AQA A level Biology Revision
1. Describe how you would use a biochemical test to show that a solution contained a non-
reducing sugar, such as sucrose. [3] - Answer-,first reducing sugars test; boil with dilute HCl
acid then Neutralise with NaHCǑ, add benedict and heat to 95 degrees C brick red ppt forms
if reducing sugar is present
2. Describe a chemical test you could carry out to show that a piece of coconut contains lipids.
[3] - Answer-(Crush in) ethanol / alcohol; Add (to) water (Order of adding is critical for this
point); Emulsion / white colour
3. Explain what is meant by a polymer. [1] - Answer-Molecule) made up of many
identical/similar molecules/monomers/ subunits;
4. Name the reaction which occurs when starch is broken down into maltose. [1] - Answer-
Hydrolysis
5. What is the formula for lactose? [2] - Answer-C12 ; H22Ō1
6. Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - Answer-H at top
right end (instead of OH) / OH at bottom (carbon 1)
7. Show two ways in which the structure of cellulose is different from the structure of starch.
[2] - Answer-Starch 1,4 and 1,6 bonds / branching Cellulose 1,4 bonds / no 1,6 bonds /
straight; starch All glucoses /monomers same way up cellulose Alternate glucoses upside
down; starch Helix / coiled/compact cellulose Straight; Starch monomer Alpha glucose
Cellulose monomer Beta glucose
8. Describe the structure of starch and explain how its structure is related to its function. [3] -
Answer-Formed from α glucose; Joined by condensation/ by the removal of a water
molecule/ glycosidic bonds; Between (carbons) 1 and 4 (and 1 and 6); Coiled chain; compact;
(Allows) storage of large amount in a small space; Insoluble so has no effect on
osmosis/water potential; Branches; (Allows) rapid breakdown/release of glucose /
hydrolysis;
9. The structure of a phospholipid molecule is different from that of a triglyceride. Describe
how. [2] - Answer-triglyceride has three fatty acids and phospholipid has two; no phosphate
group present in triglyceride but present in phospholipid.
, 10. What is an unsaturated fatty acid? [1] - Answer-Some / two carbons with only one hydrogen
/ (double bonds) between carbon atoms / not saturated with hydrogen;
11. Describe the structure of cellulose and explain how its structure is related to its function. [3]
- Answer-Alternate β-glucose rotated 180o, long straight chains, Many hydrogen bonds join
(polysaccharide) chains/molecules to each other / makes microfibrils / gives tensile strength;
12. Which elements are found in proteins? [1] - Answer-Carbon, hydrogen, oxygen, nitrogen
(sometimes sulphur)
13. Describe how you would use a biochemical test to show that a solution contained protein.
[2] - Answer-Biuret / alkali + copper sulphate; Lilac/purple/mauve/violet;
14. Which bonds are found in a)Primary structure [1]b)Secondary structure [1] c)Tertiary
structure [2] - Answer-a)Peptide b) Hydrogen (and peptide) c)Ionic, disulphide bridges,
hydrophobic interactions (hydrogen and peptide)
15. Explain how a change in the primary structure of a globular protein may result in a different
three-dimensional structure. [3] - Answer-Sequence of amino acids changes; tertiary
structure changes/folds in a different way; bonds form in different places (not peptide);
16. Describe how two-way chromatography is carried out. [2] - Answer-Run chromatogram then
turn through 90/right angle; With a different solvent;
17. Explain the advantage of using two-way chromatography to separate short polypeptides. [2]
- Answer-Spreads spots/polypeptides out more/ make sure spot only contains one
substance;
18. Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - Answer-
Statement about two types, competitive and non-competitive; Competitive: Similar shape to
substrate;Inhibitor can enter/bind with active site (of enzyme);Non-competitive: Affect/bind
to enzyme other than at active site; Distorts shape of active site; Inhibitors: Prevent entry
of/binding of substrate to active site; Therefore fewer/no enzyme-substrate complexes
formed;
1. Describe how you would use a biochemical test to show that a solution contained a non-
reducing sugar, such as sucrose. [3] - Answer-,first reducing sugars test; boil with dilute HCl
acid then Neutralise with NaHCǑ, add benedict and heat to 95 degrees C brick red ppt forms
