AQA GCSE Biology Biology Paper 1 (Foundation), June 2022: Question 2

✅ Correct Answer

1/4 (box 2 ticked)

📐 Step-by-Step Counting

1. Count the total number of whole cells visible in Figure 1: 8 cells in total.
2. Identify which cells have visible, condensed chromosomes being pulled apart (characteristic mitotic figures): 2 cells (one top right, one middle right).
3. Calculate the fraction: 2 out of 8 = ²/₈ = ¹/₄.

❌ Common Errors

Confusing ²/₈ with ¹/₈ or ¹/₂ by miscounting the total number of cells or counting background debris.

✅ Correct Answer

10 (box 2 ticked)

💡 Key Knowledge

• Mitosis produces two genetically identical daughter cells.
• Because the DNA replicates before the cell divides, each new daughter cell receives an exact, full copy of chromosomes.
• If the parent cell has 10 chromosomes, each new daughter cell also has 10 chromosomes.

❌ Common Errors

Ticking 5 (halving the number — confusing mitosis with meiosis) or ticking 20 (thinking the doubled DNA is kept in a single cell).

✅ Correct Answer

Before mitosis occurs, the cell grows. [1]

The genetic material in the cell doubles when the DNA replicates. [1]

After the chromosomes have been pulled to each end of the cell, the cytoplasm divides. [1]

💡 Cell Cycle Stages (in order)

1. Stage 1 (Interphase): Cell grows, increases sub-cellular structures (ribosomes, mitochondria), and DNA replicates to form two copies of each chromosome.
2. Stage 2 (Mitosis): One set of chromosomes is pulled to each end of the cell; the nucleus divides.
3. Stage 3 (Cytokinesis): Cytoplasm and cell membranes divide to form two identical cells.

🧠 Exam Technique

Cross off words from the box as you use them. Notice how the sentence clue "when the DNA..." requires a biological term specific to genetic material (replicates, not grows or reacts).

✅ Correct Answers

02.4: C [1 mark]

02.5: 10% [1 mark]

📐 Reading Sector Sizes

• Longest stage: Sector C has the largest angle / surface area (nearly half the circle), so it takes the most time.
• Percentage for Stage A: Notice the tick marks on the circle perimeter or angle estimation: the sector represents 1 out of 10 equal divisions (36° of 360°), which equals ¹/₁₀ = 10%.
• 25% would be a full right-angle (quarter circle), whereas sector A is visibly much narrower than 90°.

❌ Common Errors

Selecting 25% for A by guessing rather than comparing to a 90° right-angle benchmark.

✅ Correct Answer

Circulatory system (box 1 ticked)

💡 Key Knowledge

The circulatory (cardiovascular) system consists of the heart, blood vessels (arteries, veins, capillaries), and blood. Heart cells (cardiac muscle cells) make up the muscular walls of the heart.

✅ Correct Answers (any one)

• Cardiovascular disease / CVD
• Coronary heart disease / CHD
• Heart attack (myocardial infarction)
• Heart failure
• Any correctly named heart condition (e.g. arrhythmia, damaged heart valves, hole in the heart)

🧠 Exam Technique

Always specify the condition clearly. While "heart disease" or "heart attack" are credited, writing generic answers like "illness" or "organ failure" will not get the mark.

✅ Correct Answers (any one)

• Ethical objection: involves destroying a potential human life / embryo.
• Religious / cultural belief: goes against religious beliefs or against God's will.
• Clinical safety: the treatment is not fully tested / may cause unforeseen side effects.
• Rejection: the patient's immune system might reject the transplanted cells.
• Infection / cancer: risk of viral infection transfer or cells dividing uncontrollably to form tumours.

❌ Common Errors & Examiner Commentary

• "Religious" alone: Writing just "religion" unqualified will be ignored. You must state it is against religious or moral beliefs.
• Do not confuse embryonic stem cells with adult stem cells (adult stem cells from the patient have no risk of rejection, but embryonic cells from a donor do).