Explain why cross-pollination produces greater genetic diversity in a plant species than self-pollination.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Cross‑pollination transfers pollen from the anther of one plant to the stigma of a different plant, so the male gamete nucleus from one plant fuses with the female gamete nucleus in the ovule of another plant during fertilisation. Consequently the offspring receive genetic material from two genetically different parents, producing a wider range of alleles and phenotypes. In contrast, self‑pollination uses gametes from the same plant, so the offspring are genetically identical or very similar, giving less variation.
Examiner tips
- Use the word ‘different’ to show contrast; mention both male and female gametes; explain that offspring inherit from two parents; keep answer concise and use exam terminology
Common mistakes
- Confusing self‑pollination with cross‑pollination; not mentioning both gametes; claiming offspring are identical in cross‑pollination; using vague terms like ‘more genes’ instead of ‘genetic diversity’
Mark scheme (4 marks)
- Cross-pollination involves pollen being transferred from an anther of one plant to the stigma of a different plant
- The male gamete nucleus from the pollen of one plant fuses with the female gamete nucleus in the ovule of a different plant during fertilisation
- This means the offspring receive genetic material / chromosomes from two genetically different parents
- Self-pollination uses gametes from the same plant so offspring are genetically identical / less variation; whereas cross-pollination produces genetically different / varied offspring
Key terms in this question
cross-pollination · self-pollination · genetic diversity
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Sexual reproduction in plants questions
- Describe the conditions needed for a seed to germinate, and explain why each con…
- Describe the structural adaptations of an insect-pollinated flower that increase…
- Compare the structural features of pollen grains from insect-pollinated flowers …
- Describe how a pollen grain reaches an ovule and fertilisation takes place in a …