Problem : In gymnosperms and angiosperms, spores of two distinct sexes are produced and give rise to sex-specific gametophytes. What is this phenomenon called?

Heterospory.

Problem : What is the difference between microspores and megaspores?

Microspores are spores that are specifically male and give rise to male gametophytes; megaspores, on the other hand, are specifically female and give rise to female gametophytes.

Problem : Define alternation of generations.

The fluctuation between the diploid (sporophyte) and haploid (gametophyte) life stages that occurs in plants.

Problem : Through what process do sporophytes generate spores?

Meiosis.

Problem : Sketch the lifecycle of an angiosperm. Which generation is dominant?

Figure %: Angiosperm Life Cycle
The dominant generation in angiosperms is the diploid sporophtye.