Answer:
Innate immunity is a non-specific immune system which provides defence against any pathogenic microorganism in early stages. It includes physical barrier such as skin, chemical barriers such as saliva, tears, et cetera, phagocytic cells such as macrophages, et cetera.
Acquired immune system is the one which develops after exposure to pathogen or antigen. It is highly specific in nature. It includes B-lymphocytes and T-lymphocytes. It includes the production of antibodies.
Vaccines are used to develop acquired immunity in people. The process is termed as vaccination or immunisation. Heat-killed or weakened pathogen or antigen is inserted into a person after which a person develops antibodies and memory cells against that pathogen or disease. So, the immune system acts more vigorously against that pathogen in secondary infection.
Thus, a person becomes immunised.
The bear population would also increase
Explanation:
Natural selection is the mechanism that is responsible for the evolution of organisms.
In the given case, the Freshwater shrimp has been introduced to a pond in which the two species with variations are introduced.
The <em>C. cantonensis </em>is brighter in color whereas the <em>C. multidentata</em> is mottled drab in color. The predator fish can feed easily on the species which is brighter therefore <em>C. cantonensis</em> is more susceptible. The mottled drab species is not easily predated by the species.
The 30 % offsprings of <em>C. cantonensis</em> can survive till the reproductive age whereas 75% of C. multidentata. This shows that natural selection has acted on the color of the shrimp species selected against the predator fish species.
The species with mottled drab color is the result of the differential reproductive rate.
