[问答题]
The mitotic index is an
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hl*q3gm1-kz s f measuring plant growth. A study was conducted on white onions (Allium cep
gl1 zqmh 3sk-*a), under controlled conditions in a lab, to investigate the effect of soil pH on the mitotic index of the roots.
1.Describe the trends shown in the graph.
2.Outline how the mitotic index is calculated.
3.Discuss whether the data support the hypothesis that onion plants should be grown in soil with a pH of 5.5.
4.Suggest how a pH of 9 affects the process of mitosis.
5.1.Explain why measuring the mitotic index in the root is an indirect way of measuring the overall growth rate of the onion plant.
5.2.Suggest another method, apart from measuring mitotic index, that could be used to measure plant growth.
6.State one of the variables that must be controlled to make this experiment valid.