Describe the process of fertilisation in a flowering plant, beginning from when a pollen grain lands on a stigma.

Cambridge International IGCSE Biology (0610) — 16.2 Sexual reproduction · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. A pollen grain lands on the sticky stigma and germinates, forming a pollen tube.
2. The pollen tube grows down through the style towards the ovary.
3. The tube delivers a sperm nucleus into the ovule.
4. The sperm nucleus fuses with the egg nucleus, forming a zygote.

Examiner tips

Use the word "germinates" for the pollen grain. Mention the pollen tube’s journey through the style. State that the sperm nucleus is delivered. Show the fusion of sperm and egg nuclei to form a zygote.

Common mistakes

Forgetting to mention the pollen tube. Confusing the pollen grain with the pollen tube. Saying the pollen grain itself fuses with the egg instead of the sperm nucleus.

Mark scheme (4 marks)

A pollen tube grows from the pollen grain
The pollen tube grows down through the style to the ovule
The nucleus from the pollen cell passes down the pollen tube
The nucleus of the pollen cell fuses with the nucleus of the ovule / egg cell, forming a zygote

Key terms in this question

pollen grain · fertilisation