Question

Which of the following is true of the virus?
A)They are obligate intracellular parasites.
B)They are bigger than bacteria.
C)They contain both DNA and RNA.
D)They are non-specific for their hosts.
E)They can reproduce in non-living mediums.

Answer 1

A virus is a submicroscopic infectious agent that cannot reproduce by itself. It can infect almost all life forms.

Complete answer:
A virus is a microscopic parasite which is unable to replicate on its own. However once it infects a susceptible cell, a virus will guide the machinery of the cell to create more viruses. The genetic material of most viruses is either RNA or DNA. The nucleic acid may be single-stranded or double-stranded. The entire particle of the infectious virus called a virion, consists of a nucleic acid and an outer protein shell.

Let us analyze the options to find out the correct option.
Option A: Viruses are intracellular parasites that are obligatory and can only be retained within living cells. They are "obligate" means that the virus must do or act in the manner defined. Outside a living cell, they do not reproduce, they can only replicate within a specific host. Therefore, this is the correct option.

Option B: Viruses are smaller than bacteria not bigger. Therefore, this is an incorrect option.

Option C: They either contain DNA or RNA as their genetic material not both. Therefore, this is an incorrect option.

Option D: Viruses are specific for their hosts. Therefore, this is an incorrect option.

Option E: Viruses can only reproduce in living mediums. Therefore, this is an incorrect option.

Hence, the correct answer is option (A)

Note: 1)Viruses need to access the host body to spread infection.
2)They bind to cell surface receptors in hosts.
3)Common viral diseases are Dengue fever and yellow fever.