Question

Leafy gametophytes are formed from protonema in
A. Riccia
B. Marchantia
C. Anthoceros
D. Funaria

Answer 1

Hint: A gametophyte is one of the two alternating multicellular phases in the life cycles of algae and plants. A gametophyte is a haploid multicellular organism that grows from a haploid spore that has a single set of chromosomes. The gametophytes produce gametes, haploid sex cells that partake in fertilization to form a diploid zygote which has two sets of chromosomes.
Complete step-by-step answer: Unspecialized cells in various parts of the sporogonium can form green protonemal filaments. The protonemal filaments bear lateral buds that develop into leafy gametophores. Apospory refers to the production of leafy gametophytes directly from vegetative cells of the sporogonium without the involvement of spores. While gametophores produced aposporously appear normal, genetically they are diploid. In Funaria, the plant body is a free-living gametophyte that exists in two forms, leafy gametophore (adult gametophyte) and protonema (juvenile gametophyte).
Riccia plants are generally monoecious, and sexual reproduction takes place by archegonia and antheridia. Asexual reproduction takes place through spores, the formation of apical tubers, or the fragmentation of the rosettes.
Marchantia can reproduce both asexually and sexually. Sexual reproduction occurs between sperm from the antheridia of the male plant and an ovum in the archegonium of a female plant. The archegonia and antheridia are produced from gametophore stalks called archegoniophores and antheridiophores, respectively.
Anthoceros species show multiple forms of asexual reproduction. Except for fragmentation, a closely universal form, these hornworts show persistent apices, apospory, and tubers.
Hence, the correct answer is option D.
Note: A protonema is a thread-like chain of cells that constitutes the earlier stage of development of the gametophyte in the moss life cycle. When moss grows from a spore, it initiates as a germ tube, which elongates and branches into a filamentous complex called a protonema, which grows into a leafy gametophore, the mature form of a gametophyte.