MCAT Biology : Viruses
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Example Questions
Example Question #11 : Viruses
Which of the following is not a property of viruses?
Some viruses can specifically target bacteria
Viruses are intracellular parasites
Viruses contain genetic information and have a capsid protein coat
Viruses can make copies of themselves using the host's machinery
Viruses cannot survive without a host
Viruses cannot survive without a host
Viruses cannot reproduce and make copies of themselves without a host; however, they can survive on their own. Viruses can remain dormant in a non-biological environment before being transferred to a biological host.
All viruses carry some form of genetic material, either in the form of DNA or RNA, and have a protein coat to contain the genetic material. Bacteriophages are viruses that specifically target bacteria. By hijacking the cellular machinery of host cells, viruses are able to replicate, essentially becoming intracellular parasites.
Example Question #12 : Viruses
Viral genomic material can be comprised of which types of nucleic acids?
I. Single-stranded DNA
II. Double-stranded DNA
III. Single-stranded RNA
IV. Double-stranded RNA
III and IV
I and III
I and II
I, II, III, and IV
I, II, III, and IV
Different classes of viruses store genetic material in different forms.
Double-stranded RNA (dsRNA) viruses, single-stranded RNA (ssRNA) viruses, double-stranded DNA (dsDNA) viruses, and single-stranded DNA (ssDNA) viruses are all large classes of viral classification. Retroviruses can be classified as ssRNA viruses, but are often left in their own category.
Example Question #12 : Viruses
Polio is a highly infectious disease caused by the polio virus, which can be a debilitating disease in the worst case scenarios. The first effective vaccine for treating polio was developed by Jonas Salk at the University of Pittsburgh in 1952.
Salk's vaccine consisted of inactivated (dead) virus, administered orally. Which of the following statements is true regarding vaccines containing inactivated virus?
The process of inactivating viruses for these vaccines results in the exposure of more viral antigens, leading to a greater host immune response.
These vaccines are highly immunogenic that adjuvants (a substance that enhances the host immune response to the antigen) are not needed.
Generally, vaccines containing inactivated viruses only need a small dosage and no booster shots are necessary to achieve immunity.
None of these
Vaccines containing inactivated viruses (if made correctly) have no chance of reactivating and causing an actual viral infection.
Vaccines containing inactivated viruses (if made correctly) have no chance of reactivating and causing an actual viral infection.
The process of inactivating live viruses results in dead (noninfectious) virus. In terms of safety (if the virus is inactivated correctly), inactivated virus vaccines have no risk of inducing a viral infection from the contents of the vaccine. In terms of effectiveness of inducing protective immunity, inactivated virus vaccines are typically less effective than attenuated but live virus vaccines. Therefore, the induction of long-term protective immunity against the virus is questionable. Inactivated virus vaccines normally require larger doses, multiple doses, and adjuvants to be effective.
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