The cell cycle and mitosisAQA A-Level Biology: Mind map

Exam questions on The cell cycle and mitosis

1. A student prepared a stained squash of onion root tip cells and examined it with an optical microscope. In one field of view she counted 180 cells, of which 27 were in one of the stages of mitosis.
   Explain why the student used the tip of the root, and why she squashed the stained tissue.2 marks
2. A cell biologist is studying a human skin cell that has 46 chromosomes in its nucleus before it divides by mitosis.
   Explain how the sister chromatids of this cell are moved to opposite poles during anaphase.2 marks
3. A pharmaceutical company is testing a new drug on cultured tumour cells. The drug stops spindle fibres from forming, but it does not affect DNA replication. A technician counted cells in samples before treatment and 24 hours after treatment.
   Explain how the drug would reduce the growth of a tumour.3 marks