Explain how a sperm cell is specialised to carry out its function.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
1. Many mitochondria in the midpiece supply ATP for the flagellum, allowing the sperm to swim.
2. The long flagellum (tail) provides propulsion, enabling the sperm to reach the egg.
3. The acrosome at the head contains enzymes that digest the zona pellucida, permitting penetration of the egg.
4. The sperm carries a haploid nucleus; after fertilisation the zygote has the correct diploid chromosome number.
2. The long flagellum (tail) provides propulsion, enabling the sperm to reach the egg.
3. The acrosome at the head contains enzymes that digest the zona pellucida, permitting penetration of the egg.
4. The sperm carries a haploid nucleus; after fertilisation the zygote has the correct diploid chromosome number.
Examiner tips
- Use the word "provides" for energy supply, "enables" for movement, "contains" for acrosome enzymes, and "haploid" for the nucleus.
- Mention the flagellum as the tail to show understanding of structure-function.
Common mistakes
- Confusing the tail with the head; forgetting the flagellum’s role. Not specifying that the nucleus is haploid. Using vague terms like "helps" instead of "provides" or "enables".
Mark scheme (4 marks)
- Many mitochondria provide energy for movement towards the egg cell
- A tail enables the sperm cell to move / swim towards the egg cell
- The acrosome contains enzymes that digest the membrane / cells surrounding the egg to allow fertilisation
- The sperm cell has a haploid nucleus so that after fertilisation the embryo has the correct / full number of chromosomes
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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