Infectious Viruses Diseases Quiz
Based on chapter 8 of Robbins and Cotran pathologic Basis of Disease, 7th edition.
Questions and Answers
- 1.
Viruses are classified by
- Their nucleic acid genome (DNA or RNA) (Double stranded or single stranded)
- The shape of the capsid (icosahedral or ______)
- The presence or absence of a ______ envelope
- Their mode of replication
- The preferred cell type for replication ( ie tissue _______)
- The type of pathology
- A.
Helical, lipid, tropism
- B.
Spherical, bilayer, prostatism
- C.
Spherical, protein, pleomorphism
Correct Answer
A. Helical, lipid, tropismExplanation
Tissue tropism is determined by several factors such as host cell receptors for the virus, transcription factors that recognise the virus, temperature and pH.Rate this question:
- 2.
- (Viruses are only 20-300 nm in size and so are best visualised with the electron microscope. However, some viral particles aggregate within the cells they infect and form characteristic inclusion bodies.)
- Ebstein Barr virus infected cells have large eosinophilic cytoplasmic inclusions.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
EBV does not give rise to inclusions.Rate this question:
- 3.
Where does herpes zoster virus reside during latency?
- A.
Langerhan cells
- B.
Dorsal root ganglia
- C.
Ventral root ganglia
- D.
Lateral horn of spinal cord
- E.
Pons
- F.
Hypothalamus
Correct Answer
B. Dorsal root gangliaExplanation
During latency, the herpes zoster virus resides in the dorsal root ganglia. The dorsal root ganglia are clusters of nerve cells located along the spinal cord that receive sensory information from the body. This is where the virus remains dormant after the initial infection, and it can reactivate later in life, causing the characteristic symptoms of herpes zoster or shingles.Rate this question:
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- 4.
Bacterial cells are _ _ _ _ _ _ _ _ _ _ s, meaning that they have a cell membrane but lack membrane bound nuclei and other membrane bound organelles
Correct Answer
prokaryote
prokaryotesExplanation
Bacterial cells are classified as prokaryotes because they lack membrane-bound nuclei and other membrane-bound organelles. Prokaryotes have a cell membrane, but their genetic material is not enclosed within a nucleus. Instead, the DNA is present in the cytoplasm. This distinguishes them from eukaryotes, which have a true nucleus and other membrane-bound organelles such as mitochondria and endoplasmic reticulum. Therefore, the term "prokaryote" or "prokaryotes" accurately describes the cellular structure of bacteria.Rate this question:
- 5.
Which of the following are obligate intracellular organisms? (4)
- A.
Chlamydia
- B.
Neisseria
- C.
Rickettsiae
- D.
HIV
- E.
Mycoplasma
- F.
Clostridium
Correct Answer(s)
A. Chlamydia
C. Rickettsiae
D. HIV
E. MycoplasmaExplanation
Chlamydia, Rickettsiae, HIV, and Mycoplasma are obligate intracellular organisms because they are unable to replicate or survive outside of host cells. They require the cellular machinery of host cells in order to reproduce and carry out their metabolic functions. This is in contrast to Neisseria, Clostridium, and other bacteria that are able to survive and replicate extracellularly.Rate this question:
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- 6.
Mycoplasma is a gram negative bacteria because it has a cell wall that does not retain crystal violet stain.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Crystal-violet is the stain used in gram-staining, but mycoplasma does not have a cell wall.Rate this question:
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- 7.
Chlamydia trachomatis is the most common cause of female infertility.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
By scarring and narrowing the fallopian tubes.Rate this question:
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- 8.
How is Mycoplasma pneumonia transmitted?
- A.
Blood-borne
- B.
Aerosol
- C.
Faecal-oral
- D.
Sexually transmitted
- E.
Insect vector
- F.
Animal contact
- G.
Contaminated water
- H.
Contaminated food
Correct Answer
B. AerosolExplanation
Mycoplasma pneumonia is transmitted through aerosol, which means it is spread through small droplets that are released into the air when an infected person coughs or sneezes. These droplets can then be inhaled by others, leading to the transmission of the bacteria. This mode of transmission is common for respiratory infections and explains why Mycoplasma pneumonia can easily spread in crowded places or close quarters.Rate this question:
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- 9.
