٚ٤ٗثٞثالسؽٝ ش ثُخؼشثء٣ج ثٌُذش٣ش٤دٌض ّٞو٤ٖ ك٤ؽٝذس٤ُٜذ ث٤ض٣ثكش ًذشٞض٣ ظ٤ ٓجء ثُذشى ف٢ش ك٤صؼٝ / ١َ ثُؼجد٤كٝسٌُِٞذج ٖٓ ث٤ً ثدغؾ صش١ش٤َ دٌض٤كٝسًِٞ جٜ ألٕ د-ػ . ذسثس٤ٖٛٞ ثٌُشد٣ٌٞ ُضCO2 ٍٖ دجخضضث٤ؽٝذس٤ُٜث
2- The light and dark reactions: ز٤ةٞ ثُال ػٝ ز٤ةٞثُضلجػالس ثُؼ * Blackman ( العربلن ثالموربى1905) during his experiments to study the limiting factors of Photosynthesis as light, heat, and Carbon dioxide, concluded that Photosynthesis process is divided into two types of reactions: ذ٤ أًغ٢ٗ عج- ثُقشثسر-ءٞ (ثُؼ:ٍ ٓغج-٢ةٞز ثُذ٘جء ثُؼ٤ِٔثَٓ ثُٔقذدر ُٔؼذٍ ػٞ ُذسعز ثُؼٚػـ ثُؼجُْ دالًٔجٕ ٖٓ خالٍ صؾجسدٝأ : ٖ ٖٓ ثُضلجػالس٤ػٞٗ ٢ُ ص٘وغْ إ٢ةٞز ثُذ٘جء ثُؼ٤ِٕٔ) إٕ ػٞثٌُشد
1. Light reactions: o Reactions sensitive to light. o Light reactions take place in grana. o In which light acts as the limiting factor of the rate of photosynthesis. o Raw materials required: light – water – chlorophyll – ADP and NADP. o Products: Oxygen released, Hydrogen stored as NADPH2, and energy is stored as ATP. o Its equation : H2O + chlorophyll + Light H 2 + O2
، ثُؼجَٓ ثُٔقذد ُغشػز ثُضلجػالسٞٛ ءٞج ثُؼٜ٤ٕ كٌٞ٣ ،ٚٗ ثُؾشث٢ صقذط ك،ءٞ صلجػالس فغجعز ُِؼ٢ٛ : ز٤ةٞ صلجػالس ػ-)(أ .) ٠ د٠ صٚ٣ (ث٢ؿجهز صخضٕ كٝ )ٞ ثصش ص٠ (ٗجس د٢خضٕ ك٣ ٖ٤ؽٝذس٤ٛ ، ضظجػذ٣ ٖ٤ج أًغؾٜ٘٘ضؼ ػ٣
2. Dark reactions or enzymatic reaction or light- independent reactions: o Reactions are sensitive to temperature as it depends on enzymes. o These reactions are not affected by light, it take place in both light and darkness. o Dark reactions take place in stoma. o In which temperature is the limiting factor for the rate of the process. o Raw materials required: ATP + NADPH2 + CO2. o Products: Glucose (stored in the form of starch) + NADP + ADP + Phosphate group + Water. 47
٢ٌٖٔ إٔ صقذط ك٣ٝ ،ءٞال صضؤعش دجُؼٝ فغجعز ُذسؽز ثُقشثسر: ز٤ٔ٣ صلجػالس ثٗضٝ صلجػالس ثُظالّ أٝز أ٤ةٞ صلجػالس ال ػ-)(ح .ز٤ِٔ ثُؼجَٓ ثُٔقذد ُغشػز ثُؼ٢ٛ ٕ دسؽز ثُقشثسرٌٞصٝ ، ثُ٘خجع٢ صقذط ك،ثءٞ ثُغ٠ِ ثُظالّ ػٝء أٞثُؼ 1-Light reactions of Photosynthesis [In grana]:-ز٤ةٞثُضلجػالس ثُؼ
* Light is the limiting factor a. When light falls on chlorophyll of the grana inside the chloroplast, some electrons in the atoms of chlorophyll molecule gain light energy. َ٤كٝسٌُِٞٗجس رسثس ؽضا ثٝذر ثُخؼشثء كجٕ إٌُضش٤ ثُذالعض٢خ ثُؾشثٗج ك٤ً صش٢د كٞؽَُٞٔ ث٤كٝسٌُِٞ ث٠ِء ػٞغوؾ ثُؼ٣ ػ٘ذٓج . صٌضغخ ؿجهز
b. These electrons are shifted up from their low energy levels to higher ones. So, the kinetic light energy is stored as potential chemical energy in the chlorophyll. Molecules of chlorophyll are therefore said to be in an excited or activated state. ػغٝ ز ًـجهز٤ًء ثُقشٞدزُي صخضضٕ ؿجهز ثُؼٝ ثُـجهز٢ ك٠ِجس أػ٣ٞ ٓغض٠ُ ثُـجهز إ٢ج ثألهَ كٜجص٣ٞٗجس ٖٓ ٓغضٝصضقشى ث ٌُضش . ثُٔغجسرَٝ دجُٔ٘شـز أ٤كٝسٌُِٞتجس ث٣ ػ٘ذةز ؽض٠ٔصغٝ ،َ٤كٝسٌُِٞ ث٢ز ك٤جة٤ٔ٤ً
c. When the stored energy is released, the electrons fall once more to the lower energy levels. So, the chlorophyll will returns to the stable state, ready to receive another influx صذكنof light, to become excited once more. ٌٔ٘ز ثٓضظجص٣ٝ ش ٓ٘شؾ٤َ ؿ٤كٝسٌُِٞظذـ ث٣ٝ َ ثُـجهز ثألهٟٞ ٓغض٠ُ إٟٗجس ٓشر أخشٝذؾ ث ٌُضشٜػ٘ذٓج صضقشس ثُـجهز ثُٔخضضٗز ص .ٟظذـ ٓ٘شـج ٓشر أخش٤ُ ءٞذث ٖٓ ثُؼ٣ٓض
d. Part of the energy released during transfer of electrons of the excited chlorophyll from high energy level to lower one. Is used in splitting up water molecules into Hydrogen and Oxygen ions. e. the 2nd part of the energy of the excited chlorophyll is stored in ATP (Adenosine Tri-Phosphate) molecules, by combination of ADP (Adenosine Di-Phosphate) molecule, in the plastids with a phosphate group (P), by means of high-energy bond (~): علجسٞػز كٞٔذر ثُخؼشثء ٓغ ٓؾ٤ ثُذالعض٢د كٞؽُٞٔ) ث٠ دٟز د٣) دجصقجد ؽضا (ث٠ د٠ صٚ٣ ؽضا (إ٢خضضٕ ؽضء آخش ٖٓ ثُـجهز ك٣
ADP + P + energy ATP Adenosine – P~ p + P ------------------ Adenosine P ~ P ~ P f. The 3rd part released as heat which cause elevation of the leaf temperature. g. Hydrogen (resulting from decomposition of the water molecules) combines with a coenzyme (present in the chloroplast) NADP [ Nicotine Amide Dinucleotide Phosphate) which acts as a Hydrogen receptor] , to give NADPH2, Which is benefit in 2 ways: 1- Fix (store) Hydrogen to prevent its escape or recombine with Oxygen once more. Also 2- NADPH2 will be use to fix CO2 in dark reactions. ٢ٕ ٓشًخ (ٗجد دٌٞض٣ٝ )٢ (ٗجد د٠ٔغ٣ ذر ثُخؼشثء٤ ثُذالعض٢د كٞؽٞٓ ْ٣ٖ ثُ٘جصؼ ٖٓ ثٗشـجس ؽضا ثُٔجء ٓغ ٓغجػذ أٗض٤ؽٝذس٤ُٜضقذ ث٣ .ٖ٤ز ٓغ ثألًغؾ٤ٗضقذ ٓشر عج٣ ٖٝ أ٤ؽٝذس٤ُٜشح ثٜ٣ دزُي الٝ )ٞثصش ص
h. Oxygen released from decomposition of water is released as a bi-product.
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Equation of Photosynthesis: 6CO2 + 12H2O
Light + Chlorophill
C6H12O6 + 6H2O + 6O2
NB: ATP : o It is a compound called Adenosine Triphosphate. o It consists of: Adenine and ribose sugar joined to 3 phosphate groups (linked together by 2 high – energy bonds). o ATP acts as the energy currency of living cells. o Formation of ATP in leaf occurs during…….. a- Light reactions of photosynthesis. b- Glucose breakdown during respiration.
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NADP : It is Nicotinamide Adenine Dinucleotide Phosphate A co-enzyme present in the chloroplast. It acts as a Hydrogen receptor i.e. fix (store) Hydrogen produced during light reaction (to prevent its escape or recombine with Oxygen once more) and transformed to NADPH2. NADPH2 use to fix CO2 in dark reactions. It consists of two nucleotides joined through their phosphate groups, with one nucleotide containing an adenine base and the other containing nicotinamide.
