Which reagent is used to detect the presence of protein?
Sudan IV
Benedict's
Biuret
Iodine
The Correct Answer is C
Choice A rationale: Sudan IV is not a reagent for protein detection, but a reagent for lipid detection. Sudan IV is a red dye that binds to non-polar molecules, such as fats and oils. Sudan IV stains lipids red, while leaving water-soluble molecules, such as proteins, unstained¹.
Choice B rationale: Benedict's is not a reagent for protein detection, but a reagent for sugar detection. Benedict's is a blue solution that contains copper sulfate, sodium carbonate, and sodium citrate. Benedict's reacts with reducing sugars, such as glucose and fructose, and reduces the copper ions from blue to orange-red².
Choice C rationale: Biuret is a reagent for protein detection. Biuret is a blue solution that contains copper sulfate and sodium hydroxide. Biuret reacts with peptide bonds, which are the bonds that link amino acids in proteins. Biuret changes color from blue to violet when it binds to protein molecules³.
Choice D rationale: Iodine is not a reagent for protein detection, but a reagent for starch detection. Iodine is a brown solution that forms a complex with starch, a polysaccharide composed of glucose units. Iodine changes color from brown to blue-black when it interacts with starch molecules⁴.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale: Locates the specimen is incorrect because the fine adjustment knob does not help to find the specimen on the slide, but rather to adjust the focus of the specimen. The fine adjustment knob is a small knob that is located on the side of the microscope, next to the coarse adjustment knob. The fine adjustment knob is used to make small changes in the distance between the objective lens and the specimen, which improves the sharpness of the image.
Choice B rationale: All of the answer choices are correct is incorrect because only one of the answer choices is correct. The fine adjustment knob only fine-tunes the focus of the specimen, not locates the specimen or the focus plane.
Choice C rationale: Locates the focus plane is incorrect because the fine adjustment knob does not help to find the focus plane, but rather to adjust the focus of the specimen. The focus plane is the plane that is perpendicular to the optical axis of the microscope and passes through the focal point of the objective lens. The focus plane is where the specimen is in focus and the image is clear.
Choice D rationale: Fine-tunes the focus is correct because the fine adjustment knob is used to fine-tune the focus of the specimen, which means to make small adjustments in the focus to obtain the best image quality. The fine adjustment knob is used after the coarse adjustment knob, which is used to bring the specimen into approximate focus.
Correct Answer is A
Explanation
Choice A rationale: The rate of diffusion is the speed at which particles move from an area of high concentration to an area of low concentration. This depends on the temperature, the size of the particles, and the medium they are in. Temperature affects the kinetic energy and the speed of the particles, which in turn affects the frequency and intensity of their collisions. Higher temperatures mean higher kinetic energy and faster particles, which leads to faster diffusion. ³
Choice B rationale: The change in rate of diffusion is not unaffected by temperature. Temperature is one of the main factors that influences the rate of diffusion, as explained above. Therefore, this choice is incorrect.
Choice C rationale: Diffusion does not halt when temperature is increased. On the contrary, diffusion becomes faster when temperature is increased, as explained above. Therefore, this choice is incorrect.
Choice D rationale: The change in rate of diffusion is not unpredictable when temperature is increased. There is a clear relationship between temperature and diffusion, as explained above. Therefore, this choice is incorrect.
Choice E rationale: The rate of diffusion does not decrease when temperature is increased. On the contrary, diffusion becomes faster when temperature is increased, as explained above. Therefore, this choice is incorrect..
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