AQA A-LEVEL BIOLOGY PAPER 1 2025
MARK SCHEME
How do enzymes affect the rate of reaction? - They increase the rate of reaction at normal
temperatures.
How does increasing lactose concentration affect enzyme activity? - It increases the rate of
reaction and product formation.
How does the mark scheme address gender identity in exam responses? - Students are not
disadvantaged based on gender identity, and the use of 'they/them' as singular pronouns is
credited.
How is phonetic spelling treated in the mark scheme? - Phonetic spelling of correct scientific
terms is credited unless it could cause confusion with another term.
How many sperm cells are produced from one A1 cell? - = 1 mark
How should answers using 'it' be evaluated? - Credit is given only if it is clear what 'it' refers to
in the context of the answer.
What are the components of a tissue and organ? - Tissue and organ = 1 mark
What biological molecule contains glucose? - Both glycogen and sucrose contain glucose.
What do the hydrophobic tails of phospholipids do? - They repel water, pointing away from it.
What does 'ignore' mean in the comments column of the mark scheme? - It indicates that the
information given is irrelevant to the question and does not affect the marking.
, What does 'right + wrong = wrong' mean in the context of marking lists? - If a student provides
both correct and incorrect responses, the errors negate the correct ones, potentially resulting in
zero marks.
What does a high resolution in microscopy allow for? - It allows for the visualization of smaller
structures, such as mitochondria.
What does a small sample size in an experiment indicate? - It may limit the reliability and
generalizability of the results.
What does ECF stand for in the marking scheme? - Errors Carried Forward, allowing for the use
of incorrect values in subsequent calculations.
What does the 'Comments' column in the mark scheme provide? - Extra information to help
examiners make judgments and clarify acceptable responses.
What does the term 'consequential marking' refer to? - It allows for marks to be awarded based
on the correct use of values derived from previous answers, even if those values are incorrect.
What does the use of brackets in the mark scheme indicate? - Information that is not essential
for awarding marks but helps clarify the required sense of the answer.
What effect does temperature have on hemoglobin's oxygen affinity at low pO2? - At low pO2,
hemoglobin unloads more O2 at higher temperatures.
What happens to bacteria with a resistant allele? - They survive, reproduce, and increase the
allele frequency
MARK SCHEME
How do enzymes affect the rate of reaction? - They increase the rate of reaction at normal
temperatures.
How does increasing lactose concentration affect enzyme activity? - It increases the rate of
reaction and product formation.
How does the mark scheme address gender identity in exam responses? - Students are not
disadvantaged based on gender identity, and the use of 'they/them' as singular pronouns is
credited.
How is phonetic spelling treated in the mark scheme? - Phonetic spelling of correct scientific
terms is credited unless it could cause confusion with another term.
How many sperm cells are produced from one A1 cell? - = 1 mark
How should answers using 'it' be evaluated? - Credit is given only if it is clear what 'it' refers to
in the context of the answer.
What are the components of a tissue and organ? - Tissue and organ = 1 mark
What biological molecule contains glucose? - Both glycogen and sucrose contain glucose.
What do the hydrophobic tails of phospholipids do? - They repel water, pointing away from it.
What does 'ignore' mean in the comments column of the mark scheme? - It indicates that the
information given is irrelevant to the question and does not affect the marking.
, What does 'right + wrong = wrong' mean in the context of marking lists? - If a student provides
both correct and incorrect responses, the errors negate the correct ones, potentially resulting in
zero marks.
What does a high resolution in microscopy allow for? - It allows for the visualization of smaller
structures, such as mitochondria.
What does a small sample size in an experiment indicate? - It may limit the reliability and
generalizability of the results.
What does ECF stand for in the marking scheme? - Errors Carried Forward, allowing for the use
of incorrect values in subsequent calculations.
What does the 'Comments' column in the mark scheme provide? - Extra information to help
examiners make judgments and clarify acceptable responses.
What does the term 'consequential marking' refer to? - It allows for marks to be awarded based
on the correct use of values derived from previous answers, even if those values are incorrect.
What does the use of brackets in the mark scheme indicate? - Information that is not essential
for awarding marks but helps clarify the required sense of the answer.
What effect does temperature have on hemoglobin's oxygen affinity at low pO2? - At low pO2,
hemoglobin unloads more O2 at higher temperatures.
What happens to bacteria with a resistant allele? - They survive, reproduce, and increase the
allele frequency
