Question 1: Define mitosis and explain its role in cell division.

Answer: Mitosis is a type of cell division where a single parent cell divides to produce two genetically identical daughter cells, essential for growth, repair, and asexual reproduction in multicellular organisms.

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

Answer: Prophase, Metaphase, Anaphase, Telophase.

Question 3: Describe what happens during metaphase of mitosis.

Answer: During metaphase, chromosomes align at the cell equator, attached to spindle fibres, preparing for separation.

Question 4: Calculate the time taken for a cell to complete mitosis if a researcher observes that mitosis lasts 1 hour in 20% of the cells observed in a sample. Show your working.

Answer: Total cell cycle time = (Duration of mitosis / Proportion of cells in mitosis) = 1 hour / 0.20 = 5 hours.

Question 5: Identify two variables that could affect the rate of mitosis in a tissue sample.

Answer: Variables include temperature and availability of nutrients.

Question 6: Which phase of mitosis is most susceptible to errors leading to genetic disorders, and why?

Answer: Anaphase, because errors during chromosome separation can lead to uneven distribution of genetic material.

Question 7: Explain how mitosis is utilised in asexual reproduction in plants.

Answer: In plants, mitosis occurs in the meristematic tissue to produce new cells for growth and the formation of new structures, enabling asexual reproduction such as runners or tubers. This process allows plants to propagate without the need for fertilisation, ensuring genetic consistency across offspring.

Question 8: Design an outline for a simple experiment to observe mitosis in onion root tips. Include key variables and safety precautions.

Answer: An experiment involves preparing onion root tip slides by staining with a suitable dye like acetic orcein, then observing under a microscope. The independent variable is the treatment duration or temperature; the dependent variable is the number of cells in mitosis. Safety precautions include wearing gloves and eye protection, handling dyes carefully, and disposing of biological waste properly.

Question 9: A sample of 200 cells was observed, and 40 cells were in mitosis. Calculate the mitotic index and interpret what this indicates about the cell cycle stage distribution.

Answer: Mitotic index = (Number of cells in mitosis / Total number of cells) × 100 = (40 / 200) × 100 = 20%. This indicates that 20% of the cells are actively dividing, suggesting a moderate rate of cell division.

Question 10: Discuss the importance of mitosis in medical treatments, such as cancer therapy.

Answer: Mitosis is targeted in cancer therapy because uncontrolled cell division leads to tumour growth. Treatments aim to inhibit mitosis in cancer cells to prevent tumour expansion, using drugs that disrupt spindle formation or DNA replication.

Question 11: Identify a technological advancement that has improved the study of mitosis and briefly explain its impact.

Answer: The development of high-resolution microscopes and live-cell imaging techniques has allowed scientists to observe mitosis in real-time, leading to a better understanding of cell cycle errors and potential targets for medical interventions.

Question 12: In what way does understanding mitosis benefit industries such as agriculture or pharmaceuticals?

Answer: Understanding mitosis helps improve crop propagation techniques and develop drugs that can regulate cell division, such as anti-cancer drugs, thereby enhancing agricultural productivity and medical treatments.