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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