Prescott’s Microbiology 11Th Edition By Joanne Willey – Test Bank

Prescott’s Microbiology 11Th Edition By Joanne Willey – Test Bank

Prescott’s Microbiology, 11e (Willey)

Chapter 6 Viruses and Other Acellular Infectious Agents

1) Viruses have typical cellular structure like other living organisms.

2) Viruses in the extracellular state possess few, if any, active enzymes.

3) Which is not true of viruses?

1. A) They can exist in an intracellular or extracellular phase.
2. B) They infect animal and plant cells only.
3. C) They can be observed with an electron microscope.
4. D) They are acellular.
5. E) They replicate only inside host cells.

4) Which of the following is true of viruses in the extracellular phase?

1. A) They possess many different enzymes.
2. B) They can reproduce independently of living cells but only at a slow rate.
3. C) They behave as a macromolecular complex and are no more alive than are ribosomes.
4. D) They possess many different enzymes and they can reproduce independently of living cells but only at a slow rate.

5) A complete virus particle is called a ________.

1. A) capsid
2. B) nucleocapsid
3. C) virion
4. D) cell

6) The nucleic acids carried by viruses usually consist of ________.

1. A) DNA
2. B) RNA
3. C) either DNA or RNA
4. D) both DNA and RNA simultaneously

7) Which of the following is not true of viruses?

1. A) Viruses are acellular.
2. B) Viruses consist of one or more molecules of DNA or RNA enclosed in a coat of protein and sometimes in other more complex layers.
3. C) Viruses can exist in two phases: intracellular and extracellular.
4. D) Viruses replicate by binary fission.

8) Viruses infecting protists, including algae, have never been detected.

9) One way in which small viruses package more information into a very small genome is to use overlapping genes so that the same base sequence is read in more than one reading frame.

10) Almost all known plant viruses are RNA viruses.

11) Virus morphology does not include which of the following characteristics?

1. A) Size
2. B) Shape
3. C) Presence or absence of an envelope
4. D) Host range

12) ________ are glycoprotein spikes that protrude from the outer surface of the viral envelope.

13) Icosahedral viruses are constructed from ring- or knob-shaped units called ________.

14) Viruses that are polyhedrons with 20 sides are said to have ________ symmetry.

15) The most common capsid morphologies are icosahedral and helical.

16) The largest of the viruses are similar in size to some small bacteria and are large enough to be seen with a light microscope.

17) The presence or absence of an envelope is not useful in classifying viruses because any given virus may at one time have an envelope and at another time not have an envelope.

18) Viruses such as MS2 and Qß pack additional information into their genomes through the use of overlapping genes.

19) The simplest viruses consist of ________.

1. A) RNA only
2. B) protein only
3. C) RNA or DNA in a protein coat
4. D) RNA or DNA in a protein coat covered with lipid envelope
5. E) RNA, DNA, and enzymes in a protein coat with a lipid envelope

20) Viral capsid protein subunits are called ________.

1. A) auxomers
2. B) elastomers
3. C) protomers
4. D) viromers

21) In an enveloped virus, the part of the virus including the nucleic acid genome and the surrounding protein coat but not the envelope is called the ________.

1. A) capsid
2. B) nucleocapsid
3. C) matrix
4. D) virion

22) Some complex viruses have icosahedral symmetry in the head region and helical symmetry in the tail. Overall, these viruses are said to have ________ symmetry.

1. A) bilateral
2. B) binal
3. C) complex
4. D) radial

23) Glycoprotein spikes protruding from the outer surface of viral envelopes function as ________.

1. A) toxins
2. B) factors that bind to host cells
3. C) cell lysis factors
4. D) factors needed for site specific recombination

24) A ________ genome exists as several separate, nonidentical molecules that may be packaged together or separately.

1. A) diploid
2. B) segmented
3. C) polyploid
4. D) fractionated

25) Many of the enzymes found in virus particles are ________.

1. A) required for viral attachment to host cells
2. B) involved in viral entry into host cells
3. C) involved in the replication of viral nucleic acid
4. D) All of the choices are correct.