Thermal dimorphic fungi grow as hyphal forms at room temperature but as yeasts at body temperature.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Thermal dimorphic fungi have the ability to grow as hyphal forms at room temperature and as yeasts at body temperature. This means that their morphology changes depending on the temperature they are exposed to. At room temperature, they grow as filamentous hyphae, which are branching, thread-like structures. However, when the temperature increases to body temperature, they transition into yeast-like cells, which are single-celled, round or oval structures. This phenomenon is important for the pathogenicity of these fungi, as it allows them to adapt to different host environments and cause infections.Rate this question:
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- 10.
Which of the following have eukaryotic cell/s? (5)
- A.
Fungi
- B.
Bacteria
- C.
Protazoa
- D.
Viruses
- E.
Prions
- F.
Algae
- G.
Helminths
- H.
Humans
Correct Answer(s)
A. Fungi
C. Protazoa
F. Algae
G. Helminths
H. HumansExplanation
Protazoa are single celled eukaryotes
Bacteria are prokaryotic
Prions have no cellsRate this question:
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- 11.
How is Toxoplasma gondii transmitted? (2)
- A.
Blood-borne
- B.
Aerosol
- C.
Faecal-oral
- D.
Sexually
- E.
Insect vector
- F.
Animal contact
- G.
Contaminated water
- H.
Contaminated food
Correct Answer(s)
F. Animal contact
H. Contaminated foodExplanation
Contact with oocyst shedding kittens or eating undercooked cyst containing meat.Rate this question:
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- 12.
Most ingested enveloped viruses are killed by bile and digestive enzymes, but non-enveloped viruses may be resistant.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
For eg. non-enveloped viruses include Hep A and rotavirus.Rate this question:
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- 13.
Which of the following enteropathogenic bacteria causes symptoms by:
- multiplying inside the mucous layer overlying the gut epithelium and releasing exotoxins that cause the gut epithelium to secrete high volumes of watery diarrhoea? (2)
- A.
Campylobacter jujeni
- B.
Vibrio cholerae
- C.
Shigella species
- D.
Salmonella species
- E.
Toxigenic Escherichia coli
- F.
Serratia marcescens
Correct Answer(s)
B. Vibrio cholerae
E. Toxigenic Escherichia coliExplanation
Vibrio cholerae and Toxigenic Escherichia coli are the correct answers because they both cause symptoms by multiplying inside the mucous layer overlying the gut epithelium and releasing exotoxins. These exotoxins cause the gut epithelium to secrete high volumes of watery diarrhea. Campylobacter jujeni, Shigella species, Salmonella species, and Serratia marcescens do not cause symptoms in the same way as Vibrio cholerae and Toxigenic Escherichia coli.Rate this question:
- 14.
Which of the following enteropathogenic bacteria causes symptoms by:
- invading and damaging the intestinal mucosa and lamina propria, causing ulceration, inflammation and haemorrhage, clinically manifesting as dysentry? (3)
- A.
Campylobacter jujeni
- B.
Vibrio cholerae
- C.
Shigella species
- D.
Salmonella species
- E.
Toxigenic Escherichia coli
- F.
Serratia marcescens
Correct Answer(s)
A. Campylobacter jujeni
C. Shigella species
D. Salmonella speciesExplanation
Campylobacter jujeni, Shigella species, and Salmonella species are enteropathogenic bacteria that cause symptoms by invading and damaging the intestinal mucosa and lamina propria. This invasion leads to ulceration, inflammation, and hemorrhage, which clinically manifests as dysentery. These bacteria can cause severe gastrointestinal symptoms such as bloody diarrhea, abdominal pain, and fever. Vibrio cholerae, Toxigenic Escherichia coli, and Serratia marcescens do not typically cause symptoms through invasion and damage to the intestinal mucosa, and therefore are not the correct answer for this question.Rate this question:
- 15.
Why does a viral resipratory infection predispose to a secondary bacterial respiratory infection? (This question is not graded)
Correct Answer(s)
Viral infection can cause loss of ciliated epithelium thereby losing one of the respiratory tract's defence mechanisms.Explanation
A viral respiratory infection can weaken the respiratory tract's defense mechanisms by causing a loss of ciliated epithelium. Cilia are tiny hair-like structures that line the respiratory tract and help to move mucus and trapped particles out of the airways. When the ciliated epithelium is damaged or lost, the clearance of mucus and bacteria from the respiratory tract is impaired. This creates an environment where bacteria can multiply and cause a secondary bacterial respiratory infection.Rate this question:
- 16.
The vagina is protected from pathogens by a ____ pH resulting from catabolism of _______ in the normal epithelium by ________.
- A.
