AQA A Level Biology Paper 2 (7402/2) from June 2025 covers topics 3.5 to 3.8: energy transfers, responding to change, genetics and ecosystems, and gene expression. It is 91 marks in 2 hours. The question paper, mark scheme and examiners’ report are on the AQA past papers page.
What the paper tested
The marks were spread more evenly than on Paper 1. Gene technologies (3.8.4) and stimuli and receptors (3.6.1) each took about 10 marks, homeostasis 8 (blood glucose and the principles of negative feedback in Question 2), inheritance 8 (a sweet-pea dihybrid cross with autosomal linkage in Question 5), respiration 7, and energy transfers, nutrient cycles, populations in ecosystems and gene mutation about 6 each. Question 10 was a passage about tropical rainforests with questions on biodiversity, nutrient cycling and succession hung off it, which is a format AQA uses most years.
Good starting points: the gene technologies quiz, the stimuli and receptors quiz, the inheritance quiz and the nutrient cycles quiz.
Where students lost marks
10.2 Abiotic factors and nutrient recycling (2 marks)
Fewer than 10% of students scored both marks. The question asked how two abiotic factors in a rainforest speed up nutrient recycling. Many gave a biotic factor, and those who named temperature and water often explained them loosely: temperature was linked to ‘faster decomposition’ rather than to enzyme activity or a named process, and water was linked to waterlogging and denitrification rather than to hydrolysis. Name the factor, then name the process it speeds up.
8.2 Why the E. coli proteome is easier to determine (2 marks)
Under 5% of students scored both marks. Most gained one for saying prokaryotes have no introns. The second mark, which almost nobody reached, was that eukaryotic genomes contain far more regulatory (non-coding) DNA. Saying the genome is shorter or has fewer genes scored nothing, and some students talked about histones or organelles, which are irrelevant to determining a proteome.
5.3 Autosomal linkage (3 marks)
One of the strongest discriminators on the paper: about 10% scored all three marks. Students could usually say that crossing over produces the recombinant types, but most could not define autosomal linkage properly, writing about alleles or traits rather than two genes on the same chromosome. Very few gave the genotypes of the gametes or their relative proportions. Our {a('/tutoring-blog/autosomal-linkage-epistasis-chi-squared','linkage, epistasis and chi-squared')} explainer works through exactly this.
7.4 Concluding from a chi-squared value (4 marks)
Fewer than 10% scored full marks. Most students correctly said the calculated value exceeded the critical value, but some did not quote the critical value, and some used the wrong degrees of freedom. The marks for probability and chance need the standard wording: the probability that the difference is due to chance is less than 0.05, so the difference is significant and the null hypothesis is rejected.
8.4 Evaluating an odds-ratio table (4 marks)
Fewer than 10% scored four marks. Most students wrote that more repeats meant a higher risk, which the table did not show; the mark was for noticing that two repeats lowered the risk. Students who did not understand odds ratios, where 1.0 means no change in risk, could not access three of the four marks. It is worth knowing how to read an odds ratio and a confidence interval before this paper.
10.1 Why a varied plant community supports high animal biodiversity (3 marks)
Under 10% scored three marks. The point most students missed was the first one: that ‘varied plant community’ means many plant species, which creates more niches and habitats and a greater variety of food. ‘More food’ on its own was not credited. A sizeable minority answered a different question altogether, writing about succession or speciation.
6.2 Demyelination and reflex times (3 marks)
About 10% scored full marks. Most knew that loss of myelin stops saltatory conduction so depolarisation has to happen along the whole axon. The lost marks came from students who then concluded that impulses would travel faster, or who read ‘increase reflex response times’ as a quicker response.
Maths and practical skills on this paper
Statistics featured heavily: a chi-squared conclusion, standard deviations and confidence in 7.4 and 8.4, and about 9 marks on margins of error and accuracy. Required Practical 10 (an environmental variable and a plant response) appeared for 5 marks. If statistics is your weak spot, the means and standard deviation explainer and the handling data questions are the place to start.
How to use this paper
Sit it timed, 2 hours, then mark it strictly.
Read the examiners’ comment on every part you dropped marks on. On this paper most lost marks were for vague wording (‘faster decomposition’, ‘more food’, ‘alleles on the same chromosome’) rather than missing knowledge.
Work the topics you lost marks on with the AQA quizzes, then return to the paper a few weeks later.
Convert your mark with the June 2025 grade boundaries.
Questions and examiners’ comments are summarised from AQA’s published question paper, mark scheme and report for 7402/2 June 2025, © AQA. Figures quoted are AQA’s.