LIFE SCIENCE

Detailed explanation-1: -Plants alternate between the diploid sporophyte and haploid gametophyte, and between asexual and sexual reproduction. Therefore, the life cycle of plants is known as alternation of generations. The ability of the plants to reproduce sexually and asexually helps them to adapt to different environments.

Detailed explanation-2: -Gametes develop in the multicellular haploid gametophyte (from the Greek phyton, “plant”). Fertilization gives rise to a multicellular diploid sporophyte, which produces haploid spores via meiosis. This type of life cycle is called a haplodiplontic life cycle (Figure 20.1).

Detailed explanation-3: -All plants transition between a haploid (n) gametophyte and a diploid (2n) sporophyte in the alternation of generation life cycle. Depending on the species, sometimes one or the other is the dominant stage. Bryophytes are a group of simple non-vascular plants that include mosses, liverworts, and hornworts.

Detailed explanation-4: -This process is called plasmogamy. Actual fusion to form diploid nuclei is called karyogamy, and may not occur until sporangia are formed. Karogamy produces a diploid zygote, which is a short-lived sporophyte that soon undergoes meiosis to form haploid spores.