Ch 3
The alpha helix and beta pleated sheet represent which level of protein structure? a. quaternary structure b. tertiary structure c. pentiary structure d. secondary structure e. primary structure
d
The polysaccharide that you are most likely to have eaten recently is __________. a. lactose b. glucose c. chitin d. starch e. ribose
d
The structural level of a protein least affected by a disruption in hydrogen bonding is the a. All structural levels are equally affected. b. quaternary level. c. secondary level. d. primary level. e. tertiary level.
d
Amylase is an enzyme that breaks down starch. Why can't the same enzyme break down cellulose? a. The monosaccharide monomers in cellulose are bonded together differently than in starch. b. The enzyme cannot attack cellulose because of its helical shape. c. Starch is made of glucose; cellulose is made of fructose. d. The bonds between the monosaccharide monomers in cellulose are much stronger. e. Cellulose molecules are much too large.
a
A straight-chain carbon compound constructed from __________ must contain at least one carbon-carbon double bond. a. six hydrogen, three carbon b. six hydrogen, two carbon c. 14 hydrogen, 6 carbon d. six hydrogen, two carbon, one oxygen e. eight hydrogen, three carbon, three oxygen
a
Carbohydrates are used in our bodies mainly for __________. a. energy storage and release b. lipid storage c. structural molecules, such as hair and fingernails d. membrane construction e. building genetic material
a
Carbon atoms are the most versatile building blocks of the molecules used by living organisms because __________. a. each carbon atom acts as an intersection point from which a molecule can branch off in up to four directions b. carbon is the central atom of carbon dioxide, a necessary molecule for photosynthesis c. carbon can combine with hydrogen to form hydrocarbons d. carbon is the central atom in urea, a molecule used by many living organisms to transport wastes from the body e. All of the listed responses are correct.
a
A nucleotide is made of which of the following chemical components? a. a nitrogenous base, an amino acid, and a phosphate group b. a nitrogenous base, a phosphate group, and a pentose sugar c. a nitrogenous base, an amino acid, and a pentose sugar d. a series of nitrogenous bases, a nucleic acid backbone, and a hexose sugar e. a nitrogenous base, a fatty acid, and an amino acid
b
Although the structures of the functional groups that are most important to life vary, they share one thing in common: They __________. a. always cause the carbon to which they are attached to become an asymmetric carbon, thus converting the molecule into an enantiomer b. all are hydrophilic and increase the organic compound's water solubility c. all contain oxygen d. all have at least one double bond e. force straight chains of carbons into closed rings of carbon
b
Glucose and hexanoic acid each contain six carbon atoms, but they have completely different properties. Glucose is a nutrient found in food; hexanoic acid is poisonous. Their differences must be due to different __________. a. monomers b. functional groups c. macromolecules d. isomers e. quaternary structures
b
Manufacturers make vegetable oils solid or semisolid at room temperature by __________. a. removing hydrogen atoms and forming additional double bonds in the fatty acid hydrocarbon chains b. adding hydrogen atoms to the double bonds in the fatty acid hydrocarbon chains c. removing hydrogen atoms and forming additional single bonds in the fatty acid hydrocarbon chains d. adding hydrogen atoms to the single bonds of the fatty acid hydrocarbon chains e. None of the listed responses is correct.
b
On the basis of the principle of complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________. a. adenine ... guanine b. adenine ... thymine c. thymine ... cytosine d. adenine ... cytosine e. thymine ... guanine
b
The lipids that form the main structural component of cell membranes are __________. a. carbohydrates b. phospholipids c. proteins d. cholesterol e. triacylglycerols
b
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? a. C60H120O60 b. C60H102O51 c. C60H111O51 d. C60H100O50 e. C6H12O6
b
The overall three-dimensional shape of a single polypeptide is called the __________. a. quaternary structure b. tertiary structure c. secondary structure d. primary structure e. double helix
b
The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules? a. nucleic acids b. lipids c. carbohydrates d. amino acids e. proteins
b
Which chemical group is most likely to be responsible for an organic molecule behaving as a base (see Concept 2.5)? a. carbonyl b. amino c. hydroxyl d. carboxyl e. phosphate
b
Which functional group is not present in this molecule? a. carboxyl b. sulfhydryl c. hydroxyl d. amino
b
A glucose molecule is to starch as __________. a. an amino acid is to a nucleic acid b. a nucleic acid is to a polypeptide c. a protein is to an amino acid d. a nucleotide is to a nucleic acid e. a steroid is to a lipid
d
A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________. a. proteins b. fatty acids c. sucrose d. DNA e. cellulose
d
Cellulose is a __________ made of many __________. a. polypeptide ... monomers b. lipid ... triacylglycerols c. protein ... amino acids d. polymer ... glucose molecules e. carbohydrate ... fatty acids
d
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? a. Cholesterol is an important constituent of nucleotides. b. Cholesterol aids in the formation of amino acids that are used to build proteins. c. Cholesterol is an important energy storage molecule. d. Cholesterol is the basis for many important molecules such as sex hormones. e. Cholesterol is not important for humans anymore. It is a holdover from hunter-gatherer days when food was scarce.
