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The structures that can move fluid, mucus, or cells over the surface of a cell are:
- A. cilia
- B. fimbriae
- C. flagella
- D. microvilli
Correct Answer: C
Rationale: The correct answer is C: flagella. Flagella are whip-like structures that move fluid, mucus, or cells over the surface of a cell. They are longer and fewer in number compared to cilia, which are shorter and more numerous. Fimbriae are small, bristle-like structures that help bacteria attach to surfaces but do not move fluid. Microvilli are tiny projections that increase the surface area for absorption but do not have a role in moving fluid or cells. Therefore, flagella is the correct answer as it specifically fits the function described in the question.
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A scolex is a structure found in:
- A. Enterobius vermicularis
- B. Necator americanus
- C. Ascaris lumbricoides
- D. Ancylostoma duodenale
Correct Answer: D
Rationale: The correct answer is D: Ancylostoma duodenale. A scolex is a structure found in tapeworms, not in the other options which are roundworms. Ancylostoma duodenale is a species of hookworm, a type of intestinal parasite that has a distinct scolex with hook-like mouthparts for attachment to the host's intestinal wall. Enterobius vermicularis is a pinworm, Necator americanus is a hookworm species without a scolex, and Ascaris lumbricoides is a roundworm with a cylindrical body lacking a scolex. Therefore, the presence of a scolex specifically points to Ancylostoma duodenale.
All of the following are ways the kidney are used for urine formation and drug clearance except:
- A. Filtration
- B. Tubular secretion
- C. Tubular filtration
- D. Tubular reabsorption
Correct Answer: C
Rationale: The correct answer is C: Tubular filtration. The kidney does not perform tubular filtration as a method for urine formation and drug clearance. The process of urine formation involves filtration, secretion, and reabsorption. Filtration occurs at the glomerulus, where blood is filtered to form the initial filtrate. Tubular secretion involves the active transport of substances from the blood into the renal tubules to be eliminated in urine. Tubular reabsorption is the process of reclaiming useful substances from the filtrate back into the blood. Therefore, tubular filtration is not a valid process in urine formation and drug clearance, making it the correct answer. Choices A, B, and D are incorrect as they are essential processes in urine formation and drug clearance.
A Gram-negative, comma-shaped bacterium was isolated from a patient with cholera. What is the most likely causative agent?
- A. Vibrio cholerae
- B. Shigella dysenteriae
- C. Salmonella typhi
- D. Campylobacter jejuni
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This is because Vibrio cholerae is a Gram-negative, comma-shaped bacterium known to cause cholera. The characteristic shape and the association with cholera make it the most likely causative agent in this case.
Explanation for incorrect choices:
B: Shigella dysenteriae - Shigella dysenteriae is a Gram-negative bacterium that causes bacillary dysentery, not cholera.
C: Salmonella typhi - Salmonella typhi is a Gram-negative bacterium that causes typhoid fever, not cholera.
D: Campylobacter jejuni - Campylobacter jejuni is a Gram-negative bacterium that commonly causes foodborne gastroenteritis, not cholera.
An enzyme process of producing two identical copies of DNA from one original DNA molecule is called:
- A. Translation
- B. Transcription
- C. Replication
- D. Cell division
Correct Answer: C
Rationale: The correct answer is C: Replication. In DNA replication, the original DNA molecule is unwound and each strand serves as a template to synthesize a new complementary strand. This results in two identical copies of the original DNA molecule. Translation (A) is the process of synthesizing proteins from mRNA. Transcription (B) is the process of synthesizing mRNA from DNA. Cell division (D) is the process of a cell dividing into two daughter cells, not specifically producing identical DNA copies. Therefore, replication is the correct answer as it specifically refers to the process of copying DNA to produce two identical copies.
The degree or extent of disease-evoking power that a microorganism has is referred to as:
- A. virulence
- B. strength
- C. resistance
- D. competence
Correct Answer: A
Rationale: The correct answer is A: virulence. Virulence refers to the degree or extent of disease-evoking power that a microorganism possesses. This term specifically describes the ability of a microorganism to cause disease in a host. It is a crucial factor in understanding the pathogenicity of different microorganisms.
Choice B: strength is incorrect because it does not specifically relate to the disease-causing potential of a microorganism. Choice C: resistance refers to the ability of an organism to withstand the effects of a particular agent, such as a drug or environmental factor. Choice D: competence is not directly related to the disease-causing ability of a microorganism, but rather refers to the ability of an organism to perform a specific function effectively.