Final answer:
The plant life cycle features alternation of generations with two distinct stages: the haploid gametophyte and the diploid sporophyte. The gametophyte produces gametes, and following fertilization, a zygote forms and develops into the sporophyte, which creates spores that grow into new gametophytes.
Step-by-step explanation:
Alternation of Generations in Plants
All plants exhibit a life cycle that includes a two-stage process known as alternation of generations. This process involves a cyclic transition between two distinct forms: the gametophyte stage and the sporophyte stage. The gametophyte is a multicellular, haploid phase where the organism produces gametes (male and female reproductive cells) through mitosis. The sporophyte is a multicellular, diploid phase that forms after the fusion of gametes and grows to maturity, eventually undergoing meiosis to produce haploid spores. These spores germinate to become new gametophytes, thus continuing the cycle.
Gametophyte Stage
The gametophyte stage is characterized by being haploid, meaning each cell contains a single set of chromosomes. In plants like mosses, the gametophyte is the dominant form and is more visually apparent. In seed plants such as flowering plants, the gametophyte exists as a smaller part of the plant, often as a pollen grain or ovule.
Sporophyte Stage
The sporophyte stage involves the diploid organism, which has developed from the zygote. This stage is dominant in higher plants, such as ferns and seed plants, where it can become a large and conspicuous part of the plant, like a towering tree or a fern. The sporophyte produces sporangia, structures in which meiosis occurs to form spores.