Final answer:
The gametophyte is usually self-sufficient, while the sporophyte relies on the gametophyte for nutrition and growth in plants.
Step-by-step explanation:
In the alternation of generations in plants, the gametophyte is typically self-sufficient. It is the haploid, multicellular phase that produces gametes through mitosis. Examples include the male gametophyte being produced within the pollen grain in seed plants and the male and female gametophytes in mosses and ferns.
The sporophyte, on the other hand, is the diploid, multicellular phase that produces spores through meiosis. It is physically dependent on the gametophyte for nutrition and growth. The sporophyte obtains the necessary nutrients from the gametophyte to support its development. This relationship between the gametophyte and sporophyte varies among different plant groups, with some plants being more dependent on the gametophyte than others.