COAS Biology 1 Teacher Resources. Original material ... 7 Marking scheme: End
-of-chapter test. 1 a Carbon, hydrogen and oxygen (all three for 1 mark). [1].
7 Marking scheme: End-of-chapter test 1
a b c d
2
[1] [2] [2] [2]
a
b
c d e 3
Carbon, hydrogen and oxygen (all three for 1 mark) Fatty acids, glycerol Any two: storage of energy/heat insulator/metabolic source of water/buoyancy (in sea mammals)/shock absorber around organs Nitrogen, sulfur
Diagram should show: δ+ on H δ– on O bond between molecules from H to O A lot of energy is needed to raise the temperature of water in the cells; so it is easier to keep the temperature of the body constant/metabolic rate stays constant/enzymes are unaffected. The columns of water in the vessels would break up; so water would not be carried up the stem/trunk/vessels of the plant. When the sweat evaporates; this takes a lot of heat from the skin/cools the skin. A molecule with an uneven distribution of charge. Carbohydrate
Chemical nature
One function
(glucose)
[1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [8]
source of energy/main substrate for respiration
(ribose)
monosaccharide/pentose
(maltose)
disaccharide of two glucose molecules
(starch)
polysaccharide of α-glucose
(glycogen)
polysaccharide of α-glucose
(cellulose)
COAS Biology 1 Teacher Resources
part of RNA/ATP
storage of carbohydrate in animals/fungi/bacteria present in plant cell walls
Diagram should show: SH groups (on cysteine side-chains) [1] form disulfide bonds [1] between polypeptide chains. [1] Globular protein molecules curl into a ‘ball’ shape; fibrous protein molecules form long strands (or equivalent); in globular proteins, hydrophilic/polar R groups are on the outside of the molecule, hydrophobic/non-polar R groups are on the inside of the molecule; globular proteins are (usually) soluble; fibrous proteins are (usually) insoluble. [max. 4] It consists of more than one polypeptide chain. [1] Glycine is a small (or the smallest) amino acid; [1] it allows the (three) strands/polypeptide chains (of collagen) to lie close together. [1]
Add Benedict’s solution to X and heat; if the colour changes to brick-red/orange/yellow/green, then reducing sugar is present; add dilute acid to X and heat; cool and add alkali (to neutralise acid); repeat Benedict’s test/description of test; if the test was negative before and is now positive, then only non-reducing sugar is present; if the test was positive before and is now darker red, then X is a mixture of reducing sugar and non-reducing sugar; credit need to dilute X to show difference, when testing for mixture. [max. 6]
