Nokea
Which bacteria is responsible for causing the disease known as tetanus?
- A. Clostridium tetani
- B. Clostridium perfringens
- C. Streptococcus pyogenes
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Clostridium tetani. Clostridium tetani is responsible for causing tetanus due to its production of tetanospasmin toxin. This neurotoxin leads to muscle stiffness and spasms characteristic of tetanus. Clostridium perfringens is associated with gas gangrene, not tetanus. Streptococcus pyogenes causes strep throat and skin infections, not tetanus. Escherichia coli is a common gut bacteria and is not responsible for tetanus. Therefore, choice A is the correct answer for causing tetanus.
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Infections of CNS can be caused by:
- A. Clostridium botulinum
- B. Morbillivirus morbillorum
- C. Clostridium tetani
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D because all three choices, Clostridium botulinum, Morbillivirus morbillorum, and Clostridium tetani, can cause infections of the central nervous system (CNS). Clostridium botulinum can lead to botulism, which affects the nervous system. Morbillivirus morbillorum can cause measles, which can lead to viral encephalitis. Clostridium tetani can cause tetanus, which affects the CNS by producing neurotoxins. Therefore, all three choices are pathogens that can cause infections of the CNS.
A patient of oral surgery department has developed a purulent complication. Bacteriological analysis of the wound discharge allowed to isolate a culture producing a blue-and-green pigment. Which of the listed microorganisms may be a causative agent of the infection?
- A. Pseudomonas aeruginosa
- B. Proteus vulgaris
- C. Bacillus subtilis
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which is characteristic of its colonies. This bacterium is commonly associated with purulent infections, especially in immunocompromised patients. Proteus vulgaris (B) is not typically associated with blue-green pigment production. Bacillus subtilis (C) is not a common pathogen in wound infections. Klebsiella pneumoniae (D) does not produce blue-green pigment and is more commonly associated with respiratory infections. Therefore, based on the clinical presentation and pigment production, Pseudomonas aeruginosa is the most likely causative agent in this case.
The cell organelles found only in algae and plant cells are:
- A. chloroplasts
- B. mitochondria
- C. vacuoles
- D. vesicles
Correct Answer: A
Rationale: The correct answer is A: chloroplasts. Algae and plant cells have chloroplasts, which are responsible for photosynthesis. This organelle contains chlorophyll, enabling these cells to convert sunlight into energy. Mitochondria (B) are found in all eukaryotic cells, not specific to algae and plants. Vacuoles (C) are present in plant cells but also in other eukaryotic cells. Vesicles (D) are membrane-bound sacs found in all types of cells for transport and storage purposes, not unique to algae and plants. Therefore, A is the correct answer.
The lysozyme hydrolyzes:
- A. The glycoside bonds between the N-acetylmuramic acid and the N-acetylglucosamine in the peptidoglycan of the cell wall
- B. The phosphate bonds between the carbon atoms in the phospholipids
- C. The disulfide bonds in the immunoglobulin molecule
- D. The hydrogen bonds between the monosaccharides in the bacterial capsules
Correct Answer: A
Rationale: The correct answer is A: The lysozyme hydrolyzes the glycoside bonds between the N-acetylmuramic acid and the N-acetylglucosamine in the peptidoglycan of the cell wall. This is because lysozyme is an enzyme that specifically targets the peptidoglycan layer of bacterial cell walls, breaking down the structure by cleaving the glycosidic bonds between these two specific sugar molecules. This action weakens the cell wall, leading to bacterial cell lysis. The other choices are incorrect because lysozyme does not target phosphate bonds in phospholipids (B), disulfide bonds in immunoglobulins (C), or hydrogen bonds in bacterial capsules (D).
For destruction of spore forms of microorganisms is used:
- A. pasteurization
- B. autoclaving
- C. freezing
- D. boiling
Correct Answer: B
Rationale: The correct answer is B: autoclaving. Autoclaving is a process that uses high pressure and steam to achieve temperatures above the boiling point of water, typically around 121-134°C. This high heat and pressure are effective in destroying spore forms of microorganisms, which are highly resistant structures that can withstand boiling temperatures. Autoclaving ensures the complete destruction of spores, making it an effective method for sterilization.
Rationale:
A: Pasteurization uses lower heat compared to autoclaving and is not sufficient to destroy spore forms.
C: Freezing does not effectively destroy spore forms, as most microorganisms can survive freezing temperatures.
D: Boiling, while effective for many microorganisms, may not be sufficient to destroy spore forms due to their high resistance, unlike autoclaving.