Question

In Bryophytes, diploid numbers of chromosomes occur in
A. Gametes
B. Spores
C. Spore mother cells
D. Nuclei of gametes

Answer 1

Hint: Bryophytes are nonvascular land plants of moist habitat, in which diploid sporophyte lives as a parasite on independent haploid gametophyte. They include about 25,000 species.
These are also called the amphibians of the plant kingdom because they can live on land as well as in water. Their body is commonly differentiated into stem and leaf-like structures.

Complete answer:
The life cycle of Bryophytes is haplo-diplontic which means in some structures it shows haploid (n) chromosomes and some shows diploid (2n) chromosomes.
The dominant phase or main plant body of bryophytes is a gametophyte (which is haploid in nature having ‘n’ number of chromosomes) and which is not differentiated into true roots, stems and leaves and called thallus. The sporophyte remains attached to the gametophyte for support, shelter and nutrition and also called as sporogonium (having ‘2n’ number of chromosomes and diploid in nature).
A gametophyte having the sex organs – antheridia (male sex organs produce sperms or antherozoids) and archegonia (female sex organs produce egg or oosphere) having ‘n’ number of chromosomes. In the presence of water (which is essential for swimming the sperms to the eggs for fertilization) gametes produces a diploid zygote, then mitosis occur the zygote develops to form a diploid (2n) embryo, which grows into a sporophyte. In sporophyte, sporophyll is present in leaves and in this the spore mother cells (SMC) are present. Both sporophyll and SMC are diploid in nature because no reductional division occurs. After meiosis, spores (n) are produced and germinate to form free living gametophyte (n).

So, the correct answer is option (C) Spore mother cell.

Note-
Bryophytes are called the first embryophyte because in this the embryo is formed after the zygote formation. They occur in damp and shady places and they grow densely together and form green carpets on damp soils, rocks, walls, tree trunks, etc. during the rainy season.