Answer is A. A population becomes separated by environmental factors into two groups that do not reproduce with one another.
When a population of a species become geographically separated then gene flow between them stops. Over a period of time, the population may become genetically different in response to the natural selection due to different environments. Selection and genetic drift will act differently on these two separated populations. This will results into two separate species. This type of speciation is called allopatric speciation.
When a population is
small in a habitat, its population growth is exponential. This means it doubles
its population with every generation. This is because there is plenty of resources
and little competition between individuals of the population. However, as the population
grows bigger, the population reaches carrying
capacity (the maximum number that the ecosystem can hold). The growth slows and
stagnates as stiff competition results to an equal death rate as birth rate.
It synthesizes proteins and lipids, and puts them in vesicles and sends it to where it has to go
The animal prepares for the hibernation ahead of time gathering food and eating so that it can sleep for the extended period of time without leaving
D. One sex has a higher chance to inherit it than the other (male).
These can be either recessive or dominant. We usually think more of the recessive traits like color blindness and hemophilia but dominant sex-linked traits also exist (fragile X).