Macromolecule Lab Quiz

Which reagent is used to detect the presence of protein? A. Biuret B. Benedict's C. Sudan IV D. Iodine

A. Biuret

The negative control used in the tests for protein, lipids, sugars, and starch was A. Distilled water. B. Albumin solution. C. Starch solution. D. Olive oil. E. Glucose solution.

A. Distilled water.

Which reagent is used to detect the presence of starch? A. Iodine B. Biuret C. Benedict's D. Phenol red E. Sudan IV

A. Iodine

When Benedict reagent is added to a solution containing simple sugars, the solution turns green, orange, or red. In the absence of simple sugars, the solution is blue. Benedict reagent was added to solutions that may or may not contain simple sugars. The data can be seen in the table below. The color change that occurs is considered the A. Control variable. B. Dependent variable. C. Unknown variable. D. Independent variable.

B. Dependent variable.

Proteins are polymers composed of A. Monosaccharides. B. Fatty acids. C. Nucleotides. D. Nucleic acids. E. Amino acids.

E. Amino acids.

The biuret test would indicate a positive result for proteins in which of the following solutions? A. Starch solution B. Olive oil C. Distilled water D. Albumin solution E. Glucose solution

D. Albumin solution

Which of the following tests requires heating prior to observing results? A. Brown paper test B. Biuret test C. Wendelspecht test D. Benedict's test E. Iodine test

D. Benedict's test

Polysaccharides are polymers composed of A. Nucleotides. B. Sugars. C. Amino acids. D. Nucleic acids. E. Fatty acids.

B. Sugars.

While testing an unknown solution a student adds Benedict's reagent and watches as the contents of the test tube turn green. The student then added amylase and heats the test tube. This causes the contents to turn red. Which of the following conclusions could the student make? A. The solution has both simple sugars and starch. B. The solution contained neither simple sugars nor starch. C. The solution contained only simple sugars. D. The solution contained starch only.

A. The solution has both simple sugars and starch.

Amy is asked to determine the chemical composition of an unknown liquid sample. She determines that the sample is negative for protein, simple sugars, and lipids. However, someone else has used up all of the iodine reagent. Which scenario would allow Amy to test the unknown sample for the presence of starch? A. Incubate the unknown sample with pepsin and then test for proteins. B. Incubate the unknown sample with amylase and then test for simple sugars. C. Add a known amount of starch to the unknown sample and then run the Benedict's test. D. Incubate the unknown sample with catalase and then test for proteins. E. Put a small amount of the unknown sample onto a fresh potato slice and observe for color changes.

B. Incubate the unknown sample with amylase and then test for simple sugars.

Which color change represents a positive reaction for the presence of sugar using the Benedict's test? A. Yellow to purple B. Yellow to clear C. Blue to orange D. Green to blue E. Brown to blue-black

C. Blue to orange

Which reagent is used to detect the presence of simple sugars? A. Sudan IV B. Phenol red C. Benedict's D. Biuret E. Iodine

C. Benedict's

Which category of macromolecules is associated with catalytic (enzymatic) activity? A. Polysaccharides B. Lipids C. Proteins D. Carbohydrates E. Steroids

C. Proteins

When biuret reagent is added to a solution containing protein, the solution turns pink or purple. In the absence of protein, the solution is blue. Biuret reagent was added to solutions that may or may not contain protein. The data can be seen in the table below. What conclusion can be drawn from this data? A. Tube D contains protein, while tubes A, B, and C contain water. B. Tube D contains water, while tubes A, B, and C contain protein. C. Tube D contains protein, while tubes A, B, and C do not. D. Tube D does not contain protein, while tubes A, B, and C do.

C. Tube D contains protein, while tubes A, B, and C do not.

At room temperature, Biuret reagent should react with protein within A. 5 minutes. B. 1.5 minutes. C. 10 minutes. D. 30 seconds. E. 3 minutes.

D. 30 seconds.

Biuret reagent contains ________ ions which react with peptide bonds under the alkaline conditions of the reagent and produce the color change associated with the presence of protein. A. Potassium B. Sodium C. Iron D. Copper E. Magnesium

D. Copper

A negative control is a sample that you know will give you a negative result. You are testing for the presence of proteins, simple sugars, starch, and lipids in various foods. What would be the best negative control for this experiment? A. Artificial cytoplasm, because it is a good buffer. B. A solution containing protein, sugar, starch, but no lipids. C. Candy, because it has no nutritional value. D. Distilled water, because it does not contain any of the molecules you are testing for.

D. Distilled water, because it does not contain any of the molecules you are testing for.

While testing for an emulsifier, one of the test tubes showed a layer of oil sitting on top of the water. What property of lipids causes this to occur? A. Lipids are larger molecules than water molecules. B. Lipids contain carbon while water molecules do not. C. Lipids are only found in solid form, not liquid form. D. Lipids are nonpolar and so do not mix with polar water molecules.

D. Lipids are nonpolar and so do not mix with polar water molecules.

Emulsifiers are A. Molecules with two nonpolar ends that can be used to disperse lipids into polar liquids such as water. B. Proteins that transport nonpolar substances in the bloodstream. C. Proteins that transport polar substances in the bloodstream. D. Molecules with a polar end and a nonpolar end that can be used to disperse lipids into polar liquids such as water. E. Molecules with two polar ends that can be used to disperse lipids into polar liquids such as water.

D. Molecules with a polar end and a nonpolar end that can be used to disperse lipids into polar liquids such as water.

The positive control for the Iodine test was the A. Glucose solution. B. Olive oil. C. Albumin solution. D. Starch solution. E. Distilled water.

D. Starch solution.

Which color change represents a positive reaction for the presence of starch using the iodine test? A. Yellow to green B. Blue to red C. Blue to brownish-red D. Green to red E. Amber to blue/black

E. Amber to blue/black

Which color change represents a positive reaction for the presence of protein using the Biuret test? A. Color change from purple to blue B. Color change from blue to red C. Color change from yellow to green D. Color change from green to red E. Color change from blue to purple

E. Color change from blue to purple

When testing for starch within the potato and onion, the test tube containing potato turned purple while the test tube containing onion turned orange. What can you conclude about the amount of starch in these two vegetables? A. Neither the potato nor the onion contained starch. B. The potato contained starch, but the onion did not. C. The potato contained no starch, but the onion did. D. The potato contained lower concentration of starch than the onion did. E. The potato contained a higher concentration of starch than the onion.

E. The potato contained a higher concentration of starch than the onion.