AQA A level Biology Revision Questions
Get a hint
Describe how you would use a biochemical test to show that a solution contained a non-reducing sugar,
such as sucrose. [3] - ✔✔,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] - ✔✔
(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] - ✔✔Molecule) made up of many identical/similar
molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] - ✔✔Hydrolysis
What is the formula for lactose? [2] - ✔✔C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - ✔✔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] - ✔✔
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] - ✔✔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] - ✔✔
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] - ✔✔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] - ✔✔
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] - ✔✔Carbon, hydrogen, oxygen, nitrogen (sometimes
sulphur)
Describe how you would use a biochemical test to show that a solution contained protein. [2] - ✔✔
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] - ✔✔
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] - ✔✔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] - ✔✔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] - ✔✔
Spreads spots/polypeptides out more/ make sure spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - ✔✔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] - ✔✔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] - ✔✔(Enzyme has) active site; Only substrate
fits (the active site);
Describe the induced fit model of enzyme action. [2] - ✔✔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] - ✔✔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] - ✔✔(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] - ✔✔149
How do you calculate magnification? [1] - ✔✔M= I (Image)/ A (actual size)
Describe the ways in which prokaryotic cells and eukaryotic cells differ. [3] - ✔✔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] -
✔✔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] - ✔✔
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;
Why an electron microscope can be used to produce images [2] - ✔✔EM gives high resolution due to
short wavelength of electrons;
Explain how viruses cause damage to cells. [3] - ✔✔uses / breaks up / digests host nuclear / genetic
material (allow references made to DNA /RNA instead of nuclear /genetic); virus DNA / genetic material
inserted into hosts DNA / chromosome / genetic material; host cells amino acids are used to synthesize
viral proteins; cell lysis; by enzyme (produced by expressing a virus gene); toxin production;
Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria
from a suspension of animal cells. [5] - ✔✔Cell homogenisation to break open cells; 1. Accept suitable
method of breaking open cells. Filter to remove (large) debris / whole cells; 2. Reject removes cell walls.
Use isotonic solution to prevent damage to mitochondria / organelles; Keep cold to prevent / reduce
Get a hint
Describe how you would use a biochemical test to show that a solution contained a non-reducing sugar,
such as sucrose. [3] - ✔✔,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] - ✔✔
(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] - ✔✔Molecule) made up of many identical/similar
molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] - ✔✔Hydrolysis
What is the formula for lactose? [2] - ✔✔C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - ✔✔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] - ✔✔
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] - ✔✔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] - ✔✔
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] - ✔✔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] - ✔✔
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] - ✔✔Carbon, hydrogen, oxygen, nitrogen (sometimes
sulphur)
Describe how you would use a biochemical test to show that a solution contained protein. [2] - ✔✔
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] - ✔✔
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] - ✔✔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] - ✔✔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] - ✔✔
Spreads spots/polypeptides out more/ make sure spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - ✔✔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] - ✔✔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] - ✔✔(Enzyme has) active site; Only substrate
fits (the active site);
Describe the induced fit model of enzyme action. [2] - ✔✔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] - ✔✔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] - ✔✔(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] - ✔✔149
How do you calculate magnification? [1] - ✔✔M= I (Image)/ A (actual size)
Describe the ways in which prokaryotic cells and eukaryotic cells differ. [3] - ✔✔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] -
✔✔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] - ✔✔
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;
Why an electron microscope can be used to produce images [2] - ✔✔EM gives high resolution due to
short wavelength of electrons;
Explain how viruses cause damage to cells. [3] - ✔✔uses / breaks up / digests host nuclear / genetic
material (allow references made to DNA /RNA instead of nuclear /genetic); virus DNA / genetic material
inserted into hosts DNA / chromosome / genetic material; host cells amino acids are used to synthesize
viral proteins; cell lysis; by enzyme (produced by expressing a virus gene); toxin production;
Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria
from a suspension of animal cells. [5] - ✔✔Cell homogenisation to break open cells; 1. Accept suitable
method of breaking open cells. Filter to remove (large) debris / whole cells; 2. Reject removes cell walls.
Use isotonic solution to prevent damage to mitochondria / organelles; Keep cold to prevent / reduce
