AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025
QUESTIONS AND ANSWERS
Large molecules often contain carbon. why?
they can readily form bonds with other carbon atoms. this forms a 'backbone'. other
atoms can then attach.
describe benedicts test for reducing sugars add equal volumes
of the sugar sample and benedicts reagent. heat the mixture
in a water bath for 5 minutes. brick red precipitate will form.
what is a reducing sugar?
a sugar that can reduce (give electrons to) another chemical.
describe the benedicts test for non reducing sugars with food sample, add an
equal volume of dilute hydrochloric acid in a test tube. place test tube in water
bath for 5 mins. add sodium hydrogencarbonate solution.
heat resulting solution with an equal volume of benedicts. solution for 5 minutes.
turns orange/brown.
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
,what does dilute hydrochloric acid do in the benedicts test for non reducing sugars?
it hydrolyses any disaccharide into monosaccharides, thus also forming reducing
sugars.
describe the structure of starch chains
of alpha glucose
some chains are branched= amylopetcin some
chains are coiled= amylose
what purpose does the structure of amylose serve?
makes the molecule compact so it is stored more easily.
what purpose does the structure of amylopectin serve?
more surface area for enzymes to work on, thus glucose molecules can be released
at a much quicker rate.
how is the structure of starch suited to its function?
1. starch is insolube so it doesnt affect water potential
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
,2. it is large enough that it doesnt diffuse out of cells
3. compact enough so that a lot of it can be stored in a small space
4. branched= each end can simultaneously be acted on by enzymes, so glucose is
quickly released
how is the structure of glycogen suited to its function?
1. insoluble, so no effect on water potential of cell
2. insoluble, so doesnt diffuse out of cells
3. compact, a lot of it can be stored in a small space
4. very highly branched= each end can simultaneously be acted on by enzymes, so
glucose is quickly released
why do animals need highly branched glycogen?
because animals metabolic rate is faster than plants and so needs glucose to be
released quicker.
describe the structure of cellulose made
up of straight chains of beta glucose the
chains are parallel to each other, so H
bonds form cross-linkages all the H
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
, bonds together strengthens the cellulose
forms microfibrils
draw alpha and beta glucose
how does the structure of triglycerides relate to their properties?
1. triglycerides have a high ratio of energy-storing carbon-hydrogen bonds to
carbon atoms, so its a good source of energy.
2. low mass to energy ratio, so theyre good energy storage molecules.
3. large and non-polar, therefore insoluble, therefore don't affect osmosis.
4. high ratio of hydrogen to oxygen atoms, so can release water when oxidised,
hence provide a source of water
what are the roles of lipids?
1. source of energy
2. waterproofing
3. insulation
4. protection
how does the structure of phospholipids relate to their properties?
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
QUESTIONS AND ANSWERS
Large molecules often contain carbon. why?
they can readily form bonds with other carbon atoms. this forms a 'backbone'. other
atoms can then attach.
describe benedicts test for reducing sugars add equal volumes
of the sugar sample and benedicts reagent. heat the mixture
in a water bath for 5 minutes. brick red precipitate will form.
what is a reducing sugar?
a sugar that can reduce (give electrons to) another chemical.
describe the benedicts test for non reducing sugars with food sample, add an
equal volume of dilute hydrochloric acid in a test tube. place test tube in water
bath for 5 mins. add sodium hydrogencarbonate solution.
heat resulting solution with an equal volume of benedicts. solution for 5 minutes.
turns orange/brown.
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
,what does dilute hydrochloric acid do in the benedicts test for non reducing sugars?
it hydrolyses any disaccharide into monosaccharides, thus also forming reducing
sugars.
describe the structure of starch chains
of alpha glucose
some chains are branched= amylopetcin some
chains are coiled= amylose
what purpose does the structure of amylose serve?
makes the molecule compact so it is stored more easily.
what purpose does the structure of amylopectin serve?
more surface area for enzymes to work on, thus glucose molecules can be released
at a much quicker rate.
how is the structure of starch suited to its function?
1. starch is insolube so it doesnt affect water potential
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
,2. it is large enough that it doesnt diffuse out of cells
3. compact enough so that a lot of it can be stored in a small space
4. branched= each end can simultaneously be acted on by enzymes, so glucose is
quickly released
how is the structure of glycogen suited to its function?
1. insoluble, so no effect on water potential of cell
2. insoluble, so doesnt diffuse out of cells
3. compact, a lot of it can be stored in a small space
4. very highly branched= each end can simultaneously be acted on by enzymes, so
glucose is quickly released
why do animals need highly branched glycogen?
because animals metabolic rate is faster than plants and so needs glucose to be
released quicker.
describe the structure of cellulose made
up of straight chains of beta glucose the
chains are parallel to each other, so H
bonds form cross-linkages all the H
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
, bonds together strengthens the cellulose
forms microfibrils
draw alpha and beta glucose
how does the structure of triglycerides relate to their properties?
1. triglycerides have a high ratio of energy-storing carbon-hydrogen bonds to
carbon atoms, so its a good source of energy.
2. low mass to energy ratio, so theyre good energy storage molecules.
3. large and non-polar, therefore insoluble, therefore don't affect osmosis.
4. high ratio of hydrogen to oxygen atoms, so can release water when oxidised,
hence provide a source of water
what are the roles of lipids?
1. source of energy
2. waterproofing
3. insulation
4. protection
how does the structure of phospholipids relate to their properties?
AQA A LEVEL BIOLOGY PAPER 1 EXAM 2025 QUESTIONS AND ANSWERS
