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Fertilisation

Fertilisation. In plants. Learning outcome. Describe the process of fertilisation in flowering plants. Starting with pollen tube growth and ending with the fusion of the nuclei. Parts of a flower. The pollen grain. Male gametes are found in pollen grains

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Fertilisation

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  1. Fertilisation In plants

  2. Learning outcome • Describe the process of fertilisation in flowering plants. • Starting with pollen tube growth and ending with the fusion of the nuclei

  3. Parts of a flower

  4. The pollen grain • Male gametes are found in pollen grains • Each grain contains 2 haploid nuclei – a tube nucleus and generative nucleus. • Grain lands on surface of stigma = pollination • If stigma is of same species, it secretes substances that allow pollen grain to germinate. Outer wall = Exine Inner wall = Intine

  5. Part 1: Pollen germination • Tough outer coating breaks down and a pollen tube grows out. • Generative nucleus divides by mitosis to form 2 male gametes

  6. Part 2: Pollen tube growth • Pollen tube grows down the style. • It secretes enzymes and digests style and uses products to continue tube growth. • The tube nucleus controls growth of tube • Tube enters the ovule through a little gap called the micropyle • Pollen tube nucleus degenerates

  7. Clip • http://www.bbc.co.uk/learningzone/clips/fertilisation-in-plants/120.html

  8. Part 3: Fertilisation One male gamete fuses with female gamete and produces a diploid zygote (2n) The other male gamete fuses with the two haploid polar nuclei to form a triploid endosperm nucleus. (3n) This becomes the endosperm (nutrient store)

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