Question

Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?

(A) skin commensalist

(B) decomposer

(C) gut mutualist

(D) pathogen

Short answer

(A) The option “skin commensalist” is false.

(B) The option “decomposer” is true.

(C) The option “gut mutualist” is false.

(D) The option “pathogen” is false.

Step-by-step solution

Symbiosis

Symbiosis is a process by which different unrelated organisms live together and exhibit positive or negative interactions. Some of the examples of symbiotic associations include commensalism, mutualism, and parasitism. These interactions are necessary for the survival of organisms.

Explanation of option ‘(A)’

The normal microbes residing on the skin are referred to as skin commensalists. These organisms can protect the body from invading harmful microbes that can enter the body and cause serious damages. However, these organisms are not benefited in any way apart from habitat.

Thus, skin commensalist exhibits symbiosis.

Therefore, the given statement is false.

Explanation of option ‘(B)’

Decomposition is a biological process in which microbes feed on dead and decaying organisms. This does not exhibit any form of symbiosis because it is exhibited only in living organisms. Decomposition is a mode of nutrition that is observed in organisms that cannot manufacture their food.

Thus, decomposers do not exhibit symbiosis.

Therefore, the given statement is true

Explanation of option ‘(C)’

Gut microorganisms exhibit mutualistic symbiotic association. These microbes produce enzymes and nutrients essential for digestion. In return, the human body provides them with nutrition and also provides them a safe habitat for their growth and survival.

Thus, gut mutualists exhibit mutualistic symbiosis.

Therefore, the given statement is false.

Explanation of option ‘(D)’

Pathogens are harmful agents that enter the body and cause immune variations. These organisms exhibit parasitic symbiotic association with the host. They destroy the host cells to obtain nutrition and flourish within the body without being killed.

Thus, pathogens exhibit parasitic symbiosis.

Therefore, the given statement is false.