AQA A-Level Biology Mark Scheme Specific
Study online at https://quizlet.com/_hb77mk
1. Hydrolysis Breaks a chemical bonds between two molecules; Using water;
2. Glycogen Polysaccharide of α-glucose; (Joined by) glycosidic bonds; Branched structure;
3. Cellulose Made up of β-glucose (monomers); Cellulose molecule has straight chain and
glycogen is branched; Glycogen has 1,4- and 1,6- glycosidic bonds and cellulose
has only 1,4- glycosidic bonds;
4. Glycogen Struc- Insoluble (in water), so doesn't affect water potential; Branched / coiled / (α-)-
ture Related to helix, so makes molecule compact; Polymer of (α-)glucose so provides glucose
Function for respiration; Branched / more ends for fast breakdown / enzyme action; Large
(molecule), so can't cross the cell membrane;
5. Starch Properties Insoluble; Don't affect water potential; Helical; Compact; Large molecule; Cannot
leave cell;
6. Phospholipids vs Both contain ester bonds (between glycerol and fatty acid); Both contain glycerol;
Triglycerides Fatty acids on both may be saturated or unsaturated; Both are insoluble in water;
Both contain C, H and O but phospholipids also contain P; Triglyceride has three
fatty acids and phospholipid has two fatty acids plus phosphate group; Triglyc-
erides are hydrophobic/non-polar and phospholipids have hydrophilic/polar
and hydrophobic/polar region; Phospholipids form monolayer (on surface)/mi-
celle/bilayer (in water) but triglycerides don't;
7. Protein Structure Polymer of amino acids; Joined by peptide bonds; Formed by condensation;
Primary structure is order of amino acids; Secondary structure is folding of
polypeptide chain due to hydrogen bonding; Tertiary structure is 3-D folding due
to hydrogen bonding and ionic/disulfide bonds; Quaternary structure is two or
more polypeptide chains;
8. Induced Fit Mod- (before reaction) active site not complementary to/does not fit substrate; Shape
el of active site changes as substrate binds/as enzyme-substrate complex forms;
Stressing/distorting/bending bonds (in substrate leading to reaction);
, AQA A-Level Biology Mark Scheme Specific
Study online at https://quizlet.com/_hb77mk
9. Increased Tem- Particles have more kinetic energy; therefore they move more; so there are more
perature and Re- collisions between substrates and active sites; so more ES complexes form;
action Rate
10. Enzyme Denatu- Heat above the optimum breaks hydrogen bonds; this causes the tertiary structure
ration to unfold; so the active site changes shape; substrate can no longer bind to the
active site, as it's no longer complementary; so fewer ES complexes form;
11. Effect of Changes Ionic bonds holding tertiary structure break; active site distorts and substrate no
in pH longer binds to active site; charges on amino acids in active site affected; fewer
ES complexes form;
12. Concentration of (Rate of) increase in concentration of product slows as substrate is used up OR
Substrate High initial rate as plenty of substrate/more E-S complexes; No increase after 25
minutes/at end/levels off because no substrate left;
13. Temperature Initial rate of reaction faster at 37 °C (than 25 °C); Because more kinetic energy; So
Graph of Enzyme more E-S collisions/more E-S complexes formed; Graph reaches plateau /levels
Rate off at 37 °C; Because all substrate used up;
14. Competitive vs Competitive inhibitor binds to active sites of enzyme but non-competitive inhibitor
Non-Competi- binds at allosteric site/away from active site; (Binding of) competitive inhibitor
tive Inhibition does not cause change in shape of active site but (binding of) non-competitive
does (cause change in size of active site); So with competitive inhibitor, at high
substrate concentrations (active) enzyme still available but with non-competitive
inhibitor (active) enzymes no longer available; At higher substrate concentrations
likelihood of enzyme-substrate collisions increases with competitive inhibitor but
this is not possible with non-competitive inhibitor;
15. Effect of Temper- Enzyme activity reduced/(some) enzymes denatured; Less photosynthesis, so
