A researcher studies early development in a moth species. Sample A contains the two gametes immediately before fertilisation. Sample B contains all the cells of the embryo after the zygote has divided by mitosis.
| Sample | Cells present | Chromosomes in each cell |
|---|---|---|
| A | 2 | 9 |
| B | 8 | not recorded |
Calculate the total number of chromosomes in all the cells in sample B. Show your working.
A treatment prevents meiosis from halving the chromosome number in this moth. Calculate the number of chromosomes in a zygote formed from two treated gametes and explain what would happen to the chromosome number if the treatment affected every generation.
92 exam-style questions on Edexcel GCSE Biology 3.1 Reproduction and meiosis, covering 3.1.1 Advantages and disadvantages of reproduction and 3.1.2 Role of meiotic cell division. Each one has a worked solution and a mark scheme showing where the marks go.