AQA A LEVEL BIOLOGY REVISION 2023
REVISION PAPERS WITH CORRECT
QUESTIONS AND ANSWERS
Describe how you would use a biochemical test to show that a solution contained a non-
reducing sugar, such as sucrose. [3](Correct Answers) ,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
Describe a chemical test you could carry out to show that a piece of coconut contains
lipids. [3](Correct Answers) (Crush in) ethanol / alcohol; Add (to) water (Order of adding
is critical for this point); Emulsion / white colour
Explain what is meant by a polymer. [1](Correct Answers) Molecule) made up of many
identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1](Correct
Answers) Hydrolysis
What is the formula for lactose? [2](Correct Answers) C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1](Correct
Answers) H at top right end (instead of OH) / OH at bottom (carbon 1)
Show two ways in which the structure of cellulose is different from the structure of
starch. [2](Correct Answers) 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
Describe the structure of starch and explain how its structure is related to its function.
[3](Correct Answers) 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;
, The structure of a phospholipid molecule is different from that of a triglyceride. Describe
how. [2](Correct Answers) triglyceride has three fatty acids and phospholipid has two;
no phosphate group present in triglyceride but present in phospholipid.
What is an unsaturated fatty acid? [1](Correct Answers) Some / two carbons with only
one hydrogen / (double bonds) between carbon atoms / not saturated with hydrogen;
Describe the structure of cellulose and explain how its structure is related to its function.
[3](Correct Answers) Alternate β-glucose rotated 180o, long straight chains, Many
hydrogen bonds join (polysaccharide) chains/molecules to each other / makes
microfibrils / gives tensile strength;
Which elements are found in proteins? [1](Correct Answers) Carbon, hydrogen, oxygen,
nitrogen (sometimes sulphur)
Describe how you would use a biochemical test to show that a solution contained
protein. [2](Correct Answers) Biuret / alkali + copper sulphate; Lilac/purple/mauve/violet;
Which bonds are found in a)Primary structure [1]b)Secondary structure [1] c)Tertiary
structure [2](Correct Answers) a)Peptide b) Hydrogen (and peptide) c)Ionic, disulphide
bridges, hydrophobic interactions (hydrogen and peptide)
Explain how a change in the primary structure of a globular protein may result in a
different three-dimensional structure. [3](Correct Answers) Sequence of amino acids
changes; tertiary structure changes/folds in a different way; bonds form in different
places (not peptide);
Describe how two-way chromatography is carried out. [2](Correct Answers) Run
chromatogram then turn through 90/right angle; With a different solvent;
Explain the advantage of using two-way chromatography to separate short
polypeptides. [2](Correct Answers) Spreads spots/polypeptides out more/ make sure
spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6](Correct
Answers) 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;
Describe and explain how an increase in temperature affects the rate of an enzyme
controlled reaction. [5](Correct Answers) Rate of reaction increases; Increasing
temperature increases rate of movement of molecules/ kinetic energy; Collide more
often/substrate enters active site more often/more enzyme-substrate complexes formed;
Up to optimum; Rate of reaction decreases; High temperatures cause denaturation/loss
REVISION PAPERS WITH CORRECT
QUESTIONS AND ANSWERS
Describe how you would use a biochemical test to show that a solution contained a non-
reducing sugar, such as sucrose. [3](Correct Answers) ,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
Describe a chemical test you could carry out to show that a piece of coconut contains
lipids. [3](Correct Answers) (Crush in) ethanol / alcohol; Add (to) water (Order of adding
is critical for this point); Emulsion / white colour
Explain what is meant by a polymer. [1](Correct Answers) Molecule) made up of many
identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1](Correct
Answers) Hydrolysis
What is the formula for lactose? [2](Correct Answers) C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1](Correct
Answers) H at top right end (instead of OH) / OH at bottom (carbon 1)
Show two ways in which the structure of cellulose is different from the structure of
starch. [2](Correct Answers) 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
Describe the structure of starch and explain how its structure is related to its function.
[3](Correct Answers) 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;
, The structure of a phospholipid molecule is different from that of a triglyceride. Describe
how. [2](Correct Answers) triglyceride has three fatty acids and phospholipid has two;
no phosphate group present in triglyceride but present in phospholipid.
What is an unsaturated fatty acid? [1](Correct Answers) Some / two carbons with only
one hydrogen / (double bonds) between carbon atoms / not saturated with hydrogen;
Describe the structure of cellulose and explain how its structure is related to its function.
[3](Correct Answers) Alternate β-glucose rotated 180o, long straight chains, Many
hydrogen bonds join (polysaccharide) chains/molecules to each other / makes
microfibrils / gives tensile strength;
Which elements are found in proteins? [1](Correct Answers) Carbon, hydrogen, oxygen,
nitrogen (sometimes sulphur)
Describe how you would use a biochemical test to show that a solution contained
protein. [2](Correct Answers) Biuret / alkali + copper sulphate; Lilac/purple/mauve/violet;
Which bonds are found in a)Primary structure [1]b)Secondary structure [1] c)Tertiary
structure [2](Correct Answers) a)Peptide b) Hydrogen (and peptide) c)Ionic, disulphide
bridges, hydrophobic interactions (hydrogen and peptide)
Explain how a change in the primary structure of a globular protein may result in a
different three-dimensional structure. [3](Correct Answers) Sequence of amino acids
changes; tertiary structure changes/folds in a different way; bonds form in different
places (not peptide);
Describe how two-way chromatography is carried out. [2](Correct Answers) Run
chromatogram then turn through 90/right angle; With a different solvent;
Explain the advantage of using two-way chromatography to separate short
polypeptides. [2](Correct Answers) Spreads spots/polypeptides out more/ make sure
spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6](Correct
Answers) 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;
Describe and explain how an increase in temperature affects the rate of an enzyme
controlled reaction. [5](Correct Answers) Rate of reaction increases; Increasing
temperature increases rate of movement of molecules/ kinetic energy; Collide more
often/substrate enters active site more often/more enzyme-substrate complexes formed;
Up to optimum; Rate of reaction decreases; High temperatures cause denaturation/loss
