Sexual Reproduction in Flowering Plants b) Pollination & Fertilisation.
Sexual Reproduction In Flowering Plant
Transcript of Sexual Reproduction In Flowering Plant
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Sexual Reproduction inFlowering Plant
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Male Reproductive Structure
- Male reproductive structure is the stamen
- Stamen consists of anther and filament
- Filament : hold the anther
- Anther : place where pollen grains
are produced
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Female ReproductiveStructure
- Female reproductive structure are the carpels- Several carpels fused together becoming pistil
- Pistil consists of stigma, style and ovary
- Stigma: sticky surface at the apex of style
- Style : join stigma to ovary
- Ovary : carries ovule
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Formation of Pollen Grain
-Anther has 4 pollensacs
-Each pollen sac hashundreds of pollen
mother cells
-Each pollen mothercell (diploid)undergoes meiosisand produces 4haploidmicrospores
-Nucleus of eachmicrospore divide
by mitosis to form atube nucleus &
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Formation of Embryo Sac
N
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Formation of Embryo Sac
-Ovule develop from ovarian tissue
-Ovule has embryo sac mother cell
-Embryo sac mother cell undergoesmeiosis forming 4 haploidmegaspores
-
3 megaspores die, 1 left in the ovule-Functional megaspore enlarges andfills most of the ovule
-Nucleus of megaspore undergoesmitosis 3 times and form 8 haploid
nuclei
-3 nuclei migrate to one end formingantipodal cells
-2 move to the centre to form polar
nuclei-
B
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Pollination
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Pollination
ipe pollen from anthertransferred to stigma
Sugar in stigma stimulate the
pollen grain to germinate &form pollen tube
Pollen tube grows intostyle towards ovule
At the same time, generat
nucleus divide by mitosiforming 2 male gamete nu
Tube nucleus lead the
male nuclei down thepollen grain
en pollen grain reaches
vary, it penetrates thevule through micropyle
Tube nucleusdisintegrates
One male nuclei fuseswith egg cell forming
diploid zygote (2n)
The other fuses with twpolar nuclei forming
triploid nucleus (3n)
Triploid nucleus then dividforming endosperm
(special nutritive tissue)
Zygote divides &grows into embryo
Outer layer of ovuleses moisture & develops
hard seed coat
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(1) What is
doublefertilisation?
(2) Why is doublefertilisation
important?
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After an egg has been
fertilised :• Ovule Seed
• Multiple ovules Multiple
seeds• Ovary Fruit
• Wall of ovule Seed
coat• Zygote Embryo
• Ovary wall Fruit
wall