2-Dark reactions [In Stroma]:-ز٤ةٞثُضلجػالس ثُالػ * A group of reactions that takes place in the stroma of the chloroplast outside the grana, in which CO2 gas is fixed by combination with Hydrogen carried on NADPH2 by the help of the energy stored in ATP molecules, into carbohydrates * It occurs after light reactions which produce ATP & NADPH2 , i.e. these reactions take the products of the light-dependent reactions and perform further chemical processes on them. * Products: PGAL [Phospho Glyceric Aldahyde] which is the first stable compound produced on the photosynthesis. Glucose stored in the form of starch. Water. NADP & ADP. Phosphate group. ٓغٕٙ دجصقجدٞذ ثٌُشد٤ أًغ٢ٗش ؿجس عج٤ضْ صغذ٣ ظ٤ذر ثُخؼشثء خجسػ ثُؾشثٗج ف٤ز ثُذالعض٤ أسػ٢ صقذط ك٢ػز ثُضلجػالس ثُضٞٔ ٓؾ٢ٛ ثدُٕٞٔ ثٌٞدزُي صضٝ )٠ د٠ صٚ٣ ؽضا (إ٢) دٔغجػذر ثُـجهز ثُٔخضضٗز كٞ ثصش ص٢ ٓشًخ (ٗجد د٠ٍِ ػٖٞٔ ثُٔق٤ؽٝذس٤ُٜث .ز٤ذسثص٤ٛٞثٌُشد
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Melvin Calvin Experiment to reveal the nature of Dark reactions: * Melvin Calvin and his associates in California University (1949) revealed the nature of dark reactions by using the radio-active isotope C14 : ٕ ثُٔشغٞش ثٌُشد٤ز دجعضخذثّ ٗظ٤ةٞؼز ثُضلجػالس ثُالػ٤ج ٖٓ ثٌُشق ػٖ ؿذ٤ٗسٞل٤ُ ؽجٓؼز ًج٢ كٙٝٓغجػذٝ ِٖلٖ ًجُل٤ٓ ُْصٌٖٔ ثُؼج .14
Steps: a. They placed the Chlorella alga in the apparatus shown in figure ( ), and supplied it with CO2 gas containing radio-active C14 then exposed the alga to light for few seconds to allow photosynthesis to occur. ءٞ عْ ػشع ثُـقِخ ُِؼ، 14 ٕ ٓشغٞ ًشدٕٚ دٞذ ًشد٤ أًغ٢ٗ دـجص عجٙٝأٓذٝ ٌَػـ دجُشُٞٔجص ثٜ ثُؾ٢ال ك٣سٌُِٞث ؿقِخ ثٞػؼٝ . ٢ةٞط ثُذ٘جء ثُؼٝغٔـ دقذ٤ُ ٕثُٞؼذر ع
b. The chlorella alga is then immersed in a beaker containing hot alcohol to kill the alga protoplasm to stop the biochemical reactions. . ز٤جة٤ٔ٤ًٞ٤هق ثُضلجػالس ثُذٝٝ ز٤ٍِ عجخٖ ُوضَ ثُخٞ ًقٚ ًؤط د٢ػغ ثُـقِخ كٝ ْع
c. They separate the product of photosynthesis by special means and tested for the presence of radio-active C14 in these products by Giger counter. .ؾش٤ٕ ثُٔشغ دؼذثد ؽٞج ػٖ ثٌُشدٜ٤ث كًٞشلٝ دـشم خجطز٢ةٞز ثُذ٘جء ثُؼ٤ِٔٗش خالٍ ػٌٞ ص٢ث ثُٔشًذجس ثُضِٞعْ كظ
The results: 1. When photosynthesis occurred for 2 seconds a 3-carbon compound was formed which is PGAL [ PhosphoGlyceric Aldahyde ] which is: It is the first stable compound produced on the photosynthesis. It acts as crossroads in the metabolic network, from which all other products in plant cells (glucose, starch, proteins, and fats) can be produced. It represents the process of fixation of CO2 in leaf. It can also used in cellular respiration as a high energy compound. 2. Synthesis of a hexose sugar is not completed in one step but through several intermediate reactions catalyzed by specific enzymes. ثُٔشًخٞٛ زثٛٝ ذ٤ٛغش ثُذ٤ِ ؽٞكغلٞ كٞٛ ٕٞ عالط رسثس ًشدٕٝ ٓشًخ رٌٖٞ كوؾ ص٤ض٤ٗ ُٔذر عج٢ةٞز ثُذ٘جء ثُؼ٤ِٔػ٘ذٓج ثعضٔشس ػ ٌٖٔ٣ ٕ – ًٔجٞٛثُذٝ جس٤٘٤صٝثُذشٝ ثُ٘شجٝ صًِٞٞزث ثُٔشًخ ُذ٘جء ثُؾٛ َٔغضؼ٣ ٌٕٖٔ أ٣ٝ ٢ةٞجً ثُ٘جصؼ ػٖ ثُذ٘جء ثُؼ٤جة٤ٔ٤ً ٍ ثُغجدشٝثأل دَ ٖٓ خالٍ ػذر، ثفذرٝ رٞ خـ٢ضْ ك٣ ُْ ٕٞ ثٌُشد٢ٖ ثُغٌش عذثع٣ٌٞ إٔ ص. ثُـجهز٢ُ ًٔشًخ ػج١ِٞ ثُض٘لظ ثُخ٢غضؼَٔ ك٣ ٕأ .ٔجس خجطز٣ج أٗضٜ فلضص،ـز٤عٝ صلجػالس
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Grana
Dark React
PGAL
Glucose
NB: ATP and NADPH2 are collectively called energy fixing compounds: Because Both ATP and NADPH2 fix CO2 in dark reactions: by combining CO2 with H2 carried on NADPH2 , by the help of energy stored in ATP molecule to form carbohydrates in stoma of chloroplast . i.e. ATP fix energy- NADPH2 fix hydrogen – Both ATP and NADPH2 fix CO2 in dark reactions. 52
Q- G.R. (O18) has a role in Prove the correctness of Van Neil theory? A- Scientists of California University (1941) Verifying the theory of Van Neil experimentally i.e. prove that Oxygen released during Photosynthesis comes from water, not CO2. Steps: * They used the green alga called (Chlorella) and provided it with all conditions favorable for photosynthesis. But they used water containing the Oxygen isotope 18 (O18) instead of the ordinary Oxygen 16 (O16) and CO2 contained ordinary oxygen ( O16). Result: * They found that the Oxygen evolved during photosynthesis of the alga was the isotope Oxygen 18 (O18), and not Oxygen 16 (O16), i.e. the source of Oxygen evolved is water and not Carbon dioxide. As in the following equation: 16
18
6CO2 + 12H2O
Light energy
16
16
C 6H12O6 + 6 H2O + 6O2
Chlorophyll
18
* In order to confirm this result, they repeated the experiment using ordinary water containing the ordinary Oxygen 16 (O16), and Carbon dioxide containing the isotope Oxygen 18 (O18). The Oxygen evolved was ordinary Oxygen 16. The ordinary Oxygen 16 (O16) comes from the ordinary water. As in the following equation: 18
6CO2 + 12H2O
16
18
Light energy
18
16
C6H12O6 + 6 H2O + 6O2
Chlorophyll
Q- G.R. Hydrogen resulting from decomposition of the water molecules combines with NADP during photosynthesis? A- Hydrogen combines with a co-enzyme (present in the chloroplast) NADP [Nicotin Amide Dinucleotide Phosphate) which acts as a Hydrogen receptor], to give NADPH 2, Which is benefit in 2 ways: 1- Fix (store) Hydrogen to prevent its escape or recombine with Oxygen once more. Also 2- NADPH2 will be use to fix CO2 in dark reactions. Q- G.R. ATP and NADPH2 are collectively called energy fixing compounds? A- Because: (1) Part of energy of excited chlorophyll stored in ATP by combination of a molecule of ADP present in chloroplast with phosphate group. (2) NADPH2 fixes hydrogen and prevents its escape, to be used in CO 2 reduction to form sugar. (3) Fixation of energy present in ATP in sugar, by using it in reduction of NADPH2. Both ATP and NADPH2 fix CO2 in dark reactions: by combining CO2 with H2 carried on NADPH2 , by the help of energy stored in ATP molecule to form carbohydrates in stroma of chloroplast. i.e. ATP fix energy- NADPH2 fix hydrogen – Both ATP and NADPH2 fix CO2 in dark reactions. 53
Q- G.R. Some plants can fix CO2 in dark after previous exposure to light? * During exposure to light, light-dependent reactions occurs which produce energy fixing compounds (ATP & NADPH2). * ATP & NADPH2 are used in dark reactions in which CO2 gas is fixed by combination with Hydrogen carried on NADPH2 by the help of the energy stored in ATP molecules, into carbohydrates . * Products: PGAL [ PhosphoGlyceric Aldahyde ] which is: It is the first stable compound produced on the photosynthesis. Glucose stored in the form of starch. Water. NADP & ADP. ء؟ٞج كضشر ُِؼٜ ثُظالّ دؼذ صؼشػ٢ كCO2 ش٤جّ دضغذ٤هذسر دؼغ ثُ٘ذجصجس ثُخؼشثء ثُو ٔجٛٝ ) NADPH2 ٝ ATP( ز٤ض٤ ثُـجهز ثُضغذ٢ج ٓشًذٜ٘ ٗضؼ ػ٢ثُضٝ ز٤ةٞج ثُضلجػالس ثُؼُٜء صٔش خالٞألٕ كضشر صؼشع ثُ٘ذجس ُِؼ ٓشًخ٠ٍِ ػٖٞٔ ثُٔق٤ؽٝذس٤ُٜ ٓغ ثCO2 رُي دجصقجدٝ ز٤ةٞظ صضْ ثُضلجػالس ثُالػ٤ ثُظالّ ف٢ كCO2 )ٍش ( ثخضضث٤الصٓجٕ ٓؼجً ُضغذ . ز٤ذسثص٤ٛٞثد ثٌُشدُٕٞٔ ثٌٞدزُي صضٝ ATP ؽضا٢دٔغجػذر ثُـجهز ثُٔخضضٗز كٝ NADPH2
Difference between light and dark reactions: Site Effect of light Effect of temperature Limiting factor Raw materials required
Products
Light reactions Inside the grana of chloroplasts. Reactions sensitive to light. Reactions not sensitive to temperature Light External materials: Light – water – salts (form chlorophyll). Materials inside grana: chlorophyll – ADP and NADP – Phosphate group. 1- Oxygen released, 2- Hydrogen stored in NADPH2, and 3- Energy is stored in ATP.
Equation
H2O + chlorophyll + Light H2 + O2
Steps
1- Split water 2– ATP formation 3 – NADP reduction. Sun light
Source of energy
Dark reactions In the stroma. Does not affect by light, i.e. it can occurs in both dark and light. Affect by temperature. Temperature CO2 + ATP + NADPH2
1. Glucose stored in the form of starch and 2. Water. 3. NADP & ADP 4. Phosphate group.
1- CO2 fixation. 2- Use of ATP . 3- Glucose formation. ATP
Q- G.R. No green plants in the depth of ocean? A- Because green plants are autotrophic organisms which live on photosynthesis that require light which is not present in the depth of ocean?
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Q- G.R. Photosynthesis does not occur completely in dark? A- Because reactions of photosynthesis includes light reactions that require light and produce ATP & NADPH2 which are used in dark reactions in which CO2 gas is fixed by combination with Hydrogen carried on NADPH2 by the help of the energy stored in ATP molecules, into carbohydrates . كغش ؟، ّ ًجِٓز أع٘جء ثُظال٢ةٞز ثُذ٘جء ثُؼ٤ٌِٖٔٔ إٔ صقذط ػ٣ ال ء ) ٗضجػ ٓشًخٞد ثُؼٞؽٝ ٢ج ( ال صقذط إال كٜ٤ ثُؼجَٓ ثُٔقذد كٞٛ ءٕٞ ثُؼٌٞ٣ ز٤ةٞ صشَٔ صلجػالس ػ٢ةٞز ثُذ٘جء ثُؼ٤ِٔألٕ ػ . NADPH2 ٝ ATP ز٤ض٤ثُـجهز ثُضغذ
Q: What happen if some of green leaf of plant is vertical in position? A- The green colour of both leaf surfaces will be in the same degree, palisade layer formed behind each epidermis, with spongy layer in between and equal percent of light fall on both surfaces of the leaf.
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III- Nutrition in Man (Heterotrophic nutrition) الزغزٌخ غٍش الزارٍخ Concept - Digestion in Man – Absorption - Metabolism - Excretion
1- Concept and importance of heterotrophic nutrition جٜ٤ُثُقجؽز إٝ ز٤ش ثُزثص٤ز ؿ٣ّ ثُضـزٜٞٓل The heterotroph obtains their food as ready-made organic compounds which are complex and of large molecules (Proteins / Carbohydrates / and Fats) that can not pass (diffuse) through the cell membranes of the living organisms. تجس ػخٔز٣رثس ؽضٝ ٓؼوذرٝ ضرٛز ؽج٣ٞثد ػؼٞٓ سرٞ ط٢ كٚ ؿزثة٠ِز ػ٤ش ثُزثص٤ز ؿ٣ صـزٟضـز٣ ١ ثُز٢قظَ ثٌُجةٖ ثُق٣ .جٜ٘ٓ ذ٤غضل٤ُ ٢ج ثٌُجةٖ ثُق٣ز خال٤غ إٔ ص٘لز خالٍ أؿش٤ٕ) ال صغضـٞٛ د- جس٣ٞ ٗش- جس٤٘٤صٝ(دش
These large molecules must be broken down into molecules of smaller size and simpler structure (Amino acids / Glucose / and Fatty acids and glycerol) i.e. digestion. )ٖ٣ؽِغشٝ ز٤٘ٛص – أفٔجع دًِٞٞ ؽ- ز٤٘٤ٓذًج (أفٔجع أ٤ًأدغؾ صشٝ تجس أطـش٣ج ُؾضٛش٤ؾخ صٌغ٣ شر٤تجس ثٌُذ٣ ثُؾضٙزٛ
As these molecules are small and soluble in water, they can easily be absorbed by the cell, either by diffusion or by active transport. . ثُ٘وَ ثُ٘شؾٝز دجالٗضشجس أ٤ِ ثُخ٠ُج إُٜٞدخٝ جَٜ ثٓضظجطٜغ٣ ثُٔجء ُزُي٢رثةذز كٝ شر٤تجس طـ٣ ثُؾضٙزٛ ٕأل
Cells will then use these simple compounds as a source of energy, or in growth or in formation of new tissues. .ذر٣ ُذ٘جء أٗغؾز ؽذٝ أُِٞٔ٘ ٝـز ًٔظذس ُِـجهز أ٤ ثُٔشًذجس ثُذغٙزٛ ز٤ِظ صغضؼَٔ ثُخ٤ف
1. 2. 3. 4.
