Which of the following is an active transport mechanism?

Correct Answer: D

Rationale: The correct answer is D: pinocytosis. This is an active transport mechanism where cells engulf fluids or solutes through vesicles. Energy is required to transport substances against a concentration gradient. A is incorrect as pinocytosis is an active process, not passive like pinocytosis. B is incorrect as facilitated diffusion is a passive process that uses carrier proteins to move substances down a concentration gradient. C is incorrect as filtration is a passive process that relies on pressure gradients to move substances across a barrier. Therefore, D is the correct choice as it involves the active transport of substances into the cell.

Correct Answer: A

Rationale: The correct answer is A because spheroplasts are bacteria with defective cell walls that have a parietal layer (peptidoglycan layer) and a defective peptidoglycan layer. This is because spheroplasts have lost their rigid cell wall structure, leading to an incomplete peptidoglycan layer. Choice B is incorrect as the cytoplasmic membrane is not directly affected by the loss of cell wall integrity. Choice C is incorrect because spheroplasts do not have an outer membrane defect, but rather a defect in the peptidoglycan layer. Choice D is incorrect because spheroplasts still have peptidoglycan, even though it is defective.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae are all common causes of bacterial meningitis. Neisseria meningitidis is often associated with outbreaks in community settings. Streptococcus pneumoniae is a leading cause of bacterial meningitis in adults. Haemophilus influenzae used to be a common cause in children before the introduction of the Hib vaccine. Therefore, since all three bacteria are known to cause bacterial meningitis, the correct answer is D. Choices A, B, and C are incorrect because each bacteria individually can cause bacterial meningitis, making "All of the above" the correct comprehensive answer.

Correct Answer: A

Rationale: The correct method of laboratory diagnostics for suspected malaria is blood examination. Malaria is diagnosed by detecting the presence of the Plasmodium parasite in the patient's blood. This can be done through microscopy to identify the parasite in a blood smear or through rapid diagnostic tests (RDTs) that detect specific antigens produced by the parasite. Blood examination allows for the direct visualization of the parasite, making it the most accurate method for diagnosing malaria. Immunological tests, stool examination, and urine examination are not suitable for diagnosing malaria as the parasite primarily resides in the red blood cells. Stool and urine examinations are more commonly used for diagnosing gastrointestinal or urinary tract infections, respectively.

Correct Answer: A

Rationale: The correct answer is A: Gram staining method. The rationale is as follows: 1. Gentian violet is a primary stain used in the Gram staining procedure to stain the bacterial cells. 2. Lugol's solution is a mordant that helps to fix the crystal violet stain in Gram-positive bacteria. 3. 95% alcohol is used as a decolorizing agent in the Gram staining process to remove the stain from Gram-negative bacteria. 4. Watermagenta is not a standard reagent in the Gram staining method. Therefore, based on the reagents mentioned, the staining method applied in this case is the Gram staining method. Other choices are incorrect: B: Ziehl-Nielsen's - This staining method is used for acid-fast staining, not for lobar pneumonia. C: Romanovsky - This staining method is used for blood smears, not for bacterial staining in pneumonia. D: Neisser - This staining method is not commonly used in routine bacterial staining procedures.

Correct Answer: A

Rationale: Step 1: Streptococcus mutans is known for its ability to produce lactic acid, which contributes to the demineralization of tooth enamel, leading to dental caries. Step 2: Streptococcus pneumoniae is a common respiratory pathogen and not directly associated with dental caries. Step 3: Bacillus cereus is a foodborne pathogen and not typically found in the oral cavity or associated with dental caries. Step 4: Clostridium tetani causes tetanus, a neurological condition, and is not involved in the formation of dental caries. Summary: Choice A is correct as Streptococcus mutans is specifically linked to dental caries due to its acidogenic and aciduric properties. Choices B, C, and D are incorrect as they are not associated with dental caries.

Correct Answer: A

Rationale: The correct answer is A: vectors. Vectors are animals that transmit infectious diseases from one host to another, typically through biting or contact. They do not cause the disease themselves but serve as intermediaries. Pathogens (B) are the microorganisms that cause diseases. Carriers (C) are individuals who harbor a pathogen without showing symptoms. Parasites (D) are organisms that live on or inside another organism and may or may not transmit diseases. Therefore, the term "vectors" specifically refers to animals that transmit infectious diseases, making it the correct choice in this context.

Correct Answer: A

Rationale: Acyclovir is the correct answer because it is an antiviral drug used to treat herpes simplex and varicella-zoster viruses, not influenza. Tamiflu, Amantadine, and Relenza are used to treat influenza by inhibiting viral replication or easing symptoms. Acyclovir's mechanism of action targets different viruses, making it ineffective for treating influenza.

Correct Answer: C

Rationale: The correct answer is C: ELISA, Western blot. These tests are commonly used for diagnosing Lyme borreliosis due to their high sensitivity and specificity in detecting antibodies against Borrelia burgdorferi, the causative agent. ELISA is the initial screening test, while Western blot is used for confirmation. Widal agglutination test (A) is used for diagnosing typhoid fever, not Lyme disease. Cultivation on blood and chocolate agar (B) is not commonly used for diagnosing Lyme borreliosis as Borrelia species are difficult to culture. Ascoli thermoprecipitation test (D) is used for diagnosing pneumonia caused by Streptococcus pneumoniae, not Lyme disease.