These analogous cells evolved since the arrangement of the parts of the kelp is analogous with the arrangement of the parts of plants. The holdfast is like roots and needs sugar from the photosynthetic upper parts. The stalk is like a stem, through which the sugars are transported.
Work Step by Step
Draw side-by-side pictures of kelp (see Fig. 28.12) and a land plant to help you see the analogous nature of the three parts of these two organisms.