The negative control used in the tests for protein, lipids, sugars, and starch was
Albumin solution
Starch solution
Glucose solution
Olive oil
Distilled water
The Correct Answer is E
Choice A rationale: Albumin solution is not a negative control, but a positive control for the test for protein. Albumin is a type of protein that reacts with the biuret reagent and produces a violet color. A positive control is used to confirm that the test works and gives a positive result when the substance is present³.
Choice B rationale: Starch solution is not a negative control, but a positive control for the test for starch. Starch is a type of carbohydrate that reacts with the iodine solution and produces a blue-black color. A positive control is used to confirm that the test works and gives a positive result when the substance is present³.
Choice C rationale: Glucose solution is not a negative control, but a positive control for the test for sugar. Glucose is a type of sugar that reacts with the Benedict's solution and produces a red-orange color. A positive control is used to confirm that the test works and gives a positive result when the substance is present³.
Choice D rationale: Olive oil is not a negative control, but a positive control for the test for lipids. Olive oil is a type of lipid that reacts with the Sudan III solution and produces a red color. A positive control is used to confirm that the test works and gives a positive result when the substance is present³.
Choice E rationale: Distilled water is a negative control for the tests for protein, lipids, sugars, and starch. Distilled water is a pure solvent that does not contain any of these substances. It does not react with any of the reagents and does not produce any color change. A negative control is used to confirm that there is no response to the reagent or the microorganism used in the test. It is used to set the baseline and verify that the detecting reagent is working properly³.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale: A hypertonic solution has a higher solute concentration than the potato cell, which means it has a lower water potential. Water will move out of the potato cell by osmosis, causing it to shrink and become soft and limp.
Choice B rationale: A hypotonic solution has a lower solute concentration than the potato cell, which means it has a higher water potential. Water will move into the potato cell by osmosis, causing it to swell and become turgid and firm.
Choice C rationale: An isotonic solution has the same solute concentration as the potato cell, which means it has the same water potential. Water will move in and out of the potato cell at the same rate, causing it to remain unchanged in size and shape.
Choice D rationale: Tonic is not a valid term to describe the solute concentration of a solution. The correct terms are hypertonic, hypotonic, or isotonic.
Choice E rationale: I cannot determine anything without comparing multiple solutions is incorrect because the appearance of the potato slice after soaking in the solution provides enough information to determine the relative solute concentration of the solution.
Correct Answer is C
Explanation
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.
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