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Sperm cells and egg cells are formed by meiosis - AQA - GCSE Biology - Question 3 - 2020 - Paper 1
Question 3
Sperm cells and egg cells are formed by meiosis. 1. During meiosis a cell divides twice. How many sperm cells are formed when a cell divides by meiosis? 2. Human b... show full transcript
Worked Solution & Example Answer:Sperm cells and egg cells are formed by meiosis - AQA - GCSE Biology - Question 3 - 2020 - Paper 1
Step 1
1. How many sperm cells are formed when a cell divides by meiosis?
Answer
During meiosis, a single cell ultimately divides to form four distinct sperm cells. This occurs through two consecutive divisions: meiosis I and meiosis II, where homologous chromosomes and sister chromatids are separated, respectively.
Step 2
2. How many chromosomes are in each human egg cell?
Answer
Each human egg cell contains 23 chromosomes. This is because during meiosis, the chromosome number is halved from the original 46 in body cells to ensure that when fertilization occurs, the resulting zygote has the correct diploid number.
Step 3
Step 4
4. Suggest one way embryo screening can help people with a family history of a genetic disorder.
Answer
Embryo screening can help by allowing prospective parents to identify embryos that do not carry specific genetic disorders prior to implantation. This means that only healthy embryos can be selected, reducing the risk of the child inheriting the disorder.