sexual reproduction life cycles and the alternation of generations

Download Sexual reproduction Life cycles and the alternation of generations

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Sexual reproduction Life cycles and the alternation of generations Sexual reproduction in animals Animals have diploid body cells and haploid gametes The diploid body cells are made by mitosis The haploid gametes are made by meiosis At fertilization the haploid sperm and egg fuse to produce the diploid zygote. This then divides many times by mitosis to grow into a new individual Sexual reproduction in plants In flowering plants there are two distinctive phases of life cycle: the diploid sporophyte and the haploid gametophyte Sexual reproduction in plants The diploid sporophyte produces haploid spores by meiosis. The spores develop into the haploid gametophyte, which then produces haploid gametes by mitosis Sexual reproduction in plants In plants such as mosses and ferns, the main plant is the diploid sporophyte. It produces (genetically different) haploid spores by meiosis Sexual reproduction in plants The spore grows into the gametophyte, which produces (genetically identical) gametes by mitosis. Sexual reproduction in plants In flowering plants the water dependent gametophyte stage in the life cycle is much reduced. The dominant stage in the life cycle is the sporophyte Essential terms to know Spore A haploid cell that can be dispersed It is the product of meiosis of a diploid cell Essential terms to know Gamete A haploid cell, produced by mitosis of haploid cells. It can fuse with another gamete to produce a diploid zygote Essential terms to know Sporophyte A multicellular plant that is diploid and produces spores. Essential terms to know Gametophyte A multicellular plant that is haploid and produces gametes Essential terms to know NB These terms have been defined in terms of plant kingdoms. A fungal spore is very different!!!! Essential terms to know Alternation of generations Terrestrial plants that have a life cycle with a multicellular gametophyte and multicellular sporophyte generation which alternates are said to have a life cycle that shows alternation of generations

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