MCAT Biology Question 11: Answer and Explanation

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Question: 11

11. Herpes simplex virus (HSV) enters the human body and remains dormant in the nervous system until it produces an outbreak after exposure to heat, radiation, or other stimuli. Which of the following statements correctly describes HSV?

  • A. While it remains dormant in the nervous system, the virus is in its lytic cycle.
  • B. During an outbreak, the virus is in the lysogenic cycle.
  • C. Herpes simplex virus integrates itself into the DNA of the cell.
  • D. The herpes simplex virus contains a tail sheath and tail fibers.

Correct Answer: C

Explanation:

Viruses can exist in either the lytic or lysogenic cycle; they may even switch between them throughout their lifetime. During the lytic cycle, the virus's DNA takes control of the host cell's genetic machinery, manufacturing numerous progeny. In the end, the host cell bursts (lyses) and releases new virions, each capable of infecting other cells. In the lysogenic cycle, viral DNA is integrated into the host cell's genome, where it can remain dormant for days or years. Either spontaneously or as a result of environmental circumstances, the provirus can reemerge and enter a lytic cycle. Thus, choices (A) and (B) are incorrect because they reverse which part of the cycle the virus is in. Choice (D) describes features of bacteriophages, which are viruses that infect bacteria—not the human nervous system. Choice (C) accurately describes how HSV operates during the lysogenic cycle, making it the correct answer.

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