Pollen grains are male gametophytes, haploid male plants from the alternation of generations lifecycle of seed plants. It forms by meiosis and then mitosis in the anther, and it’s purpose is to germinate and deliver the two sperm to the egg and central cell for the production of zygote and endosperm. The pollen grain does this by growing a pollen tube to reach the ovule. Pollen was an important evolutionary step since the male gametophyte no longer needed soggy ground to grow nor the sperm a film of water in which to swim. This allowed seed plants to move into the dry interior of the land.
Work Step by Step
This question asks you to skim and summarize the material on pollen grains in this chapter. Then, think about the role of pollen in the move onto dry/drier land by the seed plants— how does pollen help them go about their life cycle in dry conditions.