Nokea
Which bacteria are commonly associated with food poisoning?
- A. Clostridium botulinum and Staphylococcus aureus
- B. Bacillus anthracis and Mycobacterium tuberculosis
- C. Treponema pallidum and Neisseria gonorrhoeae
- D. Escherichia coli and Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum and Staphylococcus aureus. Clostridium botulinum produces a potent neurotoxin causing botulism, commonly associated with improperly canned foods. Staphylococcus aureus produces toxins causing symptoms of food poisoning. Bacillus anthracis and Mycobacterium tuberculosis are not typically associated with food poisoning. Treponema pallidum and Neisseria gonorrhoeae are bacteria causing sexually transmitted infections. Escherichia coli and Klebsiella pneumoniae are not directly linked to food poisoning.
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A lot of pyoinflammatory processes in oral cavity are caused by anaerobes. What nutrient medium can be used for control of wound textile contamination by anaerobes?
- A. Kitt-Tarozzi
- B. Endo
- C. Roux
- D. Sabouraud's
Correct Answer: A
Rationale: The correct answer is A: Kitt-Tarozzi. This medium contains blood and hemin, which are essential nutrients for the growth of anaerobes. Blood provides a source of iron, while hemin stimulates the growth of anaerobes. This combination creates an environment conducive for the isolation and identification of anaerobic organisms.
B: Endo and C: Roux are selective media primarily used for the isolation of gram-negative bacteria and not specifically designed for anaerobes.
D: Sabouraud's is a medium used for the cultivation of fungi, not anaerobes.
In summary, Kitt-Tarozzi is the correct choice due to its specific nutrient composition that supports the growth of anaerobes, unlike the other options which are not suitable for this purpose.
Which of the following proteins are encoded by herpesviruses and required for viral DNA replication?
- A. viral DNA polymerase
- B. ribonucleotide reductase
- C. neuraminidase
- D. thymidine kinase
Correct Answer: A
Rationale: The correct answer is A: viral DNA polymerase. This enzyme is essential for replicating the viral DNA during the herpesvirus life cycle. It catalyzes the synthesis of new DNA strands using the viral genomic template. Ribonucleotide reductase (B) is involved in nucleotide synthesis, but not directly in DNA replication. Neuraminidase (C) is an enzyme found in influenza viruses, not herpesviruses. Thymidine kinase (D) is an enzyme that phosphorylates thymidine, but its role is more related to nucleotide metabolism rather than viral DNA replication.
The typical site for replication of DNA viruses is:
- A. Nucleus
- B. Cytoplasm
- C. Endoplasmic Reticulum
- D. Golgi Apparatus
Correct Answer: A
Rationale: The correct answer is A: Nucleus. DNA viruses replicate in the host cell's nucleus because they require access to the host cell's DNA replication machinery. The nucleus contains the necessary enzymes and factors for DNA replication to occur accurately. The DNA viruses need to utilize these host cell components to replicate their own genetic material.
Summary of why other choices are incorrect:
B: Cytoplasm - Cytoplasm lacks the necessary enzymes and machinery for accurate DNA replication.
C: Endoplasmic Reticulum - ER is involved in protein synthesis and processing, not DNA replication.
D: Golgi Apparatus - Golgi apparatus is responsible for processing and packaging proteins, not DNA replication.
Which fact is correct about the nucleoids in bacteria:
- A. Contain a haploid bacterial chromosomes in each nucleus
- B. Are reabsorbed well by the method of Neisser
- C. Are 1 to 4 in each bacterial cell depending on the nature of the cell and the phases of growth and replication
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because nucleoids in bacteria can vary in number from 1 to 4 depending on the specific bacterial cell and its growth and replication phases. This is due to the dynamic nature of bacterial cells and their genetic material organization.
Choice A is incorrect because nucleoids do not contain nuclear membranes or multiple haploid chromosomes like eukaryotic nuclei. Choice B is incorrect as there is no known method of reabsorbing nucleoids by Neisser. Choice D is incorrect as option C is indeed the correct statement regarding the number of nucleoids in bacterial cells.
A patient with a sore throat had a throat culture revealing Gram-positive cocci in chains. The bacteria were catalase-negative and beta-hemolytic. What is the most likely causative agent?
- A. Streptococcus pyogenes
- B. Streptococcus pneumoniae
- C. Enterococcus faecalis
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes.
1. Gram-positive cocci in chains suggest streptococci.
2. Catalase-negative indicates it's not staphylococci.
3. Beta-hemolytic points towards Group A Streptococcus (S. pyogenes).
Summary:
B. Streptococcus pneumoniae is not beta-hemolytic.
C. Enterococcus faecalis is not typically chains.
D. Staphylococcus aureus is catalase-positive.