Nokea
Bacteria that use organic compounds as the source of both carbon and energy are referred to as:
- A. photoautotrophs
- B. chemoautotrophs
- C. photoheterotrophs
- D. chemoheterotrophs
Correct Answer: D
Rationale: The correct answer is D: chemoheterotrophs. Chemoheterotrophs use organic compounds as both their carbon source and energy source. They obtain energy by breaking down organic molecules through cellular respiration. Photoautotrophs (A) use light energy to produce organic compounds, chemoautotrophs (B) use inorganic compounds for energy, and photoheterotrophs (C) use light energy but require organic compounds as a carbon source. Therefore, chemoheterotrophs best describe bacteria that obtain both carbon and energy from organic compounds.
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Subcutaneous mycoses occur predominantly in the:
- A. tropics
- B. deserts
- C. forests of the Northern Hemisphere
- D. Rocky Mountains
Correct Answer: A
Rationale: Subcutaneous mycoses are fungal infections that affect the skin, subcutaneous tissues, and bones. The correct answer is A: tropics, as these infections are more commonly found in warm and humid regions. Fungi that cause subcutaneous mycoses thrive in tropical climates due to the favorable conditions for their growth and transmission. Choices B, C, and D are incorrect because deserts (B) have dry conditions not conducive to fungal growth, forests of the Northern Hemisphere (C) have varying climates that may not support the specific fungi causing subcutaneous mycoses, and the Rocky Mountains (D) are not typically associated with the high humidity required for these infections.
The causative agent of bacterial dysentery belongs to which of the following genera?
- A. Genus Shigella
- B. Genus Salmonella
- C. Genus Klebsiella
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Genus Shigella. Shigella is known to be the causative agent of bacterial dysentery. It invades the intestinal lining, leading to symptoms like severe diarrhea and abdominal cramps. Salmonella (choice B) typically causes food poisoning, not dysentery. Klebsiella (choice C) is associated with pneumonia and urinary tract infections, not dysentery. "None of the above" (choice D) is incorrect as Shigella does belong to a specific genus responsible for bacterial dysentery.
A patient with diarrhea had stool microscopy revealing large, oval protozoa with a single nucleus and four flagella. What is the most likely causative agent?
- A. Giardia lamblia
- B. Entamoeba histolytica
- C. Balantidium coli
- D. Trichomonas vaginalis
Correct Answer: A
Rationale: Step 1: Large, oval protozoa with a single nucleus and four flagella indicate Giardia lamblia.
Step 2: Giardia lamblia is a flagellated protozoan causing diarrhea.
Step 3: It has a distinct appearance under microscopy.
Step 4: Entamoeba histolytica causes dysentery with no flagella.
Step 5: Balantidium coli is a ciliated protozoan with a larger size.
Step 6: Trichomonas vaginalis lacks a cyst stage and causes genitourinary infections.
For the structure of rubella virus is true that
- A. has icosahedral type of symmetry
- B. is ssDAN virus
- C. does not have an envelope
- D. does not have glycoprotein spikes
Correct Answer: A
Rationale: The correct answer is A. Rubella virus has icosahedral type of symmetry due to its spherical shape with 20 faces. This symmetry allows for efficient packaging of genetic material and structural stability. Choice B is incorrect as rubella virus is an ssRNA virus, not ssDNA. Choice C is incorrect as rubella virus does have an envelope derived from the host cell membrane. Choice D is incorrect as rubella virus does have glycoprotein spikes on its surface that aid in host cell recognition and entry.
Which of the following bacteria produce a neurotoxin that affects the nervous system?
- A. Clostridium botulinum
- B. Clostridium tetani
- C. Both A and B
- D. None of the above
Correct Answer: C
Rationale: Rationale: Both Clostridium botulinum and Clostridium tetani produce neurotoxins. Botulinum toxin affects the nervous system by blocking neurotransmitter release, causing paralysis. Tetanus toxin affects the nervous system by interfering with neurotransmitter release, leading to muscle stiffness and spasms. Therefore, Choice C is correct. Choices A and B alone are incorrect because they only mention one of the bacteria that produces a neurotoxin. Choice D is incorrect because both bacteria mentioned in Choices A and B produce neurotoxins.