Lab 03 Post Lab: Organic Compound Tests

yellow to purple

Which color change represents a positive reaction for the presence of starch using the iodine test?

blue to orange

Which color change represents a positive reaction for the presence of sugar using the Benedict's test?

lipids

Which group of molecules are insoluble in water?

starch

Which molecule is hydrolyzed (digested) by amylase?

brown paper test

Which of the following tests is used to detect the presence of lipids?

Benedict's test

Which of the following tests requires heating prior to observing results?

biuret

Which reagent is used to detect the presence of protein?

Benedict's

Which reagent is used to detect the presence of simple sugars?

iodine

Which reagent is used to detect the presence of starch?

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

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?

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

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?

copper

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.

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

Emulsifiers are

sugars.

Polysaccharides are polymers composed of

amino acids.

Proteins are polymers composed of

red, yellow, or green.

The Benedict's test indicates a positive result when the solution turns

albumin solution

The biuret test would indicate a positive result for proteins in which of the following solutions?

distilled water.

The negative control used in this experiment was

starch solution.

The positive control for the Iodine test was the

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

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?

the color change from blue to purple

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 is the dependent variable in this experiment?

proteins

Which category of macromolecules is associated with catalytic (enzymatic) activity?

blue to purple

Which color change represents a positive reaction for the presence of protein using the Biuret test?