AQA GCSE Biology Biology Paper 2 (Higher), June 2023: Question 8
10 marks · Standard Demand difficulty · Short Answer
Order stages of meiosis, determine chromosome counts and explain their significance, describe genetic variation in meiosis, and identify DNA components from a diagram.
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Question text
08 Figure 13 shows six stages in the process of meiosis.
Figure 13
08.1 In Figure 13, A is the first stage and F is the final stage.
Stages B to E are not in the correct order.
Give the correct order of stages A to F.
[1 mark]
A → → → → → F
At the end of meiosis the number of chromosomes is different from the number of
chromosomes at the start of meiosis.
08.2 Give the number of chromosomes in one cell in Figure 13:
• at the start of meiosis
• at the end of meiosis.
[2 marks]
Start
End
08.3 Explain why the change in the number of chromosomes is important.
[3 marks]
08.4 Meiosis produces cells that are genetically different.
Describe how meiosis produces cells that are genetically different.
[2 marks]
Chromosomes contain DNA.
Figure 14 shows part of a DNA molecule.
*35* Figure 14
08.5 What type of substances are labelled A, C, G and T in Figure 14?
[1 mark]
08.6 DNA is made of nucleotides.
How many nucleotides are shown in Figure 14?
[1 mark]
Mark scheme
Show the mark scheme
Question 8
AO /
Question Answers Extra information Mark
Spec Ref.
08.1 (A) → E → D → C → B → (F) must be in this order 1 AO3
4.6.1.2
4.1.2.2
AO /
Spec Ref.
08.2 (start) 16 allow 8 pairs 1 AO3
(end) 8 the answer must be half the 1 AO2
value of the number at the start 4.6.1.2
AO /
Spec Ref.
08.3 (meiosis) forms gametes allow (meiosis) forms sex cells 1 AO1
allow (meiosis) forms eggs and 4.6.1.2
sperm
(two gametes) fuse / fertilise 1
(so) keeps chromosome number 1
constant (from generation to
generation)
or
(so) prevents doubling /
increase in chromosome
number (in each generation)
or
(so) gives normal / correct allow gives correct chromosome
chromosome number (for number (for offspring)
embryo / new cell)
AO /
Spec Ref.
08.4 random chromosome from ignore half the chromosomes 1 AO1
each pair (of chromosomes) ignore half the DNA 4.6.1.2
allow other processes for creating
variation
ignore mutation
moves to one end of the cell 1
or
goes into each new cell or
gamete
AO /
Spec Ref.
08.5 base(s) allow organic / nitrogenous base(s) 1 AO1
4.6.1.5
ignore adenine / cytosine / guanine
/ thymine
AO /
Spec Ref.
08.6 12 / twelve allow 6 pairs or six pairs 1 AO3
4.6.1.5
Total Question 8 10
How to answer it
Meiosis, Gamete Formation & DNA Structure
This question assesses your understanding of cell division by meiosis and the molecular structure of DNA (AQA Biology Specification 4.6.1.2 and 4.6.1.5):
- Tracing the sequence of cellular events during two consecutive divisions of meiosis.
- Counting chromosomes in diagrammatic cells and calculating the reduction from diploid to haploid.
- Explaining the biological importance of halving chromosome numbers for sexual reproduction and fertilization.
- Describing how meiosis generates genetic variation (independent assortment/random distribution of chromosomes).
- Identifying the components of a nucleotide: bases (A, C, G, T), pentose sugars, and phosphate groups.
Ordering the Stages of Cell Division
AO3 (Analysis of visual scientific data)
✅ Correct Answer
A → E → D → C → B → F
💡 Stage-by-Stage Breakdown
- A: Interphase / uncoiled chromatin copies itself.
- E: Chromosomes condense and pair up (8 pairs visible).
- D: Homologous pairs separate and pull apart to opposite poles (First division).
- C: Cell divides into 2 cells (end of first division).
- B: Chromatids pull apart in both cells (Second division).
- F: 4 genetically distinct haploid gametes form.
Number of Chromosomes at Start vs. End
AO3 & AO2 (Observation and application)
✅ Correct Answer
- Start: 16 (allow 8 pairs) [1 mark]
- End: 8 [1 mark]
📐 How to Count Correctly
- Look at image E: the label explicitly states "One pair of chromosomes" for two adjacent X-shaped chromosomes.
- Count all the chromosome pairs in cell E: there are 8 pairs = 16 chromosomes.
- Meiosis halves the number: 16 ÷ 2 = 8 chromosomes in each gamete at stage F.
❌ Common Errors
- Writing 46 and 23 — this is true for human cells, but the question asks about Figure 13!
- Counting each chromatid arm individually and writing 32.
Why Halving the Chromosome Number Matters
AO1 (Recall and scientific explanation)
✅ 3-Point Model Answer
- Meiosis produces gametes (sex cells / sperm and egg cells). [1 mark]
- So that when two gametes fuse / fertilise... [1 mark]
- The full, normal chromosome number is restored / kept constant from generation to generation (prevents doubling every generation). [1 mark]
🧠 Exam Technique: Chain of Cause & Effect
Always state the biological consequence:
Halved (n) + Halved (n) ⟶ Fertilisation ⟶ Normal Diploid (2n)
If gametes remained diploid (16), fertilisation would create 32, then 64, doubling each generation indefinitely!
❌ Common Errors
- Saying "so the baby has 46 chromosomes" (Figure 13 has a base number of 16, not 46).
- Failing to mention fertilisation or fusion of gametes.
How Meiosis Produces Genetically Different Cells
AO1 (Mechanism of genetic variation)
✅ Marking Points
- A random chromosome from each homologous pair is chosen / separated... [1 mark]
- ...and moves to each pole / goes into each new cell or gamete (independent assortment). [1 mark]
💡 What the Examiner Looks For
Examiners accept either a description of:
- Independent assortment: Random alignment and separation of maternal and paternal chromosomes.
- Crossing over: Swapping of alleles between non-sister chromatids in homologous pairs.
❌ Ignored & Rejected Answers
- Do not write "mutation" — this is not the standard mechanism during normal meiosis.
- Vague phrases like "they get half the DNA" or "half the chromosomes go in" get 0 marks. You must mention random distribution or selection from pairs.
Interpreting the DNA Diagram (Figure 14)
AO1 & AO3 (Molecular recognition and counting)
✅ Part 08.5 Answer [1 Mark]
Base(s)
Also allowed: Organic base(s), nitrogenous base(s).
✅ Part 08.6 Answer [1 Mark]
12 (twelve nucleotides)
Also allowed: 6 pairs / six pairs.
💡 Anatomy of a Nucleotide
Each individual nucleotide consists of 3 parts:
- One circular phosphate group
- One pentagonal deoxyribose sugar
- One rectangular base (A, T, C, or G)
In Figure 14, there are 6 rungs. Each rung contains 2 bases paired together. Therefore: 6 rungs × 2 nucleotides per rung = 12 nucleotides.
❌ Common Errors in 08.6
- Writing "6" instead of 12 (counting base pairs instead of single nucleotides without adding the word "pairs").
- Writing "24" or "4" by guessing based on base types.
Topics
Biology · B1: Cell Biology · B6: Inheritance, Variation and Evolution
Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Higher), June 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.