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| 1. |
What is A sexual reproduction |
| Answer» Sexual reproduction occurs in many one-celled organisms and in all multicellular plants and animals. In higher invertebrates and in all vertebrates it is the exclusive form of reproduction, except in the few cases in which parthenogenesis is also possible. Sexual reproduction is essentially cellular in nature.Multicellular plants alternate sexual reproduction, or gametophyte, and asexual reproduction, or sporophyte, generations. The gametophyte produces gametes, and the union of gametes results in the growth of a sporophyte; the sporophyte produces spores that give rise to a gametophyte. The prominent generation in lower plants and the complex fungi is the gametophyte; in the vascular plants it is the sporophyte. The less prominent generation may be an independent plant, as is the small inconspicuous gametophyte of ferns, or a reduced organism consisting of only a few cells and dependent for survival on the prominent form, like the pollen grain, which is the male gametophyte of seed plants. | |