A scientist is investigating sexual reproduction in flowering plants. Explain how fertilisation occurs in a flowering plant and why the offspring produced by sexual reproduction show genetic variation.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Flowering plants reproduce sexually. During this process, male and female gametes are produced and must combine to form a new organism.
Model answer (5 marks)
Pollen, which contains the male gamete, is transferred to the stigma during pollination.
The male gamete travels through the pollen tube to reach the female gamete in the ovule.
Fertilisation is the fusion of the male and female gametes (their nuclei).
Gametes are formed by meiosis, producing cells with half the normal chromosome number (haploid).
Meiosis creates gametes with different combinations of chromosomes/alleles, so the offspring inherit a unique mix of genetic information from both parents, giving rise to genetic variation.
The male gamete travels through the pollen tube to reach the female gamete in the ovule.
Fertilisation is the fusion of the male and female gametes (their nuclei).
Gametes are formed by meiosis, producing cells with half the normal chromosome number (haploid).
Meiosis creates gametes with different combinations of chromosomes/alleles, so the offspring inherit a unique mix of genetic information from both parents, giving rise to genetic variation.
Examiner tips
- Use the exact terms: pollen, stigma, pollen tube, ovule, fertilisation, meiosis, haploid, genetic variation.
- Show the sequence: pollination → pollen tube → fertilisation → meiosis → variation.
- Include both male and female gamete roles.
- Mention haploid nature of gametes.
Common mistakes
- Confusing fertilisation with pollination; they are separate steps.
- Omitting that meiosis produces haploid gametes.
- Failing to explain that genetic variation comes from different chromosome combinations.
Mark scheme (5 marks)
- Pollen (containing the male gamete) is transferred to the stigma (pollination)
- The male gamete (nucleus) travels through the pollen tube to reach the female gamete (in the ovule)
- Fertilisation is the fusion of the male and female gametes (nuclei)
- Gametes are formed by meiosis, producing cells with half the normal chromosome number (haploid)
- Meiosis produces gametes with different combinations of chromosomes / alleles, so offspring inherit a unique mix of genetic information from both parents, leading to genetic variation
Key terms in this question
fertilisation · genetic variation
Related
- All Pearson Edexcel A-Level Biology A (9BI0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Cells, Viruses and Reproduction questions
- A student is studying onion root tip cells undergoing mitosis. Explain why mitos…
- Explain why a cell from a multicellular organism, such as a muscle cell, contain…
- Explain why viruses are not considered to be living cells, and describe how viru…
- A student observes two types of cells under a microscope. One cell has a nucleus…