So Hetetrophic nutrition carried out by man includes 4 main steps: Digestion of food. Absorption of food. Food Metabolism Excretion of Waste remains ث خشثػ- ٢َ ثُـزثة٤ؼْ – ثالٓضظجص – ثُضٔغُٜ ث: جس٤ِٔ ػ4 ٍ ث ٗغجٕ صضْ ٖٓ خال٢ز ك٤ش ثُزثص٤ز ؿ٣ثُضـز
NB Carbohydrates are the main source of energy in the human body. 2- Digestion in Man:ٕ ث ٗغج٢ؼْ كُٜث Digestion - Enzymes - Structure of digestive system - Steps of food digestion:
Digestion: الهضن It is the conversion of large food molecules (polymers) into smaller ones (monomers) by means of hydrolysis, by help of enzymatic action. .ٔجس٣ رُي ػَٔ ث ٗض٠ِغجػذ ػ٣ٝ ٢ثعـز ثُضقَِ ثُٔجةٞشر د٤جس طـ٤ ؽضة٢ُشر إ٤تجس ثُـؼجّ ثٌُذ٣َ ؽض٣ٞ صقٞٛ
Enzymes: ٔجس٣ثألٗض Definition – Properties -
Definition: 56
A protein substance that has the properties of a catalyst, as it has specific ability to activate a particular chemical reaction. Characterized by its sensitivity to temperature and PH. ز٤جة٤ٔ٤ٌُؾ ثُٔضخظض ُِضلجػالس ث٤ ثُض٘ش٢ِج ثُخجطز ػٜؾز ُوذسثص٤ثَٓ ثُٔغجػذر ٗضٞج خظجةض ثُؼُٜ ز٤٘٤صٝثد دشٞٓ Properties of enzymes ٔجس٣خظجةض ث ٗض:
1. Enzymes are specific هزخصصخin their actions: Each enzyme catalyzed قلض٣ a certain chemical reaction ٘ز٤ز ثُٔؼ٤جة٤ٔ٤ٌُ ثُضلجػالس ثٟ إفذdepends on the structure of the reacting molecules, and the shape and nature of the enzyme:
An
+ The reacting substance
Unstable intermediate
compound
Enzyme The enzyme
+
Products of the reaction
2. When the reaction is completed the resulting molecules break away from the enzyme leaving it in the same form as it was before the reaction . Enzyme + reacting substance unstable intermediate compound products of reaction
enzyme +
.َج هذَ ثُضلجػٜ٤ِ ػ٢سر ثُضٞ دجُظٙج٣ْ صجسًز إ٣تجس ثُ٘جصؾز ػٖ ثألٗض٣ضْ ثُضلجػَ ص٘لظَ ثُؾض٣ ػ٘ذٓج
Enzyme reacting substance
unstable intermediate compound
enzyme + products of reaction
3. Some enzymes have a reversible effect ٢ش ػٌغ٤ج صؤعُٜ ٌٕٞ٣ ٔجس هذ٣دؼغ ث ٗض.: this means that the same enzyme that catalyzes ٠ِغجػذ ػ٣ the decomposition ش٤ صٌغof a complex molecule into two simpler ones and may recombine ذ سدؾ٤ؼ٣ the two simple molecules to give the same complex molecule once more. Enzymatic hydrolysis (by enzyme + water)
Complex molecules
Simple molecules The same enzyme by remove of water
4. Enzymes acts as a catalyst ػجَٓ فلجصin chemistry because they are not effect the products of the reactions, َثصؼ ثُضلجػٞٗ ٠ِٔجس ػ٣ ال صؤعش ث ٗضIt only accelerate the rate of reaction until it reaches a case of equilibrium ٕفجُز ثصضث. 5. Some enzymes are secreted by the cell in an inactive state ش ٗشـز٤ؿ, to avoid its effects on the cells that produce it. So, they need certain substances to be present to activate 57
them. Ex.: Pepsin enzyme is secreted by the stomach as inactive (Pepsinogen), that is changed into active Pepsin in the presence of Hydrochloric acid in the stomach. Stomach Pepsinogen (inactive) pepsin (active) HCl 6- The activity of the enzyme (intensity of an enzymatic reaction) depends on the temperature and the PH value of the medium. ؾ٤عؾ ثُٔقُِٞ ٢٘٤ؽٝذس٤ُٜدسؽز ثألط ثٝ ٔجس دذسؽز ثُقشثسر٣ضؤعش ػَٔ ث ٗض٣ Q- G.R. Enzymes are specific in their actions? A- Because each enzyme catalyzed a certain chemical reaction depends on the structure of the reacting molecules, and the shape and nature of the enzyme. And when the reaction is completed the resulting molecules break away from the enzyme leaving it in the same form as it was before the reaction. Q- G.R. Enzymes acts as a catalyst in chemistry ? A- Because they are not effect the products of the reactions. It only accelerates the rate of reaction until it reaches a case of equilibrium. Q- G.R. Some enzymes are secreted in an inactive state? A- To avoid its effects on the cells that produces it. So, they need certain substances to be present to activate them. Ex.: (1) Pepsin enzyme is secreted by the stomach as inactive (Pepsinogen), that is changed into active Pepsin in the presence of Hydrochloric acid in the stomach. (2) Trypsin enzyme is secreted by the pancreas as inactive (Trypsinogen) , that is changed into active Trypsin by the action of a co-enzyme enterokinase (secreted by small intestine). Q- G.R. Some enzymes have a reversible effect? A- Because the same enzyme that catalyzes the decomposition of a complex molecule into two simpler ones, may recombine the two simple molecules to give the same complex molecule once more. Q- G.R. Trypsin secreted as inactive trypsinogen , while Amylase secreted in active form? A- Because active trypsin digest protein, so if activated inside pancreatic cells, pancreatic cells will digested, also its activation require enterokinase which present in small intestine. While amylase does not digest protein. سر ٗشـز ؟ٞ ط٢ض ك٤ِ٤ٓلشص ثأل٣ ٘ٔج٤ش ٗشـز د٤سر ؿٞ ط٢ٌزث كٛ ٖ٤ؽٞ٘٤ُلشص ثُضشدغ٣ ، جٜجط ٗلغ٣ج ثُذٌ٘ش٣صآًَ خالٝ ْؼٛ ٠ُ رُي إٟجط ألد٣ج ثُذٌ٘ش٣ دثخَ خالٚـ٤ كئرث صْ ص٘ش، ٖ٤صٝجػْ ُِذشٛ ٖ ثُ٘شؾ٤ ألٕ ثُضشدغ-ػ ٝ ( أ٢جع٣ض ثُذٌ٘ش٤ِ٤ٓأٓج ثأل. جٜ٤٘شؾ ك٤وز ك٤ ثألٓؼجء ثُذه٢ؽذ كٞ٣ ض٤٘٤ًٝ ث ٗضشٞٛ ُٚ ْ ثُٔ٘شؾ٣جط ألٕ ث ٗض٣ ثُذٌ٘ش٢٘شؾ ك٣ ًٔج ال . ٘جس٤صٝؼٔجٕ ثُذشٜ٣ ٔج الٜٗٔج ٗشؾ ألٛض ) كٌال٤ذ٤ُِث
Q- G.R. Enzymes are specific in their actions? A- Each enzyme catalyzed a certain chemical reaction depends on the structure of the reacting molecules, and the shape and nature of the enzyme. Q: What happen if an animal injected with substance lead to stop enzymatic activity? Enzymes are protein substance that has the properties of a catalyst, as it has specific ability to activate a particular chemical reaction. If its activity stops, most of the vital process stopped as it depends on enzymes and the animal die.
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Structure of digestive system: ٢ٔؼُٜجص ثٜخ ثُؾ٤ًصش Human digestive system is built up of : ٙزُٜ ؿذد ِٓقوزٝ ز٤ٔؼُٜٗغجٕ ٖٓ ثُو٘جر ث
ث٢ ك٢ٔؼُٜجص ثٜضشًخ ثُؾ٣
ثُو٘جر
(1) Digestive tract: ز٤ٔؼُٜثُو٘جر ث A long tube extending from the mouth to the anus. . ثُششػ٠ُِز صٔضذ ٖٓ ثُلْ إ٣ٞدز ؿٞأٗذ It comprises the mouth, the pharynx, the esophagus, the stomach, the small intestines, the large intestines, and the anus. . ثُششػ- ظز٤ِوز – ثألٓؼجء ثُـ٤ ثألٓؼجء ثُذه- ثُٔؼذر- ء١ ثُٔش- ّٞ ثُذِؼ- ْ ثُو٘جر ٖٓ ثُلٙزٛ ٌٕٞصض (2) Its accessory glands: ثُو٘جرٙزُٜ ثُـذد ثُِٔقوز Including the salivary glands- Liver – Pancreas. جط٣ثُذٌ٘شٝ ثٌُذذٝ ز٤صشَٔ ثُـذد ثُِؼجد
Steps of food digestion: ّؼْ ثُـؼجٛ ثسٞخـ Food digestion in man occurs as following: ٠ِ ث ٗغجٕ ًٔج د٢ؼْ كُٜز ث٤ِٔصضْ ػ 1. Buccal Digestion (Digestion inside the mouth): ْ ثُل٢ؼْ كُٜث Structure - function
Structure: Mouth contains: a. The teeth: -
The shape of the teeth differs to adapt with its function. In each jaw ثُليteeth are differentiated ٠ُض إ٤ٔ صinto: 4 incisors ثؿغٞ ثُو: at the front of the jaw ٓوذٓز ثُلي٢ كto cut food ّغ ثُـؼج٤ ُضوـ. 2 canines جح٤ٗ ثأل: one at each side of the incisors to tear food ّن ثُـؼج٣ ُضٔض. 4 premolars: two at each side to crush and grind food. 6 molars ثألػشثط: three at each side to crush عقنand grind ٖ ؿقfood.
