Biology 9700 · AS & A Level · Testing for biological molecules

Testing for biological molecules — practice question

Fig. 3.1 depicts the nematode worm, Caenorhabditis elegans. Stem cells from C. elegans have been investigated. Fig. 3.2 illustrates how the mass of DNA per nucleus in a stem cell changes during one cell cycle. $1\,\text{pg} = 1 \times 10^{-12}\,\text{g}$.
(a(i))[2]

State the interphase stages shown by A and B in Fig. 3.2.

(a(ii))[1]

State the mitotic stage shown by D in Fig. 3.2.

(a(iii))[2]

Outline the changes that occur in a cell as it prepares for cytokinesis.

(a(iv))[2]

A stem cell from a female C. elegans contains 12 chromosomes. Complete Table 3.1 to show the number of nuclei in stages A, B and D of the cell cycle shown in Fig. 3.2, and the number of chromosomes in each nucleus during these stages.

(ii)[1]

State which mitotic stage is shown at D in Fig. 3.2.

(iii)[2]

Outline what happens in a cell as it prepares for cytokinesis.

(iv)[2]

A stem cell of a female C. elegans has 12 chromosomes. Complete Table 3.1 to show the number of nuclei in the stem cell during stages A, B and D of the cell cycle shown in Fig. 3.2, together with the number of chromosomes in each nucleus at these stages.

(b)[3]

With reference to Fig. 3.3, Outline the role of stem cells in animals.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: A represents the $G_1$ phase

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