Unit 5 Chemistry of Cells Lab

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

color change from blue to purple

A change in color away from the blue of the reagent, which may range from green to yellow to red and then to brick red or brown is a positive reaction for ______ when testing with Benedict's reagent. Multiple choice question. protein fats starch sugars

d

Which is a lipid? Multiple choice question. DNA Enzyme Starch Cholesterol

d

A positive reaction for starch with iodine is indicated by Multiple choice question. the production of a blue color. the production of a purple to black color. a change from green to yellow to orange to red.

b

Carbohydrate molecules consist of what three types of atoms? Multiple select question. Oxygen Carbon Hydrogen Phosphate Nitrogen

1-3

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 Result A Blue B Blue C Blue D Purple

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

If an iodine test for starch is negative, what color would you expect to see in the tested sample? Multiple choice question. Yellow Black Blue Clear

a

Starch is best classified as a Multiple choice question. carbohydrate. lipid. protein. sugar.

a

Which type of molecule is starch? Multiple choice question. Polysaccharide Oligosaccharide Monosaccharide Disaccharide

a

Glycogen is which type of carbohydrate? Multiple choice question. Disaccharide Polysaccharide Monosaccharide

b

Which of the following tests is best suited for the detection of fat and oils? Multiple choice question. Benedict's Brown paper Biuret solution Litmus paper

b

Why don't water and oil mix? Multiple choice question. Because lipids are insoluble in nonpolar solvents such as water. Because lipids are insoluble in water and other polar solvents. Because lipids are soluble in nonpolar solvents such as water. Because lipids are soluble in water and other polar solvents.

b

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

brown paper test

Fructose is which type of carbohydrate? Multiple choice question. Disaccharide Polysaccharide Monosaccharide

c

The image (purple liquid in vile) shows a _____ Biuret test for protein. Multiple choice question. inconclusive negative positive

c

To investigate whether or not a food contains starch, you could test it with Multiple choice question. brown paper. Biuret solution. iodine.

c

Varying shades of purple indicate a positive reaction for _____ when testing with Biuret reagent. Multiple choice question. starch sugar protein fats

c

Test tube ____ (letter) indicates a STRONG positive reaction for the presence of reducing sugars using the Benedict's test. Multiple choice question. A B C D

c (brick red/brown)

Which of these might be used to test for glucose in urine for a person with diabetes? Multiple choice question. Iodine Biuret solution Amylase Benedict's reagent

d

The negative control used in the tests for protein, lipids, sugars, and starch was

distilled water

In experiments, it is common to include a sample of a substance known to react with the reagent. This allows the experimenter to verify that the test (reagent) is working correctly. This sample is known as a negative control.

false

The formation of an orange or purple color after the addition of iodine indicates that a sample contains lipids.

false

To test a solution for the presence of starch, _____ can be used.

iodine

Buiret reagent is used to test for the presence of

protein

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

protein, sugar

The three types of macromolecules that are used to build cells are carbohydrates, lipids, and

proteins

The positive control for the Iodine test was the

starch solution

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

To test a solution for the presence of _____, Benedict's reagent can be used.

sugar

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?Tube Result A Blue B Blue C Blue D Purple

the color change from blue to purple

Proteins have many functions, including Multiple select question. support. transport. motion. energy storage. defense.

1, 2, 3, 5

Which of the following are examples of proteins? Multiple select question. Enzymes Energy storage molecules Antibodies Structural molecules

1, 3, 4

If a sample is spotted on brown paper, and an oily spot will remain on the paper after 15 minutes of drying time, which of these has occurred? Multiple select question. A positive result is indicated. A negative result is indicated. Starch is present. Fats or oils are present. Sugar is present. Protein is present.

1, 4

Examples of lipids include ______. Multiple select question. cholesterol steroids integral proteins oils fats

1,2,4,5

Which of the following molecules can be formed when monosaccharides combine? Multiple select question. Glucose Glycogen Polysaccharides Disaccharides Fructose Sucrose

2, 3, 4, 6

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

Benedict's

A drop of liquid that does not evaporate from brown paper after a 20-minute period at room temperature contains lipids.

true

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

true