Test 4- Outline+3b

Test 4- Outline+3b - NOTES FOR BIOLOGY 1002 Outline 3B...

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NOTES FOR BIOLOGY 1002 Outline 3B CHAPTER 25 Plant Reproduction and Development Sexual versus Asexual Reproduction Many plant species can reproduce both sexually and asexually. Asexual reproduction can occur via fragmentation Fragmentation can be an artificial process (cuttings) or a natural process. The parent plant sends out horizontal stems ( runners ) that can lead to completely new plants. Asexual reproduction is natural cloning where all the offspring are genetically identical to the parent plant. Sexual offspring combine the genes from two parents and are genetically different from their parents Plant Life Cycles Alternation of generations revisited (see fig 25-1) 2 distinct multicellular adult forms sporophyte : diploid plant which produces haploid spores Two types of spores are seen in the flowering plants. They are heterosporous (see fig 25-2) Megaspores - gives rise to the female gametophyte Microspores - gives rise to the male gametophyte gametophyte : haploid plant which produces gametes o In mosses and ferns the gametophyte is small and independent o Water is essential for sexual reproduction o In seed plants, gymnosperms and angiosperms, the gametophyte is very small and relies on the sporophyte (it’s part of the sporophyte) The two different gametophytes produce two types of gametes female gametophyte is an embryo sac containing an egg cell male gametophyte is a pollen grain (sperm) After fertilization the zygote develops into the seed (plant embryo), which will grow into a new sporophyte. Water no longer needed for transporting the gametes
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The Evolution of Flowers Gymnosperms were the earliest seed plants The gymnosperms relied on wind pollination for fertilization (see fig 25-3 and 25-8). Advantage - don’t need any biological help
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This note was uploaded on 04/29/2008 for the course BIOL 1002 taught by Professor Pomarico during the Spring '08 term at LSU.

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Test 4- Outline+3b - NOTES FOR BIOLOGY 1002 Outline 3B...

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