Sexual asexual reproduction
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Sexual & Asexual Reproduction. Pollination and Fertilization: Presentation 2 of 3. Pollination. Pollination occurs when mature pollen grains (male sex cells from the stamen) come into contact with the moist, sticky surface of a flower stigma (female flower part). . stigma.

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Sexual & Asexual Reproduction

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Sexual asexual reproduction

Sexual & Asexual Reproduction

Pollination and Fertilization: Presentation 2 of 3


Pollination

Pollination

  • Pollination occurs when mature pollen grains (male sex cells from the stamen) come into contact with the moist, sticky surface of a flower stigma (female flower part).

stigma

stamen


Sexual asexual reproduction

  • Pollen grains transfer to the stigmas of flowers by means of:

  • gravity,

  • insects,

  • wind, and

  • animals.


Sexual asexual reproduction

  • Self-pollination occurs when pollen comes into contact with a stigma within the same flower or other flowers on the same plant.

  • Cross-pollination occurs when pollen from the flower of one plant transfers to stigmas of flowers on another plant.


Sexual asexual reproduction

  • After a pollen grain anchors on the moist, sticky surface of a flower stigma, it germinates and produces a pollen tube.

  • The pollen tube grows down through the style and into the ovary where it eventually reaches an ovule


Fertilization

Fertilization

  • In angiosperms (flowering plants), two haploid nuclei or sperm cells are released from the pollen tube.


Sexual asexual reproduction

  • Double Fertilization is known as, one sperm cell unites with the egg cell in the ovule to form a zygote (diploid), while the second sperm cell unites with two separate polar nuclei to form a primary endosperm nucleus (triploid).


Sexual asexual reproduction

  • The zygote, formed through the union of the sperm cell and egg cell, proceeds through cell division and develops into a seed embryo.

  • The primary endosperm nucleus develops to form a food source to be used by the embryonic plant during seed germination.


Sexual asexual reproduction

  • For each seed a plant produces, a separate grain of pollen must reach and unite with an ovule.


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