define doble fertilization and process in detail
Answers
Answer:
Double fertilization is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). ... The pollen tube proceeds to release the two sperm in the megagametophyte
ANSWER:
After pollen grain land on a suitable stigma, it absorbs water and germinates by producing a pollen tube, which grows between the cells of the style toward the ovary. The nucleus of the generative cell divides by mitosis and forms two sperm, while the tip of the pollen tube grows toward the micropyle. Its arrival initiates the death of one of the two synergids, providing a passageway into the embryo sac for the two sperm that is discharged from the pollen tube.
Before reaching the female gametophyte, one sperm fertilizes the egg, forming a zygote. The other sperm combines with the two polar nuclei, forming a triploid (3n) nucleus in the centre of the large central cell of female gametophyte; this large cell will give rise to endosperm, the food-storing tissue of the seed.
The union of the two sperm cells with different nuclei of the female gametophyte is referred to as double fertilization. This ensures that endosperm develops only in ovules where the egg has been fertilized and prevents angiosperms from squandering nutrients on infertile ovules.
So, the correct option is 'Process of joining a female gametophyte with two male gametes.'