Chapter 19 Flashcards
Which of the following descriptions correctly identifies a main structural difference between viruses with envelopes and viruses without envelopes?
A) Only viruses with envelopes have their contents enclosed by a layer containing lipids
B) Only viruses with envelopes package their genetic material by engulfing it.
C) Only viruses without envelopes can release their genetic material into the cytoplasm of the host.
D) Only viruses without envelopes interact with receptor proteins on the surface of the host cell.
A) Only viruses with envelopes have their contents enclosed by a layer containing lipids
Which of the following statements accurately describes the lysogenic cycle of lambda (λ) phage?
A) The viral genes immediately turn the host cell into a lambda-producing factory. Then the host lyses.
B) The product of one prophage gene is made and it activates most of the other prophage genes.
C) The phage genome is integrated in the host chromosome where it is passed on to daughter cells through binary fission.
D) The phage DNA is copied and accumulates in the cytoplasm. Then a trigger causes capsid proteins to be made and phages are assembled.
C) The phage genome is integrated in the host chromosome where it is passed on to daughter cells through binary fission.
What is the function of reverse transcriptase in retroviruses?
A) It uses viral RNA as a template for DNA synthesis.
B) It converts host cell RNA into viral DNA.
C) It translates viral RNA into proteins.
D) It uses viral RNA as a template for making more viral RNA strands.
A) It uses viral RNA as a template for DNA synthesis.
The virus genome and viral proteins are assembled into virus particles during which of the following parts of the reproductive cycle?
A) the lytic cycle and the lysogenic cycle in all known host organisms
B) the lysogenic cycle only
C) the lytic cycle only
D) the lytic cycle in all host organisms but the lysogenic cycle only in bacteria
C) The lytic cycle only
If a viral host cell has a mutation that interferes with the addition of carbohydrates to proteins during processing in the Golgi apparatus, which of the following processes is most likely to occur?
A) The viral envelope proteins would not have glycoproteins added to them and might not arrive at the host plasma membrane.
B) The viral capsid proteins would not have glycoproteins added to them and might not arrive at the host plasma membrane.
C) The viral core proteins would not have glycoproteins added to them and might not arrive at the host plasma membrane.
D) The virus would be unable to reproduce within the host cell.
A) The viral envelope proteins would not have glycoproteins added to them and might not arrive at the host plasma membrane.
Which of the following best defines prions?
A) mobile segments of DNA that can disrupt host gene expression
B) circular molecules of RNA that can infect plants
C) viral DNA that attaches itself to the host genome and causes disease
D) misfolded versions of normal proteins that can cause disease
D) misfolded versions of normal proteins that can cause disease
- In 2009, a flu pandemic was believed to have originated when viral transmission occurred from pig to human, thereby earning the designation “swine flu.” Although pigs are thought to have been the host for the 2009 virus, sequences from bird, pig, and human viruses were all found within this newly identified virus. What is the most likely explanation for the presence of sequences from bird, pig, and human viruses?
A) The virus was descended from a common ancestor of bird, pig, and human flu viruses.
B) The infected individuals happened to be infected with all three virus types.
C) The RNA of related viruses can reassort during viral assembly resulting in new genetic combinations.
D) The human was likely infected with various bacterial strains that contained all three RNA viruses.
C) The RNA of related viruses can reassort during viral assembly resulting in new genetic combinations.
RNA viruses require their own supply of certain enzymes because ________.
host cells lack enzymes that can replicate the viral genome
Which of the following statements best supports the argument that viruses are nonliving?
They do not carry out metabolic processes.
Which of the following characteristics, structures, or processes is common to both bacteria and viruses?
genetic material composed of nucleic acid
Which of the following methods would be best to use for distinguishing between an infectious agent that is a virus and one that is a prion?
Treat the substance with enzymes that destroy all nucleic acids, and then determine whether the substance is still infectious.
Which of the following statements correctly describes vaccines and how they help prevent viral infection?
Vaccines are inactive versions of a virus that stimulate an immune reaction in a person.
Which of the following characteristics is typical of the lytic cycle of a bacteriophage?
The host membrane ruptures, releasing many phages.
