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AQA A level Biology Revision Questions with Answers
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AQA A level Biology Revision Questions with Answers
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AQA A level Biology Revision Questionswith Answers
Describe how you would use a biochemical test to show that a
solution contained a non-reducing sugar, such as sucrose. [3] -
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] - 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] - Answer>> Molecule)
made up of many identical/similar molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into
maltose. [1] - Answer>> Hydrolysis
What is the formula for lactose? [2] - Answer>> C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-
glucose. [1] - 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] - 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] - 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] - 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] - 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] - 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] - Answer>> Carbon,
hydrogen, oxygen, nitrogen (sometimes sulphur)
Describe how you would use a biochemical test to show that a
solution contained protein. [2] - 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] - 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] -
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] -
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] - Answer>> Spreads
spots/polypeptides out more/ make sure spot only contains one
substance;
Explain how inhibitors affect the rate of enzyme-controlled
reactions. [6] - 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] - Answer>> Rate of
reaction increases; Increasing temperature increases rate of
movement of molecules/ kinetic energy; Collide more
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