Bio Lab Exam #1 (Chemical Composition Q's)

Which molecule is hydrolyzed (digested) by amylase?

starch

Which of the following are functions of carbohydrates? (Select all that apply)

storage of energy; structural support

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?

the color change from blue to purple

The student tests an unknown solution using each of the tests and observes that the solution turns blue-black when he tests for protein. Which of the following conclusions can the student make?

No conclusion can be drawn; the student made an error.

Which classes of macromolecules have a significant role in energy storage? (Select all that apply)

lipids, carbohydrates

During the paper test, solution 2 left a faint stain behind and was determined to be milk while solution 4 left a very definite and greasy stain behind and was determined to be oil. What can be concluded about the lipid content of milk?

It contains a lower concentration of lipids than oil.

The positive control for the Iodine test was the:

Starch solution

True or False: The formation of a green color after heating with Benedict's reagent indicates that a sample contains simple sugars.

True (low)

Proteins are polymers composed of:

amino acids.

Which reagent is used to detect the presence of protein?

biuret

The negative control used in this experiment was:

distilled water

Which group of molecules are insoluble in water?

lipids

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

yellow to purple

What is the minimal drying time for the paper lipid test?

15 minutes

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

Benedict's

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

Benedict's test

An unknown liquid sample is tested for chemical composition. You receive the following results: iodine test = yellow; biuret test = blue; Benedict's test = blue; and paper lipid test = clear. Which of the following are present in this sample? (Select all that apply)***

None

An unknown sample is tested for chemical composition. You receive the following results: iodine test = purple; biuret test = blue; Benedict's test = green; and paper lipid test = greasy spot. Which of the following are present in this sample? (Select all that apply)

Starch, sugar, lipids

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?

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

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? (Testing for carbs)

The solution has both simple sugars and starch.

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?

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

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 contents of the unknown solutions would be considered the:

independent variable.

Emulsifiers are:

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