MeiosisAQA A-Level Biology: Mind map

Exam questions on Meiosis

1. A grasshopper has 24 chromosomes in each of its body cells. Sperm cells are produced in the testes by meiosis, starting from diploid cells that have already replicated their DNA.
   Explain why the first division of meiosis is known as a reduction division.2 marks
2. In a species of seaweed, the main plant body is haploid. It releases gametes, and two gametes fuse to form a diploid zygote. The zygote grows by mitosis into a diploid plant body, which releases spores. Each spore grows by mitosis into a new haploid plant body. Cells of the diploid plant body contain 18 chromosomes.
   State the number of chromosomes in a spore of this seaweed and explain how this number is produced from the diploid plant body.2 marks
3. A biologist studies cells in the testis of a mouse, where each body cell has 40 chromosomes. Some testis cells divide by mitosis to produce more of the same cell type, while others divide by meiosis to form sperm.
   Describe what happens to the chromosomes in the first division of meiosis and how this differs from what happens in the second division.3 marks