Biology 9700 · AS & A Level · Gene control

Gene control — practice question

Bread wheat, Triticum aestivum, is a hexaploid that originated from diploid wild grasses.
(a)[4]

Outline how T. aestivum developed from wild grasses.

(b)

Wheat seeds start to germinate when conditions are warm and they are able to absorb water. Fig. 4.1 shows a germinating wheat seedling.

(c(i))[2]

Suggest why the researchers searched for mRNA transcribed from the TaSUT1 gene rather than for the gene itself.

(c(ii))[2]

Explain what the results in Fig. 4.2 show about the sequence of TaSUT1 activity, from day 3 to day 10, in the root, seed and shoot of a seedling.

(d(i))[2]

Suggest how this allowed the researchers to find the regions in which SUT was located.

(d(ii))[2]

Explain how these results support the hypothesis that the first source of sugar for the embryo during germination is sucrose from the aleurone layer and not sugars produced by the hydrolysis of starch.

(d(iii))[3]

Outline the way sucrose is moved in phloem.

(c(iii))[3]

Outline the way sucrose is moved in phloem.

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