Which of the following best describes a virus?
a) They are measured in microns because they are small
b) They are filterable
c) They have at least DNA or RNA
d) They have nucleic acid and protein
e) They cause disease in humans
The correct answer and explanation is:
The correct answer is d) They have nucleic acid and protein.
Viruses are unique biological entities that cannot be classified as living organisms in the traditional sense because they do not possess the full set of characteristics that define life. Viruses consist of two main components: nucleic acid and protein. The nucleic acid is either DNA or RNA, which carries the genetic information necessary for the virus to replicate. The protein component, typically in the form of a protein coat called a capsid, protects the genetic material. Some viruses also have an outer lipid membrane, known as an envelope, which aids in their entry into host cells.
Option a) is incorrect because viruses are typically measured in nanometers, not microns, as they are much smaller than most bacteria and are often invisible under a regular light microscope.
Option b) is true in the sense that viruses can be filtered out using filters that are capable of trapping bacteria, as viruses are small enough to pass through typical bacterial filters. However, this characteristic alone does not fully describe what a virus is.
Option c) is partially true, as viruses contain either DNA or RNA, but they do not necessarily have both.
Option e) is also true in many cases, as viruses are known to cause diseases in humans, animals, and plants. However, not all viruses cause disease, and some viruses exist in a latent state without causing immediate harm to their host.
In summary, viruses are fundamentally composed of nucleic acid and protein, making answer d the most accurate and comprehensive description of what a virus is.