Correct Answer: A

Rationale: Rationale: 1. Iodine solution contains iodine, a halogen with antiseptic properties. 2. Iodine is effective against fungi, making it suitable for treating dermatomycosis. 3. Iodine solution is commonly used in dermatology for its fungicidal properties. 4. Formalin, methylene blue, and brilliant green do not contain halogens or have fungicidal properties. Summary: - Formalin is a disinfectant, not an antiseptic for dermatomycosis. - Methylene blue is an antifungal dye, not used as an antiseptic. - Brilliant green is an antiseptic, but does not contain halogens or have fungicidal properties.

Correct Answer: C

Rationale: The correct answer is C: cytoplasmic membrane. The cytoplasmic membrane is the fluidlike portion of a cell that separates the cell's contents from the external environment. It regulates the passage of substances in and out of the cell, maintains cell shape, and provides protection. Rationale: 1. Cytosol (choice A) is the liquid component of the cytoplasm where organelles are suspended, not the fluidlike portion of the cell. 2. Nucleoplasm (choice B) refers to the liquid component of the nucleus, not the entire cell. 3. Inclusion (choice D) refers to non-living substances within the cell that are not considered the fluidlike portion. Summary: The cytoplasmic membrane is the correct answer as it encompasses the entire cell and is responsible for maintaining cell integrity and regulating transport. Choices A, B, and D are incorrect as they do not represent the fluidlike portion of the cell.

Correct Answer: B

Rationale: The correct answer is B: Alpha-hemolytic streptococci. Streptococcus pneumoniae are classified as alpha-hemolytic streptococci based on their ability to partially break down red blood cells, causing a greenish discoloration on blood agar plates. This distinguishes them from beta-hemolytic streptococci, which completely break down red blood cells. Streptococcus pneumoniae are not resistant to bile (choice A), as they are bile soluble. They are not stained by the Ziehl-Neelsen staining method (choice C), which is used for acid-fast bacteria such as Mycobacterium tuberculosis. They are sensitive to optochin (choice D), which is a key differentiating factor in identifying them from other alpha-hemolytic streptococci.

Correct Answer: C

Rationale: The correct answer is C: the hydrolysis of the four-membered ring present in penicillin. Beta-lactamase enzyme catalyzes the hydrolysis of the four-membered beta-lactam ring present in penicillin, rendering the antibiotic ineffective against bacterial cell walls. This enzyme breaks the bond in the beta-lactam ring, thus inactivating the antibiotic. Incorrect choices: A: the final cross-linking reaction to form the bacterial cell wall - This is incorrect as beta-lactamase does not participate in the formation of bacterial cell walls. B: the biosynthesis of the penicillin structure from the amino acid valine and cysteine - This is incorrect as beta-lactamase is not involved in the biosynthesis of penicillin. D: the hydrolysis of the acyl side chain from penicillin structures - This is incorrect as beta-lactamase specifically targets the beta-lactam ring, not the

Correct Answer: A

Rationale: The correct answer is A: Metronidazole. Rationale: 1. Metronidazole is the drug of choice for amebic dysentery due to its effectiveness against the causative agent, Entamoeba histolytica. 2. Metronidazole has good tissue penetration and is able to reach the site of infection in the gut. 3. It is a bactericidal drug that acts by disrupting the DNA structure of the parasite. 4. Metronidazole is well-absorbed orally and has minimal side effects. Summary of other choices: B: Furazolidonum - Not the drug of choice for amebic dysentery. It is primarily used for treating bacterial diarrhea. C: Levomycetin - Not effective against Entamoeba histolytica and not recommended for amebic dysentery. D: Phthalazol - Not commonly used for amebic dysentery treatment. Metronidazole is preferred due