Which of the following is a characteristic feature of Gram-positive bacteria?

Correct Answer: C

Rationale: The correct answer is C: Thick peptidoglycan layer. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet stain during Gram staining. This thick layer is a key characteristic feature that helps differentiate Gram-positive bacteria from Gram-negative bacteria. Rationale: 1. Gram-positive bacteria retain the crystal violet stain due to their thick peptidoglycan layer. 2. This thick layer provides structural support and protection to the cell. 3. Gram-positive bacteria lack an outer membrane, which is a feature of Gram-negative bacteria (Choice A). 4. Thin peptidoglycan layer is a characteristic of Gram-negative bacteria, not Gram-positive (Choice B). 5. Presence of LPS (lipopolysaccharide) is a feature of Gram-negative bacteria, not Gram-positive (Choice D). In summary, the presence of a thick peptidoglycan layer is a characteristic feature of Gram-positive

Correct Answer: C

Rationale: The correct answer is C: Candida albicans. Candida albicans is a common fungal organism that causes diaper rash in infants due to its ability to thrive in warm, moist environments. It can overgrow in the diaper area, leading to irritation and inflammation. Sporothrix schenckii (A) is a fungus that causes skin infections, but not typically diaper rash. Actinomyces (B) is a bacterium that is not commonly associated with diaper rash. Malassezia furfur (D) is a yeast that causes conditions like dandruff and seborrheic dermatitis, but not diaper rash in infants.

Correct Answer: D

Rationale: The correct answer is D because HIV can be transmitted from a mother to a child through multiple modes: during delivery through mixing of blood, during pregnancy through the placenta, and via breastmilk during lactation. Each mode presents a risk of transmission due to the presence of the virus in bodily fluids. Therefore, all of the above options are preferred modes of transmission for HIV from a mother to a child. Choices A, B, and C alone do not fully encompass all the possible routes of transmission, making them incorrect.

Correct Answer: B

Rationale: The correct answer is B: Protein synthesis. Bacterial ribosomes are responsible for translating the genetic information from mRNA into proteins. This process involves the binding of transfer RNA molecules carrying amino acids to the ribosome and the formation of peptide bonds between the amino acids to create proteins. DNA replication (A) is carried out by DNA polymerase enzymes, not ribosomes. Energy production (C) is primarily the function of mitochondria in eukaryotic cells, and cell division (D) is regulated by a complex network of proteins and signaling pathways, not ribosomes.

Correct Answer: C

Rationale: The correct answer is C: Thick peptidoglycan layer. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet stain during Gram staining. This thick layer is a key characteristic feature that helps differentiate Gram-positive bacteria from Gram-negative bacteria. Rationale: 1. Gram-positive bacteria retain the crystal violet stain due to their thick peptidoglycan layer. 2. This thick layer provides structural support and protection to the cell. 3. Gram-positive bacteria lack an outer membrane, which is a feature of Gram-negative bacteria (Choice A). 4. Thin peptidoglycan layer is a characteristic of Gram-negative bacteria, not Gram-positive (Choice B). 5. Presence of LPS (lipopolysaccharide) is a feature of Gram-negative bacteria, not Gram-positive (Choice D). In summary, the presence of a thick peptidoglycan layer is a characteristic feature of Gram-positive

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a bluish-green pigment called pyocyanin, which presents as a cyan pigment. This bacterium is commonly associated with wound infections and is often found in oral surgery complications. Proteus vulgaris (B) and Klebsiella pneumoniae (D) are not typically associated with cyan pigment production, making them less likely causative agents. Bacillus subtilis (C) is not known to produce cyan pigment and is not a common pathogen in wound infections. Therefore, based on the presence of cyan pigment and the clinical context of an oral surgery complication, Pseudomonas aeruginosa is the most probable causative agent.

Correct Answer: B

Rationale: The correct answer is B: M.tuberculosis. The description of bacillus in the form of accumulations resembling a pack of cigarettes and staining red with Ziehl-Neelsen staining is characteristic of Mycobacterium tuberculosis. M.leprae (Choice A) is associated with leprosy and does not typically appear as described. A.bovis (Choice C) is a type of Mycobacterium but is not typically found in the oral cavity. A.israilii (Choice D) is not associated with the characteristics mentioned in the question. Therefore, based on the specific characteristics described, M.tuberculosis is the most likely pathogenic organism revealed in the tissue sampling.

Correct Answer: C

Rationale: The correct answer is C: Reaction haemagglutination inhibition. This method is used to detect antibodies against influenza viruses by measuring the ability of the patient's serum to inhibit haemagglutination. This is a specific and sensitive technique for detecting influenza antibodies. A: Agglutination reaction is not specific for influenza viruses and may give false positives. B: Precipitation reaction in agar gel is not typically used for detecting influenza antibodies. D: Ration haemagglutination is not a standard method for detecting influenza antibodies.

Correct Answer: C

Rationale: The correct answer is C because lymphocytic choriomeningitis virus belongs to the family Arenaviridae. This virus is a well-known member of the Arenaviridae family and is associated with various diseases. Option A is incorrect as Arenaviruses can be isolated from clinical materials using suitable methods. Option B is incorrect because Arenaviruses replicate in the cytoplasm, not the nucleus. Option D is incorrect as Arenaviruses can infect various hosts, not just humans. Therefore, the statement that lymphocytic choriomeningitis virus belongs to the family Arenaviridae is true.