microbiology chapter 1 test bank

Correct Answer: A

Rationale: The correct answer is A: Balantidium coli. Balantidium coli is a large ciliated protozoa with a kidney-shaped macronucleus, commonly found in the feces of individuals with dysentery symptoms. Its morphology matches the description given in the question, making it the most likely causative agent. Summary of other choices: B: Entamoeba histolytica - This is not the correct answer because Entamoeba histolytica is a small amoeba with no cilia and a different nucleus shape. C: Giardia lamblia - This is not the correct answer as Giardia lamblia is a flagellated protozoa with a pear-shaped nucleus, different from the description provided. D: Trichomonas hominis - This is not the correct answer as Trichomonas hominis is a flagellated protozoa with multiple flagella and an undulating membrane, which does not match the characteristics of the

Correct Answer: B

Rationale: The correct answer is B: Cholera. Cholera is caused by Gram-negative curved rod-like bacteria called Vibrio cholerae, commonly found in contaminated water or food. The characteristic symptom of cholera is profuse watery diarrhea, which matches the patient's presentation. Typhoid fever (A) is caused by Salmonella typhi, which is not a curved rod-like bacteria. Diphtheria (C) is caused by Corynebacterium diphtheriae, a Gram-positive bacterium, and does not typically cause diarrhea. Intestinal form of plague (D) is caused by Yersinia pestis, which is not a curved rod-like bacteria and does not typically present with diarrhea.

Correct Answer: D

Rationale: The correct answer is D. Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae are all known to cause meningitis. Neisseria meningitidis is a common cause of bacterial meningitis in young adults. Haemophilus influenzae is a leading cause of meningitis in children, and Streptococcus pneumoniae is a common cause in adults. Therefore, all three bacteria are responsible for causing meningitis, making option D the correct choice. Option A, B, and C are incorrect because they each represent only one of the bacteria responsible for causing meningitis, while option D includes all three.

Correct Answer: A

Rationale: Rationale: 1. Listeria monocytogenes is a Gram-positive bacterium known for causing foodborne illnesses. 2. Gram-negative bacteria have a different cell wall structure than Gram-positive bacteria, making choice A correct. 3. Choice B is incorrect as Listeria monocytogenes is not encapsulated or sporulating. 4. Choice C is incorrect as Listeria monocytogenes does have a cell wall. 5. Choice D is incorrect as Listeria monocytogenes is indeed a Gram-positive coccobacilli.

Correct Answer: D

Rationale: The correct answer is D: All of the above. HIV can be transmitted from mother to child during delivery through mixing of blood, during pregnancy through the placenta, and via breastmilk during lactation. Each mode of transmission carries a risk of HIV transmission to the child due to the presence of the virus in the mother's blood and bodily fluids. It is important to note that all three modes contribute to the risk of mother-to-child transmission of HIV, and preventive measures should be taken to reduce this risk. Option A, during delivery through mixing of blood, is correct as HIV can be transmitted through exposure to infected blood during childbirth. Option B, during pregnancy through placenta, is also correct as the virus can cross the placenta and infect the fetus. Option C, via breastmilk during lactation, is correct as HIV can be present in breastmilk and transmitted to the child through breastfeeding. Therefore, the preferred mode of transmission of HIV from a mother to a child