Which of the following is a difference between a viroid and a virus?
A. Viroids infect only plants while viruses infect only animals and prokaryotes.
B. Viroids are alive and viruses are not.
C. Viroids are not infectious particles and viruses often cause disease.
D. Viroids are composed solely of nucleic acid while viruses are composed of nucleic acid surrounded by a protein coat.
E. Viroids contain some genes important for their own replication while viruses rely entirely on host cell enzymes for their replication.
Answer: D
You might also like to view...
Studies in knockout mice have demonstrated an important role of the FOXP2 transcription factor in the development of vocalizations
Recent sequence comparisons of the FOXP2 gene in Neanderthals and modern humans show that while the DNA sequence may be different, the protein sequence it codes for is identical. What might logically be inferred from this information? A) There was a problem with the experiment because different DNA sequences cannot result in the same protein sequence. B) The differences in DNA sequence support the hypothesis that Neanderthals were primitive beings that could only grunt. C) Human and Neanderthal vocalizations may have been more similar than previously thought. D) The experiments in mice demonstrating the function of the FOXP2 gene are not relevant to humans and Neanderthals because they are not primates.
In Table 20.1, the minimal bactericidal concentration of antibiotic X is
a. 2 g/ml. b. 10 g/ml. c. 15 g/ml. d. 25 g/ml. e. Can't tell.
The heartbeat originates in the:
A. sinoatrial node located at the junction of the vena cava and the right atrium. B. sinoatrial node located at the junction of the vena cava and the left atrium. C. atrioventricular node located in the wall of the atrioventricular valve. D. atrioventricular node located in the tissue separating the atria and ventricles. E. sinoatrial node and atrioventricular node simultaneously.
Which of the following is TRUE about energy
releasing chemical reactions?
a. they all require ATP to proceed. b. the activation energy required is greater than for energy requiring chemical reactions c. the reactants have more energy than the products d. the reactants have the same amount of energy as the products e. the reactants have less energy than the products