Nokea
Microscopy of a smear obtained from a patient with acute purulent periostitis revealed gram-positive bacteria arranged in clusters resembling bunch of grapes. What microorganisms is this morphology typical for?
- A. Staphylococci
- B. Sarcina
- C. Tetracocci
- D. Candida fungi
Correct Answer: A
Rationale: Rationale:
Staphylococci are gram-positive bacteria that typically arrange in clusters resembling a bunch of grapes. This characteristic morphology is specific to staphylococci due to their division pattern. Sarcina, Tetracocci, and Candida fungi do not exhibit this clustering pattern. Staphylococci are commonly associated with purulent infections, making them the most likely microorganisms in this scenario.
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In which of the following GIT infections, the bacteria adhere to the intestine wall and damage the microvilli:
- A. Enteropathogenic E. Coli (EPEC)
- B. Enterohemorrhagic E. Coli (EHEC)
- C. Enterotoxigenic E Coli (ETEC)
- D. Enteroinvasive E Coli (EIEC)
Correct Answer: A
Rationale: The correct answer is A: Enteropathogenic E. Coli (EPEC). EPEC bacteria adhere to the intestine wall using a protein called intimin, leading to microvilli damage. This attachment disrupts the normal absorption function of the intestine.
Summary of why other choices are incorrect:
B: Enterohemorrhagic E. Coli (EHEC) primarily causes bloody diarrhea and does not specifically target microvilli.
C: Enterotoxigenic E. Coli (ETEC) produces toxins that lead to watery diarrhea but does not directly target microvilli.
D: Enteroinvasive E. Coli (EIEC) invades and replicates within intestinal cells, causing inflammatory diarrhea, but does not specifically damage microvilli.
The causative agent of tuberculosis is:
- A. Mycobacterium leprae
- B. Mycobacterium tuberculosis
- C. Bacillus anthracis
- D. Staphylococcus aureus
Correct Answer: B
Rationale: The correct answer is B: Mycobacterium tuberculosis. Mycobacterium tuberculosis is the causative agent of tuberculosis, as it specifically infects the lungs and can spread to other parts of the body. Mycobacterium leprae (Choice A) causes leprosy, not tuberculosis. Bacillus anthracis (Choice C) causes anthrax, not tuberculosis. Staphylococcus aureus (Choice D) is a common bacterium known for causing skin infections, not tuberculosis. Therefore, Mycobacterium tuberculosis is the correct answer for the causative agent of tuberculosis.
Enriched growth media:
- A. Belong to the minimal media and inhibit the development of gram+ cocci
- B. Support the development of the target bacteria groups without suppressing the growth of other microorganisms
- C. Are intended for the cultivation of only one microbial species
- D. Support the development of target bacteria groups and suppress the development of other microorganisms
Correct Answer: B
Rationale: The correct answer is B because enriched growth media provide essential nutrients that support the growth of target bacteria groups without inhibiting the growth of other microorganisms. This allows for the selective cultivation of specific microbes while still allowing for the growth of other organisms present in the sample. Choice A is incorrect because enriched media do not belong to minimal media and do not inhibit the development of gram+ cocci. Choice C is incorrect because enriched media can support the growth of multiple microbial species. Choice D is incorrect because enriched media do not suppress the development of other microorganisms but rather provide nutrients to support their growth alongside the target bacteria groups.
Family Parvoviridae can cause all of these, except:
- A. Aplastic crisis in patients with chronic anemia
- B. Herpangina
- C. Fetal infections
- D. Fifth disease
Correct Answer: B
Rationale: The correct answer is B: Herpangina. Family Parvoviridae includes Parvovirus B19, which causes Fifth disease, aplastic crisis in chronic anemia, and fetal infections. Herpangina is caused by Enteroviruses, not Parvoviridae. Parvovirus B19 specifically targets erythroid progenitor cells, leading to anemia in susceptible individuals. Fetal infections can result in hydrops fetalis. Aplastic crisis occurs in patients with chronic anemia due to suppression of erythropoiesis by the virus.
Which type of RNA carries the genetic code for protein synthesis?
- A. mRNA
- B. tRNA
- C. rRNA
- D. snRNA
Correct Answer: A
Rationale: The correct answer is A: mRNA. mRNA carries the genetic code from the DNA in the cell nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. It serves as a template for protein synthesis by specifying the order of amino acids. tRNA (choice B) brings amino acids to the ribosome during protein synthesis. rRNA (choice C) is a structural component of ribosomes. snRNA (choice D) is involved in RNA processing and splicing, not protein synthesis. Therefore, choice A is correct as it directly carries the genetic code for protein synthesis.