How can the chromosomes be identified?

There is a sub-population $A$ and another sub-population $B$. Both are separated by a natural barrier. What will happen in such a case?

Select the incorrect statement.

In human beings, sex is determined by:

Explain the following scenarios in a group of organisms,providing reasons for each:
$(a)$ Predators are more in the group.
$(b)$ Organisms survive accidentally.
$(c)$ Organisms are not able to survive in changing environmental conditions.

$(a)$ Which type of organs are shown in the figure below?
$(b)$ What is the origin and structure of these organs?