d
In what polysaccharide form do plants store glucose to be available later as an energy source? a. protein b. fatty acids c. glycogen d. starch e. cellulose
d
Lipids differ from other large biological molecules in that they __________. a. do not contain nitrogen and phosphorus atoms b. do not contain carbon c. do not have specific shapes d. are not truly polymers e. are much larger
d
The "primary structure" of a protein refers to __________. a. coiling due to hydrogen bonding between amino acids b. the alpha helix or beta pleated sheets c. the weak aggregation of two or more polypeptide chains into one functional macromolecule d. the sequence of amino acids e. interactions among the side chains or R groups of the amino acids
d
Which of these is found in all amino acids? a. -COOH b. -COH c. -OH d. -NH2 e. both -COOH and -NH2
e
Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass? a. Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units. b. Cows and other herbivores are exceptions and make some cellulose-digesting enzymes. c. They have to eat a lot of it. d. The flat teeth and strong stomachs of herbivores break the cellulose fibers so that the cows get enough nutrition from the cell contents. e. All of the listed responses are correct.
a
One characteristic shared by sucrose, lactose, and maltose is that __________. a. they are all disaccharides b. they are all monosaccharides c. they all contain fructose d. they are all indigestible by humans e. they are all polysaccharides
a
Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________. a. ester linkages b. ionic bonds c. peptide bonds d. glycosidic linkages e. phosphodiester linkages
a
The fatty acid tails of a phospholipid are __________ because they __________ . a. hydrophobic ... have no charges to which water molecules can adhere b. hydrophobic ... consist of units assembled by dehydration reactions c. hydrophilic ... are easily hydrolyzed into their monomers d. hydrophobic ... dissolve easily in water e. hydrophilic ... consist of units assembled by dehydration reactions
a
The subunits (monomers) in cellulose are linked together by __________. a. glycosidic linkages b. peptide bonds c. ionic bonds d. ester linkages e. phosphodiester linkages
a
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. a. covalent b. ionic c. van der Waals d. peptide e. hydrogen
a
What is the three-dimensional shape created by hybrid orbitals that are formed when a carbon atom is covalently bonded with four other atoms? a. a tetrahedron with carbon in the center b. a cube with carbon in the center c. a flat sheet with carbon in the center d. a triangle with carbon in the center e. All of the listed responses are possible.
a
Which of the following categories includes all others in the list? a. carbohydrate b. polysaccharide c. disaccharide d. monosaccharide e. starch
a
Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least? a. cellulose (in the lettuce) b. starch (in the croutons) c. sugar (in the dressing) d. protein (in the bacon bits) e. oil (in the dressing)
a
Which of the following is a polymer? a. cellulose, a plant cell wall component b. testosterone, a steroid hormone c. fructose, a component of sucrose d. triacylglycerol, or fat e. glucose, an energy-rich molecule
a
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. two fatty acid molecules pointing in different directions b. two charged ends c. a charged end and a noncharged end d. both a saturated fatty acid and an unsaturated fatty acid e. three fatty acid molecules, all pointing in different directions
c
In a 1-4 glycosidic linkage, __________. a. the number 1 carbon in one nucleotide is bound to the number 4 carbon in another nucleotide b. there are four possible isomers of the structure c. the number 1 carbon in one monosaccharide is bound to the number 4 carbon in another monosaccharide d. one monosaccharide is bound to four others e. one glycerol molecule is bound to four fatty acids
c
Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them? a. Saturated triacylglycerols are liquid at room temperature. b. Saturated triacylglycerols are fats; unsaturated triacylglycerols are carbohydrates. c. Saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols. d. Saturated triacylglycerols have more double bonds than unsaturated triacylglycerols. e. All of the listed responses are correct.
c
The peptide bond is __________. a. a covalent bond joining nucleotides together to form a nucleic acid b. a hydrogen bond joining nucleotides together to form a nucleic acid c. a covalent bond joining amino acids together to form a polypeptide d. a covalent bond joining simple sugars together to form a polypeptide e. a hydrogen bond joining amino acids together to form a polypeptide
c
What do Alzheimer's, Parkinson's, and mad cow disease have in common? a. They all associated with plaque buildup in arteries (atherosclerosis). b. All are caused by the buildup of misfolded proteins in cells. c. All have been associated with the buildup of misfolded proteins in cells. d. They all cause the misfolding of nucleic acids. e. All are associated with the buildup of lipids in brain cells due to faulty lysosome activity.
