During sexual reproduction in flowering plants, fertilisation produces a zygote. Describe the roles of the male and female gametes in sexual reproduction in flowering plants, and explain how the process leads to variation in the offspring.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Flowering plants reproduce sexually by producing male and female gametes that fuse during fertilisation. The offspring produced show variation compared with both parent plants.
Model answer (5 marks)
The male gamete is contained in the pollen grain, which is produced by the anther of the stamen. The female gamete is the egg cell, located inside the ovule in the ovary of the carpel.
During fertilisation the pollen grain lands on the stigma, germinates and the pollen tube carries the male gamete to the ovule. The male gamete fuses with the egg cell, forming a diploid zygote.
Both gametes are haploid, each carrying half the chromosome number of the parent plant. When they combine, the zygote receives genetic material from both parents, producing a new combination of alleles. This mixing of genetic information generates variation in the offspring.
During fertilisation the pollen grain lands on the stigma, germinates and the pollen tube carries the male gamete to the ovule. The male gamete fuses with the egg cell, forming a diploid zygote.
Both gametes are haploid, each carrying half the chromosome number of the parent plant. When they combine, the zygote receives genetic material from both parents, producing a new combination of alleles. This mixing of genetic information generates variation in the offspring.
Examiner tips
- Use the terms "pollen grain" and "ovule" to show knowledge of male and female structures.
- Explain that each gamete is haploid and that fertilisation restores diploidy.
- Show that the combination of two different sets of alleles creates genetic variation.
Common mistakes
- Confusing the pollen grain with the pollen tube; the pollen grain contains the male gamete, the tube is the delivery system.
- Forgetting to mention that the egg cell is in the ovule, not the ovary as a whole.
- Failing to state that each gamete is haploid and that fertilisation restores diploidy.
Mark scheme (5 marks)
- Pollen grain / pollen contains the male gamete (haploid)
- Ovule / egg cell is the female gamete (haploid) / female gamete is found in the ovary
- Fertilisation occurs when the male and female gametes fuse to form a zygote (diploid)
- Each gamete is haploid / contains half the number of chromosomes, so offspring receive genetic material from both parents
- This mixing / combination of genetic information from two parents results in genetic variation in the offspring
Key terms in this question
gamete · fertilisation · zygote · variation
Related
- All Pearson Edexcel A-Level Biology A (9BI0) revision notes →
- How to answer a "Describe and Explain" question →
- Decode the mark scheme abbreviations →
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