Question

why are viruses considered to be nonliving?
a. they have no genetic material.
b. they do not respond to their environment.
c. they cannot reproduce without a host cell.
d. they cannot use energy.

Explanation:

Viruses are acellular entities. One of the key characteristics of living organisms is the ability to reproduce independently. Viruses lack the cellular machinery to reproduce on their own. They rely on host cells (such as bacterial, plant, or animal cells) to provide the necessary components (like enzymes, ribosomes, nucleotides, amino - acids etc.) for their replication.

• Option A is incorrect because viruses do have genetic material (either DNA or RNA).
• Option B is incorrect as viruses can respond to their environment in a limited way. For example, they can recognize and bind to specific host cell receptors.
• Option D is incorrect because although viruses do not carry out metabolic processes in the traditional sense (like cellular respiration) when they are outside a host cell, once inside a host cell, they can hijack the host's energy - generating mechanisms. But the most fundamental reason for considering them non - living is their inability to reproduce independently.

Answer:

C. They cannot reproduce without a host cell.