1
AQA A LEVEL BIOLOGY REVISION EXAM |
QUESTIONS AND ANSWERS | VERIFIED
AND WELL DETAILED ANSWERS (100%
CORREECT) | LATEST EXAM UPDATE
Describe how you would use a biochemical test to show that a solution contained
a non-reducing sugar, such as sucrose. [3] - (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] - (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] - (answers)Molecule) made up of many
identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] -
(answers)Hydrolysis
What is the formula for lactose? [2] - (answers)C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] -
(answers)H at top right end (instead of OH) / OH at bottom (carbon 1)
,2
Show two ways in which the structure of cellulose is different from the structure
of starch. [2] - (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] - (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] - (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] - (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] - (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] - (answers)Carbon, hydrogen, oxygen,
nitrogen (sometimes sulphur)
, 3
Describe how you would use a biochemical test to show that a solution contained
protein. [2] - (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] - (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] - (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] - (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] - (answers)Spreads spots/polypeptides out more/ make sure
spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] -
(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;
AQA A LEVEL BIOLOGY REVISION EXAM |
QUESTIONS AND ANSWERS | VERIFIED
AND WELL DETAILED ANSWERS (100%
CORREECT) | LATEST EXAM UPDATE
Describe how you would use a biochemical test to show that a solution contained
a non-reducing sugar, such as sucrose. [3] - (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] - (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] - (answers)Molecule) made up of many
identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] -
(answers)Hydrolysis
What is the formula for lactose? [2] - (answers)C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] -
(answers)H at top right end (instead of OH) / OH at bottom (carbon 1)
,2
Show two ways in which the structure of cellulose is different from the structure
of starch. [2] - (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] - (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] - (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] - (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] - (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] - (answers)Carbon, hydrogen, oxygen,
nitrogen (sometimes sulphur)
, 3
Describe how you would use a biochemical test to show that a solution contained
protein. [2] - (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] - (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] - (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] - (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] - (answers)Spreads spots/polypeptides out more/ make sure
spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] -
(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;
