Campbell Biology: Concepts and Connections, 8e (Reece et al.)
Chapter 2 The Chemical Basis of Life
2.1 Multiple-Choice Questions
1) The four most common elements in living organisms are
A) C, H, O, Fe.
B) C, H, O, Na.
C) C, H, O, N.
D) C, N, O, Na.
2) Which of the following is a trace element in the human body?
A) nitrogen
B) zinc
C) oxygen
D) hydrogen
3) Which of the following statements regarding matter is false?
A) All life is composed of matter.
B) All matter has mass.
C) All matter is composed of elements.
D) All matter exists in the form of compounds.
4) Which of the following statements best describes a compound?
A) A compound is a pure element.
B) A compound contains two or more different elements in a fixed ratio.
C) A compound is exemplified by sodium.
D) A compound is a solution.
5) In the equation 2 H2 + O2 → 2 H2O,
A) H2, O2, and H2O are all compounds.
B) H2, O2, and H2O are all elements.
C) only H2O is a compound.
D) only H2 and O2 are compounds.
6) Which of the following trace elements needed by humans is commonly added to table salt?
A) iodine
B) iron
C) magnesium
D) fluoride
7) In some areas, fluoride is added during the municipal water treatment process in order to help
A) prevent goiter.
B) prevent the growth of bacteria.
C) prevent the development of mental retardation.
D) reduce tooth decay.
8) Which of the following particles are found in the nucleus of an atom?
A) protons and neutrons
B) protons and electrons
C) only protons
D) only electrons
9) Electrons move about the nucleus of an atom in the same way that
A) insects fly around a bright lamp at night.
B) cars are parked along the sides of a street.
C) boats cross a lake.
D) birds migrate to a new winter home.
10) What is the atomic mass of an atom that has 6 protons, 6 neutrons, and 6 electrons?
A) 6
B) 8
C) 12
D) 18
11) An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How
many electrons does boron have?
A) 11
B) 15
C) 5
D) 2
12) Which of the following is another term used for atomic mass?
A) darwin
B) mendel
C) dalton
D) calvin
13) The sodium atom contains 11 electrons, 11 protons, and 12 neutrons. What is the mass
number of sodium?
A) 11
B) 22
C) 23
D) 34
14) Which of the following best describes the atomic number of an atom?
A) the number of protons in the atom
B) the number of electrons in the atom
C) the number of neutrons in the atom
D) the number of protons, electrons, and neutrons in the atom
15) Typically, nitrogen atoms are composed of electrons, protons, and neutrons. An isotope of
nitrogen could
A) be positively charged.
B) be negatively charged.
C) have more protons than the usual nitrogen atom.
D) have more neutrons than the usual nitrogen atom.
16) A radioactive isotope is an isotope that
A) is stable.
B) decays.
C) has more protons than the common variant of the element.
D) has the same atomic mass but a different atomic number than the common variant of the
element.
17) If you found a fossilized dinosaur bone, what could be done to determine the age of the
fossil?
A) Extract and sequence DNA from the bone.
B) Look at pieces of the bone under a microscope.
C) Analyze the isotopes of carbon in the fossil.
D) Compare the appearance of the bone to other fossilized bones.
18) Which of the following statements about radioactive isotopes is true?
A) The nuclei of radioactive isotopes are unusually stable, but the atoms tend to lose electrons.
B) When given a choice between radioactive and nonradioactive isotopes of the same atom,
living cells are more likely to incorporate the radioactive isotopes into their structures.
C) The energy emitted by radioactive isotopes can break chemical bonds and cause molecular
damage in cells.
D) Radioactive elements are natural and therefore not harmful.
19) Radioactive isotopes
A) are frequently added to foods as nutritional supplements.
B) can be used in conjunction with PET scans to diagnose diseases.
C) do not occur naturally.
D) are never incorporated into organic compounds.
20) When full, the innermost electron shell of argon contains ________ electrons, and the
outermost shell contains ________ electrons.
A) 2; 2
B) 2; 8
C) 4; 8
D) 8; 8
21) What happens to an atom if the electrons in the outer shell are altered?
A) The atom becomes radioactive.
B) The atom disintegrates.
C) The properties of the atom change.
D) The atom’s characteristics change, and it becomes a different element.
22) A(n) ________ forms when two atoms share electrons.
A) ion
B) covalent bond
C) ionic bond
D) hydrogen bond
23) A hydrogen atom has one electron. How many covalent bonds can hydrogen form?
A) one
B) two
C) four
D) none
24) Table salt is formed when
A) chlorine gives an electron to sodium.
B) a hydrogen bond forms between sodium and chlorine.
C) sodium and chlorine share electrons to form a bond.
D) sodium donates its single outer electron to chlorine.
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25) The body uses atoms in different ways to accomplish different tasks. For example, one
portion of the body’s calcium supply strengthens bones, whereas another portion combines with
proteins to stimulate blood clotting after tissue injury. Which of the following statements
provides the most logical chemical explanation of calcium’s ability to perform such different
functions?
A) The bone contains calcium salts, which are less reactive than the calcium ions found in the
blood.
B) The calcium in blood is a more reactive form of the atom and therefore has fewer protons than
the calcium in bone.
C) There are many different isotopes of calcium, and the most reactive isotope is found in the
bone.
D) The calcium in blood has a lighter atomic mass than the calcium in bone and is in a more
reactive form.