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Q- G.R. The shape of the teeth differs. A- To adapt with its function. In each jaw teeth are differentiated into: - 4 incisors: at the front of the jaw to cut food. - 2 canines: one at each side of the incisors to tear food. - 4 premolars: two at each side to crush and grind food. - 6 molars: three at each side to crush and grind food. Q- G.R. Food must be Chew well in mouth especially carbohydrates? A- To cut, tear, crush and grind food, so disintegrate it which increases its surface area exposed to the action of salivary amylase enzyme which change starch into disaccharide maltose. .ز٣ٞز ثُ٘ش٣ ثُلْ خجطز ثألؿز٢ذثً ك٤سر ٓؼؾ ثُـؼجّ ؽٝػش . ) ش٤ص ( عٌش شؼٞ ٓجُض٢ عٌش ع٘جة٠ُؼْ ثُ٘شج إٛ ٢ كٙسٖٝ دذ٤ُج٤ْ ثُض٣ّ إٗضٞو٣ ٠فض
Q- G.R. Food must be breakdown to simple substances ? Because food particles are complex and of large molecules (Proteins / Starch / and Fats) that can not pass (diffuse) through the cell membranes of the living organisms. These large molecules must be broken down into molecules of smaller size and simpler structure (Amino acids / Glucose / and Fatty acids and glycerol) as these molecules are small and soluble in water, they can easily be absorbed by the cell, either by diffusion of by active transport. Cells will then use these simple compounds as a source of energy, or in growth or in formation of new tissues. b. The tongue: Acts as the taste organ. مٝ ثُضزٞػؼ Manipulates ي٣ صقشthe food in order to be chewed ٔؼؾ٣ by the teeth and mixing it with saliva خِـز دجُِؼجح. c. Saliva: ثُِؼجح Is secreted by 3 pairs of salivary glands ز٤ثػ ٖٓ ثُـذد ثُِؼجدٝ عالط أصthat open in the mouth cavity through ducts ثسٞ٘ خالٍ ه٠ٔق ثُل٣ٞ ثُضؾ٢ صلضـ كthat pour صظخsaliva over food. Saliva ثُِؼجحcontains : o Mucous ٓخجؽ: that softens food ّٖ ثُـؼج٤ِ٣ and lubricate it ٓ٘ضُنِٚؾؼ٣ to facilitate its swallowing َٚ دِؼٜغ٣ . o Salivary Amylase (Ptyalin) enzyme: that acts in a weak alkaline medium. It catalyzes the hydrolysis َِق٣ of starch ثُ٘شجto the disaccharide ٢ عٌش ع٘جةmaltose (malt' sugar ش٤)عٌش شؼ. ٞٛ ٢ عٌش ع٘جة٠ُجً إ٤قَِ ثُ٘شج ٓجة٣ ٞٛٝ ، ق٤ ػؼ١ِٞعؾ هٝ ٢ؼَٔ ك٣ ١ٖ ثُز٤ُ دجُضج٠ٔض ثُٔغ٤ِ٤ْٓ ثأل٣ أٗض٠ِ ثُِؼجح ػٟٞقض٣ . )ش٤ص (عٌش شؼٞثُٔجُض
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Starch + Water
Amylase (Ptyalin)
Maltose
Weak alkaline medium
Comparison between Salivary and pancreatic Amylase? Source Strength Importance
Salivary amylase (ptyalin) Salivary gland Weak Help in starch digestion
Act on
Cooked starch only (as bread )
Pancreatic amylase Pancreas Stronger than salivary amylase The main enzyme for carbohydrate digestion Cooked and uncooked starch + glycogen
Q- G.R. Salivary amylase doesn't work after wake up from sleep? A- Because the PH of saliva become acidic due to the effect of bacteria on food ruminant in the mouth. So we must wash mouth before sleep and after wake up. Q: What happen if All Salivary glands are removed from man? A - Saliva contains :(1) Mucous that softens food and lubricate it to facilitate its swallowing. (2) Salivary Amylase (Ptyalin) enzyme: that catalyzes the hydrolysis of starch to the disaccharide maltose (malt' sugar). On removal of all salivary glands: (1) Swallowing become difficult due to absence of mucous. (2) Hydrolysis of starch in mouth stops due to absence of Ptyalin enzyme. (3) Man feels continuous dryness of the mouth. d. The pharynx: ّٞثُذِؼ Structure: Pharynx is a cavity at the back of the mouth ْ ٓؤخشر ثُل٢ؽذ كٞ٣, leads to 2 tubes extend downwards from the pharynx (oesophagus –trachea) ز٤ثةُٜٞثُوظذز ثٝ ءٟدضجٕ ثُٔشٞٔضذ ٓ٘ز أٗذ٣ .
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Esophagus ء١( ثُٔشleads to the stomach )ثُٔؼذرand the trachea (which is a part of the respiratory system). Its function: A - It is a common passage for both food and air. Swallowing process: ز ثُذِغ٤ِٔػ o It is an organized reflex action كؼَ ٓ٘ؼٌظ ٓ٘غن: Because it occurs involuntary ًج٣ال أسثد under control of medulla oblongata َ٤ ثُ٘خجع ثُٔغضـ, to push food from the mouth to the esophagus ء١ ثُٔش٠ُُذكغ ثُـؼجّ ٖٓ ثُلْ إ, and prevent passage of food to respiratory system. During which when food is on the posterior part of tongue, the top of the trachea together with the larynx are elevated ثُق٘ؾشرٝ ز٤ثةُٜٞأع٘جء رُي صشصلغ هٔز ثُوظذز ث, causing the epiglottis to close over the glottis (entrance to the air passage). ثءُٜٞ ٓٔشثس ث٠ُس ثُـؼجّ إٝولَ كضقز ثُق٘ؾشر ُٔ٘غ ٓش٣ صؾؼَ ُغجٕ ثُٔضٓجس
o Respiration stop during swallowing: because: During swallowing the top of the trachea together with the larynx are elevated causing the epiglottis to close over the glottis (entrance to the air passage) to prevent passage of food into it, consequently air can not pass into it i.e. respiration stop. Q: What happen if Respiration occurs during swallowing? Food will pass to larynx which lead to cough and cilia of trachea expel any food particles enter the respiratory tract. If failed pneumonia occurs.
Q- G.R. Swallowing process is a reflex action ? كؼَ ٓ٘ؼٌظ A- Because it occurs involuntary ًج٣ ال أسثدunder control of medulla oblongata َ٤ثُ٘خجع ثُٔغضـ , to push food from the mouth to the esophagus and prevent passage of food to respiratory system. During which when food is on the posterior part of tongue, the top of the trachea together with the larynx are elevated, causing the epiglottis to close over the glottis (entrance to the air passage). 62
. ز ثُذِغ كؼَ ٓ٘ؼٌظ ٓ٘غن٤ِٔصُؼضذش ػ رُي٢ضقٌْ ك٣ٝ . جٜثُق٘ؾشر أٓجّ ُغجٕ ثُٔضٓجس ُضولَ كضقضٝ ز٤ثةُٜٞأع٘جء رُي صشصلغ هٔز ثُوظذز ثٝ ثُٔشا٠ُج صذكغ ثُـؼجّ ٖٓ ثُلْ إٜٗأل
Q- G.R. Respiration stops during swallowing? A- Because: During swallowing the top of the trachea together with the larynx are elevated causing the epiglottis to close over the glottis (entrance to the air passage) to prevent passage of food into it, consequently air can not pass into it i.e. respiration stop. Q: What happen if Person swallow button? ض٤ٔصسثس ه A- Button pass through digestive tract, not digested because there is no enzymes specific to digest substance of button and will excrete with feaces. e. The Oesophagus: ء١ثُٔش Structure – function - peristalsis
Structure: - A tube of 25 cm long. - Extends from the pharynx downwards through the neck, into the chest cavity, (where it lies parallel to the vertebral column in the neck and chest, between the 2 lungs, behind the heart and trachea) and passes to the stomach through the diaphragm . خِق ثُوِخ، ٖ٤ٖ ثُشةض٤ د١د ثُلوشٞٔجً ُِؼ٣ثصٞٓ وغ٣ ظ٤( ف١ق ثُظذس٣ٞثُضؾٝ ثُؼ٘ن٢ٔش ك٣ ،ّٞ عْ صٔضذ ٖٓ ثُذِؼ05 ٍٞدز دـٞأٗذ . ثُٔؼذر خالٍ ثُقؾجح ثُقجؽض٠ُ إ، )ز٤ثةُٜٞثُوظذز ثٝ
Function: 1- It has no digestive function: It doesn’t secrete any digestive enzymes. 2- It is lined with mucous membrane contains glands secreting mucous. ء ٓذـٖ دـشجء١ثُٔش ؿذد صلشص ثُٔخجؽ٠ِ ػٟٞقض٣ ٢ ٓخجؿwhich lubricate food make its movement to the stomach easy. 3- It carried food from pharynx to the stomach by peristalsis. ز٣دٝثعـز ثُقشًز ثُذٞ ثُٔؼذر د٠ُّ إٞطَ ثُـؼجّ ٖٓ ثُذِؼٞ٣ ء١ثُٔش
Peristalsis : ز٣دٝثُقشًز ثُذ o A series of involuntary ز٣ ال إسثدrhythmical ٓ٘ضظٔزmuscular contractions and relaxations of circular muscles. ز ثُٔ٘ضظٔز٤ِثألٗذغجؿجس ثُؼؼٝ ػز ٖٓ ثالٗوذجػجسٞٔٓؾ o This movement is extends downwards along the length of the alimentary canal. ز٤ٔؼٍُٜ ثُو٘جر ثٞ ؿ٠ِ فشًز ٓغضٔشر ػ٢ٛ
o It is responsible for : 1. Sweeps ٌ٘ظ٣ any food within the canal. 2. Pushing the food forwards through the digestive tube, ّز ُألٓج٤ٔؼُُٜز ػٖ دكغ ثُـؼجّ خالٍ ثُو٘جر ثٞ ثُٔغت٠ٛ
3. Churning the food ٚ خؼ, and mixing it with the digestive juices 4. Help absorption of the digested food.
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Q: What happen if Peristaltic movement stopped? o It is responsible for : 1- Sweeps any food contained within the canal, and Pushing the food forwards through the digestive tube. 2-Churning the food and mixing it with the digestive juices does not occurs ---maldigestion. o If not present : 1- Sweeps any food contained within the canal stop, and Pushing the food forwards through the digestive tube stop ---- constipation and decay of food in the colon ---inflammation of colon. 2-Churning the food and mixing it with the digestive juices does not occurs ---maldigestion. Q- G.R. Oesophagus has no digestive function? A- Because: It doesn’t secrete any digestive enzymes, but it secreting mucous (by mucous glands in the lining mucous membrane) which lubricate food make its movement to the stomach easy. Also it carried food from pharynx to the stomach by peristalsis.
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2-Gastric Digestion (Digestion inside the stomach): ثُٔؼذر٢ؼْ كُٜث Structure - function
Stomach structure:o Is a dilated muscular sac ٓ٘ضلخ٢ِظ ػؼ٤ً lies in the abdominal cavity, between the esophagus and small intestine. o It has two opening: one at the beginning of the stomach (at it’s junction with the lower part of oesophagus ) (cardiac opening ) كضقز ثُلؤثدand another at the end of the stomach (at its junction with the small intestine ) (pyloric openingثحٞ) كضقز ثُذ: o It has two constricted circular muscle at both ends So food stored long enough to digest protein by pepsin enzyme: 1. Constricted circular muscle at it’s junction with the lower part of oesophagus called cardiac sphincter , which control the cardiac opening and separate stomach from oesophagus. ثدز ثُلؤثدٞ د٠ٔز هجدؼز صغ٤ء ػؼِز فِو١ج دجُؾضء ثألعلَ ٖٓ ثُٔشُٜؽذ ػ٘ذ ثصظجٞ٣ 2. Constricted circular muscle at its junction with the small intestine called pyloric sphincter, which control the pyloric opening and separate stomach from small intestine. ثحٞثدز ثُذٞ د٠ٔز هجدؼز صغ٤وز ػؼِز فِو٤ج دجألٓؼجء ثُذهُٜؽذ ػ٘ذ ثصظجٞ٣
o Wall of stoach contains two types of cells : (1) Cells secrete HCl . (2) Cells secrete protein digested enzymes.
1= Cardiac sphincter, 2 = Oeosophagus, 3 = Gastric muscles, 4=pyloric sphincter, 5= Duodenum of S.I.
