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
    Image Upload 1
  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
Card Set
Plant Reproduction
Plant Reproduction
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