In flowering plants, the pollen grains are transferred to stigma by pollination but the female germ cells are present in the ovary. Explain with the help of a labelled diagram (only concerned parts), how the male germ cell reaches the ovary.
Generated by claude-sonnet-4-6 · 2026-06-15 06:47 · grounding rag
Model Answer
After pollination, the pollen grain lands on the stigma and germinates. A pollen tube grows out of the pollen grain, passes down through the style, and reaches the ovary. The male germ cell travels through this pollen tube to reach the ovule, where it fuses with the female germ cell (egg cell) to form a zygote — this process is called fertilisation.
Labelled Diagram:
```
Stigma ← pollen grain germinates here
|
Style ← pollen tube grows through style
|
Ovary ← pollen tube enters ovary
|
Ovule ← male germ cell fuses with egg cell
```
(Students must draw and label: pollen grain on stigma, pollen tube, style, ovary, ovule.)
Source: Chapter 7, Section 7.3.2 — Sexual Reproduction in Flowering Plants
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Explanation
- The key process here is pollen tube formation — examiners specifically look for this term.
- Mention all three stages: germination on stigma → pollen tube through style → reaches ovule in ovary.
- The diagram must show the pistil (stigma, style, ovary, ovule) with the pollen tube drawn as a line from the pollen grain down to the ovule. Label all four parts for full marks.
- "Fertilisation" should be named at the end for completeness.