Describe how a pollen grain reaches an ovule and fertilisation takes place in a flowering plant.

Cambridge International IGCSE Biology (0610) — 16.3 Sexual reproduction in plants · 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 of the flower.
2. The pollen grain germinates and a pollen tube grows down the style towards the ovary.
3. The tube carries the sperm nucleus (or nuclei) through the style and into the ovule.
4. The sperm nucleus fuses with the egg nucleus in the ovule, forming a zygote.

Examiner tips

Use the exact sequence of events; each step is worth one mark.
Mention the pollen tube and the movement of the sperm nucleus.
Show the final fusion to form the zygote.
Keep the answer concise and avoid extra detail.

Common mistakes

Confusing the pollen grain with the pollen tube; they are different stages.
Forgetting to mention the sperm nucleus travelling down the tube.
Writing that the pollen grain itself fuses with the ovule instead of the sperm nucleus.

Mark scheme (4 marks)

Pollen grain lands on the stigma
A pollen tube grows (down through the style) towards the ovule
The nucleus from the pollen grain travels down the pollen tube to the ovule
The nucleus of the pollen grain fuses with the nucleus of the ovule (to form a zygote)

Key terms in this question

pollen grain · ovule · fertilisation