A student prepared a slide from the growing tip of an onion root. Fig. 1 shows four cells from the same root tip at different stages of mitosis. The chromos...
Question 1 Report
A student prepared a slide from the growing tip of an onion root. Fig. 1 shows four cells from the same root tip at different stages of mitosis. The chromosomes have been stained so that they can be seen clearly. Each new body cell produced by this process should receive the same genetic information.
(a) Name the stage of mitosis shown by cell B. [1]
(b) Complete this sequence of stages: C, ___, ___, D. [2]
(c) Describe two changes shown in cell D. [2]
(d) Explain why mitosis is important for growth of the onion root. [3]
Answer Details
(a) Cell B is in metaphase. [1 mark] Its chromosomes are arranged across the middle of the cell.
(b) The sequence is C, A, B, D. The missing stages are A, prophase, followed by B, metaphase. [2 marks]
(c) In cell D, the chromosomes or chromatids are at opposite ends of the cell. Also, two nuclei are forming, or the cell is dividing into two cells. [2 marks]
(d) Mitosis produces more cells. The extra cells increase the length and size of the growing onion root. Each daughter cell receives the same chromosomes, or DNA, as the original cell, so the new cells can carry out the same functions. [3 marks]
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