Chapter 5 Practice Questions
What do Alzheimer's, Parkinson's, and mad cow disease have in common?( Concept 5.4)
All have been associated with the buildup of misfolded proteins in cells.
Which of the following is true regarding complementary base pairing in DNA and RNA molecules? (Concept 5.5)
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.
Which of the following molecules is a monosaccharide? ( Concept 5.2)
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? ( Concept 5.3)
Cholesterol is the basis 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 _____. ( Concept 5.5)
DNA
When a protein is denatured, why does it lose its functionality? ( Concept 5.4)
Denaturation breaks the weak 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.
Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass? ( Concept 5.2)
Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units.
What is a distinguishing feature of most naturally occurring fats? ( Concept 5.3)
Nearly all naturally occurring unsaturated fats have cis double bonds.
What is a key feature of omega-3 fatty acids that distinguishes them from other types of fatty acids? (Concept 5.3)
None of the listed responses correctly describes a distinguishing key feature of omega-3 fatty acids.
To what does the term "polypeptide" refer? ( Concept 5.4)
None of the listed responses is correct.
Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)? ( Concept 5.3)
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? ( Concept 5.5)
RNA molecules consist of a single polynucleotide chain, whereas DNA molecules consist of two polynucleotide chains organized into a double helix; one of their nitrogenous bases is different; they contain different sugars
Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them? ( Concept 5.3)
Saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols.
Amylase is an enzyme that breaks down starch. Why can't the same enzyme break down cellulose? (Concept 5.2)
The monosaccharide monomers in cellulose are bonded together differently than 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 _____. ( Concept 5.3)
a charged end and a noncharged end
The peptide bond is _____. ( Concept 5.4)
a covalent bond joining amino acids together to form a polypeptide
A nucleotide is made of which of the following chemical components? ( Concept 5.5)
a nitrogenous base, a phosphate group, and a pentose sugar
A glucose molecule is to starch as _____. ( Concept 5.5)
a nucleotide is to a nucleic acid
In a hydrolysis reaction, _____, and in this process water is _____. ( Concept 5.1)
a polymer is broken up into its constituent monomers ... consumed
Manufacturers make vegetable oils solid or semisolid at room temperature by _____. ( Concept 5.3)
adding hydrogen atoms to the double bonds in the fatty acid hydrocarbon chains
On the basis of the principle of complementary base pairing, you would expect the percentage of _____ to be equal to the percentage of _____. ( Concept 5.5)
adenine ... thymine
Protein molecules are polymers (chains) of _____. ( Concept 5.4)
amino acid molecules
Lipids differ from other large biological molecules in that they _____. ( Concept 5.3)
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? ( Concept 5.2)
cellulose (in the lettuce)
Which of the following is a polymer? ( Concept 5.2)
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? ( Concept 5.4)
chaperonins
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 _____. ( Concept 5.2)
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. ( Concept 5.1)
covalent
What is the process by which monomers are linked together to form polymers? ( Concept 5.1)
dehydration or condensation reactions
Carbohydrates are used in our bodies mainly for _____. ( Concept 5.2)
energy storage and release
Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by _____. ( Concept 5.3)
ester linkages
Which of the following carbohydrate molecules has the lowest molecular weight? ( Concept 5.2)
glucose
A polysaccharide that is used for storing energy in human muscle and liver cells is _____. ( Concept 5.2)
glycogen
The subunits (monomers) in cellulose are linked together by _____. ( Concept 5.2)
glycosidic linkages
Which is the term for compounds that do not mix with water? ( Concept 5.3)
hydrophobic
The fatty acid tails of a phospholipid are _____ because they _____. ( Concept 5.3)
hydrophobic ... have no charges to which water molecules can adhere
The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules? (Concept 5.3)
lipids
Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein? ( Concept 5.4)
of the listed responses are correct: change in salt concentration or pH; mixing in a chemical that removes hydrogen bonds; heating the protein; denaturing the protein
Which of the following is the major energy storage compound of plant seeds? ( Concept 5.3)
oils
The lipids that form the main structural component of cell membranes are _____. ( Concept 5.3)
phospholipids
Cellulose is a _____ made of many _____. ( Concept 5.2)
polymer ... glucose molecules
Which of the following lists ranks these molecules in the correct order by size? ( Concept 5.4)
protein, sucrose, glucose, water
The alpha helix and beta pleated sheet represent which level of protein structure? ( Concept 5.4)
secondary structure
In what polysaccharide form do plants store glucose to be available later as an energy source? (Concept 5.2)
starch
The polysaccharide that you are most likely to have eaten recently is _____. ( Concept 5.2)
starch
Carbohydrates can function in which of the following ways? ( Concept 5.2)
structural support and energy storage
The overall three-dimensional shape of a single polypeptide is called the _____. ( Concept 5.4)
tertiary structure
In a 1-4 glycosidic linkage, _____. ( Concept 5.2)
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 _____. ( Concept 5.4)
the sequence of amino acids
One characteristic shared by sucrose, lactose, and maltose is that _____. ( Concept 5.2)
they are all disaccharides
Which of the following are pyrimidines found in the nucleic acid DNA? ( Concept 5.5)
thymine and cytosine
