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free microbiology test bank questions pdf Questions
Question 1 of 9
Which of the following viral infections can result in chronic carrier state.
Correct Answer: D
Rationale: The correct answer is D: All of these. HBV, HCV, and HDV can all lead to chronic carrier states due to their ability to establish persistent infections in the liver. HBV can result in chronic hepatitis, cirrhosis, and even liver cancer. HCV can also lead to chronic hepatitis and liver damage. HDV is a defective virus that requires HBV for replication and can worsen the outcome of HBV infection, potentially leading to chronic liver disease. Therefore, all three viruses have the potential to cause chronic carrier states.
Question 2 of 9
The class of immunoglobulins most abundant in body is:
Correct Answer: A
Rationale: The correct answer is A: IgG. IgG is the most abundant class of immunoglobulins in the body, constituting about 75% of total immunoglobulins. IgG plays a crucial role in long-term immunity, neutralizing toxins, and enhancing phagocytosis. IgE is involved in allergic reactions, IgD is mainly found on B cells and functions as a receptor, and IgM is the first antibody produced in response to an infection but is less abundant compared to IgG. Therefore, IgG is the correct choice based on its abundance and diverse functions in the immune system.
Question 3 of 9
Which of the following proteins are encoded by herpesviruses and required for viral DNA replication?
Correct Answer: A
Rationale: The correct answer is A: viral DNA polymerase. This enzyme is essential for replicating the viral DNA during the herpesvirus life cycle. It catalyzes the synthesis of new DNA strands using the viral genomic template. Ribonucleotide reductase (B) is involved in nucleotide synthesis, but not directly in DNA replication. Neuraminidase (C) is an enzyme found in influenza viruses, not herpesviruses. Thymidine kinase (D) is an enzyme that phosphorylates thymidine, but its role is more related to nucleotide metabolism rather than viral DNA replication.
Question 4 of 9
A patient with a sore throat had a throat culture revealing Gram-positive cocci in chains. The bacteria were catalase-negative and beta-hemolytic. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. 1. Gram-positive cocci in chains suggest streptococci. 2. Catalase-negative indicates it's not staphylococci. 3. Beta-hemolytic points towards Group A Streptococcus (S. pyogenes). Summary: B. Streptococcus pneumoniae is not beta-hemolytic. C. Enterococcus faecalis is not typically chains. D. Staphylococcus aureus is catalase-positive.
Question 5 of 9
A patient working at a pig farm complains about paroxysmal abdominal pain, liquid feces with admixtures of mucus and blood, headache, weakness, fever. Examination of large intestine revealed ulcers from 1 mm up to several cm large, feces contained oval unicellular organisms with cilia. What disease should be suspected?
Correct Answer: A
Rationale: Rationale: The symptoms described are consistent with Balantidiasis, caused by the parasite Balantidium coli. The presence of ciliated oval organisms in the feces is characteristic of this disease. Ulcers in the large intestine are common in Balantidiasis due to tissue invasion by the parasite. Headache, fever, and abdominal pain are typical symptoms. Other choices can be ruled out: B) Amebiasis presents with similar symptoms but usually involves the liver. C) Toxoplasmosis typically presents with lymphadenopathy and flu-like symptoms. D) Lambliasis usually causes watery diarrhea without blood or mucus. Therefore, the correct answer is A: Balantidiasis.
Question 6 of 9
In order to prevent wound infection associated with surgical procedures a patient was given a synthetic antiprotozoan drug with a high activity against Helicobacter pylori. Specify this drug:
Correct Answer: A
Rationale: The correct answer is A: Metronidazole. Metronidazole is a synthetic antiprotozoan drug with high activity against Helicobacter pylori, a bacterium that can cause wound infections. Metronidazole specifically targets anaerobic bacteria like H. pylori, making it effective in preventing wound infections. Incorrect choices: B: Doxycycline hydrochloride - Doxycycline is primarily used for bacterial infections, not protozoan infections like H. pylori. C: Chingamin - Chingamin is not a commonly used drug for treating H. pylori infections or preventing wound infections. D: Acyclovir - Acyclovir is an antiviral drug used to treat herpes infections, not bacterial or protozoan infections like H. pylori.
Question 7 of 9
Which bacteria are commonly associated with food poisoning?
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum and Staphylococcus aureus. Clostridium botulinum produces a potent neurotoxin causing botulism, commonly associated with improperly canned foods. Staphylococcus aureus produces toxins causing symptoms of food poisoning. Bacillus anthracis and Mycobacterium tuberculosis are not typically associated with food poisoning. Treponema pallidum and Neisseria gonorrhoeae are bacteria causing sexually transmitted infections. Escherichia coli and Klebsiella pneumoniae are not directly linked to food poisoning.
Question 8 of 9
Viruses cannot multiply in:
Correct Answer: A
Rationale: The correct answer is A: Artificial nutrient media. Viruses are obligate intracellular parasites, meaning they require living host cells to replicate. They cannot multiply in artificial nutrient media as they lack the cellular machinery necessary for viral replication. Living cells, including human embryonic cells and bacteria, provide the required cellular environment for viruses to replicate. Therefore, options B, C, and D are incorrect as they all contain living cells that can support viral multiplication.
Question 9 of 9
Antibiotics are distributed into following groups:
Correct Answer: A
Rationale: The correct answer is A: Blockaders of protein synthesis because antibiotics in this group target bacterial ribosomes, preventing protein synthesis. This disrupts bacterial growth and replication. Choice B is incorrect as cell wall synthesis inhibitors target a different bacterial component. Choice C is incorrect as antibiotics do not alter bacterial cytoplasm. Choice D is incorrect as antibiotics do fall into different categories based on their mechanism of action.