Which bacteria are responsible for causing the disease known as 'whooping cough'?

Correct Answer: A

Rationale: The correct answer is A: Bordetella pertussis. Bordetella pertussis is the bacterium responsible for causing whooping cough, also known as pertussis. It produces toxins that damage the respiratory tract, leading to severe coughing fits. Haemophilus influenzae, Streptococcus pneumoniae, and Mycobacterium tuberculosis are not associated with whooping cough. Haemophilus influenzae can cause respiratory infections but not whooping cough. Streptococcus pneumoniae is known for causing pneumonia, and Mycobacterium tuberculosis causes tuberculosis, both different from whooping cough. Therefore, the correct answer is A as it is the specific bacterium linked to the disease in question.

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.

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.

Correct Answer: A

Rationale: The correct answer is A: Yersinia pestis. Y. pestis is responsible for causing the plague, a severe infectious disease. This bacterium is transmitted via fleas from rodents to humans. It causes bubonic, septicemic, and pneumonic plague. Clostridium difficile causes gastrointestinal infections, Neisseria gonorrhoeae causes gonorrhea, and Pseudomonas aeruginosa can cause various infections but not the plague.

Correct Answer: C

Rationale: The correct answer is C: Escherichia coli. E. coli is a gram-negative bacterium, which means it has an outer membrane containing lipopolysaccharides (LPS), also known as endotoxins. Endotoxins are released when the bacterium is destroyed, causing an inflammatory response. Streptococcus pneumoniae (choice A) is a gram-positive bacterium and does not produce endotoxins. Clostridium tetani (choice B) produces exotoxins, not endotoxins. Staphylococcus aureus (choice D) is also a gram-positive bacterium and does not produce endotoxins. In summary, E. coli is the correct answer because it is a gram-negative bacterium that produces endotoxins, while the other choices are gram-positive bacteria that do not produce endotoxins.