Nokea
Which bacteria is commonly associated with foodborne illnesses?
- A. Streptococcus pneumoniae
- B. Campylobacter jejuni
- C. Mycobacterium tuberculosis
- D. Haemophilus influenzae
Correct Answer: B
Rationale: The correct answer is B: Campylobacter jejuni. This bacteria is commonly associated with foodborne illnesses due to its presence in undercooked poultry and unpasteurized milk. Campylobacteriosis is a leading cause of bacterial gastroenteritis. Streptococcus pneumoniae (A) causes pneumonia, not foodborne illnesses. Mycobacterium tuberculosis (C) causes tuberculosis, not foodborne illnesses. Haemophilus influenzae (D) can cause respiratory infections but is not commonly associated with foodborne illnesses.
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All of the following are beta-lactam antibiotics except
- A. Benzylpenicillin
- B. Monobactam
- C. Cephalosporin
- D. Vancomycin
Correct Answer: D
Rationale: The correct answer is D, Vancomycin, because it is not a beta-lactam antibiotic. Beta-lactam antibiotics contain a beta-lactam ring in their molecular structure, which Vancomycin lacks. Benzylpenicillin, Cephalosporin, and Monobactam all contain the beta-lactam ring, making them beta-lactam antibiotics. Vancomycin belongs to a different class of antibiotics called glycopeptides.
A patient with severe pneumonia had a sputum culture revealing Gram-negative rods that are non-lactose fermenters. What is the most likely causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Enterobacter cloacae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas aeruginosa is a common Gram-negative rod that is a non-lactose fermenter and a common cause of severe pneumonia, especially in immunocompromised individuals. It is also known for its resistance to many antibiotics, making it difficult to treat.
Summary of other choices:
B: Escherichia coli is a lactose fermenter and is not commonly associated with severe pneumonia.
C: Klebsiella pneumoniae is a lactose fermenter and is more commonly associated with pneumonia in alcoholics or debilitated patients.
D: Enterobacter cloacae is a lactose fermenter and is not a common cause of severe pneumonia.
The organisms to be identified have a nucleus surrounded by a nuclear membrane. Genetic material is concentrated predominantly in the chromosomes which consist of DNA strands and protein molecules. These cells divide mitotically. Identify these organisms:
- A. Eukaryotes
- B. Bacteriophages
- C. Prokaryotes
- D. Viruses
Correct Answer: A
Rationale: Step-by-step rationale:
1. The presence of a nucleus with a nuclear membrane indicates eukaryotic cells.
2. Eukaryotes have genetic material in chromosomes made of DNA and proteins.
3. Mitotic division is characteristic of eukaryotic cells.
4. Therefore, the organisms described are eukaryotes.
Summary:
- Bacteriophages (B) are viruses that infect bacteria.
- Prokaryotes (C) lack a nucleus and their genetic material is not organized into chromosomes.
- Viruses (D) are not considered living organisms and do not have a nucleus or chromosomes.
Which of the following transport mechanisms transports water across the plasma membrane?
- A. osmosis
- B. facilitated diffusion
- C. phagocytosis
- D. exocytosis
Correct Answer: A
Rationale: Osmosis is the correct answer because it is the process by which water molecules move across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration. This movement occurs passively, driven by the concentration gradient. Facilitated diffusion (B) involves the transport of specific molecules with the help of carrier proteins, not water. Phagocytosis (C) is a process where cells engulf solid particles, not water molecules. Exocytosis (D) is the process of releasing substances from a cell by fusion of vesicles with the cell membrane, not the transport of water across the membrane.
A 32 year old patient complains about heartburn and dull pain in the epigastrium that appear 2-3 hours after meal. Exacerbations happen in spring and in autumn. The patient has food intolerance of eggs and fish. Objectively: stomach palpation reveals painfulness in the gastroduodenal area. Electrophasoduodenoscopy revealed a 5 mm ulcer on the anterior wall of duodenum. Urease test is positive. What is the most probable leading mechanism of disease development?
- A. Helicobacterial infection
- B. Dietary allergy
- C. Autoantibody production
- D. Reduced prostaglandin synthesis
Correct Answer: A
Rationale: The correct answer is A: Helicobacterial infection. This is the most probable leading mechanism of disease development in this case because the patient's symptoms, such as heartburn, epigastric pain, food intolerance, and presence of a duodenal ulcer with a positive urease test, are classic signs of Helicobacter pylori infection. This bacterium colonizes the stomach lining, leading to inflammation and ulcer formation. The exacerbations in spring and autumn could be due to seasonal variations in immune response.
Choice B: Dietary allergy is incorrect because the symptoms and findings in the patient are more indicative of an infectious etiology rather than an allergic reaction to specific foods.
Choice C: Autoantibody production is unlikely as there are no indications of an autoimmune process in this case.
Choice D: Reduced prostaglandin synthesis is not the leading mechanism as the symptoms and findings are more consistent with an infectious cause rather than a deficiency in prostaglandin synthesis.