The correct hierarchical order for virus classification is
- A. order, genus, family, subfamily, species.
- B. species, genus, family, subfamily, order.
- C. order, family, subfamily, genus, species.
- D. genus, order, family, subfamily, species.
Correct Answer: C
Rationale: The correct hierarchical order for virus classification is order, family, subfamily, genus, species. This is because classification starts at a broader level (order) and narrows down to a more specific level (species). Order comes first to group viruses based on common characteristics, followed by family, which further categorizes them. Subfamily refines the classification, then genus groups similar viruses together, and species distinguishes different strains within a genus. Choice A is incorrect because it places genus before family, which is not the correct sequence. Choice B is incorrect as it starts with species, which is the most specific level. Choice D is incorrect because it places genus at the beginning, which is too specific for the hierarchical order.
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Ribosomes take part in:
- A. protein synthesis
- B. break down of different substances
- C. oxidative phosphorylation
- D. inactivation of antibiotics
Correct Answer: A
Rationale: Ribosomes are responsible for protein synthesis, where they translate the genetic information from mRNA into specific amino acid sequences to form proteins. This process occurs in both prokaryotic and eukaryotic cells. Ribosomes do not participate in the breakdown of substances, which is mainly carried out by lysosomes or proteasomes. Oxidative phosphorylation involves the generation of ATP in mitochondria, not ribosomes. Ribosomes do not inactivate antibiotics; this is typically done by enzymes or chemical modifications. Therefore, the correct answer is A as ribosomes play a crucial role in protein synthesis.
Which of the following bacteria is responsible for causing gonorrhea?
- A. Chlamydia trachomatis
- B. Neisseria gonorrhoeae
- C. Treponema pallidum
- D. Escherichia coli
Correct Answer: B
Rationale: The correct answer is B: Neisseria gonorrhoeae. This bacterium is responsible for causing gonorrhea. Neisseria gonorrhoeae is a sexually transmitted bacterium that infects the mucous membranes of the reproductive tract. It is known for causing symptoms such as painful urination and discharge. Chlamydia trachomatis (choice A) is another sexually transmitted bacterium but is not responsible for gonorrhea. Treponema pallidum (choice C) causes syphilis, not gonorrhea. Escherichia coli (choice D) is a common bacterium found in the gut and is not associated with causing gonorrhea. Therefore, Neisseria gonorrhoeae is the correct answer for this question.
A 47-year-old patient came to see a doctor on the 7th day of disease. The disease developed very fast: after the chill body temperature rose to 40oC and lasted up to 7 hours, then dropped abruptly, which caused profuse sweat. There were three such attacks occur in once in two days. Two days ago the patient arrived from Africa. Objectively: pale skin, subicteric sclera, significantly enlarged liver and spleen. What is the cause of fever attacks in this disease?
- A. Erythrocytic schizogony
- B. Tissue schizogony
- C. Exotoxin of a causative agent
- D. Gametocytes
Correct Answer: A
Rationale: The correct answer is A: Erythrocytic schizogony. In this case, the patient most likely has malaria, specifically caused by Plasmodium falciparum. The fever attacks every 2 days (tertian fever) are characteristic of P. falciparum infection. The cycle of erythrocytic schizogony in P. falciparum is around 48 hours, leading to the recurring fever pattern. Choices B, C, and D are incorrect as tissue schizogony does not cause the characteristic fever pattern, exotoxins are not typically involved in malaria fever, and gametocytes do not directly cause fever attacks.
Routes for transmission of nosocomial infections are
- A. air droplets and fecal-oral mechanism
- B. air droplets and contact mechanism
- C. parenteral mechanism
- D. all are correct
Correct Answer: D
Rationale: The correct answer is D because nosocomial infections can be transmitted through various routes, including air droplets, fecal-oral mechanism, contact mechanism, and parenteral mechanism. Air droplets can carry infectious agents through the air, while contact with contaminated surfaces or individuals can spread infections. Fecal-oral transmission occurs through ingesting contaminated food or water. Parenteral transmission involves the introduction of pathogens directly into the bloodstream. Therefore, all the options listed in D are correct routes for transmission of nosocomial infections. Choices A, B, and C are incorrect because they do not encompass all possible routes of transmission for nosocomial infections.
The human pinworm Enterobius vermicularis lives in the __________ of humans.
- A. duodenum
- B. ileum
- C. transverse colon
- D. rectum
Correct Answer: D
Rationale: The correct answer is D: rectum. Pinworms typically inhabit the rectum area in humans, where they lay their eggs. This is because the female pinworm migrates to the rectum at night to deposit her eggs near the anus. Other choices are incorrect because pinworms do not reside in the duodenum (A), ileum (B), or transverse colon (C) as their primary location is in the lower gastrointestinal tract near the anus.
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