This free quiz has 12 real AQA A-level Biology exam questions on mutation and meiosis (25 marks, about 35 minutes). It marks itself: tick-box, diagram and calculation questions are marked for you, and for written answers you check your work against the real AQA mark scheme.
What the quiz covers (AQA 3.4.3)
identifying nuclear division in a fungus life cycle
how a polar body ends up with its combination of alleles
using the genetic code to pick out a single base substitution
why not all gene mutations change a polypeptide
the chromosome content of cells after each meiotic division
using independent segregation to predict chromosome arrangements in a sample of cells
non-disjunction and Edwards’ syndrome
how a mutation makes a non-functional receptor (4 marks), and how meiosis produces haploid cells and genetic variation (5 marks)
How to use it
Write each written answer in full before you open the mark scheme, then tick only the points you really made. Say chromatids or homologous chromosomes rather than just chromosomes, and for the calculation show your working and carry it through to the number of cells in the sample.
Where students lose marks (from AQA examiners’ reports and mark schemes)
Each point below is followed by wording that gained marks.
Defining a gene mutation. Only a minority of students said that a mutation is a change in the DNA base sequence, and some wrote that a mutation always changes the amino acid sequence. Few realised that any gene mutation forms a new allele.
✔ Gains credit: a gene mutation is a change in the base (nucleotide) sequence of DNA, such as a substitution, addition or deletion of a base, and it results in a new allele.
Coded for, not formed. Students often wrote that different amino acids are “formed” or that base sequences “produce” amino acids, which was rejected. Many lost a mark by calling the binding site of a receptor its “active site”.
✔ Gains credit: the changed base sequence codes for a different amino acid sequence (primary structure), which alters the hydrogen, ionic or disulfide bonds and so changes the tertiary structure.
The genetic code is degenerate. The idea that a mutation can have no effect was often very poorly expressed, with some writing about the “degenerate code of amino acids”. Others assumed that every mutation changes the primary structure.
✔ Gains credit: the genetic code is degenerate, so some amino acids have more than one triplet, or the mutation may be in an intron, so the amino acid sequence may not change.
Homologous pairs. 62% of students couldn't say what a homologous pair of chromosomes is, often confusing it with the pair of chromatids in a single chromosome. “Same alleles” was rejected.
✔ Gains credit: a homologous pair is two chromosomes that carry the same genes (at the same loci).
Divisions, not stages. Some students compared “stages” rather than divisions. General statements such as “mitosis is asexual and meiosis is sexual” or “mitosis produces diploid cells” weren't credited, because they aren't true of all life cycles.
✔ Gains credit: each difference is a direct comparison, for example mitosis has one division and produces two genetically identical cells, while meiosis has two divisions and usually produces four genetically different cells.
Naming non-disjunction. “Addition” and “non-disfunction” were common mistakes for the name of the mutation. Very few explained how the extra chromosome ends up in one cell, and many simply repeated that the gamete has an extra chromosome.
✔ Gains credit: non-disjunction, where chromosomes or chromatids fail to separate, so both are pulled to the same pole of the cell.
Explaining independent segregation. Independent segregation was often named but rarely explained, and answers that left out the word “homologous” struggled to describe it. Many good answers stopped before saying what the extra variation actually is.
✔ Gains credit: each gamete gets either the maternal or the paternal chromosome from each homologous pair, in any combination, producing new combinations of alleles.
Keep practising
The other AQA 3.4 self-marking quizzes: DNA, genes and chromosomes · Protein synthesis · Natural selection · Species and biodiversity
Topic 3.3 quizzes start with surface area to volume ratio
Mutation and meiosis: common questions and mark scheme insights
The AQA topic index
weekly AQA group classes: Year 12 on Tuesdays at 5.15pm, Year 13 on Wednesdays or Thursdays at 6.30pm
Questions © AQA, from past A-level and AS Biology papers, with their mark schemes and examiners’ reports.