Correct Answer: A

Rationale: The correct answer is A: Clostridium botulinum and Staphylococcus aureus. Clostridium botulinum produces a potent neurotoxin causing botulism, commonly associated with improperly canned foods. Staphylococcus aureus produces toxins causing symptoms of food poisoning. Bacillus anthracis and Mycobacterium tuberculosis are not typically associated with food poisoning. Treponema pallidum and Neisseria gonorrhoeae are bacteria causing sexually transmitted infections. Escherichia coli and Klebsiella pneumoniae are not directly linked to food poisoning.

Correct Answer: B

Rationale: The correct answer is B: Neisseria gonorrhoeae. This bacterium is responsible for causing gonorrhea. Neisseria gonorrhoeae is a sexually transmitted bacterium that infects the mucous membranes of the reproductive tract. It is known for causing symptoms such as painful urination and discharge. Chlamydia trachomatis (choice A) is another sexually transmitted bacterium but is not responsible for gonorrhea. Treponema pallidum (choice C) causes syphilis, not gonorrhea. Escherichia coli (choice D) is a common bacterium found in the gut and is not associated with causing gonorrhea. Therefore, Neisseria gonorrhoeae is the correct answer for this question.

Correct Answer: D

Rationale: The correct answer is D. Isoniazid inhibits pyridoxal phosphate synthesis, which is the active form of vitamin B6. Pyridoxal phosphate is essential for various enzymatic reactions, including neurotransmitter synthesis and myelin formation. Therefore, isoniazid-induced pyridoxal phosphate deficiency can lead to neurological symptoms like polyneuritis, paresthesia, memory disorders, and convulsions. A: Disruption of cell membrane synthesis - This is not the mechanism of isoniazid side-effects. B: Inhibition of protein synthesis - Isoniazid does not directly inhibit protein synthesis. C: Inhibition of RNA-synthesis - Isoniazid does not inhibit RNA synthesis; it affects vitamin B6 metabolism.

Correct Answer: D

Rationale: The correct answer is D because the catarrhal stage of whooping cough is characterized by mild respiratory symptoms such as mild coughing, sneezing, or a runny nose. During this stage, the cough may start to worsen but is not yet severe. A: Incorrect - Decrease in paroxysms of coughing is not seen in the catarrhal stage; it occurs later in the paroxysmal stage. B: Incorrect - Subsequent respiratory infection for many months after the onset of pertussis is not a characteristic of the catarrhal stage. C: Incorrect - Uncontrollable coughing followed by a high pitched 'whoop' sound is typical of the paroxysmal stage, not the catarrhal stage.

Correct Answer: A

Rationale: The correct answer is A: Clostridium perfringens. Clostridium perfringens is a gram-positive spore-forming bacillus commonly found in soil. It produces hemolysis on blood agar, as described in the question. Clostridium botulinum is also a gram-positive spore-forming bacillus, but it does not typically cause hemolysis. Staphylococcus aureus is a gram-positive cocci, not a bacillus. Pseudomonas aeruginosa is a gram-negative bacterium, not a gram-positive spore-forming bacillus.