2024 AQA BIOLOGY HARD EXAM
QUESTIONS WITH VALID AND
DETAILED ANSWERS
Respiration produces more ATP per molecule of glucose in the presence of
oxygen than it does when oxygen is absent. Explain why. - CORRECT-
ANSWERSoxygen combines with electrons and protons;
Oxidative phosphorylation / electron transport chain provides (most) ATP
explain how resistance to an antibiotic could become widespread in a
bacterial population following a gene mutation conferring resistance in just
one bacterium - CORRECT-ANSWERS1. frequent use of antibiotic creates
selection pressure / antibiotic kills bacteria;
2. bacteria with mutation / resistance have (selective) advantage over others
/ described;
3. (survive to) reproduce more than other types pass on advantageous
allele / mutated allele in greater numbers;
4. frequency of (advantageous) allele increases in subsequent generations;
5. frequency of resistant types increases in subsequent generations;
explain why nucleotides can only be added in a 5' to 3' direction - CORRECT-
ANSWERSDNA polymerase forms the bonds between the new nucleotides, it
is specific to that function. however it is only complementry to the 5' end of
the strand. Seeing as one template strand will be running in the opposite
direction to the other, DNA polymerase must work in opposite directions as
the 5' and 3' end are different shapes.
sympatric speciation - CORRECT-ANSWERS1. Occurs in the same
habitat/environment/population;
2. Mutation/s cause different flowering times;
3. Reproductive separation/isolation
OR
No gene flow
OR
Gene pools remain separate;
4. Different allele/s passed on/selected OR
Change in frequency of allele/s;
5. Disruptive (natural) selection;
QUESTIONS WITH VALID AND
DETAILED ANSWERS
Respiration produces more ATP per molecule of glucose in the presence of
oxygen than it does when oxygen is absent. Explain why. - CORRECT-
ANSWERSoxygen combines with electrons and protons;
Oxidative phosphorylation / electron transport chain provides (most) ATP
explain how resistance to an antibiotic could become widespread in a
bacterial population following a gene mutation conferring resistance in just
one bacterium - CORRECT-ANSWERS1. frequent use of antibiotic creates
selection pressure / antibiotic kills bacteria;
2. bacteria with mutation / resistance have (selective) advantage over others
/ described;
3. (survive to) reproduce more than other types pass on advantageous
allele / mutated allele in greater numbers;
4. frequency of (advantageous) allele increases in subsequent generations;
5. frequency of resistant types increases in subsequent generations;
explain why nucleotides can only be added in a 5' to 3' direction - CORRECT-
ANSWERSDNA polymerase forms the bonds between the new nucleotides, it
is specific to that function. however it is only complementry to the 5' end of
the strand. Seeing as one template strand will be running in the opposite
direction to the other, DNA polymerase must work in opposite directions as
the 5' and 3' end are different shapes.
sympatric speciation - CORRECT-ANSWERS1. Occurs in the same
habitat/environment/population;
2. Mutation/s cause different flowering times;
3. Reproductive separation/isolation
OR
No gene flow
OR
Gene pools remain separate;
4. Different allele/s passed on/selected OR
Change in frequency of allele/s;
5. Disruptive (natural) selection;