Q- G.R. Stomach has two constricted circular muscle at both ends? A- Constricted circular muscle at it’s junction with the lower part of oesophagus (cardiac sphincter): control the cardiac opening and separate stomach from oesophagus. Constricted circular muscle at its junction with the small intestine (pyloric sphincter): control the pyloric opening and separate stomach from small intestine. So food stored long enough to digest protein by pepsin enzyme. Function: 5 حبخبد 1- Secrete Gastric juice:- ز٣ثُؼظجسر ثُٔؼذ o A colorless acidic liquid ُِْٕٞ ث٣ ػذ٢ عجةَ فٔؼthat consists of: 65
1. Water: 90% 2. Hydrochloric acid: Formed in stomach cells by carbonic anhydrase enzyme. Create an acidic medium ٢عؾ فٔؼٝ ( خِنPH 2.5 – 1.5) that stops the action of Ptyalin enzyme and kills the harmful bacteria that may enter with the food and activates the gastric enzyme Pepsinogen into active Pepsin. 3. Pepsin enzyme: Secreted in an inactive form (Pepsinogen) , that is activated by HCl acid into active Pepsin. Pepsin catalyses the hydrolysis ٢َ ثُٔجة٤ِثُضق of protein by breaking certain peptide linkage in the long chain of protein to smaller fragment (polypeptides). Q: What happen if Stomach secretes pepsin directly? A- Stomach will digest its wall, and gastric ulcer developed, because active pepsin digests proteins. Q: What happen if Stomach stopped HCl secretion? A- Gastric HCl: Create an acidic medium (PH 2.5 – 1.5) that : (1) Stops the action of Ptyalin enzyme (2) kills the harmful bacteria that may enter with the food. (3) Activates the gastric enzyme Pepsinogen into active Pepsin. If stomach stop HCl secretion: (1) Action of Ptyalin enzyme continue. (2) Harmful bacteria that may enter with the food persist, that may cause harm to the man. (3) Pepsinogen not activated into active Pepsin, so protein digestion in stomach stop. 2- Digestion of Proteins: o Proteins are the only food substances that are affected by the gastric juice. o Because gastric juice contain Pepsin enzyme only which catalyzes the hydrolysis of proteins ٖ٤صٝ ُِذش٢ ثُضقَِ ثُٔجةby breaking ًغشcertain peptide linkages ٘ز٤ز ٓؼ٣ذ٤ثدؾ دذضٝ سin the long chain of the protein ِز٣ٖٞ ثُـ٤صٝ ٖٓ عالعَ ثُذشto form smaller chains of polypeptides جُٜٞق٣ٝ ذثس٤ذثس ثُذذض٣شر ٖٓ ػذ٤ عالعَ هظ٢ُآ
o Gastrin hormone released by G cells in the stomach, duodenum, and the pancreas. activate stomach to secrete digestive enzymes ; and stimulates secretion of gastric acid (HCl) by the stomach . Protein + water
Pepsin HCl
polypeptides (peptones))عذٌذاد الججزٍذاد (ثجزىًبد
3- Act as a food reservoir to store food long enough to be digested because: o It has a large capacity . o Its cardiac and pyloric sphincter separates it from oesophagus and small intestine. 4- Churning صخغand mixing up the food with gastric juice by the muscular contractions of the stomach wall ُِٔؼذر٢ِثعـز ثٗوذجػجس ثُؾذثس ثُؼؼٞز د٣خِؾ ثُـؼجّ ٓغ ثُؼظجسر ثُٔؼذٝ خغ Chyme:- النٍوىس o It is the food at the end of the gastric digestion, it take the form of a heavy semi-fluid mass, mixed with gastric juice, with a consistency suitable for being discharged from the stomach into the small intestines on gushes by the relaxation of the pyloric sphincter . .١ش ثُٔؼذ٤ٓخضِـز دجُؼظٝ ّثٞلز ثُو٤ شٌَ ًضِز ًغ٠ِٕ ػٌٞ٣ٝ ثُٔؼذر٢د كٞؽُٞٔ ثُـؼجّ ثٞٛ: النٍوىس
o Formed in stomach as a result of : 66
A- Churning and mixing up the food with gastric juice by the muscular contractions of the stomach wall. B- Storage of food long enough to be digested (protein digestion by pepsin). 5- Secrete copious mucous secretion ز٤إكشثصثس ٓخجؿwhich protects the stomach against the effect of the digestive enzymes. جػٔزُٜٔجس ث٣ ثُٔؼذر ٖٓ كؼَ ثألٗض٠ٔصق Q- Why does the gastric juice not affect the inner epithelial lining of the stomach? Why stomach does not digest itself? Because: ج؟ٜؼْ ثُٔؼذر ٗلغٜج ثُٔذـ٘ز ُِٔؼذر؟ ُٔجرث الص٣ ثُخال٠ِز ػ٣ُٔجرث ال صؤعش ثُؼظجسر ثُٔؼذ 1. The inner epithelial lining of the stomach ٢ِ ثُـشجء ثُٔذـٖ ُؾذثس ثُٔؼذر ثُذثخsecrete صلشصcopious شر٤جس ًذ٤ًٔ mucous secretion ز٤ إكشثصثس ٓخجؿwhich protects the stomach against the effect of the digestive enzymes. جػٔزُٜٔجس ث٣ ثُٔؼذر ٖٓ كؼَ ثألٗض٠ٔصق 2. Pepsinogen enzyme is inactive form ش ٗشـز٤سر ؿٞ ط٢ٖ ك٤ؽٞ٘٤ْ ثُذذغ٣ؽذ أٗضٞ٣ will be activated
only after its exit from gastric cells , and mixed with the acid in the cavity of the stomach away from its wall. . ذثً ػٖ ثُؾذثس٤ي دؼ٣سًِٞٝذس٤ُٜج دلؼَ فجٓغ ثٜل٣ٞ صؾ٠ُج ثُٔؼذر إ٣ ٖٓ خالٚؽٝ٘شؾ إال دؼذ خش٣ ال
Q: What happen if certain area in gastric wall stops mucous secretion? Stomach secretes copious mucous secretion which protects the stomach against the effect of the digestive enzymes. If mucous secretion stopped in certain area: gastric ulcer developed in this area (severe pain due to the effect of gastric juice on the ulcer). Q- G.R. Action of Ptyalin enzyme (salivary amylase) stops in stomach? A- Because it act in weak alkaline medium, while the medium of stomach is strong acid by Hydrochloric acid (PH 2.5 – 1.5) to activates the gastric enzyme Pepsinogen into active Pepsin. Q- G.R. Role of gastric Hydrochloric acid in food digestion? A- It creates an acidic medium (PH 2.5 – 1.5) to activate the gastric enzyme Pepsinogen into active Pepsin. Pepsin catalyses the hydrolysis of protein by breaking certain peptide linkage in the long chain of protein to smaller fragments (polypeptides), as in the following equation: Protein + water
Pepsin HCl
polypeptides (peptones))عذٌذاد الججزٍذاد (ثجزىًبد
Q- G.R. Proteins are the only food substances that are affected by the gastric juice? A- Because gastric juice contain Pepsin enzyme only which secreted in an inactive form (Pepsinogen) and activated by HCl to Pepsin, that catalyzes the hydrolysis of proteins by breaking certain peptide linkages in the long chain of the protein to form smaller chains of polypeptides. Q- G.R. Hyperacidity patients advised to chewing gum? ٕػز دٔؼؾ ثُِذجٞٔجدر ثُق٣ ٖٓ ص٠ٗؼج٣ ٖٓ ٘ظـ٣ A- Because chewing gum increases salivary secretion in mouth which is weak alkaline, so on swallowing it neutralize the gastric acidity (HCl). Q- G.R. Digestive enzymes does not present in stomach? Q70- Most of the digestive enzymes act in S.I. and stop in stomach?
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A- Because most of digestive enzymes need alkaline medium to activate, and its activity stop in acidic medium. In stomach: gastric Hydrochloric acid create an acidic medium (PH 2.5 – 1.5) that activates the gastric enzyme Pepsinogen into active Pepsin for protein digestion, but stops the action of most of digestive enzymes. In small intestine: sodium bicarbonate in the pancreatic juice that poured into S.I. create an alkaline medium (PH = 8) that activate most of the digestive enzymes. Q- G.R. Gastric juice not affects the inner epithelial lining of the stomach? A- Because: 1. The inner epithelial lining of the stomach secrete copious mucous secretion which protects the stomach against the effect of the digestive enzymes. 2. Pepsinogen enzyme is inactive form, will be activated only after its exit from gastric cells, and mixed with the acid in the cavity of the stomach away from its wall. Q- G.R. Occurrence of Gastric ulcer هشفز ثُٔؼذرin some patients? A- Due to: Stop mucous secretion in certain area in the inner epithelial lining of the stomach so it is affected by the digestive juice , inflamed خٜ صِضand ulcerate صضوشؿ. Q- G.R. Man can live without stomach but can not live without intestine? A- Because: man can replace gastric function which is: (1) Digestion of protein: it can be digested in small intestine, (2) storage of food: overcome by frequent small meals. But man can not replace small intestine functions which are: (1) Digestion of all food (carbohydrates, proteins and fat), (2) Food absorption in which digested food transferred to heart to be distributed to all body parts. So removal of S.I. lead to death. Q- G.R. Most of the digestive enzymes not present in stomach? A- Because of the acidic medium of stomach (Ph = 1.5 : 2.5), which is suitable for pepsin enzyme only, while most of the enzymes need alkaline medium which is available in the small intestine (PH = 8) , or weak alkaline medium which is available in the mouth. So most of the digestive enzymes present in small intestine. . ثُٔؼذر٢ؼْ كُٜٔجس ث٣ؽذ ٓؼظْ إٗضٞال ص ٝ أ١ِٞعؾ هٝ ٢ٔجس صؼَٔ ك٣ز ث ٗض٤ٖ إٔ دو٤ ف٢ٖ ك٤ْ ثُذذغ٣٘جعخ كوؾ ػَٔ إٗض٣ ٞٛٝ ) PH = 0.5– 1.5( ٢عؾ ثُٔؼذر فٔؼٝ ٕأل . جُٜ ثُٔ٘جعخٞٛٝ PH=8 ظ٤وز ف٤ ثألٓؼجء ثُذه٢ؽذ كٞجػٔز صُٜٔجس ث٣ كِزُي كئٕ ٓؼظْ ث ٗض، ق٤ ػؼ١ِٞه
Q: What happen if Stomach is removed from a man? A- Stomach act as a food reservoir, Secrete Gastric HCl, Digest Proteins, Churning and mixing up the food with gastric juice. When removed in a man: he can not eat large meal, my infected with harmful bacteria entered with the food. But he can live because pancreas and small intestine secrete enzymes that can digest protein. 3-Intestinal Digestion (Digestion inside the small intestine): Structure – function
Structure of Small intestine:- وز٤ثألٓؼجء ثُذه o It is about 8 meters long, 3.5cm in diameter (at its beginning) to 1.25 cm (at its end). جٜض٣جٜٗ ٢ عْ ك1.05ٝ جٜض٣ دذث٢ عْ ك3.5 ٖ٤ؿ دٝضشث٣ جٛهـشٝ ٓضش8 ٢ُثٞج فُٜٞذِؾ ؿ٣: - وز٤ثألٓؼجء ثُذه
o Coils ِٓلجسand loops فِوجسof the small intestines are connected together by a membranous structure which is called the mesenteric membrane (mesentery). 68
. وج٣ ثُٔغجسٝوج أ٣ ؿشجء ثُٔغجس٠ٔغ٣ ج دـشجءٜوز دذؼؼ٤ج ثألٓؼجء ثُذهٜفِوجصٝ صشصذؾ ِٓلجس
o The small intestine is differentiated into 2 parts: duodenum and ileum: Duodenum : It is the first 25 cm of small intestine, which receive secretion from pancreas and liver through one common opening. Ileum : it is the rest of small intestine, in which digestion is completed and absorption of digested food occurs (it is the main site of food absorption). o Inside the small intestine, the following 3 juices are secreted over food: Q- Loops of small intestine do not bend over each other? A- Because of the mesentery which is a membranous structure which connects coils and loops of the small intestines, and fix it to the posterior abdominal wall. جٍٜ ٗلغٞوز ف٤جس ثألٓؼجء ثُذه٤٘ال صِضق ع
Function: ٖ٤فجؽض A. Transport function: o The small intestine has both circular and longitudinal muscles and uses them to conduct peristalsis of food materials along the digestive tract. o The small intestine is also connected to the stomach by the pyloric sphincter and to the colon by the ileo-caecal valve, which control the entry and exit of food materials. b. Digestion: o The small intestine produces enzymes to complete the final chemical digestion of some of the food materials (such as peptidases for protein digestion). o The small intestine also receives digestive secretions from other organs (Pancreas and gall bladder) to assist with the digestion of food. (1)- Complete digestion of all foods (carbohydrates, proteins and fat) by the action of 3 juices poured in the small intestine, which are: وز٤ ثألٓؼجء ثُذه٢ ػظجسثس صظخ ك3 A- Bile :- ز٣ٝثُؼظجسر ثُظلشث o Source : Secreted from liver, stored in gall bladder (which concentrate it by absorbing of water and salts), and pass from gall bladder to the duodenum through common bile duct during passage of food containing fat in the duodenum o Composition: It is formed of bile salts and sodium bicarbonate. o Action : It help digestion but not digestive as it does not contain any digestive enzymes. جػٔزٛ ش٤ج ؿٌُٜ٘ٝ ْؼُٜ ث٠ِٓغجػذر ػ 1- Bile salts : It emulsify fats (i.e. divides large masses of fats that are insoluble in water into small globules increase surface area to facilitate and accelerate the enzymatic action on fats. 2- Sodium bicarbonate : neutralize HCl; and make PH of small intentine alkaline which helpt intestinal enzyme action.
