AQA A-Level Biology Paper 1 Exam
Questions and Answers 100% Solved
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.
1
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,turns orange/brown.
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
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
2
©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
, 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 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
©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Questions and Answers 100% Solved
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.
1
©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
,turns orange/brown.
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
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
2
©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
, 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 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
©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
