You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
I. treating the substance with nucleases that destroy all nucleic acids
and then determining whether it is still infectious
II. filtering the substance to remove all elements smaller than what can
be easily seen under a light microscope
III. culturing the substance by itself on nutritive medium, away from
any plant cells
IV. treating the sample with proteases that digest all proteins and then
determining whether it is still infectious
1) Which treatment could definitively determine whether or not the component is a viroid?
B) II
C) III
D) IV
E) first II and then III
Answer: A
2) If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?
B) II
C) III
D) IV
E) either II or IV
Answer: C
3) Which treatment would you use to determine if the agent is a prion?
B) II only
C) III only
D) IV only
E) either I or IV
Answer: D