Which of the following bacteria is associated with the disease tuberculosis?

Correct Answer: B

Rationale: Step 1: Mycobacterium tuberculosis is a bacterium known to cause tuberculosis. Step 2: Mycobacterium leprae causes leprosy, not tuberculosis. Step 3: Streptococcus pneumoniae causes pneumonia, not tuberculosis. Step 4: Neisseria gonorrhoeae causes gonorrhea, not tuberculosis. Conclusion: Mycobacterium tuberculosis is the correct answer as it is the only bacterium associated with tuberculosis among the choices provided.

Correct Answer: B

Rationale: The correct answer is B: Helicobacter pylori. This bacterium is known to be the primary cause of peptic ulcers by colonizing the stomach lining and causing inflammation. It produces urease enzyme to neutralize stomach acid and has a flagellum for mobility. Escherichia coli (A) is mainly associated with foodborne illnesses. Streptococcus pyogenes (C) causes strep throat and skin infections. Mycobacterium tuberculosis (D) causes tuberculosis, a respiratory infection. Therefore, Helicobacter pylori is the correct choice for peptic ulcers based on its unique characteristics and pathogenicity.

Correct Answer: B

Rationale: The correct answer is B. Vaginitis is often caused by an imbalance in vaginal flora. Antibiotics can disrupt the natural balance, leading to overgrowth of harmful bacteria or yeast. Pregnancy alters hormone levels, making the vagina more susceptible to infection. Menopause decreases estrogen levels, thinning the vaginal walls and reducing beneficial bacteria. A: Urinary blockage does not directly relate to vaginitis. Drug use and stress may weaken the immune system but are not direct causes of vaginitis. C: Puberty, HPV exposure, and smoking/tobacco use do not directly increase the chances of vaginitis. HPV is a viral infection, not a direct cause of vaginitis. D: While menopause can increase the risk of vaginitis due to hormonal changes, stress and steroid use are not primary factors in developing vaginitis.

Correct Answer: D

Rationale: The correct answer is D: Ancylostoma duodenale. A scolex is a structure found in tapeworms, not in the other options which are roundworms. Ancylostoma duodenale is a species of hookworm, a type of intestinal parasite that has a distinct scolex with hook-like mouthparts for attachment to the host's intestinal wall. Enterobius vermicularis is a pinworm, Necator americanus is a hookworm species without a scolex, and Ascaris lumbricoides is a roundworm with a cylindrical body lacking a scolex. Therefore, the presence of a scolex specifically points to Ancylostoma duodenale.

Correct Answer: C

Rationale: The correct answer is C because disinfectants are non-selective and can harm a wide range of microbial cells. Disinfectants work by disrupting cell membranes, proteins, and nucleic acids, affecting both harmful and beneficial microorganisms. Choices A and B are incorrect because disinfectants are designed to be potent and non-selective. Choice D is incorrect because the effects of disinfectants are often permanent and irreversible on microbial cells.