Answer:
5%
Explanation:
The adrenal cortex in both males and females produce a small amount of weak androgens. One of the major weak androgen secreted by adrenal cortex is dehydroepiandrosterone (DHEA).
Levels of dehydroepiandrosterone secretion exhibit changes with age. The dehydroepiandrosterone secretion increases till the age of 20-24 years and falls off with increasing age after the age of 30 years in both males and females. The DHEA production at the age of 80 years is about 5% of its secretion at the age of 30 years.
Phagocytosis is the process by which immune cells engulf and then destroy bacteria
Answer:
B) There is an increase in the number of giraffes with long necks in areas of Africa where low-growing trees have died
Explanation:
The directional selection is one of the ways of the natural selection in which the natural selection selects or favours the most extreme trait of the species and the extreme trait show higher fitness than the normal or average trait.
In the given question, the case of Giraffe necks shows directional selection as the normal length of the neck is not favoured by the environment but the extreme trait that is long neck is favoured by the environment and the selection shifted to that level.
Thus, Option-B is the correct answer.
