(a) Explain the process of the development of a male gametophyte in an angiosperm.(b) Why is it called a male gametophyte ?

Answer :

(a) Cells of sporogenous tissue/Microspore mother cell/Pollen Mother Cell/(PMC) in anther undergoes meiotic division, to form microspore tetrad which mature and dissociate to form pollen grains or male gametophyte.
(b) Because its generative cell divides, to form two male gametes.