Nokea
Which of the following is a host-dependent bacterium?
- A. Mycoplasma
- B. Ureaplasma
- C. Rickettsia
- D. Micrococcus
Correct Answer: C
Rationale: The correct answer is C: Rickettsia. Rickettsia is a host-dependent bacterium because it requires living cells of a host organism to survive and replicate. This bacterium is an obligate intracellular pathogen, meaning it cannot grow outside of a host cell.
A: Mycoplasma and B: Ureaplasma are not host-dependent as they can grow and reproduce in cell-free environments due to possessing their own unique cell wall structures.
D: Micrococcus is a free-living bacterium that can survive and reproduce independently without relying on a host organism.
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Which statement about leptospirosis is INCORRECT:
- A. Leptospirosis is acute infectious disease with typical geographic distribution
- B. Reservoirs of leptospira are different wild and domestic animals-mainly rodents
- C. Leptospira can be cultivated on blood and chocolate agar
- D. doxycycline and penicillins are drugs of choice for treatment of leptospirosis
Correct Answer: C
Rationale: The correct answer is C because Leptospira cannot be cultivated on blood and chocolate agar. The bacterium requires specialized media such as Ellinghausen-McCullough-Johnson-Harris (EMJH) medium for growth. Blood and chocolate agar do not provide the necessary nutrients for the bacterium's growth. Leptospira is a fastidious organism that has unique culture requirements. Therefore, the statement that Leptospira can be cultivated on blood and chocolate agar is incorrect. The other choices are correct: A - Leptospirosis is an acute infectious disease with a typical geographic distribution, B - Reservoirs of leptospira are different wild and domestic animals, mainly rodents, and D - Doxycycline and penicillins are drugs of choice for the treatment of leptospirosis.
The taxonomic resource for information on bacteria is __________.
- A. Gray's Anatomy
- B. Bergey's Manual of Systematic Bacteriology
- C. WHO Manual
- D. Darwin's Origin of Species
Correct Answer: B
Rationale: The correct answer is B: Bergey's Manual of Systematic Bacteriology. This manual is a comprehensive and authoritative resource specifically dedicated to bacterial taxonomy, classification, and identification. It provides detailed descriptions and classification schemes for bacteria, aiding in accurate identification and understanding of bacterial species. Gray's Anatomy (choice A) focuses on human anatomy, the WHO Manual (choice C) focuses on global health guidelines, and Darwin's Origin of Species (choice D) discusses evolution and natural selection, none of which are specialized taxonomic resources for bacteria.
Which of the following cell organelles contain digestive enzymes?
- A. lysosomes
- B. chloroplasts
- C. peroxisomes
- D. peroxisomes
Correct Answer: C
Rationale: The correct answer is C: peroxisomes. Peroxisomes contain enzymes involved in breaking down fatty acids and detoxifying harmful substances. They do not contain digestive enzymes. Lysosomes contain digestive enzymes involved in breaking down waste materials. Chloroplasts are involved in photosynthesis and do not contain digestive enzymes. Mitochondria are involved in energy production and do not contain digestive enzymes. Therefore, the correct answer is peroxisomes.
A fecal smear from a patient with severe diarrhea revealed motile Gram-negative rods with a comma shape. What is the likely causative agent?
- A. Vibrio cholerae
- B. Shigella dysenteriae
- C. Salmonella typhi
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This bacterium is the likely causative agent because it is known to cause severe diarrhea, and it is characterized by its motile, comma-shaped Gram-negative rods. Vibrio cholerae produces cholera toxin, leading to profuse watery diarrhea. Shigella dysenteriae causes dysentery with bloody diarrhea, Salmonella typhi causes typhoid fever, and Escherichia coli can cause various types of diarrhea but typically does not have a comma shape.
Which of the following bacteria is associated with the disease known as whooping cough?
- A. Bordetella pertussis
- B. Clostridium tetani
- C. Haemophilus influenzae
- D. Staphylococcus aureus
Correct Answer: A
Rationale: 1. Bordetella pertussis causes whooping cough.
2. It secretes toxins that damage the respiratory tract.
3. Symptoms include severe coughing fits and the characteristic "whoop" sound.
4. Clostridium tetani causes tetanus, not whooping cough.
5. Haemophilus influenzae causes various infections, not whooping cough.
6. Staphylococcus aureus causes skin infections, not whooping cough.