Question

Explain sexual reproduction in plant ?

Answer 1

• Sexual reproduction in plants occurs in various stages and is divided into pre and post-fertilization:-

(A) Formation of pollen grains known as microsporogenesis in which microspore mother cell undergoes meiosis to form microspore tetrad which form the pollens. This process occurs in the anther of stamens

(B) Formation of ovum known as megasporogenesis in which megaspore mother cell undergoes meiosis to form megaspore tetrad in which only one forms the ovum while the rest degenerate. This process occurs in the ovule of the pistil

(C) Pollination is the process of transfer of pollen grain to the stigma of the pistil.

(D) The growth of pollen tube after reaching the stigma: At the stigma a pollen-stigma interaction occurs in which stigma recognizes the pollen and allows the growth of tube by providing nutrition

(E) Fertilization is the fusion of nuclei of pollen and ovum to form a zygote.

Post-fertilization events:-

• Double fertilization in which the polar nuclei fuse with one pollen nuclei to form endosperm that provides nutrition to the zygote.
  
• Zygote starts dividing after the formation of endosperm.
  
• The embryo is placed in seed and other parts like ovary start transforming into the fruit.