Answer:
The reason why only 3 out of the 22 possible autosomal trisomies are seen in newborns, is because the rest of them are chromosomal abnormalities not compatible with life and thus an spontaneous abortion occurs. The embryos suffering from these trisomies do not survive for more than a few weeks in the uterus, so the miscarriage often goes unnoticed for the mother as she may not have realized she was pregnant.
The only trisomies that are allow fetuses to be born are: Patau Syndrome (trisomy 13), Edwards Syndrome (trisomy 18), and Down Syndrome (trisomy 21). Out of these three, people with Down Syndrome have the largest life expectancy.
Explanation:
The plants which use animal or insects as pollination vector produce less pollen compared to the wind-pollinated plants.
This could be due to the reason that the chances of pollination by wind are less than the pollination by the animal or vectors.
The chances of pollination in animal pollination are high as the animals to feed on the useful product of plant will go to the other plants but in wind pollination, the chances are less as it depends on the speed and direction of the wind.
Thus, wind-pollinated plants produce high number of pollens.
