The tomato plant, Solanum lycopersicum, is unable to tolerate drought periods (water shortage). Scientists have bred a tomato plant with improved drought tolerance. They measured the width and length of open stomata in drought-tolerant plants and in tomato plants that are not drought tolerant. Fig. 3.1 shows the equation used to determine the size of an open stoma (stomatal aperture): $\text{stomatal aperture} = \frac{\text{width of open stoma}}{\text{length of open stoma}}$. Fig. 3.2 gives the mean stomatal aperture for the two groups of tomato plants. Fig. 3.3 shows the transpiration rates of the two groups of tomato plants when they were kept under identical drought conditions.
(a)[5]
Using Fig. 3.2, Fig. 3.3 and Fig. 3.4, describe and explain how the drought-tolerant plants differ from the non-drought-tolerant plants.
(c)[5]
With Fig. 3.2, Fig. 3.3 and Fig. 3.4 as your references, describe and explain the differences between the drought-tolerant plants and the non-drought-tolerant plants.
(b)[3]
Suggest how this microRNA may interact with messenger RNA (mRNA) to stop proteins being produced in guard cells of $S.\ lycopersicum$.
Worked solution & mark scheme
This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Drought-tolerant plants show a smaller stomatal aperture and a lower transpiration rate” …