Microscopy of dental plaque revealed unicellular organisms. Their cytoplasm had two distinct layers, barely visible core, wide pseudopodia. The patient is most likely to have:

Correct Answer: D

Rationale: The correct answer is D: Trichomonas tenax. Trichomonas tenax is a flagellated protozoan that is commonly found in the oral cavity, specifically in dental plaque. The description provided in the question matches the characteristics of Trichomonas tenax, such as unicellular structure, distinct layers in the cytoplasm, wide pseudopodia, and barely visible core. Entamoeba gingivalis (choice A) and Entamoeba histolytica (choice B) are amoebas, not flagellated protozoa, and they do not exhibit the characteristics described in the question. Lamblia (choice C) is also an incorrect choice as it is a different type of protozoan that does not match the description provided.

Correct Answer: D

Rationale: The correct answer is D: Mycobacterium tuberculosis. This bacterium can be transmitted via droplets in the air through coughing or sneezing. It is spread through respiratory droplets containing the bacteria. Streptococcus pneumoniae (A) is transmitted through direct contact with respiratory secretions, not through droplets in the air. Escherichia coli (B) is commonly transmitted through contaminated food or water, not through the air. Clostridium botulinum (C) is typically transmitted through contaminated food, not via respiratory droplets. Therefore, the correct choice is D as it is the only bacterium listed that can be transmitted via droplets in the air.

Correct Answer: C

Rationale: The correct answer is C: E + S = P. This notation represents the interaction between an enzyme (E) and a substrate (S) resulting in a product (P). Enzymes facilitate chemical reactions by binding to substrates and converting them into products. Choice A is incorrect because it does not include the enzyme in the reaction. Choice B is incorrect as it involves two substrates binding to the enzyme, not a substrate converting to a product. Choice D is incorrect as it shows two substrates reacting to form a product without involvement of an enzyme. Thus, choice C accurately represents the process of enzymatic reactions involving enzymes, substrates, and products.

Correct Answer: C

Rationale: Plasmids often carry antibiotic resistance genes, making choice C correct. Plasmids are circular DNA structures, not linear (A). They are found in both gram-positive and gram-negative bacteria, not exclusively in gram-positive bacteria (B). Plasmids are separate from the bacterial chromosome, not part of it (D). Therefore, choice C is the correct answer.

Correct Answer: A

Rationale: The correct answer is A (Escherichia coli, Gardnerella vaginalis, and Staphylococcus aureus) because they are known to commonly cause nonsexually transmitted infections of the reproductive system. Escherichia coli can cause urinary tract infections that can ascend to the reproductive system. Gardnerella vaginalis is associated with bacterial vaginosis, a common infection of the vagina. Staphylococcus aureus can cause infections in the reproductive system through various means. Choices B, C, and D are incorrect: B: Streptococcus faecalis, Klebsiella oxytoca, and Serratia marcescens are not commonly associated with reproductive system infections. C: Clostridium tetani and Bacillus cereus are not typically involved in reproductive system infections. D: Neisseria gonorrhoeae causes sexually transmitted infections, Helicobacter pylori causes gastrointestinal issues, and Pseudomonas aeruginosa is more

Correct Answer: D

Rationale: The correct answer is D: Relenza and Tamiflu. Both Relenza and Tamiflu are anti-influenza drugs that target the neuraminidase enzyme of the influenza virus, thereby inhibiting its replication and spread. Maxi Grip (A) is not an anti-influenza drug, Theraflu (B) contains different active ingredients, and Amantadine and Rimantadine (C) target a different viral protein, M2 ion channel. Therefore, choices A, B, and C are incorrect as they do not specifically target neuraminidase for influenza treatment.

Correct Answer: A

Rationale: The correct answer is A: Acid resistance. Tuberculous bacilli are acid-fast bacilli, meaning they resist decolorization by acid-alcohol after staining with Ziehl-Neelsen stain. This property is due to the high lipid content in the cell wall of Mycobacterium tuberculosis. Alkali resistance (B) and alcohol resistance (C) are not specific properties of tuberculous bacilli. Capsule formation (D) is a characteristic of some bacteria but is not a defining feature of tuberculous bacilli.

Correct Answer: D

Rationale: The correct answer is D: Q-fever. Q-fever is typically an infection that affects the lower respiratory tract, causing symptoms like pneumonia. Haemophilus influenzae pharyngitis (choice A) is an upper respiratory tract infection. Ozeana (choice B) and diphtherial croup (choice C) are not specific infections related to the lower respiratory tract. Q-fever stands out as the correct choice due to its association with lower respiratory tract infections.

Correct Answer: A

Rationale: The correct answer is A: Burri-Gins. This staining method specifically targets the detection of capsules in bacteria. It involves staining the capsules with crystal violet and the background with safranin. This staining technique helps visualize the capsules as a distinct halo around the bacteria. Summary: - Choice B (Ziehl-Neelsen) is used for acid-fast staining to detect Mycobacterium species. - Choice C (Neisser) is used for staining Neisseria species. - Choice D (Gram) is a common staining method used to differentiate bacteria based on cell wall composition (Gram-positive and Gram-negative), but it does not specifically target capsules.