Nokea
Examination of the duodenal contents revealed some pear-shaped protozoa with two nuclei and four pairs of flagella. The organisms had also two axostyles between the nuclei and a ventral adhesive disc. What protozoan representative was found in the patient?
- A. Lamblia
- B. Toxoplasma
- C. Leishmania
- D. Intestinal trichomonad
Correct Answer: A
Rationale: Step 1: Pear-shaped protozoa with two nuclei, four pairs of flagella, two axostyles, and a ventral adhesive disc match the characteristics of Giardia lamblia.
Step 2: Giardia lamblia is commonly found in the duodenum and causes giardiasis.
Step 3: Lamblia is the correct answer as it specifically matches all the described characteristics.
Summary: B, Toxoplasma, is incorrect as it does not match the described features. C, Leishmania, does not have the specific characteristics mentioned. D, Intestinal trichomonad, does not match the detailed descriptions given.
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Which description matches most to adenoviruses:
- A. Middle sized, naked icosahedral capsid, double-stranded DNA
- B. Small-sized, enveloped capsid, ssRNA
- C. Large, enveloped capsid, double stranded DNA
- D. None of the above
Correct Answer: A
Rationale: Step-by-step rationale:
1. Adenoviruses are DNA viruses, so choices B and C (ssRNA and DNA) are incorrect.
2. Adenoviruses have a middle-sized, naked icosahedral capsid, making choice A the correct description.
3. Choice D is incorrect as adenoviruses do have specific characteristics, making "None of the above" an inaccurate option.
In summary, the correct answer A is supported by the fact that adenoviruses have a middle-sized, naked icosahedral capsid and contain double-stranded DNA. Choices B, C, and D are incorrect as they do not align with the characteristics of adenoviruses.
There are __________ known forms of gastroenteritis caused by Escherichia coli.
- A. two
- B. three
- C. four
- D. five
Correct Answer: D
Rationale: The correct answer is D: five. Escherichia coli can cause enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC), enteroaggregative E. coli (EAEC), and diffusely adherent E. coli (DAEC). Each form has distinct characteristics and pathogenesis. Therefore, the other choices (A, B, C) are incorrect because they do not accurately represent the number of known forms of gastroenteritis caused by Escherichia coli.
DNA replication occurs in which phase of the cell cycle?
- A. G phase
- B. Prophase
- C. Metaphase
- D. S phase
Correct Answer: D
Rationale: The correct answer is D: S phase. During the S phase of the cell cycle, DNA replication takes place to ensure each daughter cell receives a complete set of genetic material. This phase is characterized by the synthesis of new DNA strands. In contrast, choices A, B, and C (G phase, Prophase, Metaphase) are not associated with DNA replication. The G phase is a period of cell growth, Prophase is the initial stage of mitosis, and Metaphase is when chromosomes align. Therefore, the S phase is the specific stage where DNA replication occurs, making it the correct answer.
For cultivation of Brucella, pure cultures should be incubated in CO2 enriched atmosphere. What type of breathing is typical for Brucella?
- A. Capnophilic
- B. Facultative anaerobic
- C. Obligate anaerobic
- D. Obligate aerobic
Correct Answer: A
Rationale: The correct answer is A: Capnophilic. Brucella requires a CO2 enriched atmosphere for cultivation, making it capnophilic. This is because Brucella is a microaerophilic bacterium that thrives in low oxygen conditions and elevated CO2 levels. Choice B (Facultative anaerobic) and D (Obligate aerobic) are incorrect as Brucella does not grow well under aerobic conditions. Choice C (Obligate anaerobic) is also incorrect as Brucella can grow in the presence of oxygen, although it prefers low oxygen environments.
Which of the statements is false:
- A. Spirochaetes are bacilli
- B. Diplococci possess spherical shape
- C. In rod-shaped bacteria one of the diameters is bigger
- D. Coccobacilli are a type of rod-shaped bacteria
Correct Answer: A
Rationale: The correct answer is A because spirochaetes are not bacilli; they are spiral-shaped bacteria. Bacilli are rod-shaped bacteria, making statement A false. Statement B is true as diplococci are spherical bacteria occurring in pairs. Statement C is true as rod-shaped bacteria have one diameter longer than the other. Statement D is true as coccobacilli are short, oval-shaped bacteria resembling cocci and rods. In summary, spirochaetes are spiral-shaped, not bacilli, making statement A false.