AQA A Level Biology (7402) · Paper 1 and Paper 3
AQA A Level Biology 3.4 Genetic Information and Variation Exam Questions
Free AQA A Level Biology exam questions by topic for 3.4 Genetic information, variation and relationships between organisms, with a mark scheme for every pack. Covers DNA, genes and chromosomes, protein synthesis, mutation, meiosis, natural selection, classification and biodiversity.
3.4 Genetic Information and Variation exam questions by subtopic
7 question packs covering every part of the specification, with thousands of real past exam questions between them. Do not stop after a few: answer as many as you can, without notes, and mark each one with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About AQA A Level Biology topic 3.4
Topic 3.4 links DNA to the proteins it codes for, then explains where genetic variation comes from and how scientists classify organisms and measure biodiversity. It contains a lot of key vocabulary, so precise wording in your answers earns marks.
What you need to know for 3.4 Genetic Information and Variation
- 3.4.1 DNA in prokaryotes and eukaryotes, histones and chromosomes, genes and loci, and the genetic code: a non-overlapping, degenerate and universal triplet code. Introns and exons.
- 3.4.2 Transcription of mRNA using RNA polymerase, splicing of pre-mRNA, and translation at ribosomes using tRNA and ATP.
- 3.4.3 Gene mutations, chromosome non-disjunction, and meiosis. Variation comes from crossing over and independent segregation of homologous chromosomes.
- 3.4.4 Natural selection, directional and stabilising selection, and adaptations. Using aseptic technique to investigate the effect of antimicrobial substances on bacteria.
- 3.4.5 The definition of a species, courtship behaviour, phylogenetic classification and the hierarchy of taxa, and binomial naming.
- 3.4.6 Species richness and the index of diversity, d = N(N - 1) / sum of n(n - 1), and how farming affects biodiversity.
- 3.4.7 Comparing DNA base sequences, mRNA sequences and amino acid sequences to show relationships, and using mean and standard deviation in investigations.
Common mistakes in 3.4 Genetic Information and Variation
- Calling the genetic code overlapping. It is non-overlapping and degenerate: more than one triplet can code for the same amino acid.
- Mixing up transcription (making mRNA from DNA in the nucleus) with translation (making a polypeptide at a ribosome).
- Merging crossing over and independent segregation into one point. They are separate sources of variation and earn separate marks.
- Making arithmetic slips in the index of diversity. Work out N(N - 1) and each n(n - 1) separately before dividing.
- Confusing stabilising selection (favours the average) with directional selection (favours one extreme).
Try three 3.4 Genetic Information and Variation exam-style questions
1. Explain why a substitution mutation may not change the amino acid sequence of a protein. (2 marks)
Show the mark scheme answer
The genetic code is degenerate; so the new triplet may still code for the same amino acid. (Or: the mutation may be in an intron.)
2. A sample contains three species with 10, 5 and 5 individuals. Calculate the index of diversity. (2 marks)
Show the mark scheme answer
N(N - 1) = 20 x 19 = 380; sum of n(n - 1) = 90 + 20 + 20 = 130; d = 380 / 130 = 2.92.
3. Describe how mRNA is produced from DNA in transcription. (3 marks)
Show the mark scheme answer
Hydrogen bonds between the DNA strands break and one strand acts as a template; free RNA nucleotides align by complementary base pairing; RNA polymerase joins the nucleotides to form pre-mRNA, which is spliced to remove introns.
Want more? Every pack above has many more past exam questions on genetic information and variation.
3.4 Genetic Information and Variation FAQs
What does AQA A Level Biology topic 3.4 cover?
Topic 3.4, Genetic information, variation and relationships between organisms, covers DNA, genes and chromosomes, protein synthesis, mutation, meiosis, natural selection, classification and biodiversity.
Which AQA A Level Biology paper is topic 3.4 on?
Topic 3.4 is examined in Paper 1, which covers topics 3.1 to 3.4. Paper 3 can also include questions on any topic, so it is worth revising for that paper too.
Are these AQA A Level Biology 3.4 exam questions free?
Yes. Every question pack and mark scheme on this page is a free PDF download, with no sign-up needed.
