week_15_lectures - BY 1116 Biological Sciences I Dr....

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BY 1116 Biological Sciences I Dr. Kathryn Ponnock Week 15 – Reproduction in Seed Plants I. Life Cycle of Gymosperms A. Gymnosperms produce Two Types of Spores 1. Microspores produced in Microsporangia will develop into Male Gametophyte 2. Megaspores produced in Megasporangia will develop into Female Gametophye B. Gametophyte Generation is Microscopic and consist of just a few cells 1. Male Gametophyte is the Pollen Grain which is resistant to Drought 2. Female Gametophyte is the Egg which develops in the Ovule and the Ovule will eventually become the Seed 3. Pollen grain will be transported to Female Gametophyte and will form a Pollen Tube which will transport Sperm to Egg. II. Life Cycle of Pine Tree C. Pine Tree is Mature Sporophyte that produces Male and Female Cones on the Same Tree D. Production of Male Gametophyte (Pollen Grains) 1. Male cone has many scales and under each scale is a Microsporangium or Pollen Sac 2. Microsporangium contains Diploid cells that undergo Meiosis to form Haploid Microspores 3. Microspores then undergo Mitosis to form Pollen Grains E. Production of Female Gametophyte (Ovule and Egg) 1. Female cone will contain Megasporangium 2. Within Megasporangium, one cell will undergo Meiosis to produce Four Megaspores 3. Only 1 Megaspore will last – other three will die 4. Megaspore will become the Female Gametophyte (Egg within Ovule)
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week_15_lectures - BY 1116 Biological Sciences I Dr....

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