26) Medicines are often administered in pill form. In many cases, the active ingredient of the pill
(the drug) is joined to another substance by ________. This forms a(n) ________, which is stable
in the dry environment of a pill bottle but dissociates under the wet conditions of the digestive
system to release the drug to the body.
A) ionic bonds; salt
B) hydrogen bonds; base
C) ionic bonds; acid
D) covalent bonds; salt
27) What is the fundamental difference between covalent and ionic bonding?
A) In a covalent bond, the partners share a pair of electrons; in an ionic bond, one partner accepts
electrons from the other.
B) In covalent bonding, both partners end up with filled outer electron shells; in ionic bonding,
one partner does and the other does not.
C) Covalent bonding involves only the outermost electron shell; ionic bonding also involves the
next electron shell inside the outermost shell.
D) Covalent bonds form between atoms of the same element; ionic bonds form between atoms of
different elements.
28) Which of the following statements regarding the oxygen atom of a water molecule is true?
A) Oxygen is more positively charged than the hydrogen atoms.
B) Oxygen attracts electrons less strongly than the hydrogen atoms.
C) Oxygen is more electronegative than the hydrogen atoms.
D) Oxygen is attracted to the negatively charged atoms of other molecules.
29) In a water molecule, hydrogen and oxygen are held together by a ________ bond.
A) double covalent
B) nonpolar covalent
C) hydrogen
D) polar covalent
30) A single water molecule (H—O—H) is held together by
A) a single covalent bond.
B) a double covalent bond.
C) two polar covalent bonds.
D) hydrogen bonds.
31) The hydrogen atoms of a water molecule are bonded to the oxygen atom by ________ bonds,
whereas neighboring water molecules are held together by ________ bonds.
A) hydrogen; polar covalent
B) polar covalent; hydrogen
C) ionic; covalent
D) polar covalent; ionic
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32) ________ are weak bonds that are not strong enough to hold atoms together to form
molecules but are strong enough to form bonds within and around large molecules.
A) Ionic bonds
B) Covalent bonds
C) Polar covalent bonds
D) Hydrogen bonds
33) Water molecules stick to other water molecules because
A) water molecules are neutral, and neutral molecules are attracted to each other.
B) hydrogen bonds form between the hydrogen atoms of one water molecule and the oxygen
atoms of other water molecules.
C) covalent bonds form between the hydrogen atoms of one water molecule and the oxygen
atoms of other water molecules.
D) the oxygen atoms of adjacent water molecules are attracted to one another.
34) Which of the following statements regarding chemical reactions is false?
A) Chemical reactions involve the making and breaking of chemical bonds.
B) Some chemical reactions create electrons; others destroy them.
C) The reactants contain the same number of atoms as the products.
D) Although the atoms of a reaction’s reactants and products are identical to each other, their
molecular formulas differ.
35) In the equation 2 H2 + O2 → 2 H2O, the H2 molecules are ________ and the H2O
molecules are ________.
A) reactants; products
B) products; reactants
C) created; destroyed
D) used; stored
36) In plants, the process of photosynthesis produces glucose (C6H12O6) and oxygen from
carbon dioxide and water. Which of the following statements about photosynthesis is true?
A) All of the carbon atoms from the carbon dioxide atoms are found in glucose.
B) More atoms are present at the beginning than at the end.
C) More carbon dioxide is released from the plant than is absorbed.
D) Water is synthesized by the plant from H2 and O2.
37) The tendency of water molecules to stick together is referred to as
A) adhesion.
B) polarity.
C) cohesion.
D) transpiration.
38) Water’s surface tension and heat storage capacity are accounted for by its
A) orbitals.
B) hydrogen bonds.
C) mass.
D) size.
39) The temperature of evaporation is much higher for water than for alcohol. Without knowing
more about the chemistry of alcohol, which of the following is the most logical chemical
explanation for this phenomenon?
A) Ionic bonds form between alcohol molecules. These are the weakest type of bond and are
easier to break than the hydrogen bonds between water molecules.
B) Alcohol has a higher surface tension than water. This means that alcohol molecules can easily
break away from other alcohol molecules and evaporate at a lower temperature.
C) Alcohol molecules are more cohesive than water molecules. This means that as alcohol
molecules evaporate, they pull other alcohol molecules into the air along with them.
D) Fewer hydrogen bonds form between alcohol molecules. As a result, less heat is needed for
alcohol molecules to break away from solution and enter the air.
40) As ice melts,
A) hydrogen bonds are broken.
B) water molecules become less tightly packed.
C) the water becomes less dense.
D) heat is released.
41) Which of the following statements about water is false?
A) Ice is more dense than liquid water.
B) Water naturally exists in all three physical states on Earth.
C) Floating ice on a pond insulates the liquid water below, slowing its rate of freezing.
D) If ice sank, the oceans would eventually freeze solid.
42) You’ve made a hot drink by dissolving a teaspoon of instant coffee and a teaspoon of sugar
in a cup of hot water. Which of the following statements is true?
A) You’ve just prepared an aqueous solution.
B) The water is the solute portion of the drink.
C) The instant coffee and sugar are solvents.
D) The instant coffee and sugar dissolve because they have no charged regions to repel the
partial positive and partial negative regions of the water molecules.
43) Which of the following is dependent on the ability of water molecules to form hydrogen
bonds with other molecules besides water?
A) the evaporative cooling of skin surfaces
B) the milder temperatures of coastal regions compared to inland areas
C) the ability of certain insects to walk on the surface of water
D) the universality of water as a solvent