Sexual Reproduction In Flowering Plants

Ubisch bodies : Tapetum is the innermost layer of anther wall which surrounds the sporogenous tissues. These cells are nutritive in function. In cells of taperum ubisch bodies are present, which help in the formation of microspore wall or exine of pollen grain. Pollen grain (microspore) is generally round haploid structure from which gameiophyte is developed - Pollen tube helps in carrying male gametes to female gamete for fertilization.

Polyembryony is of common occurrence among the gymnosperms. This is possible because more than one archegonia are fertilised and more than one zygotes are formed. These develop into embryos, but only one of them succeeds in developing into a complete embryo. In the conifers there is a cleavage polyembryony. In this case all the four cells of the young embryo separate and develop into 4 embryos, but only one complete development and others abort- e.g., Pinus.

Answer (b) Sporopollenin

Answer (a) apospory