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Q: What happen if Gall bladder is removed from the body. A- Gall bladder store the bile secreted from the liver and passes it to the duodenum when fat is present in the food. If removed: bile wills not stored, but pass continuously to the duodenum so fat not emulsified, so the efficacy of lipase in digestion of fat decreased. So this person must decrease fat intake. B- The pancreatic juice: - ز٤جع٣ثُؼظجسر ثُذٌ٘ش o Secreted from the pancreas and pass to the duodenum through the pancreatic duct which join the common bile duct before it open into the duodenum. o Poured on food during its passage in the duodenum. o It contains the following components: ٠ِ٣ ٓج٠ِ ػٟٞصقض 1) Sodium bicarbonate: Neutralizes HCl inside the duodenum and change the medium to alkaline (PH = 8) which is required for the action of enzymes in small intestine. If not secreted: HCl will not neutralized inside the duodenum, the medium become acidic which stop action of enzymes (as pancreatic amylase and trypsin) in small intestine which lead to mal-digestion ْؼٛ ءٞ ع, and duodenal ulcer may occurs due to acidic chyme. Secretin is a hormone that is produced in the S cells of the duodenum and controls the secretions of bicarbonate from the pancreas. Q: What happen if Sodium bicarbonate not secreted in Pancreatic juice? Sodium bicarbonate: - neutralizes HCl inside the duodenum and change the medium to alkaline (PH = 8) which is required for the action of enzymes in small intestine as pancreatic amylase and trypsin. If not secreted: HCl will not neutralized inside the duodenum, the medium become acidic which stop action of enzymes in small intestine which lead to mal-digestion ءٞع ْؼٛ, and duodenal ulcer may occurs due to acidic chyme. 2) Pancreatic amylase enzyme: Catalyzes the hydrolysis of glycogen and starch into disaccharide called maltose (malt' sugar ش٤)عٌش شؼ. ٢ص ع٘جةٞ عٌش ٓجُض٠ُٖ إ٤ؽٌٞ٤ِثُؾٝ قَِ ثُ٘شج٣ Pancreatic Amylase
Glycogen and starch
maltose. Alkaline medium: PH =8
It is the main enzyme in carbohydrate hydrolysis as it is stronger than salivary amylase (which hydrolyze cooked starch only), and digest both cooked and raw starch and glycogen. 3) Trypsinogen enzyme: Is an inactive enzyme that is activated when it reaches the duodenum by the action of a co-enzyme ْ ٓغجػذ٣ أٗضcalled enterokinase (secreted from intestinal glands in the lining of the small intestine) into active trypsin. 70
Trypsin catalyzes the hydrolysis of proteins into polypeptides. It is stronger than gastric pepsin. ٠ُوز إ٤ ُألٓؼجء ثُذه١ِٞ ثُؾذثس ثُخٙلشص٣ ١ض ثُز٤٘٤ًٝ ثٗضش٠ٔغ٣ ْ ٓغجػذ٣ ػشش دلؼَ أٗض٠٘ ثالع٢ُظَ أ٣ ٘شؾ ػ٘ذٓج٣ ، ش ٗشؾ٤ْ ؿ٣أٗض .ذثس٤ذثس ثُذذض٣ ػذ٠ُجس إ٤٘٤صٝش ثُذش٤ صٌغ٠ِٖ ػ٤ْ ثُضشدغ٣غجػذ أٗض٣ ، ٖ ٗشؾ٤صشدغ Enterokinase
Trypsinogen
Trypsin. Alkaline medium Trypsin
Proteins + water
polypeptides (peptones) Alkaline PH =8
4) Lipase enzyme : It catalyzes the hydrolysis of emulsified fats into fatty acids and glycerol. ج دجُظلشثءٜرُي دؼذ صؾضةضٝ ٖ٣غش٤ِؽٝ ز٤٘ٛ أفٔجع د٠ُٕ إٞٛج ثُذ٤قَِ ٓجة٣ Lipase
Emulsified fats by bile + water
fatty acids and glycerol. Alkaline medium PH = 8
Q: What happen if Pancreas is removed from the body of an animal? Pancreas secrete: (1) pancreatic juice and (2) pancreatic hormones (insulin – Glucagons). If removed: (1) Pancreatic juice stopped lead to stop digestion in small intestine, (2) Pancreatic insulin stopped lead to Diabetes ( ٓشع ثُغٌشincrease glucose in blood). So animal die. C- Intestinal juice :- ز٣ٞثُؼظجسر ثُٔؼ o Secreted by certain cells in the lining of the small intestines. o It contains a mixture of enzymes that completes the action of the previous enzymes for final food digestion, these enzymes are: 71
ْؼُٜز ث٤ِٔ ػ٢ٔجس ثُغجدوز ك٣ صٌَٔ ػَٔ ثألٗض٢ثُضٝ ز٤ُٔجس ثُضج٣ ث ٗض٠ِ ػ١ٞصقضٝ وز٤ ؽذثس ثألٓؼجء ثُذه٢ج خجطز ك٣ج خالٛصلشص :ٗجس ثُـزثءٌُٞٔ ٢جةُٜ٘ث A. Peptidases enzymes :- ض٣ذ٤ٔجس ثُذذض٣ػز أٗضٞٔٓؾ
- A group of several types of enzymes. - Each enzyme is able to hydrolysis a peptide linkage between certain amino acids in the polypeptide chains to give various amino acids. ٢ٕ كٌٞذثس ُضض٤ذثس ثُذذض٣ عِغِز ػذ٢ز ك٤٘٤ٓ٘ز ٖٓ ثألفٔجع ثأل٤ثع ٓؼٖٞٗ أ٤ز د٣ذ٤ثدؾ ثُذذضٝش ثُش٤ج دضٌغٜ٘ٓ ًَ خضض٣ ثعٞٗػذر أ . ز ثُٔخضِلز٤٘٤ٓز ثألفٔجع ثأل٣جُٜ٘ث Peptidase
Polypeptide + water
amino acids
Alkaline medium
B. Enzymes which hydrolysis disaccharides to mono - saccharides: these are: :ز٤جس ثُغ٘جة٣ٔجس ثُٔقِِز ُِغٌش٣ػز ث ٗضٞٔٓؾ
1- Maltase enzyme: hydrolyzes maltose sugar (malt' sugar ش٤ )عٌش شؼto two molecules of glucose. .صًِٖٞٞ ٖٓ عٌش ثُؾ٤ت٣ ؽض٢ُش) أ٤ص (عٌش ثُشؼٞقَِ عٌش ثُٔجُض٣ ض٤ْ ثُٔجُض٣أٗض Maltase
Maltose sugar + water
2 molecules of glucose
Alkaline medium
2- Sucrase (invertase) enzyme: hydrolyzes sucrose sugar (cane sugar) to glucose and fructose. .)ص (عٌش ثُؼ٘خٞكشثًضٝ صًِٞٞ ؽ٢ُص (عٌش ثُوظخ) أٝقَِ عٌش ثُغٌش٣ ض٣ْ ثُغٌش٣أٗض
Sucrose sugar (cane) + water
Sucrase
glucose + fructose
Alkaline medium
3- Lactase: hydrolyzes lactose sugar (milk sugar) to glucose and galactose. .صٞؽجٌُضٝ صًِٞٞ ؽ٢ُص (عٌش ثُِذٖ) أٞقَِ عٌش ثُالًض٣ ض٤ْ ثُالًض٣أٗض
Lactose sugar (milk) + water
Lactase
glucose + galactose
Alkaine medium
C. Enterokinase :* Not digestive enzyme, it only acts as co-enzyme which activates. Trypsinogen enzyme into trypsin ٖ٤ صشدغ٢ُٖ أ٤ؽٞ٘٤ْ ثُضشدغ٣جػٔز دَ ٓ٘شؾ ٗضُٜٔجس ث٣ظ ٖٓ ث ٗض٤ُ Q: What happen if Enterokinase enzyme not present? Conversion of Trypsinogen to active trypsin which digest protein stop ---- stop protein digestion in stomach. c. Absorption function: Small intestine is specialized for absorption. The greater the to surface area, the greater the absorption possible. The small intestine is equipped with villi, which greatly increase the inner surface area, and it is very long allowing time along the SA for absorption. 72
Q: What happen if Ileum (small intestine) is removed from body of an animal? In ileum food digestion and absorption takes place : If removed: food digestion in ileum stopped, Absorption of food digested in other parts of digestive tract stopped. So he can not get its nutrition and die. NB Starch digestion occurs in Mouth and small intestine. Fat digestion occurs in Small intestine only. Protein digestion occurs in stomach and small intestine. Q- G.R. Coils and loops of the small intestines are connected together? A- Due to a membranous structure which is called the mesenteric membrane (mesentery) which connect coils and loops of the small intestines. Q- G.R. Bile helps digestion but not digestive juice? A- Because it does not contain any digestive enzymes, but it emulsify fats (i.e. divides large masses of fats into small globules), to facilitate and accelerate the enzymatic action on fats that are insoluble in water. It secreted from liver and poured on food during its passage in the duodenum. جػٔز ؟ٛ ش٤صؼضذش ثُظلشثء ػظجسر ؿ . جػٔزٛ ٔجس٣ إٗض٠ِج ػٜثةُٞؼذّ ثفض . ز٣ٕٝ دجُؼظجسر ثُظلشثٞٛسر ثخضالؽ ثُذٝػش ٢ٔ٣ش ث ٗض٤غشع ثُضؤع٣ٝ َٜغ٤وز ك٤ز ده٤٘ٛ هـشثس د٠ُشر إ٤ذجس ثٌُذ٤ صؾضا ثُقذ١ أ، ٢٘ٛ ٓغضقِخ د٠ُٕ إَٞٛ ثُذ٣ٞ صق٠ِج صؼَٔ ػٜٗأل ز٤٘ٛ أفٔجع د٠ُ إ٢ٍ٘ٛ دؼذ رُي ثُٔغضقِخ ثُذٞق٣ ١ض ثُز٤ذ٤ُِْ ث٣َ ػَٔ إٗضٜج دزُي صغٜٗ أ١ ( أ. ثُٔجء٢ح كٝ ال صز٢ٕ ثُضٞٛ ثُذ٠ِػ . )ٖ٣غش٤ِؽٝ
Q- G.R. Liver help fat digestion ? - Importance of mixing fat with bile? A- Because it secrete bile that poured on food during its passage in the duodenum, and emulsify fats (i.e. divides large masses of fats into small globules), to facilitate and accelerate the enzymatic action on fats that are insoluble in water. Q- G.R. Pancreatic juice and bile contains Sodium bicarbonate? A- It neutralizes HCl and change the medium to alkaline (PH = 8) which is required for the action of enzymes in small intestine. . )PH=8( ١ِٞعؾ هُٞؽؼَ ثٝ HCL ُٔؼجدُز فٔض. ّٞ٣دٞٗجس ثُظٌٞشد٤ د٠ِز ػ٤جع٣ثُذٌ٘شٝ ز٣ٝثء ًَ ٖٓ ثُؼظجسر ثُظلشثٞثفض
Q- G.R. Intestinal juice contains group of enzymes for protein digestion and not one enzyme? A- It contains Peptidase enzymes which are a group of several types; each enzyme is able to hydrolysis a peptide linkage between certain amino acids in the polypeptide chains to give various amino acids. Q- G.R. Villi has essential role in get benefit from food? A- Because it absorb products of the digestive process from the ileum are transferred it to the blood and the lymph by active transport and membranal diffusion. Then to the heart which distribute it to all body parts to get benefit from it. Q- G.R. Adaptation of the villus to its function? A- (1) Folds, convolutions, villi and micro-villi on the inner epithelial lining of the ileum provides an enormous surface area for the absorption of nutrients. [About 10 m2 (approximately 5 times as the whole surface area of the human body)]. 73
(2) Outer epithelial layer encloses a lacteal vessel surrounded by a network of both venous and arterial blood capillaries to absorb digested food. Q- G.R. Intestinal juice does not affect fat? A- Because it does not contain bile which emulsify fat and lipase which digest fat . ٕٞٛ ثُذ٠ِز ػ٣ٞال صؤعش ثُؼظجسر ثُٔؼ . ٢٘ٛ ٓغضقِخ د٠ُٕ إٍٞٛ ثُذٞ صق٢ ثُظلشثء ثُض٠ِ ػ١ٕٞ ًٔج ال صقضٞٛجػْ ُِذُٜض ث٤ذ٤ُِْ ث٣ إٗض٠ِج ػٜثةُٞؼذّ ثفض
Q: What happen if Glucose concentration in intestinal lumen lowers than its concentration in the epithelial lining? A- Villi absorb it by active transport and transfer it to blood, to heart to all body parts. Summary of Food digestion 1- Stages of digestion of carbohydrates: A- In mouth: Starch is hydrolyzed by salivary amylase in weak alkaline medium to maltose. B - In small intestine: (a) Pancreatic amylase hydrolyze starch and glycogen in an alkaline medium (PH = 8) to maltose. (b) Intestinal Maltase hydrolyzes maltose to 2 molecules of glucose. (c) Intestinal Sucrase hydrolyze sucrose to one molecules of glucose + one molecule of fructose. (d) Intestinal Lactase hydrolyze lactose to one molecules of glucose + one molecule of Galactose. 2- Stages of digestion of proteins: Protein is physically digested in the mouth by chewing and in the stomach by churning. Protein is chemically digested in three steps: 1- The first step occurs in the stomach through the action of pepsin. 2- The products, polypeptide chains, further digested in the duodenum by trypsin, are converted into short amino acid sequences called peptides. The peptides are digested in the duodenum by peptidases from the small intestine. 3- The final products are amino acids. Amino acids are absorbed by the villi and they enter the blood stream to be circulated to body cells. a- In stomach: Active Pepsin enzyme catalyzes the hydrolysis of proteins by breaking certain peptide linkages in the long chain of the protein to form smaller chains of polypeptides. b- In small intestine: (1) Active Pancreatic Trypsin catalyzes the hydrolysis of proteins into polypeptides. It is stronger than gastric pepsin . (2) Intestinal peptidase: A group of several types of enzymes, each enzyme is able to hydrolysis a peptide linkage between certain amino acids in the polypeptide chains to give various amino acids.
