Biology

Pollen grain (from the Greek palynos for dust or pollen) contains the male gametophyte (micro gametophyte) bod of the plant. Pollen grains argon produced by meiosis of microspore mother booths that are visit along the inner edge of the anther sacs (microsporangium). The outer theatrical agency of the pollen is the exine, which is undisturbed of a complex polysaccharide, sporopollenin. Inside the pollen are two (or, at most, three) cells that comprise the male gametophyte. The organ pipe cell ( in any case referred to as the tube nucleus) gos into the pollen tube. The glitch cell divides by mitosis to produce two spermatozoon cells. disagreement of the germ cell can occur forrader or after pollination. The change of pollen from the anther to the female soil is termed pollination. This is urbane by a variety of methods. Entomophilies is the transfer of pollen by an insect. Anemophily is the transfer of pollen by wind. Other pollinators include birds, bats, water, and humans. Some flowers (for example tend peas) develop in such a way as to fecundate themselves. Others tolerate mechanisms to ensure pollination with another flower. inflorescence discolour is apprehension to indicate the nature of pollinator: red petals are thought to attract birds, yellow for bees, and white for moths. Wind pollinated flowers have minify petals, such as oaks and grasses.

The gynoecium consists of the stain, style, and ovary containing one or to a great extent(prenominal) ovules. These three structures are often termed a pistil or carpel. In many plants, the pistils will fuse for all or int erpreter of their length. The stigma functio! ns as a receptive surface on which pollen lands and germinates its pollen tube. Corn silk is part stigma, part style. The style serves to move the stigma some distance from the ovary. This distance is species specific. The ovary contains one or more than ovules, which in turn contain one female gametophyte, besides referred to in angiosperms as the embryo sac. Some plants, such as cherry, have only a single ovary which produces two ovules....If you accept to get a full essay, order it on our website: BestEssayCheap.com

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