Biology study guide word

Biology study guide word - Reproduction: A Primer Sex - the...

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Reproduction: A Primer Sex - the process that involves meiosis and fertilization. Meiosis ultimately results in haploid gametes that fuse during fertilization. Advantage of sexual reproduction - genetic variation Asexual reproduction - reproduction without sex (more common in plants than in animals) Offspring genetically identical to parents (clones) Budding Regeneration - small part of the organism becomes new organism Parthenogensis - offspring develops from an unfertilized egg. Fragmentation/Fission - essentially splitting in half to form 2 individuals Safer bet for offspring - less can go wrong compared to sexual reproduction Disadvantage - no genetic variation Females have the ability to discriminate between sperm of different species - unable to fertilize eggs if inseminated with the sperm of another species. Some plants and fish can change sex in order to maximize reproductive output. Plant Reproduction Alternation of Generation The alternating cycle of plants between diploid and haploid phases Diploid = Sporophyte Produces spores by meiosis Haploid = Gametophyte Produces gametes by mitosis Trend to increase time in sporophyte, decrease time in gametophyte Parts of a Flower Stem Axis (pedicel stalk and receptacle attachment) - supports the flower Sepals - Outermost layer, protect developing inner parts Petals - attract pollinators Pollination - transferring pollen from stamens to carpels. Stamens - male reproductive organ, produces pollen (anther and filament Carpels (Pistil)- female reproductive organ, produces female gametophyte, which produces the egg Stigma - pollen receptive surface Style - the stalk Ovary - enlarged basal portion that contains ovules If flower is missing male or female parts, it is termed imperfect - unisexual Sporocytes = mother cells - divide meiotically to produce: Microspores - males Undergo one division to produce a male gametophyte with two nuclei (one tube and the other generative) Megaspores - females Undergoes three mitotic divisions to produce female gametophyte (embryo sac) with eight nuclei - egg, 3 antipodals, 2 synergids, 2 polar nuclei Male "immature" gametophyte = pollen when germinated, has a pollen tube and two sperm nuclei = mature male gametophyte Female gametophyte - housed in ovule (embryo sac) Pollination - transfer of pollen from anther of stamen to carpels Wind Water Animals (birds, bees, butterflies, moths, giraffes, fungi) All plants evolutionarily adapted for its mode of pollination Fertilization - fusion of sperm and egg Occurs in ovule Pollen tube grows into the ovule - specifically the micropyle opening
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This note was uploaded on 09/04/2008 for the course BIOL 221 taught by Professor Saupe during the Spring '08 term at CSB-SJU.

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Biology study guide word - Reproduction: A Primer Sex - the...

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