Examine the positive and negative controls up front for each test tube so that y

Question

Examine the positive and negative controls up front for each test tube so that you know what each result looks like. A positive control is a scenario within an experiment that is known to yield a positive result. In this case, if we apply Benedict' reagent directly to a glucose solution it is known to yield a positive result. A negative control is a known experiment that would be expected to yield a negative result, for example applying Benedict's reagent to water or applying a different reagent to the glucose solution. By applying both positive and negative controls, you can visualize what you will expect to see in a positive or negative test, and you can also determine if the reagent is working properly (and not yielding false positive or negative results). 1. Examine the test tubes at each station. The protein and starch stations also include tests for the simpler biomolecules (amino acids and glucose, respectively) that would be produced after enzyme activity. 2. Use the data that you compile in the table to figure out which of the lettered test tubes contains each of the three enzymes using your knowledge about positive/negative test and remembering that each enzyme works on only one of the complex biomolecules. Final Conclusions of enzymes Test Tube A = _____ Test Tube B = _____ Test Tube C = _____

Explanation / Answer

Sudan IV test detects the presence of lipids in the sample. A positive control tube and a lipid containing sample tube will form a red color layer at the contact site between the lipid containing solution and the dye solution.

Biuret’s test is used to detect the presence of proteins. A violet colored coordination complex is formed after the addition of biuret reagent in a positive biuret test. Breakdown of proteins with proteases results in amino acids that can be detected by the ninhydrin test. Proteins cannot be detected by ninhydrin test.

Lugol’s reagent is used for the detection of starch in the solution. Presence of starch generates a deep blue-black color solution after the addition of lugol’s reagent. Breakdown of starch by amylases generates glucose that can be detected by Benedict’s test. Starch does not react with Benedict’s reagent until it is hydrolyzed or broken down.

The test results are not provided in the question. So, final conclusions of enzymes in test tubes A, B, and C cannot be made.

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.