Question

Choose the option which mentions the events when mitosis happens in the life cycle of the bryophytes:

• A. I - during spore formation, II - during sporophyte formation
• B. I - during sporophyte formation, II - during gametophyte formation
• C. I - during spore formation, II - during gamete formation
• D. I - during gamete formation, II - during syngamy

Answer 1

The correct option is B I - during sporophyte formation, II - during gametophyte formation

Mitosis or equational division is the cell division where the number of chromosomes in the offspring remain the same as the parent cell. It happens at several stages in the life cycle of bryophytes. They have a haplo-diplontic life cycle in which the gametophytic phase is prominent (60%) in their life cycle. The male and female gametes are antherozoid and egg, respectively. They are haploid and fuse to give a diploid zygote. This is known as syngamy.

The zygote divides by mitosis to form the sporophyte. The sporophyte is diploid and dependent on the gametophyte for nutrition. It produces spores by reductional division or meiosis.

The spores germinate in a region which have favourable conditions like enough moisture. Mitosis takes place to form the multicellular gametophyte. The gametophyte is haploid, independent (photosynthetic). It produces gametes by mitosis.