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Biol121-Final study guide

Biol121-Final study guide - Biological Principles II Biol...

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Biological Principles II Biol 121 Spring 2007 Exam IV (FINAL) Review Matzner lectures Chap 38 Read p771-780, I did not talk about the parts of self incompatability on p776-so that won’t be on the test. Chap 39 Skip stimuli and signal transduction 788-791 (you will get that next year in Cell Biol). Start with Plant Hormomes 791-801, skip brassinosteroids and I won’t cover the Arabidopsis mutants on pP 800. Also read, 808-809- gravitropism Questions Chap 38 Remember alternation of generations *Know how the male and female gametophytes develop Fig. 38.4 Male—Pollen grains develop within the micro sporangia of anthers at the tip of the stamens. Each of the micro sporangia contains diploid microsporocytes. Each microsporocyte divides by meiosis, producing four haploid microspores, each of which develops into a pollen grain. A pollen grain becomes a mature male gametophyte when its generative nucleus divides and forms two sperm. This usually occurs after a pollen grain lands on the stigma of a carpel and the pollen tube begins to grow. Female—The embryo sac develops within an ovule, itself enclosed by the ovary at the base of a carpel. Within the ovule’s megasporangium is a large diploid cell called the megasporocyte. The megasporocyte divides by meiosis and gives rise to four haploid cells, but in most species only one of these survives as the megaspore. Three mitotic divisions of the megaspore form the embryo sac, a multicellular female gametophyte. The ovule now consists of the embryo sac along with the surrounding integuments (protective tissue). *Know double fertilization. 38.6 Double fertilization is the union of two sperm cells with different nuclei of the embryo sac. If a pollen grain germinates, a pollen tube grows down the style toward the ovary. The pollen tube discharges two sperm into the female gametophyte (embryo sac) within an ovule. One sperm fertilizes the egg, forming the zygote. The other sperm combines with the two polar nuclei of the embryo sac’s large central cell, forming a triploid cell that develops into the nutritive tissue called the endosperm. *Know how gibberellic acid affects seed germination Fig. 39.11. Gibberellins mobilize nutrients during the germination of grain seeds. After a seed imbibes water, the embryo releases gibberellin (GA), which sends a signal to the aleuronem the thin outer layer of the endosperm. The aleurone responds to GA by synthesizing and secreting digestive enzymes that hydrolyze nutrients stored in the endosperm. One example is α-amylase, which hydrolyzes starch. Sugars and other nutrients absorbed from the endosperm by the scutellum (cotyledon) are consumed during the growth of the embryo into a seedling. Understand general concept of self incompatibility (but not in great detail), Fig 38.5 Pin and thrum flower types reduce self-fertilization. Pin flowers have tall stigma and short anthers. Thrum flowers have tall anthers and short stigma.
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*Understand terms (process/structure/function), Imbibation—the displacement of one fluid by another immiscible fluid. Dry seeds imbibe water before germination.
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