if reducing sugar is present
2. Describe a chemical test you could carry out to show that a piece of coconut contains lipids.
[3] - Answer-(Crush in) ethanol / alcohol; Add (to) water (Order of adding is critical for this
point); Emulsion / white colour
3. Explain what is meant by a polymer. [1] - Answer-Molecule) made up of many
identical/similar molecules/monomers/ subunits;
4. Name the reaction which occurs when starch is broken down into maltose. [1] - Answer-
Hydrolysis
5. What is the formula for lactose? [2] - Answer-C12 ; H22Ō1
6. Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - Answer-H at top
right end (instead of OH) / OH at bottom (carbon 1)
7. Show two ways in which the structure of cellulose is different from the structure of starch.
[2] - Answer-Starch 1,4 and 1,6 bonds / branching Cellulose 1,4 bonds / no 1,6 bonds /
straight; starch All glucoses /monomers same way up cellulose Alternate glucoses upside
down; starch Helix / coiled/compact cellulose Straight; Starch monomer Alpha glucose
Cellulose monomer Beta glucose
8. Describe the structure of starch and explain how its structure is related to its function. [3] -
Answer-Formed from α glucose; Joined by condensation/ by the removal of a water
molecule/ glycosidic bonds; Between (carbons) 1 and 4 (and 1 and 6); Coiled chain; compact;
(Allows) storage of large amount in a small space; Insoluble so has no effect on
osmosis/water potential; Branches; (Allows) rapid breakdown/release of glucose /
hydrolysis;
9. The structure of a phospholipid molecule is different from that of a triglyceride. Describe
how. [2] - Answer-triglyceride has three fatty acids and phospholipid has two; no phosphate
group present in triglyceride but present in phospholipid.
, 10. What is an unsaturated fatty acid? [1] - Answer-Some / two carbons with only one hydrogen
/ (double bonds) between carbon atoms / not saturated with hydrogen;
11. Describe the structure of cellulose and explain how its structure is related to its function. [3]
- Answer-Alternate β-glucose rotated 180o, long straight chains, Many hydrogen bonds join
(polysaccharide) chains/molecules to each other / makes microfibrils / gives tensile strength;
12. Which elements are found in proteins? [1] - Answer-Carbon, hydrogen, oxygen, nitrogen
(sometimes sulphur)
13. Describe how you would use a biochemical test to show that a solution contained protein.
[2] - Answer-Biuret / alkali + copper sulphate; Lilac/purple/mauve/violet;
14. Which bonds are found in a)Primary structure [1]b)Secondary structure [1] c)Tertiary
structure [2] - Answer-a)Peptide b) Hydrogen (and peptide) c)Ionic, disulphide bridges,
hydrophobic interactions (hydrogen and peptide)
15. Explain how a change in the primary structure of a globular protein may result in a different
three-dimensional structure. [3] - Answer-Sequence of amino acids changes; tertiary
structure changes/folds in a different way; bonds form in different places (not peptide);
16. Describe how two-way chromatography is carried out. [2] - Answer-Run chromatogram then
turn through 90/right angle; With a different solvent;
17. Explain the advantage of using two-way chromatography to separate short polypeptides. [2]
- Answer-Spreads spots/polypeptides out more/ make sure spot only contains one
substance;
18. Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - Answer-
Statement about two types, competitive and non-competitive; Competitive: Similar shape to
substrate;Inhibitor can enter/bind with active site (of enzyme);Non-competitive: Affect/bind
to enzyme other than at active site; Distorts shape of active site; Inhibitors: Prevent entry
of/binding of substrate to active site; Therefore fewer/no enzyme-substrate complexes
formed;
