Colorado AgriScience Plant Science

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					  Colorado Agriscience
      Plant Science
 Unit 4: Plant Reproduction & Genetics
Lesson 2: Sexual Reproduction in Plants
   Sexual Reproduction
• Involves flowers, fruit, & seed
• Sperm from male flower fuses w/the
  ovum of the female plant
• Results in recombination of DNA
  – Results in genetically unique individual
  – Allows plants to adapt & evolve to
    environmental change
• Transfer of pollen from the male to the
  female part of the plant(s)
• How pollination occurs
  – Self-Pollination
    • Pollen from a plant pollinates a flower on the
      same plant
  – Cross-Pollination
    • Pollen from a plant pollinates a flower on a
      different plant
• Necessary in flowering plants in order for a
  seed to develop
• Double Fertilization
  – Unique to plants
  – Two sperm nuclei involved in fertilization
  – 1st fertilization occurs when one sperm fuses with
    the egg creating a zygote
  – 2nd fertilization occurs when the 2 nd sperm nucleolus
    fuses with the two nuclei in the embryo sac
     • Results in the formation of the endosperm
• Hybrid
  – Fertilization occurring from parents that
    are genetically different
  – Advantages
    • Best traits of each parent is expressed
    • Results in Hybrid Vigor
       – Increased growth, drought resistance, or insect
         resistance is possible
 Fertilization & Genetics
• Genetic information is stored in
  every cell of the plant in DNA
• Segments of DNA, called genes,
  establish the code for plant
  appearance and traits
• Genes are arranged into a set of
 Fertilization & Genetics
• Diploid
  – Normal sets of cells containing two
• Haploid
  – Sex cells contain one chromosome
    • When fertilization occurs, the single sets of
      chromosomes are combined into the double
      set, one from each parent
    • Results in traits from each parent to be
      passed on to offspring.

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