In complex multicellular organisms, the female gamete is significantly larger than the male gamete. Give a biological reason for this size difference, and explain at what stage of reproduction this stored material becomes important.
Generated by claude-sonnet-4-6 · 2026-06-26 01:06 · grounding rag
Model Answer
The female gamete (egg) is larger than the male gamete (sperm) because it stores nutrients needed for the early development of the embryo. The sperm consists mainly of genetic material and a tail for movement, and thus remains small.
This stored nutrition becomes important after fertilisation, when the zygote begins dividing and developing into an embryo, before it gets implanted in the uterine wall and receives nourishment from the mother's blood via the placenta.
Source: Chapter 7, Section 7.3.3 (a) & (b)
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Explanation
- The examiner expects two clear points: why the egg is large (stored nutrients for the embryo) and when this matters (early post-fertilisation / pre-implantation development).
- The sperm description from the textbook — "tiny bodies that consist of mainly genetic material and a long tail" — directly supports why it is small; use this contrast.
- Avoid over-explaining; 2 marks = one reason + one stage/timing. Keep it tight.