ature on Plant fewer sugars formed (plants only); Less (complex) biological molecules/organ-
Growth ic substances made (that add to mass); Less respiration; Less energy/ATP for
growth; Less energy for named function associated with growth (eg mitosis);
, AQA A-Level Biology Mark Scheme Specific
Study online at https://quizlet.com/_hb77mk
16. DNA Replication Helicase unzips DNA double helix by breaking hydrogen bonds; free DNA nu-
cleotides in the nucleus complementary base pair OR A to T and C to G; with
exposed bases on both strands; hydrogen bonds between complementary base
pairs reform; both strands act as a template; DNA polymerase (causes); Nu-
cleotides to join together (to form new strand)/phosphodiester bonds to form;
17. Semi-Conserva- Idea of both original strands being copied/both are template strands; Each new
tive Replication DNA molecule consists of one original and one new strand of DNA;
18. ATP Uses and Releases relatively small amount of energy / little energy lost as heat; Releases
Properties energy instantaneously; Phosphorylates other compounds, making them more
reactive; Can be rapidly re-synthesised; Does not leave cells;
19. ATP Structure vs ATP has ribose and DNA has deoxyribose; ATP has 3 phosphates and DNA nu-
DNA Nucleotide cleotide has one phosphate; Base is always adenine in ATP and bases vary in DNA
nucleotide (A,C,G or T);
20. Water Properties A metabolite in condensation/hydrolysis/photosynthesis/respiration; A solvent so
(metabolic) reactions can occur; High heat capacity so buffers changes in tem-
perature; Large latent heat of vaporisation so provides a cooling effect (through
evaporation); Cohesion (between water molecules) so supports columns of water
(in plants); Cohesion (between water molecules) so produces surface tension
supporting organisms;
21. High heat capaci- Buffers temperature changes in biological systems.
ty
22. Latent heat of va- Cooling effect through evaporation of water.
porisation
23. Cohesion Attraction between water molecules supporting plant water columns.
24. Surface tension Supports small organisms on water surface.
Study online at https://quizlet.com/_hb77mk
1. Hydrolysis Breaks a chemical bonds between two molecules; Using water;
2. Glycogen Polysaccharide of α-glucose; (Joined by) glycosidic bonds; Branched structure;
3. Cellulose Made up of β-glucose (monomers); Cellulose molecule has straight chain and
glycogen is branched; Glycogen has 1,4- and 1,6- glycosidic bonds and cellulose
has only 1,4- glycosidic bonds;
4. Glycogen Struc- Insoluble (in water), so doesn't affect water potential; Branched / coiled / (α-)-
ture Related to helix, so makes molecule compact; Polymer of (α-)glucose so provides glucose
Function for respiration; Branched / more ends for fast breakdown / enzyme action; Large
(molecule), so can't cross the cell membrane;
5. Starch Properties Insoluble; Don't affect water potential; Helical; Compact; Large molecule; Cannot
leave cell;
6. Phospholipids vs Both contain ester bonds (between glycerol and fatty acid); Both contain glycerol;
Triglycerides Fatty acids on both may be saturated or unsaturated; Both are insoluble in water;
Both contain C, H and O but phospholipids also contain P; Triglyceride has three
fatty acids and phospholipid has two fatty acids plus phosphate group; Triglyc-
erides are hydrophobic/non-polar and phospholipids have hydrophilic/polar
and hydrophobic/polar region; Phospholipids form monolayer (on surface)/mi-
celle/bilayer (in water) but triglycerides don't;
7. Protein Structure Polymer of amino acids; Joined by peptide bonds; Formed by condensation;
Primary structure is order of amino acids; Secondary structure is folding of
polypeptide chain due to hydrogen bonding; Tertiary structure is 3-D folding due
to hydrogen bonding and ionic/disulfide bonds; Quaternary structure is two or
more polypeptide chains;
8. Induced Fit Mod- (before reaction) active site not complementary to/does not fit substrate; Shape
el of active site changes as substrate binds/as enzyme-substrate complex forms;
Stressing/distorting/bending bonds (in substrate leading to reaction);
