Ch. 2 Practice Test
1) The chemical name for table salt is sodium chloride, or simply NaCl. What type of chemical is NaCl? A) Compound B) Element C) Molecule D) Ion
A
39) All lipids are ________. A) water-loving molecules B) hydrophilic C) hydrophobic D) hydrolytic
C
19) Why is one side of a single water molecule partially negative while the other side is partially positive? A) Electron pairs are unevenly shared between the oxygen atom and the two hydrogen atoms. B) Electron pairs are unevenly shared between the two hydrogen atoms. C) Oxygen donates its electrons to hydrogen. D) Hydrogen donates its electrons to oxygen.
A
20) Water is the least dense when it ________. A) freezes B) is just above freezing C) is at room temperature D) is just below boiling
A
24) What are the ecological consequences of acidification of rain and oceans? A) They damage the health of ecosystems. B) They do not have any consequences on ecosystems. C) They improve the health of ecosystems. D) Acid rain damages ecosystems, but ocean acidification improves the health of oceans.
A
25) Something with a pH of 5 would be ________. A) acidic B) basic C) neutral D) alkaline
A
29) Which of the following large organic molecules include table sugar? A) Carbohydrates B) Lipids C) Proteins D) Nucleic acids
A
30) The breaking of a large organic molecule into smaller, individual subunits involves multiple ________. A) hydrolysis reactions B) osmotic reactions C) dehydration synthesis reactions D) hydrosynthetic reactions
A
36) Based on the suffix, a molecule of "maltose" is most likely what type of macromolecule? A) Carbohydrate B) Lipid C) Protein D) Nucleic acid
A
41) What is the basic structure of most lipids? A) A glycerol head and up to three fatty acid tails B) A linear chain of individual monomers C) A branched chain of individual monomers D) A chain of fatty acid tails
A
44) Which would have the highest concentration of C—H bonds? A) Saturated fat B) Unsaturated fat C) Trans fat D) Cholesterol
A
45) What kind of bond joins amino acids together to form a protein? A) Peptide bond B) Hydrogen bond C) Polar bond D) Protein bond
A
5) What is the most common element in your body? A) Oxygen B) Water C) Carbon D) Sugar
A
7) The majority of the elements essential to life are found in what part of the periodic table? A) The top third B) The middle third C) The bottom third D) Evenly distributed throughout the periodic table
A
8) The typical carbon atom is described in the periodic table by the accompanying box. How many protons are in a typical oxygen atom? 8 O Oxygen 16.00 A) 8 B) 12 C) 18 D) Not enough information given
A
9) How many neutrons are in a typical oxygen atom? 8 O Oxygen 16.00 A) 8 B) 12 C) 18 D) Not enough information given
A
56) Penicillin is a competitive inhibitor produced by a fungus in order to kill invading bacteria. It does this by mimicking the substrate required by the bacterium to build and repair its cell wall. Describe how mimicking the substrate would result in the death of the bacterium.
Answer: As a competitive inhibitor, it must bind to the active site of the bacterial enzyme where the correct substrate typically binds. Binding to the active site blocks the correct substrate from binding and prevents the correct products from being formed. Without these products, the bacterium cannot repair its cell wall and consequently dies.
54) Why does sweating cool your skin on a hot, dry day but make you feel warmer on a hot, humid day?
Answer: Evaporating sweat cools the skin as the water and the heat it has absorbed move from the skin to the drier air. Sweat does not evaporate as well on a humid day, tending instead to build up on the skin, insulating the body rather than cooling it.
53) Which of the three gasses is the easiest to break apart: nitrogen gas (N2), oxygen gas (O2), or hydrogen gas (H2)? Which is the most difficult to break apart? What accounts for the differences?
Answer: Hydrogen gas, with a single covalent bond, is the easiest to break apart. Nitrogen gas, with a triple covalent bond, is the most difficult. Oxygen gas has a double covalent bond, which is intermediate in strength to the weaker single and stronger triple bonds.
52) An old home remedy for anemia was to drink from a jug of water into which was added a handful of iron nails. Why might this have been effective at treating certain forms of anemia?
Answer: Iron is an essential nutrient, and the water would have contained iron. If the anemia was the result of an iron deficiency, drinking from the nail water could have added the essential element to the diet.
55) The unique chemical qualities of individual amino acids do not directly determine the function of an enzyme. What, then, is the role of the individual amino acid's unique chemical qualities, and what directly determines the function of an enzyme?
Answer: The side groups of an amino acid are what give the amino acid its unique chemical qualities. These allow specific amino acids in the polypeptide chain to bind to other specific amino acids, which fold and twist the polypeptide into a three-dimensional shape. The shape may include an indentation called the "active site" that directly functions as the binding site for the substrate. Active sites often include cofactors and coenzymes that improve its functionality.
