Meiosis and chromosome mutationsEdexcel A-Level Biology B: Flashcards
What these 13 flashcards ask
- What is the difference between diploid and haploid?
- Why must gametes be haploid?
- How many cells result from meiosis, and what is their chromosome number?
- What separates in anaphase I?
- What separates in anaphase II?
- What is a bivalent?
- What is crossing over?
- What is independent assortment?
- How many chromosome combinations from independent assortment in humans?
- What is a translocation?
- What is non-disjunction?
- Which chromosome abnormality causes Down's syndrome?
- What causes Turner's syndrome?
Exam questions on Meiosis and chromosome mutations
- A fruit fly, Drosophila, has 8 chromosomes in each of its body cells. Sperm are made by meiosis in the testes of the male fly.Explain why meiosis I, rather than meiosis II, halves the chromosome number.2 marks
- A baby girl is born with Down's syndrome. A karyotype of her cells shows 47 chromosomes, including three copies of chromosome 21. Both of her parents have a normal karyotype of 46 chromosomes.Explain how non-disjunction during meiosis could have caused this baby's condition.2 marks
- Many patients with chronic myeloid leukaemia have a Philadelphia chromosome in their white blood cell precursors. It forms when a piece of chromosome 22 breaks off and joins chromosome 9, while a piece of chromosome 9 joins chromosome 22. The change is found in the leukaemia cells but not in the patient's other body cells, such as skin cells.Explain why the Philadelphia chromosome is unlikely to be passed on to the patient's children.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).