c
Which is an organic molecule? a. H2O b. Ne c. CH4 d. O2 e. NaCl
c
Which of the following functional groups is present in all amino acids? a. -OH b. -COH c. -NH2 d. -SH e. -OPO3-2
c
Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)? a. Triacylglycerols may be saturated or unsaturated, but all phospholipids are saturated. b. Both molecules contain a phosphate group. c. Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar. d. Phospholipids are the primary storage form for fats in our bodies. e. In nature, phospholipids occur in fused rings (sterol form), whereas triacylglycerols maintain a straight-chain form.
c
Which of the following molecules is a monosaccharide? a. C22H49O10N5 b. C51H98O6 c. C6H12O6 d. C25H43O8 e. C45H84O8PN
c
What is ATP's importance in the cell? a. ATP contains a long hydrocarbon tail and is important in storing energy. b. ATP stores energy in carbonyl groups. When a carbonyl group is removed, energy is released to be used in cellular processes. c. ATP is an important component of cell membranes because it is nonpolar and hydrophobic. d. ATP stores the potential to react with water, thereby removing a phosphate group and releasing energy for cellular processes. e. ATP can add phosphate groups, thereby releasing energy that can be used in cellular processes.
d
What is the process by which monomers are linked together to form polymers? a. protein formation b. hydrolysis c. coiling d. dehydration or condensation reactions e. monomerization
d
When a protein is denatured, why does it lose its functionality? a. The protein's pH changes, causing it to lose its functionality. b. Denaturation destroys the primary structure of the protein, and the protein breaks down to monomers. c. Denaturation breaks the covalent bonds that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function. d. 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. e. Different amino acids are substituted into the sequence, so the protein's properties change.
d
Which is the term for compounds that do not mix with water? a. proteins b. hydrophilic c. phospholipids d. hydrophobic e. hydrogen-bonded
d
Which of the following carbohydrate molecules has the lowest molecular weight? a. lactose b. sucrose c. cellulose d. glucose e. chitin
d
Which of the following hydrocarbons has a double bond in its carbon skeleton? a. CH4 b. C3H8 c. C2H2 d. C2H4 e. C2H6
d
A polysaccharide that is used for storing energy in human muscle and liver cells is __________. a. glucose b. cellulose c. starch d. chitin e. glycogen
e
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 __________. a. cellulose b. linoleic acid c. glycogen d. collagen e. chitin
e
Carbohydrates can function in which of the following ways? a. structural support b. energy storage c. information storage d. enzymatic catalysis e. structural support and energy storage
e
Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein? a. a change in salt concentrations or pH b. heating the protein c. mixing in a chemical that removes hydrogen bonds d. denaturing the protein e. All of the listed responses are correct.
e
Ethanol, propanol, and methanol are three simple alcohols. They can be grouped together because they __________. a. are hydrophobic b. increase the acidity of solutions c. are soluble in water d. all contain a carbonyl group e. all share the same functional group: a hydroxyl
e
In a hydrolysis reaction, __________, and in this process water is __________. a. monomers are assembled to produce a polymer ... consumed b. a monomer is broken up into its constituent polymers ... produced c. monomers are assembled to produce a polymer ... produced d. a polymer is broken up into its constituent monomers ... produced e. a polymer is broken up into its constituent monomers ... consumed
e
Protein molecules are polymers (chains) of __________. a. purines and pyrimidines b. DNA molecules c. fatty acid molecules d. sucrose molecules e. amino acid molecules
e
To what does the term "polypeptide" refer? a. organic monomers covalently bonded b. amino acids linked by hydrolysis c. organic molecules linked by dehydration reactions d. carbohydrates with a hydrogen bond holding them together e. None of the listed responses is correct.
e
Which element is always associated with organic chemistry? a. oxygen b. nitrogen c. sulfur d. hydrogen e. carbon
e
Which of the following are properties of hydrocarbons? a. hydrophilic, containing numerous carboxyl groups, nonpolar b. hydrophobic, polar, charged c. hydrophobic, containing numerous amine groups, polar d. hydrophilic, good source of stored energy, consisting primarily of carbon and hydrogen e. hydrophobic, nonpolar, good source of stored energy
e
Which of the following functional groups increases the solubility of organic compounds in water? a. -NH2 b. -SH c. -COH d. -COOH e. All of the listed responses are correct.
e
Which of the following lists ranks these molecules in the correct order by size? a. water, sucrose, glucose, protein b. protein, water, glucose, sucrose c. glucose, water, sucrose, protein d. water, protein, sucrose, glucose e. protein, sucrose, glucose, water
e
Which of the following statements concerning unsaturated fats is true? a. They have fewer fatty acid molecules per fat molecule. b. They contain more hydrogen than do saturated fats having the same number of carbon atoms. c. They are more common in animals than in plants. d. They generally solidify at room temperature. e. They have double bonds in the carbon chains of their fatty acids.
e
Which of these is a thiol? a. -SH b. -COH c. -OH d. -NH2 e. None of the listed responses is correct.
e