Answer:
B. pre-zygotic, lock and key
Explanation:
When pollens from the different species fall on the stigma of a flower from some other species, the chemicals released from the stigma do not allow the pollens to germinate. The pollen tube is not formed to carry the male gametes to the egg cell for fertilization. Since this process does not allow the formation of zygote between the male and female gamete of two different species, it is a pre-zygotic isolating mechanism.
Here, the pollens and stigma of different plant species are not compatible with each other and the structural incompatibility of the reproductive structures prevents fertilization. This represents the lock and key mechanism of reproductive isolation.
Answer:
increased; almost 100%
Explanation:
The peppered moth witnessed a change in its color and the number at the end of the eighteenth century. The reason behind this was the Industrial Revolution that led to an increase in air pollution. With the increase in air pollution, the dark-colored moths increased in the number. Later, when air pollution decreased, the light-colored moths started to predominate. It was in 1895 that the number of dark-colored moths increased to the maximum.
