Final Exam - Biology 1202 Final Exam A Chapter 38 Flowering...

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Biology 1202- Final Exam A pril 15, 2010 Chapter 38: Flowering Plant Reproduction Angiosperms Alternation of Generations 1. Meiosis occurs in sporangia of sporophytes (Figure 30.10) 2. Alternation of generations goes though haploid gametophyte stage and the diploid sporophyte stage. 3. Animals bodies don’t go though multicellular sex cell stage. 4. Spores divide by mitosis and develop into mature gametophytes. 5. Specialized gametophyte cells divide by mitosis to form gametes. 6. Gametes fuse during fertilization to produce a zygote. FIGURE 38.2 WILL BE ON THE FINAL. A complete flower has: 1. Male parts 2. Female parts 3. Kettles 4. Sepals a. A uni-cellular flower is not a complete flower A sporophytes’ male reproductive structures: 1. Stamen a. Anther b. Filament 2. Each anther contain multiple pollen sacs (microsporangia) 3. Each pollen sac contains multiple diploid microsporocytes (microspore mother cells)
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Biology 1202- Final Exam 4. Each microsporocyte divides once by mitosis to form an immature male gametophyte (pollen grain) a. A single tube cell encloses a single generative cell. 5. The pollen grain matures into an adult male gametophyte when its generative cell divides by mitosis to produce two sperm a. The adult male gametophyte is a fully mature, independent plant with only three cells. A sporophytes’ female reproductive structures: 1. Carpel a. Stigma b. Style c. Ovary d. Ovule 2. Receptacle. 3. Each ovule contains a megasporangium 4. Each megasporangium contains a megasportocyte (megaspore mother cell) 5. A megasporocyte divides by meiosis to form 4 cells. 6. Only 1 of the 4 cells survives: the megaspore 7. The megaspore’s nucleus divides 3 times: giving 1 2 4 8 nuclei 8. Membranes then partition the 8-nucleate immature gametophyte cell into 7 smaller cells a. 7 cells 8 nuclei. One cell contains two nuclei. 9. The 7 cells: a. 1 egg b. 1 cell with 2 polar nuclei c. 5 other cells.
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Biology 1202- Final Exam 10. The 7 cells comprise the mature, completely dependent female gametophyte (embryo sac) Double fertilization of angiosperms (and independently derived in a few gymnosperms) 1. A pollen grain disperses to a stigma (pollination) 2. The tube cell grows into a pollen tube 3. The two sperm cells travel down the pollen tube to the embryo sac. a. 1 sperm fuses with the egg (fertilization) 1 st fertilization b. 1sperm fuses with the polar nuclei to form the first cell of the endosperm (triploid) 2 nd fertilization Mechanisms used by plants to avoid self-fertilization; Bisexual flowers also use: 1. Flowers with functional stamens and carpels that mature at different times 2. Dioecious plants that produce plants that are male or female. 3. Structural barriers to pollination. Eg. pin vs. thrum flowers 4. Genetic self-incompatibility, gauged by S-genes a.
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