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3- Stages of digestion of fat : 1- In small intestine: (a) Bile : emulsify fats i.e. divides large masses of fats (which is insoluble in water) into fatty emulsion (small globules which is soluble), so it facilitate and accelerate the enzymatic action on fats. (b) Pancreatic lipase: catalyzes the hydrolysis of emulsified fats into fatty acids and glycerol. Changes in pH as food pass through the digestive system: The first pH change occurs in the stomach as a result of HCl release. The food material, called acid chyme, ranges in pH depending on the pH when it was ingested. It is usually around 2 or 2.5 in the stomach. This low pH kills any bacteria that are in the food and creates a suitable environment for the activity of pepsin (from pepsinogen). The second pH change occurs when acidic chyme is buffered by bicarbonate ions released from the pancreas. The bicarbonate ions are an excellent buffer in the body and they maintain the pH between 8 and 8.5, which is the optimum pH range for the various food-digesting enzymes that are active in the duodenum. Role of mucous in Digestive tract? 1) Saliva contains Mucous: that softens food and lubricates it to facilitate its swallowing. 2) Oesophagus is lined with mucous membrane contains glands secreting mucous. Which lubricate food make its movement to the stomach easy؟ 3) Stomach Secrete copious mucous secretion which protects the stomach against the effect of the digestive enzymes. 4) The large intestines secrete mucous that facilitates passage of the wastes out Q- G.R. Chewing a piece of bread in mouth give sweaty test? A- Because chewing of bread to small fragments, mixed well with saliva, hydrolyzed its starch by salivary amylase to maltose sugar which gives sweet taste. Q - G.R. Complete water absorption does not occur in small intestine? A- Because body needs water in (1) Digestion: which is hydrolysis of food i. e. need water, (2) absorption: which occurs by diffusion or active transport and need soluble food. Q – G.R. Nervous excitement must be avoided during intake of food? A- Because Excitement leads to stop digestion as: it activates sympathetic nervous system which leads to: (1) Decrease salivary, gastric, intestinal and pancreatic sections. (2) Stop peristalsis.
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NB (A) Composition of saliva: Water; mucin; lysozyme; bicarbonate; Salivary amylase. (B) Composition of Gastric secretion (1) HCl: (2) Pepsinogen: (3) Mucus (4) Intrinsicfactor: promote B12 absorption (C) Composed of Bile : 1) Water (85%). 2) Bile salts (10%). 3) Mucus and pigments (3%). 4) Fats (1%). 5) Inorganic salts (0.7%) . 6) Cholesterol (0.3%).
(D) Composition of pancreatic juice 1) Water: 90% 2) NaHCO3: 3) Pancreatic enzymes: Trypsinogen. Chymotrypsinogen. Pancreatic amylase. Pancreatic lipase.
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(E) Composed of Intestinal juice : 1) Water. 2) Organic and inorganic substances; 3) Digestive enzymes: Amino peptidases. Disaccharidase: lactase, sucrase, maltase. Enterokinase. Monoglyceride lipase. Phosphatase. Nucleotidase.
Q - Write a brief on faeces? ثُلؼالس A= Definition: Semisolid substances, brown in colour, with bad odour, decay by bacterial action, pushed to rectum to expele it. = Formed of: (1) Cellulose. (2) Fibers. (3) Damaged cells. (4) Dead bacteria. (5) Some vitamins secrected from bacteria. = Defication (expel of faeces) : when rectum become full of faeces desire of defication The two constricted muscles on both sides of the anus are relaxed , and wall of rectum contract expel faeces through the anus.
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3- Absorption of Food
اهزصبص الطعبم
Definition – Mechanisms - Sites of absorption
Introduction: a. The digestion that occurs in the digestive system is extra cellular – it occurs in the lumen (interior) of the digestive tract. b. The nutrients do not actually enter the body until they have crossed a membrane. This first occurs in the ileum with the absorption ob the villi. Until then, the nutrients are located in a tube that runs through the body. Definition: o It is the transfer of digested food substances to blood and lymph, through the epithelial cells lining the ileum of the small intestines, and from lymph to blood, to heart to be distributed to all body parts. .وز٤ ثألٓؼجء ثُذه٢ ك٢ج ثُٔذـ٘ز ُِلجةل٣ٔق خالٍ ثُخال٤ُِ ثٝ ثُذّ أ٢ُٓز إٞؼُٜٔز ث٤ثد ثُـزثةُٞٔس ثٞػذ
Mechanisms: o The two main mechanisms used in absorption of the digested food. active transport and membranal diffusion . Sites of absorption of food: ّأٓجًٖ ثٓضظجص ثُـؼج 1- Small intestine: The structure of the wall of the small intestines: وز٤خ ؽذثس ثألٓؼجء ثُذه٤ًصش o Ileum is the main site of food absorption, because the inner epithelial lining of the ileum ٠ ثُٔذـٖ ثُِلجةل٢ِ ثُـشجء ثُذثخhas folds جس٤ ؿand convolutions ثُضلجكجسas well as multiple tiny projections ءثسٞذ ٖٓ ثُ٘ض٣ ثُؼذcalled villi. الخوالدwhich provides an enormous ؽذث ً شث٤ًغ surface area for the absorption of nutrients وز الٓضظجص ثُلذثء٤ذ ٖٓ عــ ثألٓؼجء ثُذه٣ صض٠ٛٝ. o The surface area of small intestine is about 10 m2 (approximately 5 times as the whole surface area of the human body). . ٕ خٔغز أػؼجف ٓغجفز عــ ؽغْ ث ٗغج١ ٓضش ٓشدغ آ15 ٢ُثٞزث ثُغــ فٛ صذِؾ ٓغجفز
o Villi. الخوالد: Definition: multiple tiny projections in the inner epithelial lining of the ileum to increases greatly the surface area of absorption. .وز ثُٔؼشع الٓضظجص ثُـزثء٤ذ ٖٓ عــ ثألٓؼجء ثُذه٣ صض٢ ؽذثس ثُِلجةل٢ذر ك٣إٗغ٘جءثس ػذ
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The structure of the villus: خ ثُخِٔز٤ًصش o Each villus is composed of: an outer covering of a single-celled layer of epithelial cells that encloses a lacteal vessel ٟٝٔلج٤ُ ٠٘ػجء ُذٝ surrounded by a network of both venous and arterial blood capillaries. .ز٣ذ٣سُٞثٝ ز٤ٗج٣ز ثُشش٣ٞٓشثس ثُذ٤ ثُشؼٚؾ د٤ق٣ )١ٝٔلج٤ُ( ٢٘ػجء ُذٝ جِٜز دذثخ٤ج ؿالة٣ز ٖٓ خال٤ٕ ٖٓ ؿذوز خجسؽًٌَٞ خِٔز صض
o Under the electron microscope, tiny projections protrude from the epithelial cells of the villi are seen, these are called micro-villi , which help to increase the area of the absorbing surface. ٠ِؼجً ػ٣ صؼَٔ أ٠ٛٝ وز٤الس ثُذه٤ٔز صؼشف دجُخ٤ج ثُـذوز ثُـالة٣وز ؽذث ُخال٤د أٓضذثدثس دهٞؽٝ فظُٞ ٢ٗٝش ث ٌُضشٜدجُلقض دجُٔؾ .جدر عــ ثالٓضظجص٣ص
Function of villi : o Products of the digestive process are transferred to the blood and the lymph by absorption through the villi by active transport and membranal diffusion . ثُ٘وَ ثُ٘شؾٝ ٢ز ثالٗضشجس ثُـشجة٤ثُِٔق دخجطٝ ّ ثُذ٠ُؼْ إُٜز ث٤ِٔثصؼ ػٞٗ َص٘ضو
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The ways of digested food in villus (Absorption routes): ؿشم ثٓضظجص ثُـزثء o There are two routes for absorption of the digested substances through the villi: ٕوج٣ثد ثُٔٔضظز دجُخٔالس دـشُٞٔص٘ضوَ ث
A. The blood route:١ٞٓن ثُذ٣ثُـش o It starts with the blood capillaries inside villus where blood carries: water, mineral salts, mono-saccharides (glucose), amino acids and water soluble vitamins. ٘جس٤ٓضج٤ثُلٝ ز٤٘٤ٓثألفٔجع ثألٝ ز٣جس ثألفجد٣ثُغٌشٝ ز٤ٗثألٓالؿ ثُٔؼذٝ قَٔ ثُذّ ثُٔجء٣ ظ٤ز دثخَ ًَ خِٔز ف٣ٞٓشثس ثُذ٤ذذأ دجُشؼ٣ . ثُٔجء٢ثُزثةذز ك
o These substances are carried to the hepatic portal vein, to the liver, then out of the liver through the hepatic vein to be emptied into the inferior vena cava, then to the heart. . عْ ثُوِخ٢ِف ثُغلٞذ ثألؽ٣سُٞ عْ ث١ذ ثٌُذذ٣سُٞ ثٌُذذ عْ ث٠ُٓ٘ز إٝ ١ ثٌُذذ٢ذ ثُذجد٣سُٞ ث٢ُثد إُٞٔ ثٙزٛ َص٘ضو
Blood capillaries B. The lymphatic route:١ٝٔلج٤ُِن ث٣ثُـش o Fatty acids, glycerol, and fat- solved vitamins (A,D,E, and K), pass to lacteals. ز٣ٝٔلج٤ُِز ث٤ػٝ ثأل٠ُ إK-D-A. ٘جس٤ٓضج٤ج ٖٓ كٜ٤ح كٝز٣ ٓجٝ ز٤٘ٛثألفٔجع ثُذٝ ٖ٣غش٤ِ ثُؾٚ٤ٔش ك٣-
o Some of these fatty acids and glycerol may re-combine to form fats again in the epithelial cells of the villi. .ز ُِخٔالس٤ج ثُـذوز ثُـالة٣ دثخَ خالٟٕ ٓشر أخشٖٞٛ د٣ٌٞز ُض٤٘ٛثألفٔجع ثُذٝ ٖ٣غش٤ِؼجد ثصقجد دؼغ ثُؾ٣o Some of the finely emulsified fats (Fats droplets not hydrolyzed) are absorbed directly by being engulfed صذضِغby the epithelial cells. ز٤ج ثُـذوز ثُـجة٣وز ثُذِؼٔز (ثألدضالع) دخال٣ٔجس صٔضض ٓذجششثً دـش٣ًج دج ٗض٤ ُْ صقَِ ٓجة٢ٕ ثُضٞٛشثس ثُذ٤دؼغ هـ-
o All fats pass to the lacteals inside the villi, then to the lymphatic system which carries them slowly through a network of vessels to the superior vena cava then to the heart. عْ ثُوِخ١ِٞف ثُؼٞذ ثألؽ٣سُٞ ث٢ظخ ك٣ ١ ثُز١ٝٔلج٤ُِجصثٜ ثُؾ٢ُز دجُخِٔز عْ إ٤٘ز ثُِذ٤ػٝ ثأل٢ُٕ إٞٛغ ثُذ٤ٔ ؽٚعْ صضؾ
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Comparison between Blood and lymph route of absorption: Vessels transport digested food Pathway of digested food
Type of Food
Blood route blood capillaries inside villus
Lymph route Lacteals inside villus
These substances are carried from blood capillaries inside villus to the hepatic portal vein, to the liver, then out of the liver through the hepatic vein to be emptied into the inferior vena cava, then to the heart.
