Ans.
Gametophyte shows haploid, gamete-forming stage of plant's life cycle, while sporophyte shows diploid, spore-forming stage of plant's life cycle. In green algae, gametophytes and sporophytes are isomorphic (indistinguishable). In bryophytes, such as mosses, gametophyte shows dominant stage as it is most visible stage in their life-cycle. In vascular plants, such as ferns and seed plants, sporophytes show dominant stage.
Thus, 'seed plants show briefest gametophyte stage' and 'mosses show longest gametophyte stage.'
The distinction between protostomes and deuterostomes is based on differences in their embryological development. Protostomes develop their oral end from their first developmental opening, while deuterostomes have their oral end develop from the second opening on the dorsal surface.
Answer:
B
Mutation is the ultimate source of genetic variation, but mechanisms such as sexual reproduction and genetic drift contribute to it as well Because prokaryotes are haploid, such a mutation immediately become part of the genetic makeup of the cell unlike eukaryotic diploids where a normal second copy of the gene usually protects the cell from the potentially lethal effect of such a mutation.