High, phospholipids, lactobacilli
- B.
Low, phospholipids, lactococci
- C.
High, glycogen, lactococci
- D.
Low, glycogen, lactobacilli
Correct Answer
D. Low, glycogen, lactobacilliExplanation
Thus, antibitoics that kill lactobacilli can make the vagina susceptible to infection.Rate this question:
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- 17.
Rubella infection during which trimester is most dangerous for the fetus?
- A.
First
- B.
Second
- C.
Third
Correct Answer
A. FirstExplanation
In first trimester it can cause congenital heart disease, mental retardation, cataracts and deafness.Rate this question:
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- 18.
CMV, HBV and HTLV-1 can all be transmitted to a baby via breastmilk.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
CMV (Cytomegalovirus), HBV (Hepatitis B virus), and HTLV-1 (Human T-cell lymphotropic virus type 1) are all known to be transmitted to a baby through breastmilk. These viruses can be present in the breastmilk of infected mothers and can be passed on to the baby during breastfeeding. It is important for mothers with these infections to seek medical advice and take necessary precautions to reduce the risk of transmission to their baby, such as antiviral medications or alternative feeding methods. Therefore, the statement "True" is the correct answer.Rate this question:
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- 19.
Low IgG avidity antibody marker of recent infection. High IgG avidity antibody marker of past infection.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
This statement is true because low IgG avidity antibody is a marker of recent infection, while high IgG avidity antibody indicates a past infection. IgG avidity refers to the strength of the bond between IgG antibodies and antigens. Low avidity indicates that the antibodies are still binding weakly to the antigens, suggesting a recent infection. High avidity, on the other hand, suggests that the antibodies have formed strong bonds with the antigens over time, indicating a past infection.Rate this question:
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- 20.
Exotoxins are proteins secreted by bacteria that cause cellular injury and disease. Which of the following type of exotoxin is secreted by Clostridium tetani and Clostridium botulinum?
- A.
Enzyme
- B.
A-B toxin
- C.
Neurotoxin
- D.
Superantigen
Correct Answer
C. NeurotoxinExplanation
Neurotoxins inhibit the release of neurotransmitters resulting in paralysis. p 359Rate this question:
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- 21.
Exotoxins are proteins secreted by bacteria that cause cellular injury and disease. Which of the following type of exotoxin is secreted by Bacillus anthracis, Vibrio cholerae and some strains of Escherichia coli?
- A.
Enzyme
- B.
A-B toxin
- C.
Neurotoxin
- D.
Superantigen
Correct Answer
B. A-B toxinExplanation
A-B toxins have an Active subunit and a Binding subunit. The binding subunit binds to receptors on the cell surface and delivers the active subunit into the cell cytoplasm where it alters intracellular signalling or regulatory pathways. p359Rate this question:
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- 22.
Exotoxins are proteins secreted by bacteria that cause cellular injury and disease. Which of the following types of exotoxin can be secreted by Staphylococcus aureus? (2)
- A.
Enzyme
- B.
A-B toxin
- C.
Neurotoxin
- D.
Superantigen
Correct Answer(s)
A. Enzyme
D. SuperantigenExplanation
The enzyme is a protease that cleaves proteins that link epidermal cells together.
Superantigens stimulate very large numbers of T lymphocytes leading to massive T lymphocyte proliferation and cytokine release which can lead to capillary leakage and shock. Streptococcus pyogenes also secretes superantigens.Rate this question:
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- 23.
Following infection with ______ streptococci, antibodies can cross react with cardiac proteins and become deposited in the heart leading to _______, and/or antistreptococcal antibody/streptococcal antigen complexes can form and be deposited in the renal glomeruli causing post streptococcal _______.
- A.
α haemolytic, rheumatic fever, glomerulosclerosis
- B.
α haemolytic, infective endocarditits, glomerulonephritis
- C.
β haemolytic, rheumatic fever, glomerulonehpritis
- D.
β haemolytic, infective endocarditis, glomerulosclerosis
Correct Answer
C. β haemolytic, rheumatic fever, glomerulonehpritisExplanation
Following infection with β haemolytic streptococci, antibodies can cross react with cardiac proteins and become deposited in the heart leading to rheumatic fever, and/or antistreptococcal antibody/streptococcal antigen complexes can form and be deposited in the renal glomeruli causing post streptococcal glomerulonephritis.Rate this question:
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Jun 03, 2024Quiz Edited by
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Apr 13, 2011Quiz Created by
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