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]: ,first reducing sugars
test; boil with dilute HCl acid then Neutralise with NaHCÑ, 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]: (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]: Molecule) made up of many
identi- cal/similar molecules/monomers/ subunits;
4. Name the reaction which occurs when starch is broken down into
maltose. [1]: Hydrolysis
5. What is the formula for lactose? [2]: C12 ; H22L1
6. Describe how ²-glucose molecule differs from a molecule of ±g-lucose.
[1]: 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]: 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]: Formed from ±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
triglyc- eride. Describe how. [2]: 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]: 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]: Alternate ²-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]: Carbon, hydrogen, oxygen,
nitro- gen (sometimes sulphur)
13.Describe how you would use a biochemical test to show that a solution
contained protein. [2]: 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]: 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]: 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]: Run
chro- matogram then turn through 90/right angle; With a different
solvent;
17.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;
18. 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-com- petitive: 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-
1. 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 NaHCÑ, 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]: (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]: Molecule) made up of many
identi- cal/similar molecules/monomers/ subunits;
4. Name the reaction which occurs when starch is broken down into
maltose. [1]: Hydrolysis
5. What is the formula for lactose? [2]: C12 ; H22L1
6. Describe how ²-glucose molecule differs from a molecule of ±g-lucose.
[1]: 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]: 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]: Formed from ±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
triglyc- eride. Describe how. [2]: 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]: 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]: Alternate ²-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]: Carbon, hydrogen, oxygen,
nitro- gen (sometimes sulphur)
13.Describe how you would use a biochemical test to show that a solution
contained protein. [2]: 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]: 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]: 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]: Run
chro- matogram then turn through 90/right angle; With a different
solvent;
17.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;
18. 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-com- petitive: 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-
