Plant Reproduction

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Plant Reproduction
2012-02-27 12:46:38
Plant Reproduction

Plant Reproduction
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  1. The plant sexual life cycle alternates between diploid and haploid stages

    • Alternation of generations
    • Sporophyte: diploid (2n)

    • Gametophyte: haploid (1 n)
  2. Gametophyte
    haploid (1 n

  3. Flowering plants
    • trade a few pollen grains for a sip of nectar in exchange for pollen transport
    • mutually beneficial: evolution of colorful, scented flowers
  4. A complete flower
    • four sets of modified leaves: the sepals, petals, stamens, and carpels

  5. Incomplete flowers
    • lack one or more of the four floral parts
  6. Imperfect flowers
    • incomplete flowers that lack either the male stamens or female carpels
  7. pollen grain
    • The pollen grain is the male gametophyte
    • thousands of diploid microspore mother cells
    • Each microspore mother cell undergoes meiotic cell division to produce four haploid microspores

  8. microspore mother cells
    • The pollen grain is the male gametophyte
    • thousands of diploid microspore mother cells
    • Each microspore mother cell undergoes meiotic cell division to produce four haploid microspores
    • Each microspore produces an immature pollen grain:
    • A large tube cell
    • A smaller generative cell
  9. Female Ovule
    • Ovule: integuments, a, diploid megaspore mother cell
    • megaspore mother cell produces four haploid megaspores
    • Only one megaspore survives; the other three degenerate
    • Megaspore undergoes three rounds of mitosis (8 cells, 1n)
    • Plasma membranes/cell walls then form, making 7 cells

    The egg is one of the three cells at the lower end, located near an opening in the integuments of the ovule

  10. Female Gametophyte Development
    • 1. Megaspore mother cell develops within each ovule of the ovaries of a flower
    • 2. Meiotic cell division produces four haploid megaspores. 3 degenerate
    • 3. The Single remaining megaspore forms 8 nuclei by mitosis
    • 4. Cytoplasmic division produces the 7 cells of the mature female gametophyte
  11. double fertilization
    • unique to flowering plants
    • both sperm fuse with cells of the female
    • One sperm fertilizes the egg, (diploid zygote) , then embryo, sporophyte
    • The second sperm enters the large central cell, forming a triploid nucleus
    • the central cell will develop into the triploid endosperm
    • The other five cells of the female gametophyte degenerate
  12. pollination and fertilization of a flower
    1. Pollination occurs when a pollen grain lands on the stigma of the carpel

    2. A polen tube grows down through the style of the carpel to the ovary; the tube cell nucleus travels at the tip of the tube, and the two sperm follow close behind

    3. Double fertilization- one sperm fuses with the central cell. One sperm fuses with the egg cell

  13. As the seed matures, the embryo begins to differentiate into shoot and root
    • The shoot portion includes one or two cotyledons
    • Dicot seeds have two cotyledons
    • If you strip the thin seed coat away from a bean or peanut, you will find that the inside splits easily into two halves; each is a cotyledon
    • The tiny white nub adhering to one of the cotyledons is the rest of the embryo

  14. Germination
    • the embryonic plant within a seed grows, breaks out of the seed, and forms a seedling
    • Seeds need warmth and moisture
    • May enter a period of dormancy
    • Dormant seeds can survive freezing and drying etc
    • During germination, the root emerges first, followed by the shoot
    • embryo absorbs water, which makes it swell and burst

  15. Plants and their pollinators have coevolved:
    • Animal-pollinated flowers evolved traits that attract useful pollinators
    • The pollinators evolved senses and behaviors that help them locate and identify nutritious flowers
    • Animal-pollinated flowers can be loosely grouped in three categories food, sex, or a nursery
  16. flower anatomy
  17. Sepals
    • Green leaves around the outside of the flower. Sepals are usually smaller than the petals,. Used to protect the flower while it is still in bud.
  18. Stamens
    • This is where pollen is made 
It is the male part of the flower.
The stamen has two parts: the filament (a thin stalk) and the anther which is where pollen is made
    • Male part of the flower
  19. Carpel
    • The carpel is the green stalk in the middle of the flower.
It is the female part of the flower.
The carpel has three parts:
At the top is the stigma. This is where pollen has to land. 
Below the stigma is the style and then the ovary which is where seeds are formed