Biology Chapter 5 Practice Problems

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

5′-ATGC-3′ with 5′-GCAT-3′

What do Alzheimer's, Parkinson's, and mad cow disease have in common?

All are associated with the buildup of misfolded proteins in cells.

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein?

All are associated with the buildup of misfolded proteins in cells. All cause the misfolding of nucleic acids. All are caused by the buildup of misfolded proteins in cells. All are associated with plaque buildup in arteries (atherosclerosis). All are associated with the buildup of lipids in brain cells due to faulty lysosome activity.

Which of the following is true regarding complementary base pairing in DNA and RNA molecules?

Although the base pairing between two strands of DNA in a DNA molecule can be thousands to millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of nucleotides in the same molecule or between two RNA molecules.

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?

C60H102O51

Which of the following molecules is a monosaccharide?

C6H12O6

Which of the following categories includes all others in the list?

Carbohydrates include poly/di/monosaccharides

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.

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________.

DNA

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.

Generally, animals cannot digest (hydrolyze) the glycosidic 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.

What is a distinguishing feature of most naturally occurring unsaturated fats?

Nearly all naturally occurring unsaturated fats have cis double bonds.

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.

Which of the following describes a difference between DNA and RNA?

The first three listed responses correctly describe differences between DNA and RNA.

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

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

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?

The phosphodiester linkages of the polynucleotide backbone would be broken.

Which of the following statements concerning unsaturated fats is true?

They have double bonds in the carbon chains of their fatty acids.

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

Which of the following lists represents the chemical components of a nucleotide?

a nitrogenous base, a phosphate group, and a pentose sugar

A glucose molecule is to starch as __________.

a nucleotide is to a nucleic acid

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

a polymer is broken up into its constituent monomers ... consumed

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

adding hydrogen atoms to the fatty acid hydrocarbon chains, thereby converting carbon-carbon double bonds to single bonds

Based on complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________.

adenine ... thymine

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 (in the lettuce)

Which of the following is a polymer?

cellulose, a plant cell wall component

Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form?

chaperonines

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

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

dehydration reaction

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

Which of the following carbohydrate molecules has the lowest molecular mass?

glucose

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

glycogen

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the a form. Which of the following could amylase break down?

glycogen, starch, and amylopectin

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

glycosidic linkages

Which of the following terms can be correctly used to describe compounds that do NOT mix with water?

hydrophobic

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

hydrophobic ... have no charges to which water molecules can adhere

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

lipids

Which of the following is the major energy storage compound of plant seeds?

oils

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

phospholipids

Cellulose is a __________ made of many __________.

polymer ... glucose molecules

The structural level of a protein least affected by a disruption in hydrogen bonding is the

primary level

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

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

starch

Carbohydrates can function in which of the following ways?

structural support and energy storage

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

tertiary structure

In a 1-4 glycosidic linkage, __________.

the number 1 carbon in one monosaccharide is bound to the number 4 carbon in another monosaccharide

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

Which of the following are pyrimidines found in the nucleic acid DNA?

thymine and cytosine

Which of the following lists ranks these molecules in the correct order by size from smallest to largest?

water, glucose, sucrose, protein