Correct Answer: A

Rationale: The correct answer is A: tRNA. Anticodons are sequences of nucleotides found on tRNA molecules that complement the codons on mRNA during translation. tRNA molecules carry specific amino acids to the ribosome based on the codon-anticodon pairing. Option B, rRNA, forms the structure of the ribosome and is not directly involved in anticodon recognition. Option C, mRNA, contains codons but not anticodons. Option D, ribosomes, are the site of protein synthesis but do not contain the anticodons themselves.

Correct Answer: A

Rationale: The correct answer is A: Trichomonas vaginalis. Trichomonas vaginalis is a flagellated protozoan that causes trichomoniasis, a sexually transmitted infection commonly found in vaginal discharges. In this case, the presence of flagellates in the vaginal discharge aligns with the characteristics of Trichomonas vaginalis. Leishmania donovani causes leishmaniasis, transmitted by sandflies. Trypanosoma gambiense causes African sleeping sickness through the tsetse fly bite. Trihomonas hominis is a non-pathogenic flagellate found in the human intestine. Therefore, the correct choice is A due to the correlation between the flagellates found in the vaginal discharge and the characteristics of Trichomonas vaginalis.

Correct Answer: A

Rationale: The correct answer is A: decompose hydrogen peroxide. Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. This is important in bacteria to protect them from the harmful effects of hydrogen peroxide, a byproduct of metabolism. Choice B is incorrect as peptidoglycan synthesis is not the function of catalase. Choice C is incorrect as oxidative phosphorylation is a metabolic process unrelated to catalase function. Choice D is incorrect as endotoxin production is not a role of catalase.

Correct Answer: C

Rationale: The correct answer is C: Ebola virus. The patient's symptoms align with Ebola virus infection, including fever, severe hemorrhagic syndrome, and CNS involvement. Ebola virus is known to cause hemorrhagic fevers with high mortality rates. A: SARS CoV causes Severe Acute Respiratory Syndrome, which typically presents with respiratory symptoms, not hemorrhagic fever. B: Lymphocytic choriomeningitis virus usually causes a mild illness with flu-like symptoms, not severe hemorrhagic syndrome. D: ECHO 9 virus is associated with aseptic meningitis, not hemorrhagic fever.

Correct Answer: B

Rationale: The correct answer is B: Diarrhea. Brucellosis typically presents with symptoms such as arthralgia, headache, and undulating fever, but diarrhea is not a common symptom associated with the disease. Brucellosis is primarily characterized by systemic symptoms like fever, joint pain, and headache due to the bacterial infection. Diarrhea is more commonly seen in gastrointestinal infections rather than brucellosis. Therefore, the absence of diarrhea as a symptom in brucellosis helps in differentiating it from other diseases with similar clinical presentations.