Question

When and where does reduction take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm, and an angiosperm?

Answer 1

The first division of meiosis in which the number of chromosomes reduced to half the original number of chromosomes. Sexual reproduction only takes place in eukaryotes by forming gametes during the gametes formation number is reduced to half (reduction).

Complete answer:
Liverwort-In liverworts the main plant body is haploid that means gametophytic. It bears the male and female sex organs which produces gametes. It releases haploid spores from the sporangium that developed on the sporophyte. Spores spread via water and wind settle down on the gametophytes attached to the substrate by a thin filament and then male, female gametangia developed on the separate and individual plant. These gametes fuse to form a zygote and then the zygote develops on the gametophytic plant body to form a sporophyte. This sporophyte is differentiated into foot, seta, and capsule. Many haploid spores are produced which is the results of the reduction division taking place inside the capsule

Moss-Mosses alternate between diploid and haploid generations in their life cycle which is unique among all the plants. The sexual production of moss is that in a nutshell, haploid gametophytes produce haploid gametes which can be egg or sperm. When these sperm and egg fuse together to form a zygote which is grown by the process mitosis that is in the diploid sporophyte. Sporophytes then produce haploid spores containing genetic information from both the parents and this is the reduction phase in the moss.

A Fern-In fern the main plant body is sporophytic. Its leaves are known as sporophylls and these bear sporangia. First their will be release of the spores then these spores grow into a small heart shape plant gametophyte and these bear both male and female sex organs. They mature and fuse together to produce the zygote, the zygote grown by mitosis and form sporangia which undergo reduction division and produce numerous spores.

Gymnosperm-In gymnosperms the main plant body is sporophytic. They bear two types of leaves: microsporophylls and megasporophylls. Reduction division takes place in the microsporangia producing pollen grains and in the megasporangia produces megaspores.

Angiosperm- In angiosperms the main plant body is sporophytic and which bears flowers. The male sex organ in the flower is the stamen and the female sex organ is the pistion. The reduction division takes place in the stamen by producing haploid pollen grains and in the ovary of the pistil which produces egg and then these two fuse together and form a sporophytic plant body.

Note: Meiosis produces 4 haploid cells. In meiosis 1 reduces ploidy level from 2n to n which means chromosome number 46 will reduce to 23 while in meiosis 2 divides the remaining set of chromosomes that is a division.