AQA A level Biology Revision questions and
answers 100% verified.
Describe how you would use a biochemical test to show that a solution contained a non-
reducing sugar, such as sucrose. [3] - correct 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
Describe a chemical test you could carry out to show that a piece of coconut contains
lipids. [3] - correct answer. (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 answer. Molecule) made up of many
identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] - correct
answer. Hydrolysis
What is the formula for lactose? [2] - correct answer. C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - correct
answer. 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 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
Describe the structure of starch and explain how its structure is related to its function.
[3] - correct 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;
,The structure of a phospholipid molecule is different from that of a triglyceride. Describe
how. [2] - correct answer. 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 answer. 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 answer. 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 answer. Carbon, hydrogen,
oxygen, nitrogen (sometimes sulphur)
Describe how you would use a biochemical test to show that a solution contained
protein. [2] - correct answer. 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 answer. 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 answer. 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 answer. 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 answer. Spreads spots/polypeptides out more/ make sure
spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - correct
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;
Describe and explain how an increase in temperature affects the rate of an enzyme
controlled reaction. [5] - correct answer. 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
of tertiary structure/3D structure; By breaking specified bonds (not peptide bond); Active
site altered/substrate cannot bind/fit/
An enzyme catalyses only one reaction. Explain why [2] - correct answer. (Enzyme
has) active site; Only substrate fits (the active site);
Describe the induced fit model of enzyme action. [2] - correct answer. Active site /
enzyme not complementary; Active site changes (shape) / is flexible; (Change in
enzyme allows) substrate to fit / E-S complex to form;
Describe one way that the lock and key model is different from the induced fit model. [1]
- correct answer. Active site does not change (shape) / is fixed (shape) / is rigid / does
not wrap around substrate / (already) fits the substrate / is complementary (before
binding);
Explain why the rate of reaction of an enzyme is low away from its optimum pH. [3] -
correct answer. (change in pH) leads to breaking of bonds holding tertiary structure/
changes charge on amino acids; enzyme/protein/active site loses shape/denatured;
substrate will not bind with/fit active site; fewer/no ES complexes formed;
A protein molecule contains 150 amino acids. What is the total number of peptide bonds
in this molecule? [1] - correct answer. 149
How do you calculate magnification? [1] - correct answer. M= I (Image)/ A (actual
size)
Describe the ways in which prokaryotic cells and eukaryotic cells differ. [3] - correct
answer. Prokaryotic cells do not have a nucleus / have genetic material in cytoplasm;
DNA in loop / ring; Not associated with proteins / do not have chromosomes /chromatin
/ do not divide by mitosis; Smaller ribosomes; No membrane-bound organelles; Such as
mitochondria / lysosomes / endoplasmic reticulum / Golgi / chloroplasts; Prokaryotic
cells may have mesosomes; Prokaryotic cells smaller; May be enclosed by capsule;
What is the function of: a)Ribosome b)Smooth ER c)Golgi apparatus d) Chloroplast
e)Mitochondria [5] - correct answer. a)Protein synthesis b)Lipid synthesis and
transport c)Processing and packaging proteins for secretion d)Photosynthesis e)Aerobic
respiration to produce ATP
Explain the advantages and limitations of using a transmission electron microscope [5] -
correct answer. Advantages: Small objects can be seen; TEM has high resolution as
wavelength of electrons shorter; Limitations: Cannot look at living cells as cells must be
in a vacuum; must cut section / thin specimen; Preparation may create artefact; Does
not produce 3D or colored image;
answers 100% verified.
Describe how you would use a biochemical test to show that a solution contained a non-
reducing sugar, such as sucrose. [3] - correct 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
Describe a chemical test you could carry out to show that a piece of coconut contains
lipids. [3] - correct answer. (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 answer. Molecule) made up of many
identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] - correct
answer. Hydrolysis
What is the formula for lactose? [2] - correct answer. C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - correct
answer. 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 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
Describe the structure of starch and explain how its structure is related to its function.
[3] - correct 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;
,The structure of a phospholipid molecule is different from that of a triglyceride. Describe
how. [2] - correct answer. 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 answer. 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 answer. 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 answer. Carbon, hydrogen,
oxygen, nitrogen (sometimes sulphur)
Describe how you would use a biochemical test to show that a solution contained
protein. [2] - correct answer. 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 answer. 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 answer. 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 answer. 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 answer. Spreads spots/polypeptides out more/ make sure
spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - correct
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;
Describe and explain how an increase in temperature affects the rate of an enzyme
controlled reaction. [5] - correct answer. 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
of tertiary structure/3D structure; By breaking specified bonds (not peptide bond); Active
site altered/substrate cannot bind/fit/
An enzyme catalyses only one reaction. Explain why [2] - correct answer. (Enzyme
has) active site; Only substrate fits (the active site);
Describe the induced fit model of enzyme action. [2] - correct answer. Active site /
enzyme not complementary; Active site changes (shape) / is flexible; (Change in
enzyme allows) substrate to fit / E-S complex to form;
Describe one way that the lock and key model is different from the induced fit model. [1]
- correct answer. Active site does not change (shape) / is fixed (shape) / is rigid / does
not wrap around substrate / (already) fits the substrate / is complementary (before
binding);
Explain why the rate of reaction of an enzyme is low away from its optimum pH. [3] -
correct answer. (change in pH) leads to breaking of bonds holding tertiary structure/
changes charge on amino acids; enzyme/protein/active site loses shape/denatured;
substrate will not bind with/fit active site; fewer/no ES complexes formed;
A protein molecule contains 150 amino acids. What is the total number of peptide bonds
in this molecule? [1] - correct answer. 149
How do you calculate magnification? [1] - correct answer. M= I (Image)/ A (actual
size)
Describe the ways in which prokaryotic cells and eukaryotic cells differ. [3] - correct
answer. Prokaryotic cells do not have a nucleus / have genetic material in cytoplasm;
DNA in loop / ring; Not associated with proteins / do not have chromosomes /chromatin
/ do not divide by mitosis; Smaller ribosomes; No membrane-bound organelles; Such as
mitochondria / lysosomes / endoplasmic reticulum / Golgi / chloroplasts; Prokaryotic
cells may have mesosomes; Prokaryotic cells smaller; May be enclosed by capsule;
What is the function of: a)Ribosome b)Smooth ER c)Golgi apparatus d) Chloroplast
e)Mitochondria [5] - correct answer. a)Protein synthesis b)Lipid synthesis and
transport c)Processing and packaging proteins for secretion d)Photosynthesis e)Aerobic
respiration to produce ATP
Explain the advantages and limitations of using a transmission electron microscope [5] -
correct answer. Advantages: Small objects can be seen; TEM has high resolution as
wavelength of electrons shorter; Limitations: Cannot look at living cells as cells must be
in a vacuum; must cut section / thin specimen; Preparation may create artefact; Does
not produce 3D or colored image;