, AQA A-Level Biology Mark Scheme Specific
Study online at https://quizlet.com/_hb77mk
9. Increased Tem- Particles have more kinetic energy; therefore they move more; so there are more
perature and Re- collisions between substrates and active sites; so more ES complexes form;
action Rate
10. Enzyme Denatu- Heat above the optimum breaks hydrogen bonds; this causes the tertiary structure
ration to unfold; so the active site changes shape; substrate can no longer bind to the
active site, as it's no longer complementary; so fewer ES complexes form;
11. Effect of Changes Ionic bonds holding tertiary structure break; active site distorts and substrate no
in pH longer binds to active site; charges on amino acids in active site affected; fewer
ES complexes form;
12. Concentration of (Rate of) increase in concentration of product slows as substrate is used up OR
Substrate High initial rate as plenty of substrate/more E-S complexes; No increase after 25
minutes/at end/levels off because no substrate left;
13. Temperature Initial rate of reaction faster at 37 °C (than 25 °C); Because more kinetic energy; So
Graph of Enzyme more E-S collisions/more E-S complexes formed; Graph reaches plateau /levels
Rate off at 37 °C; Because all substrate used up;
14. Competitive vs Competitive inhibitor binds to active sites of enzyme but non-competitive inhibitor
Non-Competi- binds at allosteric site/away from active site; (Binding of) competitive inhibitor
tive Inhibition does not cause change in shape of active site but (binding of) non-competitive
does (cause change in size of active site); So with competitive inhibitor, at high
substrate concentrations (active) enzyme still available but with non-competitive
inhibitor (active) enzymes no longer available; At higher substrate concentrations
likelihood of enzyme-substrate collisions increases with competitive inhibitor but
this is not possible with non-competitive inhibitor;
15. Effect of Temper- Enzyme activity reduced/(some) enzymes denatured; Less photosynthesis, so
ature on Plant fewer sugars formed (plants only); Less (complex) biological molecules/organ-
Growth ic substances made (that add to mass); Less respiration; Less energy/ATP for
growth; Less energy for named function associated with growth (eg mitosis);
, AQA A-Level Biology Mark Scheme Specific
Study online at https://quizlet.com/_hb77mk
16. DNA Replication Helicase unzips DNA double helix by breaking hydrogen bonds; free DNA nu-
cleotides in the nucleus complementary base pair OR A to T and C to G; with
exposed bases on both strands; hydrogen bonds between complementary base
pairs reform; both strands act as a template; DNA polymerase (causes); Nu-
cleotides to join together (to form new strand)/phosphodiester bonds to form;
17. Semi-Conserva- Idea of both original strands being copied/both are template strands; Each new
tive Replication DNA molecule consists of one original and one new strand of DNA;
18. ATP Uses and Releases relatively small amount of energy / little energy lost as heat; Releases
Properties energy instantaneously; Phosphorylates other compounds, making them more
reactive; Can be rapidly re-synthesised; Does not leave cells;
19. ATP Structure vs ATP has ribose and DNA has deoxyribose; ATP has 3 phosphates and DNA nu-
DNA Nucleotide cleotide has one phosphate; Base is always adenine in ATP and bases vary in DNA
nucleotide (A,C,G or T);
20. Water Properties A metabolite in condensation/hydrolysis/photosynthesis/respiration; A solvent so
(metabolic) reactions can occur; High heat capacity so buffers changes in tem-
perature; Large latent heat of vaporisation so provides a cooling effect (through
evaporation); Cohesion (between water molecules) so supports columns of water
(in plants); Cohesion (between water molecules) so produces surface tension
supporting organisms;
21. High heat capaci- Buffers temperature changes in biological systems.
ty
22. Latent heat of va- Cooling effect through evaporation of water.
porisation
23. Cohesion Attraction between water molecules supporting plant water columns.
24. Surface tension Supports small organisms on water surface.
