Biology, Eighth Edition (Raven)

Chapter 2: The Nature of Molecules

Post Test

What happens when an electron moves from a higher energy level orbital (for example "M") to a lower energy one (say, "L")? (p. 21)
A)Energy is released.
B)Energy is absorbed.
C)Another neutron is created in the nucleus.
D)The atom becomes a different element.
E)Either "A" or "B" occurs, depending on the type of atom.
Which of the following is (are) a criterion upon which the periodic table is organized? (p. 21)
A)Number of protons.
B)Number of valence electrons.
C)Number of neutrons.
D)All of the above.
E)Only two of the above.
Why do covalent bonds typically hold atoms together more tightly than ionic bonds under biological conditions? (p. 24)
A)Ionic bonds can only occur between metals and non-metals, and therefore aren't usually present in biological situations.
B)Ionic bonds are toxic to proteins.
C)You can have double covalent bonds, but not double ionic bonds, so covalent bonds provide more variety consistent with the structural demands required in biological systems.
D)Biological conditions are often aqueous, and the water would cause ionic bonds to dissociate.
E)Ions only form under extreme conditions not compatible with the cell's environment.
Within a capillary tube, which forces cause the water to rise up within the tube's lumen (internal open space)? (p. 27)
A)Ionic bonding of individual water molecules provides energy for the water to move upwards.
B)The water molecules have a high specific heat capacity, so they absorb energy from the surroundings to move upwards.
C)Adhesion and gravity combine to force the water to move upwards.
D)Cohesion on the surface of the top of the water column pulls it upwards.
E)Adhesion to the walls of the tube cause the top surface to advance upward, and cohesion between the individual water molecules pull along the molecules beneath.
Water behaves like most other molecules in all ways except that (p. 28)
A)It interacts strongly with other water molecules.
B)It can exist as a solid, liquid, or gas.
C)Its temperature correlates with how rapidly its individual molecules are moving.
D)As it freezes, its density decreases.
E)Its temperature increases when heat is applied, then holds the higher temperature after the heat source is no longer present.
A buffer exerts its effects because: (p. 30)
A)It absorbs or releases H+ ions reversibly to resist a pH change within its buffering range.
B)It releases H+ when the pH drops.
C)It absorbs H+ when the pH rises.
D)All of the above explain buffering effects.
E)None of the above explains buffering effects.
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