26) Which of the following is/are not true about viral envelopes?

1. A) The envelope proteins are virus specific.
2. B) The envelope lipids and carbohydrates are derived from the host.
3. C) They are typical lipid monolayers with embedded viral proteins.
4. D) The envelope proteins are virus specific and the envelope lipids and carbohydrates are derived from the host.

27) Viral envelopes are composed of ________.

1. A) proteins
2. B) lipids
3. C) carbohydrates
4. D) All of the choices are correct.

28) Two major types of symmetry found in viruses include ________.

1. A) icosahedral and radial
2. B) icosahedral and helical
3. C) helical and radial
4. D) radial and bilateral

29) The function of the viral protein coat is to ________.

1. A) protect the viral genetic material
2. B) aid in the transfer of the viral genetic material between host cells
3. C) elicit the production of protective antibodies
4. D) protect the viral genetic material and aid in the transfer of the viral genetic material between host cells

30) The protein coat surrounding the viral genome is called the ________.

1. A) capsule
2. B) capsid
3. C) matrix
4. D) envelope

31) Which of the following is true of a viral DNA genome?

1. A) It uses the same four nitrogenous bases found in prokaryotic and eukaryotic DNA.
2. B) It may have the normal bases found in prokaryotic and eukaryotic DNA, or it may have one or more unusual bases.
3. C) It is usually composed of unusual bases unique to viruses.
4. D) Viruses use only RNA for their genome.

32) Virion size ranges from ________.

1. A) 1–40 nm
2. B) 10–400 nm
3. C) 600–1,000 nm
4. D) 1,000–10,000 nm

33) Viral capsids are generally constructed without any outside aid once the subunits have been synthesized. This process is called ________.

1. A) facilitated assembly
2. B) self-assembly
3. C) spontaneous maturation
4. D) self-maturation

34) In which of the following stages of the viral infectious cycle do enveloped viruses usually acquire their envelopes?

1. A) Penetration
2. B) Component biosynthesis
3. C) Assembly
4. D) Release

35) Most enveloped viruses use the host ________ membrane as their envelope source.

1. A) plasma
2. B) nuclear
3. C) mitochondrial
4. D) None of these choices are correct.

36) Poliovirus receptors are found ________.

1. A) in cells of all tissues
2. B) in spinal cord anterior horn cells only
3. C) in nasopharynx, gut, and spinal cord anterior horn cells
4. D) in gut cells only

37) Nonenveloped viruses most often gain access to eukaryotic host cells by ________.

1. A) fusion with the host cell plasma membrane followed by entrance of the nucleocapsid into the cytoplasm
2. B) endocytosis
3. C) pinocytosis
4. D) nucleic acid injection through the plasma membrane

38) Which of the following represent(s) the way(s) in which enveloped viruses acquire their envelopes?

1. A) Budding through the plasma membrane.
2. B) Budding through internal cellular membranes.
3. C) Viral enzymes are responsible for production of the envelope.
4. D) Some viruses bud through the plasma membrane while other bud through internal cellular membranes.

39) Virus receptors are often not distributed uniformly over the surface of host cells, but are instead concentrated in lipid rafts.

40) Enveloped viruses may enter their host cells by fusion of their envelope with the cytoplasmic membrane, thereby depositing their nucleocapsid within the cell.

41) Enveloped viruses may enter their host cells by engulfment within coated vesicles (endocytosis).

42) Some viruses cause abnormal growth of cells rather than destruction. This is called ________.

43) Human cancer-causing viruses most often have a ________ genome.

1. A) ssDNA
2. B) dsDNA
3. C) ssRNA
4. D) dsRNA

44) Adult T-cell leukemia is thought to be caused by ________.

1. A) herpesviruses
2. B) retroviruses
3. C) parvoviruses
4. D) picornaviruses

45) Genes whose expression (or abnormal expression) cause cancer are called ________.

1. A) cancer genes
2. B) progenes
3. C) oncogenes
4. D) carcinogens