Sexual Reproduction In Flowering Plant

Sexual Reproduction in Flowering Plant

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

Female Reproductive Structure - 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

Formation of Pollen Grain - Anther has 4 pollen sacs - Each pollen sac has hundreds of pollen mother cells - Each pollen mother cell (diploid) undergoes meiosis and produces 4 haploid microspores - Nucleus of each microspore divide by mitosis to form a tube nucleus &

Formation of Embryo Sac

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Formation of Embryo Sac - Ovule develop from ovarian tissue - Ovule has embryo sac mother cell - Embryo sac mother cell undergoes meiosis forming 4 haploid megaspores - 3 megaspores die, 1 left in the ovule - Functional megaspore enlarges and fills most of the ovule - Nucleus of megaspore undergoes mitosis 3 times and form 8 haploid nuclei - 3 nuclei migrate to one end forming antipodal cells - 2 move to the centre to form polar B nuclei

Pollination

Pollination

Sugar in stigma stimulate the Ripe pollen from anther Pollen tube grows into pollen grain to germinate & transferred to stigma style towards ovule form pollen tube

hen pollen grain reachesTube nucleus lead the At the same time, generati ovary, it penetrates the male nuclei down the nucleus divide by mitosis ovule through micropyle pollen grain forming 2 male gamete nuc

Tube nucleus disintegrates

One male nuclei fuses The other fuses with two with egg cell forming polar nuclei forming diploid zygote (2n) triploid nucleus (3n)

Outer layer of ovule Triploid nucleus then divide Zygote divides & oses moisture & develops forming endosperm grows into embryo hard seed coat (special nutritive tissue)

(1)

What is

double fertilisation? (2) Why is double fertilisation important?

After an egg has been fertilised : • Ovule  • Multiple ovules seeds • Ovary  • Wall of ovule coat • Zygote • Ovary wall wall

Seed  Multiple Fruit  Seed  

Embryo Fruit