Biology 9700 · AS & A Level · Transport mechanisms
Transport mechanisms — practice question
Thale cress, $\textit{Arabidopsis thaliana}$, is employed to investigate the functions of genes and proteins in organisms. In the root hairs of $A.\ thaliana$, the cell membranes contain aquaporin proteins that enable water to move between the soil and the cytoplasm, as shown in Fig. 2.1.
(a(i))[3]
With reference to Fig. 2.1, explain the way in which water is absorbed by root hairs of $A.\ thaliana$.
(a(ii))[1]
State why aquaporins are needed in cell surface membranes.
(b)[3]
Describe the route followed by water from the cytoplasm of the root hair cell to a xylem vessel in the middle of the root.
(c(i))[1]
With reference to Fig. 2.2, explain why transpiration rate is greater during the day than at night in both groups of plants.
(c(ii))[3]
Explain how the results indicate that the cuticle is less effective in the mutant plants.
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Movement through the freely permeable cell wall by diffusion” …