The living organisms reproduce. Birth, growth, maturation, and death are very important stages in the life cycle of an organism. Plant development differs from animal development as greatly as their modes of life but they have some fundamental similarities. The fertilized egg develops into the multicellular plant body by mitotic division.
Fertilization in higher plants produces a diploid organism which are termed sporophytes. This sporophyte undergoes meiosis at some point and gives rise to haploid spore. These spores grow into a haploid phase termed a gametophyte.
This gametophytic stage contains either male or female reproductive parts. The male reproductive part gives rise to male gametes or sperms by mitotic divisions called sperms whereas the female non-motile gametes are the eggs.
These male gametes move to the female gametes either swimming through water (Bryophytes, Pteridophytes, etc.) or through some other agency. These male gametes fertilize the eggs and form zygotes. The zygotes in flowering plants develop into seeds that germinate to form a sporophytic plant.
Alternation of generations
It is a pattern in which two distinct plants bodies or organs produced in the same life cycle alternate with each other.
- Gamete: It is a sex cell or an egg or sperms.
- Spore: It is a reproductive body, usually one-celled, which is capable of developing into a new individual.
- Sporophyte: It is the plant capable of bearing spores, having the diploid number of chromosomes.
- Meiosis: It is a process in which a pair of nuclear divisions occurs successively, reducing the number of chromosomes by one-half. Meiosis develops genetic variations.
- Zygote: It is a cell formed by the fusion of two gametes.