All fats pass to the lacteals inside the villi, then to the lymphatic system which carries them slowly through a network of vessels to the superior vena cava then to the heart. Fatty acids , glycerol , and fatsolved vitamins (A,D, and K)
blood carries: water, mineral salts, monosaccharides (glucose), amino acids and water soluble vitamins.
Adaptation of the villus to its function: خ ثُخِٔز٤ًصش o Folds, convolutions, villi and micro-villi on the inner epithelial lining of the ileum provide an enormous surface area for the absorption of nutrients. [About 10 m2 (approximately 5 times as the whole surface area of the human body)]. o Outer epithelial layer encloses a lacteal vessel surrounded by a network of both venous and arterial blood capillaries to absorb digested food. Q - G.R. Vitamin k transformed by lymph not blood? A- Because it is soluble in fat and not soluble in water. 2- Large intestine: Large intestine absorbing some water and salts from the undigested residues to leave semi-solid feaces. by means of the lining of the large intestines that has many folds and convolutions helping in that.
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NB Carbohydrates------Glucose ------------------------- Blood. Proteins ------------ Amino acids ------------------ -Blood Fat ----------------- Fatty acids ------Lymph ------Blood
Explain role of water in plant leaf and small intestine of man ? 1- Role of water in plant leaf: A- In Absorption: Water dissolves mineral salts, required for photosynthesis, in soil which facilitates its absorption. B- In photosynthesis: Water is one of the important raw material required to start light reactions of photosynthesis , as it split by energy released during transfer of electrons of the excited chlorophyll from high energy level to lower one into Hydrogen and Oxygen ions. Oxygen released from decomposition of water is released as a bi-product. Hydrogen combines with a co-enzyme NADP (present in the chloroplast) to give NADPH2, Which is benefit in 2 ways: 1- Fix (store) Hydrogen to prevent its escape or recombine with Oxygen once more. Also 2- NADPH2 will be use to fix CO2 in dark reactions. C- In transpiration: Water vapour transpiration helps in: (1) transport water and salts from soil to xylem vessels to leaf. And (2) reduce high atmospheric temperature which may harm protoplasm. 4- Food Metabolism )الزوثٍل الغزائً ( األٌض Definition: It is the process by which the body can utilize the absorbed food. جٜ صْ ثٓضظجط٢ثُضٝ ٓزٞؼُٜٔز ث٤ثد ثُـزثةُٞٔج ثُؾغْ دجٜ٘ٓ ذ٤غضل٣ ٢ز ثُض٤ِٔ ثُؼ٢ٛ It includes two opposite processes: ٖ٤ٖ ٓضؼجًغض٤ض٤ِٔصشَٔ ػٝ 1- Anabolism: عولٍخ الجٌبء
o In which the simple and small sized food particles convert into complex compounds that share in the body construction ٖ٣ٌٞ صas: Conversion of simple sugars (glucose) into complex carbohydrates (polysaccharides) that are stored in animal in the liver and muscles as glycogen .٢ٗثٞ٤ٗشج فAnd stored in plants as starch. Conversion of amino acids into different form of polypeptides and proteins needed by the body to build up new tissues. Conversion of fatty acids and glycerol into fats that is stored in the body especially under the skin. 2- Catabolism: ّذُٜز ث٤ِٔػ o In which the absorbed food substances especially sugars (glucose) are oxidized, to produce energy which is needed by the body to carry out its vital process. .ز٣ٞ٤ ثُقٚظجةلُٞ ْٗضجػ ثُـجهز ثُالصٓز ألدثء ثُؾغ
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)جس٣ز ثُٔٔضظز (خجطز ثُغٌش٤ثد ثُـزثةُٞٔج أًغذر ثٜ٤ضْ ك٣
Q- G.R. Body perform metabolism? A- To allow body to utilize the absorbed food. It includes two opposite processes: 1- Anabolism: o In which the simple and small sized food particles convert into complex compounds that share in the body construction, as: Conversion of simple sugars (glucose) into complex carbohydrates (polysaccharides) that are stored in the liver and muscles as glycogen. Conversion of amino acids into different form of polypeptides and proteins needed by the body to build up new tissues. Conversion of fatty acids and glycerol into fats that is stored in the body especially under the skin. 2- Catabolism: o In which the absorbed food substances especially sugars (glucose) are oxidized, to produce energy which is needed by the body to carry out its vital process. Q: What happen if a man eats excess fat not needed by the body? A- Fat will digest to fatty acids and glycerol, after its absorption, they are reunited again to form fat which stored under the skin during anabolism.
5- Excretion of Waste remains The large intestine and defecation: ّثُضخِض ٖٓ كؼالس ثُـؼجٝ ظز٤ِثألٓؼجء ثُـ Undigested food passes from the small intestine to the large intestine. Function: 1- Water and salts absorption: o Large intestine absorbing water and some salts from the undigested residues by osmosis, to leave semi-solid feaces. By means of the lining of the large intestines that has many folds and convolutions helping in that. o Complete water absorption does not occurs in small intestine because body need water in (1) Digestion : which is hydrolysis of food i. e. need water, (2) absorption : which occurs by diffusion or active transport and need soluble food ثعـز دـجٗزٞ طِذز دٚٓز صجسًز كؼالس ثُـؼجّ شذٞؼٜٓ ش٤ج ثُـ٣دؼغ ثألٓالؿ ٖٓ ثُذوجٝ ظز دجٓضظجص ثُٔجء٤ِّ ثألٓؼجء ثُـٞصو .جٜدر دٞؽُٞٔشر ث٤ رُي ثُضقضصثس ثٌُغ٢ج كٛغجػذ٣ ظز٤ِثألٓؼجء ثُـ 2- Residues decay ج٣ صضؼلٖ ثُذوجdue to the presence of some species of bacteria in the large intestine،ج٣ش٤ثع ٖٓ ثُذٌضٞٗد دؼغ أٞؽٝ دغذخto produce some substance useful to man (vitamin
B). The presence of bacteria is responsible for the bad odour and breakdown of these remains into simple substance. 3- Expelled waste remains as faeces شٌَ دشثص٠ِ عْ صـشد ثُلؼالس ػeasily through the anus ٖٓ كضقز ثُششػdue to: 1) Strong muscular contractions of the rectum ْ٤ ػؼالس ثُٔغضو٢ذر ك٣ؾز صوِظجس شذ٤ٗض accompanied with جٜظجفذ٣ relaxation of the two muscles of the anal sphincter on both sides of the anus ثُششػ٢ ؽجٗذ٠ِٖ ػ٤ٖ ثُؼجطشص٤ ثسصخجء ثُؼؼِض. 2) The large intestines secrete mucous that facilitates passage of the wastes out . ػٝس كؼالس ثُـؼجّ ُِخشَٝ ٓشٜغ٣ ١ظز ثُٔخجؽ ثُز٤ِصلشص ثألٓؼجء ثُـٝ
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Anal sphincter The role of bacteria in the colon. A. Bacteria (E. coli) in the colon live in a symbiotic relationship with humans. They gain nutrients and have a suitable environment in which to live as well as help us breakdown the food materials, whereby manufacturing vitamins and releasing minerals that we absorb along with water. Q- G.R. Residues decay in large intestine, not in any other part of digestive tract? A- Residues decay in large intestine due to the presence of some species of bacteria in the large intestine ،which decay residues to produce some substance useful to man. Residues does not decay in other parts of digestive tract due to absence of bacteria, as (1) digestive enzymes decay bacteria , (2) PH is unsuitable for bacterial growth as HCl in stomach and Na HCO3 in small intestine. Q- G.R. Lining of the large intestines has many folds and convolutions? A To increase the surface area to absorb water and salts from the undigested residues to leave semi-solid feaces. ٚظ٤ِ ثألٓؼجء ثُـٚٗش ٖٓ ثُضقضصثس دذـج٤ؽذ ًغٞ٣ عــ ثٓضظجص ثُٔجءٚ ٓغجفٙجد٣ ُض-ػ
Q- G.R. Water absorption is delayed till large intestines? A- Because: (1) Water is necessary for: (a) Enzymatic Hydrolysis of food substances. (b) Movement of food through the digestive tract. (c) Food absorption. (2) The remaining water will be absorbed by means of its lining that has many folds and convolutions. . ظز٤ِش ثٓضظجص ٓؼظْ ثُٔجء دجألٓؼجء ثُـ٤ضْ صؤخ٣ ٢ٛ ظز٤ِ ثألٓؼجء ثُـ٢شر ك٤ ًٔج إٔ ثُضقضصثس ثٌُغ، ثُٔجء ػ٘ذ ثالٓضظجص٠ُقضجػ إ٣ ؼْ ثُـؼجّ ًٔج إٔ ثُـزثءُٜ ١سٝألٕ ثُٔجء ػش . ز ثٓضظجص ثُٔجء٤ِٔ ػ٠ِ صغجػذ ػ٢ثُض
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Q- G.R. Waste remains are expelled easily through the anus? A- Because of (1) Strong muscular contractions of the rectum accompanied with relaxation of the two muscles of the anal sphincter on both sides of the anus .(2) The large intestines secrete mucous that facilitates passage of the wastes out. Q- G.R. Large intestine secrete mucous? A- To facilitate passage of faeces to outside through the anus. . ظز ثُٔخجؽ٤ِصُلشص ثألٓؼجء ثُـ . ثُخجسػ٠ُس كؼالس ثُـؼجّ (ثُذشثص ) إَٝ ٓشٜغ٤ُ
Q: What happen if Inflammation of large intestine? 1- Stop water and salt absorption in large intestine ------ water and salt loss in faeces----dehydration ؽلجف. 2- Colic in large intestine and rectum ---- rapid expulsion of fluid faeces . Q: What happen if Large intestine is removed from the body of an animal? Large intestine absorbing water and salts from the undigested residues to leave semisolid feaces. If removed : Water and salts will not absorbed completely so feaces become semi fluid and contains some salts that is needed by the body.
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