Emerging viruses arise bya. mutation of existing viruses.b. the spread of existing viruses to new host species.c. the spread of existing viruses more widely within their host species.d. all of the above.

Prions are __________ that are thought to cause disease by __________.

What do host cells provide for viruses?a. ATPb. nucleotides and amino acidsc. ribosomesd. all of the above

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?a. metabolismb. ribosomesc. genetic material composed of nucleic acidd. cell division

What does reverse transcriptase do?

In the viral replicative cycle, what reaction do viral proteases catalyze? Select True or False for each statement.T/F They catalyze polymerization of amino acids into peptides.T/F They catalyze folding of long peptide chains into functional proteins.T/F They catalyze cutting of polyprotein chains into functional proteins.T/F They catalyze breaking of peptide bonds

To cause a human pandemic, the H5N1 avian flu virus would have toa. spread to primates such as chimpanzees.b. develop into a virus with a different host range.c. become capable of human-to-human transmission.d. become much more pathogenic.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would havea. T2 protein and T4 DNA.b. T4 protein and T2 DNA.c. T2 protein and T2 DNA.d. T4 protein and T4 DNA.

What features distinguish the seven major categories of viruses?