Nokea
Which of the following is a key feature of Mycobacterium tuberculosis?
- A. Produces spores
- B. Gram-negative
- C. Acid-fast cell wall
- D. Produces toxins
Correct Answer: C
Rationale: The correct answer is C: Acid-fast cell wall. Mycobacterium tuberculosis is characterized by its unique cell wall composition, containing high levels of mycolic acids which make it acid-fast. This property allows it to resist decolorization during acid-fast staining procedures. This distinguishes it from other bacteria.
A: Producing spores is not a key feature of Mycobacterium tuberculosis. Spore formation is more commonly associated with bacterial species such as Bacillus and Clostridium.
B: Mycobacterium tuberculosis is not Gram-negative. It is classified as acid-fast Gram-positive.
D: Mycobacterium tuberculosis does not produce toxins as a key feature. Its pathogenicity is more closely related to its ability to evade host immune responses and persist in host tissues.
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What is the function of bacterial flagella?
- A. Protein synthesis
- B. Motility
- C. Adhesion to surfaces
- D. DNA replication
Correct Answer: B
Rationale: The correct answer is B: Motility. Bacterial flagella function in providing motility to bacteria, allowing them to move towards nutrients or away from harmful substances. Flagella are long, whip-like appendages that rotate to propel the bacteria through their environment.
Incorrect choices:
A: Protein synthesis - Bacterial flagella are not involved in protein synthesis.
C: Adhesion to surfaces - While some bacteria use flagella for attachment, their main function is not adhesion.
D: DNA replication - Flagella do not play a role in DNA replication, which occurs in the bacterial cell's nucleus.
Sanitary assessment of a pond, where the children from a recreation summer camp take their swims, detected there oval cysts 50-60 micron in diameter, with 2 nuclei visible in their cytoplasm (macronucleus and micronucleus). What protozoa do these cysts belong to?
- A. Toxoplasma
- B. Amoeba
- C. Balantidium
- D. Lamblia
Correct Answer: D
Rationale: The correct answer is D: Lamblia. The cysts described match the characteristics of Giardia lamblia, a protozoan parasite. Giardia cysts are oval-shaped, 50-60 microns in diameter, and contain 2 nuclei (macronucleus and micronucleus). Giardia is commonly found in contaminated water sources and can cause gastrointestinal illness in humans.
Incorrect choices:
A: Toxoplasma - Toxoplasma gondii is a parasite that causes toxoplasmosis, transmitted through ingestion of contaminated food or water, but its cysts do not match the description given in the question.
B: Amoeba - Amoebas are single-celled organisms, but they do not typically form cysts with visible nuclei as described.
C: Balantidium - Balantidium coli is a ciliated protozoan that can cause dysentery in humans, but its cysts do not
Which bacteria are known for causing urinary tract infections?
- A. Escherichia coli
- B. Salmonella enterica
- C. Neisseria gonorrhoeae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Escherichia coli is the most common bacteria causing UTIs due to its ability to colonize the urinary tract. Salmonella enterica and Neisseria gonorrhoeae are not typically associated with UTIs. Therefore, by process of elimination, since A is correct, B and C are incorrect.
Bacteria that grow in the absence of oxygen are called:
- A. Obligate aerobes
- B. Facultative anaerobes
- C. Obligate anaerobes
- D. Aerotolerant anaerobes
Correct Answer: C
Rationale: The correct answer is C: Obligate anaerobes. These bacteria cannot survive in the presence of oxygen as they lack the necessary enzymes to detoxify reactive oxygen species. Obligate aerobes (A) require oxygen, facultative anaerobes (B) can grow with or without oxygen, and aerotolerant anaerobes (D) can survive in the presence of oxygen but do not utilize it for growth.
Infectious disease' is:
- A. Clinical term
- B. A term expressing the possibility of developing certain symptoms in an infection
- C. A+B
- D. No correct answer
Correct Answer: C
Rationale: The correct answer is C because "Infectious disease" is a combination of both a clinical term (A) and a term expressing the possibility of developing certain symptoms in an infection (B). Infectious diseases are illnesses caused by pathogenic microorganisms, such as bacteria, viruses, parasites, or fungi, that can spread directly or indirectly from person to person. Therefore, the term encompasses both the clinical aspect of the disease and the potential symptoms that may manifest in an infected individual. Choices A and B alone do not fully capture the comprehensive definition of infectious disease, making C the correct answer. Choice D is incorrect as there is a correct answer in this case.