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Fertilization and Pollination -for SSC-CGL
ABOUT ME Name: Aman Srivastava o B.tech in Electronics & Communication (I.E.T Lko) Cleared SSC-CGL 2016 pre + mains Follow me on Unacademy Please rate ,review & share
FLOWER: Flower is a special organ of flowering plants (angiosperms) which works as the reproductive system. A flower is composed of four distinct whorls. (1) The outermost whorl is called calyx. (composed of green leaf-like structures; called sepals.) (2) The second whorl is called corolla. (composed of colourful structures; called petals.) Petals are colourful so that insects and other animals can be attracted towards them. This is necessary for pollination. (3) Androecium: The third whorl is called androecium It is composed of stamens. It has a tube-like portion is called filament and a capsule like structure at the top is called anther. The anther produces pollen grains; which are the male gametes
Stigma Petal Anther Style Filament Sepal Ovary Receptacle -
POLLINATION: The transfer of pollen grains from anthers to stigma is called pollination. Self Pollination: When anthers of the same flower are transferred to the stigma. Cross Pollination: When anthers from a different flower are transferred to the stigma. Plants need help from various agents of pollination to carry out cross pollination. . .Wind, insects, birds and other animals play the role of agent of pollination.
_ Stigma Pollen Anther Ovule (egg)
FERTILIZATION: The fusion of the male gamete and the female gamete. When pollen settles on top of the stigma, it germinates to produce a pollen tube The pollen tube enters the ovary through the style. Male nuclei are transferred to the ovary, through the pollen tube. The cell formed, just after fertilization, is called zygote. Zygote develops into embryo and embryo develops into a seed. The seed is an embryo which is enclosed in a protective coat. The ovary gets transformed into fruit.
Pollen grains Stigma Style Pollen tube Polar Nuctel Ovary Embryo sac Micropyle Egg