Explanation:
In the megasporan- gium of each ovule, the megasporocyte divides by meiosis, producing four megaspores. One survives and forms a female gametophyte. Fertilization: In nucleus of developing endosperm-- Double fertilization occurs. One sperm fertilizes the egg, forming a zygote.
competition plays a very important role in ecology and evolution. The best competitors are the ones who survive and get to pass on their genes.
During a solar eclipse, when the Moon's shadow falls on the Earth, we stand in the shadow rather than looking at it. Observers standing in the umbra see a total eclipse of the Sun, while observers under the penumbra see a partial eclipse.