Question

What is ‘double fertilization’? Describe it with the help of a neat and well-labeled diagram. Give its importance.                              

Answer 1

 DOUBLE FERTILIZATION

 

The process in which fusion of male gamete with eggs and another male gamete with the nucleus takes place in an embryo sac is termed as double fertilization. In the flowering plants after entering one of the synergids the Pollen tube releases the two male gametes into the cytoplasm of synergids. One of the male gametes moves toward the Egg cell and fuses with its nucleus just completing the syngamy. This results in the formation of a diploid cell called the zygote. The other moves toward the two polar nuclei located in the central cell and fuses with them to produce triploid primary endosperm nucleus As this involve the fusion of three haploid nuclei it is termed as triple fusion. Syngamy and triple fusion both take place at the same time during the process of fertilization so it is called double fertilization.

Importance of double fertilization: Due to the formation of a zygote, the diploid condition is restored. As male and female gametes fuse, there is the recombination of maternal and paternal characters, this results in variation. Double fertilization triggers embryonic development, which leads to the formation of seed and fruit. Viable seeds with a high percentage of germination are produced.