Question

Find out what kind of development takes place in the zygote in organism with diplontic and haplo-diplontic life cycles

Answer 1

In Diplontic Life Cycle, the zygote in gametic meiosis instead of dividing meiotically, divides mitotically to produce individual or unicellular organism with diploid cells. Diplontic life cycle is mostly observed in animals.

In most of the plants, the zygote undergoes mitotic cell division and produces diploid sporophytes. The sporophyte divides meiotically to produce haploid spores. These spores again undergo mitotic cell division and produce haploid gametophytes. This gametophyte produces gametes by mitosis. This type of life cycle is known asHaplodiplontic Life Cycle.

Answer 2

In organisms with diplontic life cycle, the formation of diploid zygote takes place by mitosis to form unicellular and multi-cellular organisms.  

Both angiosperms and gymnosperms follow this pattern.

On the other hand, in haplodiplontic life cycle, the zygote undergoes mitotic division to form multicellular diploid sporophyte which then undergoes meiotic division to form spores. This pattern has been seen in pteridophytes.