Apbio

In the life cycles of a fern and a flowering plant, correspond and contrast each of the following: The gametophyte generation. Both piss gametes that be haploid. In flowering plants, male and female gametophytes are taked in the sporophyte, and are dependent on it for fodder. The male gametes are pollen grains, the females conceptus sacs. Each gametophyte develops from a different type of spore. In ferns, the archegonia produce eggs and antheridia produce sperm. The archegonia and antheridia are on the prothallus, which is a olfaction shaped structure. Archegonia has a neck and the venter, which contains the egg. The antheridia has a wall of cells nourish the gametes. The gametes dont depend on the prothallus, they are photosynthetic and have rhizoids for anchoring and water absorption. Sperm transport and fertilization In ferns, the transportation of sperm to the eggs for fertilization needs a mois t environment (for mobility). The cells of the neck distribution channel and ventral canal disappear and releases a chemical that attracts the sperm. Fertilization takes view in the venter of the archegonium. In flowering plants, pollen (the male gametes) travels from the anther to the deformity of the pistil.

A pollination agent is needed, such as a bee or a butterfly, needs to pollinate the egg. The pollen grain hence germinates and grows done the style. Double fertilizations (2 sperm, 1 conceptus sac) happen later the pollen thermionic valve goes through the ovules. Embryo protection In ferns, since the conceptus is in t he archegonium during fertilization, it depe! nds on it for protection as well. It is dependent on the gametophyte for nutrition in the early stages. In flowering plants the embryos are protected by seeds, much give care a chickens egg. The outer layer is hard, and makes up the ovule. When cover in a fruit, the fruit comes from the ovary wall. The ovary wall has triple layers,...If you compulsion to get a full essay, order it on our website: OrderEssay.net

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