Mary Jones and Geoff Jones Solutions for Chapter: Transport in Plants, Exercise 3: Exercise 8.3

In which form are carbohydrates stored in plant cells?

In spring and summer in Switzerland, the leaves of pine trees photosynthesise. Suggest two reasons why pine trees photosynthesise in spring and summer in Switzerland, but not in winter.

Would you expect the leaves to be sources or sinks in spring and summer? Explain your answer. 

Would you expect the leaves to be sources or sinks in winter? Explain your answer. 

The table shows the amount of starch, measured as a percentage of the dry mass of the tissues, in the leaves and roots of pine trees at three times of the year. 

Describe the changes in the amount of starch in the pine tree leaves from spring until autumn. 

Describe the changes in the amount of starch in the pine tree roots from spring until autumn.

Situation A: The changes in the amount of starch in the pine tree leaves from spring until autumn. 

Situation B: The changes in the amount of starch in the pine tree roots from spring until autumn. 

Suggest a reason for the changes described in situations a and b.

In summer, the researchers removed the buds from some pine trees and the leaves from other pine trees. They left some pine trees untreated, to act as controls. They measured the amount of starch in the leaves and buds of each group of trees at the end of the summer. Their results are shown in Table.

Describe and explain the results shown in the table.