bio essays - Stephanie Verrell P.6 Ch 24-28 Biology...

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Stephanie Verrell P.6 Ch. 24-28 Biology Outlines 1. Reproduction in Flowering Plants A. Fertilization 1. Pollen grain lands on a stigma of another flower 2. The grain germinates a pollen tube 3. Pollen tube digests it way down its pistil 4. Divides into two sperm nuclei 5. The polar nuclei and sperm nucleus produce triploid (3n) endosperm 6. Egg and sperm nucleus create a zygote B. Pollination 7. Pollination is the transfer of pollen from the anther to the stigma 8. May be carried by wind or insects 9. Some examples are hummingbirds, bees, and sometimes small mammals 10. The flower structure is adopted for these pollinators 11. Cross or self-pollination is possible 12. Pollen is formed by a microspore mother cell (2n) in the pollen sac 13. Then meiosis occurs and creates a 4 tetrad (n) 14. Then 4 microspores (n) 15. Mitosis creates 4 pollen grains (n) C. Gamete Formation 16. Ovule may be single or multiple in ovary 17. Ovule formation begins with the megaspore mother cell (2n) 18. From meiosis comes 4 haploid cells (n) 19. 3 of these haploids will die 20. The living one becomes a megaspore 21. Mitosis occurs again 22. 7 cells+ 8 nuclei 23. 2 nuclei are polar nuclei 24. The one cell is the egg D. Germination 25. In seed germination, the embryo resumes growth and metabolic activity 26. Germination begins with the absorption of water 27. The water initiate enzyme activity which in turn activate biochemical processes 28. In addition this water causes the seed to crack 29. The growing tips of the radicle produce roots that anchor the seedling 30. Elongation of the hypocotyl produces a young shoot The sporophyte produces haploid spores by meiosis. 31. occurs if the pollen is from the same plant. 32. Cross pollination occurs if the pollen is from a different plant or the same species. 33. The secretion of nectar is one way that pollinators are attracted to plants.
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34. When a pollen grain lands on the stigma of the same species, it germinates, forming a pollen tube The spores divide by mitosis to become haploid gametophytes. 35. This produces gametes by mitosis.
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This note was uploaded on 04/01/2008 for the course HISTORY 4A taught by Professor Norena during the Spring '08 term at Berkeley.

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bio essays - Stephanie Verrell P.6 Ch 24-28 Biology...

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