In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
polar covalent bonds.
The partial negative charge in a molecule of water occurs because
the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus
Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S
will not form hydrogen bonds with each other
Which of the following effects is produced by the high surface tension of water?
A water strider can walk across the surface of a small pond.
Liquid water's high specific heat is mainly a consequence of the
absorption and release of heat when hydrogen bonds break and form
Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?
the release of heat by the formation of hydrogen bonds
Why does ice float in liquid water?
Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water
One mole (mol) of glucose (molecular mass = 180 daltons) is
both 180 grams of glucose and 6.02 × 10^23 molecules of glucose
How many molecules of glycerol (; molecular mass = 92) would be present in 1 L of a 1 M glycerol solution?
6.02 × 10^23
Which of the following statements best describes the carbon atoms present in a seed-eating bird?
They were incorporated into organic molecules by plants, they were processed into sugars through photosynthesis, and they are ultimately derived from carbon dioxide
Why are hydrocarbons insoluble in water?
The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
Which of the following statements correctly describes cis-trans isomers?
They have variations in arrangement around a double bond.
Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that
are mirror images of one another.
What determines whether a carbon atom's covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration?
the presence or absence of double bonds between the carbon atom and other atoms
Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms, but with one or more double bonds, will
be more constrained in structure.
A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound?
It should dissolve in water.
Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what way(s) do these molecules differ from each other?
Testosterone and estradiol have different functional groups attached to the same carbon skeleton.
Which of the following statements about the formation of polypeptides from amino acids is true?
A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.
In animal metabolism, most of the monomers released by digestion of food macromolecules are metabolized to provide energy. Only a small portion of these monomers are used for synthesis of new macromolecules. The net result is that
water is consumed by animal metabolism.
What is the chemical reaction mechanism by which cells make polymers from monomers?
How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?
Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?
Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.
The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down?
Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
as a disaccharide
Which of the following is true of cellulose?
It is a major structural component of plant cell walls.
Humans can digest starch but not cellulose because
humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose.
Which of the following statements about monosaccharide structure is true?
Monosaccharides can be classified according to the spatial arrangement of their atoms.
Which of the following complex carbohydrates is listed with its correct function?
Cellulose: structural component of plant cell walls
Which of the following statements is true for the class of biological molecules known as lipids?
They are insoluble in water.
The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. What is the result of adding hydrogens to vegetable oil?
The hydrogenated vegetable oil stays solid at room temperature
Which of the following is true regarding saturated fatty acids?
They are the principal molecules in lard and butter.
The bonding of two amino acid molecules to form a larger molecule requires
the release of a water molecule.
A function of cholesterol that does not harm health is its role _____.
as a component of animal cell membranes
There are 20 different amino acids. What makes one amino acid different from another?
different side chains (R groups) attached to an α carbon
What aspects of protein structure are stabilized or assisted by hydrogen bonds?
secondary, tertiary, and quaternary structures, but not primary structure
Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins?
The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by
Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides?
Alzheimer's and Parkinson's only
Changing a single amino acid in a protein consisting of 325 amino acids would
always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and affect its biological activity.
Normal hemoglobin is a tetramer, consisting of two molecules of β hemoglobin and two molecules of α hemoglobin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits
altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.