(a)[2]
State and explain how the same leaf of a plant may be called a source or a sink, depending on the stage of maturity (age) of the leaf.
(b)[4]
From the cell types listed in Fig. 6.1, choose the correct one for each statement, A to E. A cell type may be used once, more than once, or not at all. The first one has already been matched for you. A This is a thick-walled cell that gives support. (Answer given: 5) B This cell is one member of a pair that forms a stoma. C This cell takes in water so that hydrostatic pressure builds up for mass flow. D This cell requires water for photosynthesis and has a columnar shape. E This cell releases a waxy material that helps reduce water loss.