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Microscopy of a wound abscess revealed Gram-negative rods producing blue-green pigment with a distinctive odor of jasmine. What is the likely causative agent?
- A. Pseudomonas aeruginosa
- B. Proteus vulgaris
- C. Escherichia coli
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives the characteristic color seen in the wound abscess. The distinctive odor of jasmine is also a key feature of Pseudomonas aeruginosa. Proteus vulgaris (B) and Klebsiella pneumoniae (D) do not produce blue-green pigment or have a jasmine-like odor. Escherichia coli (C) typically does not produce blue-green pigment or have a jasmine-like odor.
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Algae that contain agar in their cell walls belong to:
- A. Chrysophyta
- B. Rhodophyta
- C. Chlorophyta
- D. Phaeophyta
Correct Answer: B
Rationale: The correct answer is B: Rhodophyta. Rhodophyta is the phylum of red algae, which are known to contain agar in their cell walls. Agar is a gelatinous substance derived from these algae. Chrysophyta (A), Chlorophyta (C), and Phaeophyta (D) do not typically contain agar in their cell walls. Chrysophyta includes diatoms, Chlorophyta includes green algae, and Phaeophyta includes brown algae, none of which are known for agar production. Therefore, Rhodophyta is the correct choice based on the presence of agar in their cell walls.
Pseudomonas aeruginosa can cause:
- A. Burn wounds infection, severe pneumonia in patients with cystic fibrosis, nosocomial infections
- B. Food poisoning
- C. Bacterial pharyngitis
- D. None of the above
Correct Answer: A
Rationale: Step-by-step rationale for answer A:
1. Pseudomonas aeruginosa is known to cause burn wounds infections due to its ability to survive in moist environments.
2. It can cause severe pneumonia in patients with cystic fibrosis due to its resistance to antibiotics and ability to form biofilms.
3. It is a common cause of nosocomial infections in hospitals due to its ability to colonize medical equipment and surfaces.
Summary of other choices:
B. Pseudomonas aeruginosa typically does not cause food poisoning, as it is not a common pathogen associated with foodborne illnesses.
C. Bacterial pharyngitis is usually caused by Streptococcus pyogenes, not Pseudomonas aeruginosa, making this choice incorrect.
D. None of the above is incorrect as Pseudomonas aeruginosa is associated with specific infections mentioned in option A.
Which of the following is a general-purpose medium?
- A. Tryptic soy agar
- B. Blood agar
- C. Mannitol salt agar
- D. MacConkey agar
Correct Answer: A
Rationale: The correct answer is A: Tryptic soy agar is a general-purpose medium suitable for cultivating a wide range of microorganisms. It provides essential nutrients for growth without inhibiting specific types of bacteria. Blood agar (B), Mannitol salt agar (C), and MacConkey agar (D) are selective or differential media designed to promote the growth of specific types of bacteria or differentiate between different bacterial species. Therefore, they are not considered general-purpose mediums.
The main structure components of viruses are
- A. nucleic acid and proteins
- B. nucleic acids and lipids
- C. lipids and protein
- D. proteins and glycoproteins
Correct Answer: A
Rationale: The correct answer is A: nucleic acid and proteins. Viruses consist of genetic material (nucleic acid) surrounded by a protein coat. The nucleic acid carries the viral genetic information, while the proteins form the capsid that protects the genetic material. This combination is essential for the virus to infect host cells and replicate. Lipids (choice B) are not typically part of the main structure of viruses. Lipids are more commonly found in the host cell membrane. Lipids and proteins (choice C) may be present in the viral envelope but are not the main structural components. Proteins and glycoproteins (choice D) are important for viral attachment and entry into host cells but do not constitute the main structural components of viruses.
Chlorine belongs to which of the following chemical groups?
- A. Halogens
- B. Heavy metals
- C. Phenols
- D. Alcohols
Correct Answer: A
Rationale: The correct answer is A: Halogens. Chlorine belongs to the halogens group because it is a nonmetal element in group 17 of the periodic table. Halogens are highly reactive elements that have 7 electrons in their outer shell, making them eager to gain an electron to achieve stability. Chlorine specifically is a diatomic molecule with the chemical symbol Cl and atomic number 17.
Option B: Heavy metals are elements with high atomic weights and densities, such as lead and mercury, which are not related to chlorine.
Option C: Phenols are a class of organic compounds containing a hydroxyl group bonded to an aromatic ring, not related to chlorine.
Option D: Alcohols are organic compounds characterized by the presence of a hydroxyl group (-OH), also not related to chlorine.