Which bacteria are associated with the disease tuberculosis?

Correct Answer: B

Rationale: The correct answer is B: Mycobacterium tuberculosis. This bacterium is specifically associated with causing tuberculosis. Mycobacterium leprae (choice A) is associated with leprosy, not tuberculosis. Streptococcus pneumoniae (choice C) is associated with pneumonia, not tuberculosis. Escherichia coli (choice D) is a common bacterium found in the intestines and is not associated with tuberculosis. Mycobacterium tuberculosis is the only bacterium directly linked to the disease, making it the correct choice.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Clostridium botulinum is known for producing the neurotoxin causing botulism. 2. Botulinum toxin paralyzes muscles, leading to symptoms of botulism. 3. Clostridium tetani produces tetanus toxin causing muscle rigidity, not botulism. 4. Streptococcus pneumoniae causes pneumonia, not botulism. 5. Escherichia coli can cause food poisoning, but not botulism. Summary: Choice A is correct (Clostridium botulinum) due to its association with botulism and neurotoxin production. Choices B, C, and D are incorrect as they are associated with different diseases and toxins.

Correct Answer: A

Rationale: Step-by-step rationale for why A is correct: 1. Clostridium tetani is known to produce tetanus toxin. 2. The tetanus toxin causes muscle rigidity and spasms characteristic of tetanus. 3. Clostridium perfringens is associated with gas gangrene, not tetanus. 4. Neisseria gonorrhoeae causes gonorrhea, not tetanus. 5. Bacillus anthracis causes anthrax, not tetanus. In summary, Clostridium tetani is the correct answer as it is specifically associated with causing tetanus, while the other choices are associated with different diseases.

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.

Correct Answer: A

Rationale: The correct answer is A: HIV. HIV is an example of obligate parasitism because it requires a host cell to replicate and survive. It cannot live independently outside of a host organism. In contrast, choices B, C, and D are not obligate parasites. E. Coli and S. Epidermidis are examples of commensal bacteria that can live in the host without causing harm. Pseudomonas aeruginosa can be both an opportunistic pathogen and a free-living organism, not strictly dependent on a host for survival.