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2024 AQA A-LEVEL BIOLOGY PAPER 1 EXAM WITH CORRECT ANSWERS
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2024 AQA A-LEVEL BIOLOGY PAPER 1 EXAM WITH CORRECT ANSWERS
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2024 AQA A-LEVEL BIOLOGYPAPER 1 EXAM WITH CORRECT
ANSWERS
large molecules often contain carbon. why? - CORRECT-ANSWERSthey can
readily form bonds with other carbon atoms. this forms a 'backbone'. other
atoms can then attach.
two ways in which pathogens can cause disease - CORRECT-
ANSWERSreleases toxins
damages cell tissue
A vaccine can be used to produce immunity. Describe how memory cells are
important in this process. (3) - CORRECT-ANSWERSimportant because when
individual is in contact with virus again, antibodies can be produced at a
faster rate in a secondary immune response, and so the pathogen can be
destroyed faster.
Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells
inside the leaf (3) - CORRECT-ANSWERSit enters via stomata, which are
opened as guard cells open. if diffuses down a concentration gradient
through the air spaces.
There are large numbers of mitochondria in the epithelial cell. Explain how
these organelles help the cell to absorb the products of digestion. (2) -
CORRECT-ANSWERSmitochondria provide the ATP
this is needed for active transport of substances into the cell
red blood cells are biconcave discs. Explain one advantage of a biconcave
disc over a spherical cell of the same volume in transporting oxygen. -
CORRECT-ANSWERSLarge (surface) area; For diffusion;
Describe how oxygen in air in the alveoli enters the blood in capillaries. -
CORRECT-ANSWERSdiffusion across alveoli epithelium
Attaching lactase to the beads is a more efficient use of lactase than adding
the lactase
directly to cow's milk.
,Suggest three reasons why it is more efficient to attach lactase to the beads.
- CORRECT-ANSWERSlactase bead can be reused
continuous process
lactase not present in milk
what is a vaccine? - CORRECT-ANSWERSContains antigen / proteins / dead /
weakened microorganism / pathogen / virus / bacteria;
Stimulates production of antibodies / plasma cells / memory cells
where is amylase produced? - CORRECT-ANSWERSsalivary glands, pancreas,
small intestine
where is maltase produced? - CORRECT-ANSWERSepithelium of small
intestine
where is lactose produced? - CORRECT-ANSWERSpancreas, small intestine
where are proteases produced? - CORRECT-ANSWERSstomach, pancreas,
small intestine
describe the involvement of RER in producing chylomicrons - CORRECT-
ANSWERSRER synthesises proteins in the ribosomes, which are needed to
form chylomicrons.
suggest how chylomicrons leave the epithelial cell. - CORRECT-ANSWERSby
exocytosis because theyre too large to leave by other methods
whats the difference between species richness and diversity index? -
CORRECT-ANSWERSSpecies richness measures only number of (different)
species / does not measure number of individuals.
directional selection - CORRECT-ANSWERSselection favours individuals in one
direction from the mean of the population.
e.g. when environment changes, those with advantageous allele outside of
the mean will be more likely to survive and breed.
stabilising selection - CORRECT-ANSWERSif environmental conditions are the
same, those with alleles closer to the mean are favored. they are more likely
to survive and reproduce e.g. birth weight.
courtship behaviour results in reproductive success by... - CORRECT-
ANSWERS1. allowing recognition of own species
2. identifying those capable of breeding
3. forming a pair bond
4. synchronising mating
, describe benedicts test for reducing sugars - CORRECT-ANSWERSadd 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? - CORRECT-ANSWERSa sugar that can reduce (give
electrons to) another chemical.
describe the benedicts test for non reducing sugars - CORRECT-
ANSWERSwith 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.
what does dilute hydrochloric acid do in the benedicts test for non reducing
sugars? - CORRECT-ANSWERSit hydrolyses any disaccharide into
monosaccharides, thus also forming reducing sugars.
describe the structure of starch - CORRECT-ANSWERSchains of alpha glucose
some chains are branched= amylopetcin
some chains are coiled= amylose
what purpose does the structure of amylose serve? - CORRECT-
ANSWERSmakes the molecule compact so it is stored more easily.
what purpose does the structure of amylopectin serve? - CORRECT-
ANSWERSmore 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? - CORRECT-ANSWERS1.
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
how is the structure of glycogen suited to its function? - CORRECT-
ANSWERS1. 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
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