The generative cell divides mitotically to give rise to the two non-motile male gametes. before the pollen grains are shed at 3-celled stage in
Over 60% of angiosperms
Most angiospermic plants
About 90% of angiosperms
Around approximately 40% of angiosperms
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Answer:
Double fertilization is absent where pollen is shed in 2 - celled stage.
Explanation:
During the development of microspores into pollen grains, each microspore undergoes a mitotic division to form two cells, a large vegetative cell, and a small generative cell. The entire generative cell resides within the cytoplasm of the vegetative cell. These two cells form the juvenile pollen grain or the male gametophyte. At this stage, pollens are said to be 2-celled. Later, the generative cell divides by mitosis to form two sperm cells which remain in the cytoplasm of the vegetative cell. This three-celled structure is the mature male gametophyte or pollen grain. Pollens at this stage are said to be 3-celled. In most of the angiosperms, pollen grains are released at the 2-celled stage and the generative cell divides in the pollen tube to form two male gametes, which then fuse with the egg cell and secondary nucleus. Hence, double fertilization occurs when the pollens are shed at 2-celled stages.
Answer:
The generative cell divides mitotically to give rise to the two non-motile male gametes, before the pollen grains are shed at 3-celled stage in over 60% of angiosperms.
Explanation:
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