Question 1: Define meiosis and explain its primary purpose in organisms.

Answer: Meiosis is a type of cell division that reduces the chromosome number by half, producing four haploid gamete cells, which is essential for sexual reproduction.

Question 2: List the main stages of meiosis in the correct order.

Answer: Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, followed by Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis.

Question 3: Describe what happens during homologous chromosome pairing in meiosis.

Answer: Homologous chromosomes pair up during prophase I, aligning gene-by-gene, which allows crossing over to occur and increases genetic variation.

Question 4: What is crossing over and why is it important?

Answer: Crossing over is the exchange of genetic material between homologous chromosomes during prophase I, increasing genetic diversity in gametes.

Question 5: Explain the difference between the products of meiosis and mitosis.

Answer: Meiosis produces four genetically diverse haploid gametes, while mitosis produces two identical diploid daughter cells.

Question 1: If a human cell has 46 chromosomes, how many chromosomes will each gamete contain after meiosis?

Answer: 23

Question 2: Calculate the total number of chromatids present in a human cell during metaphase I of meiosis, given that each chromosome consists of two chromatids.

Answer: 92

Question 1: Describe a safe method for preparing a slide to observe meiotic cells in an onion root tip.

Answer: Collect root tips, fix them in a preservative, stain with a suitable dye like acetic orcein, and carefully squash the tissue onto a slide for microscopic examination, following safety protocols.

Question 2: Identify the variables that should be controlled in an experiment observing meiosis in plant cells.

Answer: Variables include temperature, stain concentration, age of the plant, and the part of the plant sampled, to ensure consistent results.

Question 1: In a sample of 200 gametes produced by meiosis, 10 show a chromosomal abnormality. Calculate the percentage of abnormal gametes and discuss its significance for genetic diversity.

Answer: The percentage of abnormal gametes is (10/200) × 100 = 5%. This indicates the rate of chromosomal errors, which can lead to genetic disorders but also contribute to genetic variation.

Question 1: Describe the significance of meiosis in maintaining the stability of the species' chromosome number across generations. (6 marks)

Answer: Meiosis ensures that each gamete contains half the number of chromosomes, preventing the doubling of chromosome numbers across generations. During fertilisation, the fusion of gametes restores the diploid number, maintaining species stability. Additionally, crossing over and independent assortment during meiosis increase genetic variation, which is vital for evolution and adaptation.

Question 1: Explain how understanding meiosis is important in the field of genetic counselling and in addressing genetic disorders.

Answer: Understanding meiosis helps genetic counsellors assess risks of inherited disorders caused by chromosomal abnormalities, and informs decisions about reproductive options, enabling early diagnosis and management of genetic conditions.