BSC 2010: Chapter 5 Practice Questions

Which of the following represents a specific description of a polypeptide?

A polypeptide is a chain of amino acids that have been linked together by dehydration reactions.

Which of the following molecules is a monosaccharide?

C6H12O6

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?

Cholesterol is the precursor for many important molecules such as sex hormones.

What is the process by which monomers are linked together to form polymers?

Dehydration reaction

When a protein is denatured, why does it lose its functionality?

Denaturation breaks the intramolecular bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function.

Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them?

For carbon skeletons of equal length, saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols do.

The sex hormones estradiol and testosterone belong to which class of molecules?

Lipids

Manufacturers make vegetable oils solid or semisolid at room temperature by __________.

Manufacturers make vegetable oils solid or semisolid at room temperature by __________.

Generally, animals cannot digest (hydrolyze) the glyosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?

Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units.

Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)?

Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar.

The α helix and β pleated sheet represent which level of protein structure?

Secondary structure

In what polysaccharide form do plants store glucose to be available later as an energy source?

Starch

Carbohydrates can function in which of the following ways?

Structural support and energy storage

Amylase is an enzyme that breaks down starch. Why can the same enzyme not break down cellulose?

The monosaccharide monomers in cellulose are bonded together differently than those in starch.

If a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __________.

a charged or polar end and an uncharged or nonpolar end

The peptide bond is __________.

a covalent bond joining amino acids together to form a polypeptide

In a hydrolysis reaction, __________, and in this process, water is __________.

a polymer is broken up into its constituent monomers; consumed

Protein molecules are polymers (chains) of __________.

amino acid molecules

Lipids differ from other large biological molecules in that they __________.

are not truly polymers

Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least?

cellulose

At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________.

chitin

The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond.

covalent

Carbohydrates are used in our bodies mainly for __________.

energy storage and release

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________.

ester linkages

A polysaccharide that is used for storing energy in human muscle and liver cells is __________.

glycogen

The subunits (monomers) in cellulose are linked together by __________.

glycosidic linkages

The fatty acid tails of a phospholipid are __________ because they __________.

hydrophobic; have no charges to which water molecules can adhere

The lipids that form the main structural component of cell membranes are __________.

phospholipids

The polysaccharide that you are most likely to have eaten recently is __________.

starch

The overall three-dimensional shape of a single polypeptide is called its __________.

tertiary structure

The "primary structure" of a protein refers to __________.

the sequence of amino acids along a polypeptide chain

One characteristic shared by sucrose, lactose, and maltose is that __________.

they are all disaccharides