10) Which number represents the atomic weight of oxygen? 8 O Oxygen 16.00 A) 6 B) 16 C) 18 D) Not enough information given
B
11) In an atom, the number of neutrons determines most specifically the ________. A) element B) isotope C) ion state D) chemical properties
B
13) The 2+ in Cu2+ tells us that this atom ________. A) has two more neutrons than protons B) has two more protons than electrons C) has two more electrons than neutrons D) has two more electrons than protons
B
15) The bond in which bonded atoms share electrons is called a(n) ________. A) ionic bond B) covalent bond C) hydrogen bond D) polar bond
B
18) Individual water molecules are held to one another by relatively weak ________ bonds. A) covalent B) hydrogen C) ionic D) nonpolar
B
21) A needle can be made to "float" on the surface tension of water. What causes this surface tension to form? A) The adhesion of water molecules to the needle B) The cohesion of water molecules to each other C) The solubility of water D) The heat capacity of water
B
27) Organic compounds are distinguished by molecules that contain ________ bonded to other elements. A) nitrogen B) carbon C) oxygen D) hydrogen
B
34) What is another name for the polymers of carbohydrates? A) Triglycerides B) Polysaccharides C) Polypeptides D) Nucleotides
B
35) Which of the following is not made from long chains of glucose? A) Starch B) Monosaccharides C) Glycogen D) Cellulose
B
46) To a large extent, a protein's function is dependent upon its shape. What determines a protein's shape? A) The location of the active site B) The sequence of amino acids C) The number of amino acids D) The number of peptide bonds
B
49) Organic molecules that end in the suffix "-ase" often function as ________ molecules. A) structural B) enzymatic C) transport D) storage
B
50) Enzymes are a type of ________. A) carbohydrate B) protein C) lipid D) monomer
B
51) What will be accomplished by lowering the activation energy of a reaction? A) The reaction will proceed more slowly. B) The reaction will proceed more quickly. C) The reaction will stop completely. D) The reaction will reverse.
B
16) While the maximum number of electrons required to fill the outermost shell of an atom varies depending on the size of the atom, almost all of the smaller atoms (atomic numbers 2-20) are considered stable (nonreactive) when they contain ________ electron(s) in the outermost shell. A) 1 B) 2 C) 8 D) 16
C
2) Identify the reactants in the following chemical reaction: C10H8 + 12 O2 → 10 CO2 + 4 H2O A) C10H8 and 10 CO2 B) 12 O2 and 4 H2O C) C10H8 and 12 O2 D) 10 CO2 and 4 H2O
C
23) Select the most complete explanation of what the pH scale measures. A) The acidity of a solvent B) The alkalinity of a solvent C) The concentration of hydrogen ions in a solution D) The concentration of hydroxide ions in a solute
C
26) How do buffers minimize change in the pH of biological systems? A) By absorbing H+ ions when there is an excess B) By donating H+ ions when there is a shortage C) Both of these D) Neither of these
C
3) During a chemical reaction, atoms are ________. A) destroyed B) created C) rearranged D) destroyed and created
C
31) The building of a large organic molecule from small subunits involves multiple ________. A) hydrolysis reactions B) osmotic reactions C) dehydration synthesis reactions D) hydrosynthetic reactions
C
37) Which of the following represents a simple sugar (also called monosaccharides)? A) Lactose B) Cellulose C) Glucose D) Sucrose (table sugar)
C
4) What is a trace element? A) An element that is very rare B) An element that is evenly distributed on the planet C) An element that is required in miniscule amounts for life D) An element that is used to identify the location of other elements
C
40) Evaluate this statement: Cholesterol is a type of lipid, and thus all cholesterol lipids are bad for human health. A) True, because high levels of cholesterol lead to increased heart disease. B) True, because high levels of cholesterol lead to obesity. C) False, because some types cholesterol increase heart disease, but other types are necessary, especially in the plasma membrane. D) False, because cholesterol levels are not related to human health.
C
42) Which of the following dietary fats is considered to be the least healthy? A) Saturated fat B) Unsaturated fat C) Trans fat D) Cholesterol
C
43) Oil hydrogenation can produce a product, such as vegetable shortening or margarine, that is spreadable at room temperature because of an unusual bond that does not occur naturally. What is the name of this category of lipid? A) Saturated fat B) Healthy fat C) Trans fat D) Cholesterol
C
6) Which is not one of the four atoms that make up the bulk of living organisms? A) Oxygen B) Nitrogen C) Calcium D) Carbon
C
12) If the number of protons in an atom does not match the number of electrons, the atom is called an ________. A) element B) isotope C) isomer D) ion
D
14) Identify the part of the atom that most determines the chemical properties of the atom. A) The number of shells B) The number of protons C) The number of neutrons D) The number of electrons
D
17) What is the maximum number of single covalent bonds a carbon atom can form with other elements? A) 1 B) 2 C) 3 D) 4
D
22) Water "beads up" on synthetic fabric such as polyester but binds to cotton. What is the most likely explanation for this? A) Polyester is not a naturally occurring substance, whereas cotton is a naturally occurring substance. B) Polyester is more flexible than cotton. C) Polyester fibers are thinner than cotton fibers. D) Polyester is nonpolar, whereas cotton is polar.
D
28) What are the four classes of large organic molecules important to life on Earth? A) Carbohydrates, lipids, proteins, and enzymes B) Carbohydrates, lipids, proteins, and sugars C) Carbohydrates, proteins, nucleic acids, and sugars D) Carbohydrates, proteins, lipids, and nucleic acids
D
32) What are the monomers of proteins? A) Glucose B) Nucleic acids C) Fatty acids D) Amino acids
D
33) What is the sum total of all the chemical reactions that take place in your body called? A) Catabolism B) Anabolism C) Embolism D) Metabolism
D
38) Which of the following is a polysaccharide? A) Glucose B) Cellulose C) Fructose D) Sucrose
D
47) Proteins are diverse molecules that perform a wide variety of functions. Which of the following is not a typical function of proteins? A) Transport B) Catalyze reactions via enzymes C) Movement D) Energy storage
D
48) What might happen if a protein has a change in one amino acid? A) The amino acid chain folds incorrectly. B) The protein can no longer function properly. C) The protein has a new shape. D) All of these happen.
D