Q. Prepare a flow-chart to depict the post-pollination events leading to viable-seed production in a flowering plant.
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I am providing you with the answer in steps. You can make the flowchart with it.
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I am providing you with the answer in steps. You can make the flowchart with it.
- When a small pollen grain from a male flower lands on the stigma of a female flower, it enters inside and reaches the ovule which in inside the ovary.
- The embryo sac present inside a matured ovule of a flowering plant contains seven cells. Among these one cell remains in the middle called central cell with two nuclei.
- Remaining six cells divide into two parts and each part with three cells move to the opposite corners of the sac.
- The three cells closest to the opening of the sac (micropyle) differentiate into one egg cell and two synergids. These three cells together are called “three celled egg apparatus of embryo”. The other three antipodal cells degenerate.
- The pollen nuclei (two) after entering inside the embryo sac fertilize the egg and the central cell. The fertilized egg produces zygote and the fertilized central cell produces endosperm.
- Thus fertilization of flowering plant is also known as double fertilization.
- Once the fertilization over, the accessory parts of the flower like petals, sepals etc. get withered and fall off.
- The fertilized ovary starts developing into fruits. If only the complete ovary changes into fruit, it is known as true fruit where as if any other part of the flower is involved in the formation of fruit, it is called pseudocarpic fruit.
- After fertilization the zygote divides mitotically and transform into multicellular embryo.
- The endosperm also divides and grows in size to provide adequate nutrition to the embryo while developing.
- As the embryo and endosperm develop, the ovules also increase in size gradually to transform into seeds. The integuments dry up to give protective coating to the seeds.
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