13.16–13.19: Viruses are at the border between living and non-living.

A virus is not alive, but it can carry out some of the same functions as living organisms, provided that it can get inside a cell.

Question 13.25

Many biologists do not consider viruses to be alive. Which of the following characteristics of viruses leads to this conclusion?

  • a) Viruses lack a metabolic system.
  • b) Viruses do not respond to external stimuli.
  • c) Viruses are unable to reproduce on their own.
  • d) All of the above are correct.
  • e) Only a) and c) are correct.

Question 13.26

The genetic information in all viruses is:

  • a) DNA.
  • b) RNA.
  • c) protein.
  • d) a polymerase enzyme.
  • e) DNA or RNA.

Question 13.27

Viruses are able to infect:

  • a) humans.
  • b) plants.
  • c) bacteria.
  • d) birds.
  • e) All of the above.

Question 13.28

Which of the following statements about HIV is incorrect?

  • a) It is a virus.
  • b) It attacks red blood cells.
  • c) It mutates frequently.
  • d) It is derived from a simian immunodeficiency virus.
  • e) It contains RNA but not DNA.