Biology, Eighth Edition (Raven)

Chapter 2: The Nature of Molecules

Pre Test

Why might scientists be interested in the "atomic mass" of an atom? (p. 19)
A)It tells how it will behave in a chemical reaction.
B)It lets us know the valence of the atom if we know the atomic number.
C)If we know the atomic number, we can determine the number of neutrons.
D)We can use it to know if the atom is radioactive or not.
E)None of the above apply.
Whether an atom will be able to interact with other atoms can be determined by (p. 22)
A)Looking at the ratio of protons to neutrons in the nucleus.
B)How large the atomic mass is.
C)Whether it has an even or odd number of electrons.
D)Determining the stability of the electrons in their orbitals around the nucleus.
E)Identifying the atom as a metal or non-metal.
True or False: Because hydrogen bonds are weaker than ionic bonds (as shown in Table 2.4), it stands to reason that NaCl, which is organized through ionic bonds, can't dissociate through the action of hydrogen bonds, such as those formed between water molecules. (p. 23)
Which of the following provide(s) evidence for the importance of water for biology? (p. 25)
A)Liquid water is abundant in rain forests, where diverse life is abundant, and rare in deserts, which have much less life within them.
B)About 2/3 of most organisms' masses consist of water.
C)Many molecules can move around and interact easily in an aqueous environment.
D)All of the above are evidence for water's importance.
E)Only two of the above provide such evidence.
True or False: The reason water slides down a tipped piece of waxed paper is because the wax is dominated by nonpolar covalent bonds, which don't interact well with water's polar covalent bonds. (p. 27)
The reason pure water is considered "neutral" with respect to pH is because: (p. 29)
A)There are no H+ ions in solution.
B)There are no OH- ions in solution.
C)There is an equivalence between the concentrations of H+ and OH- within it.
D)There are exactly 10-7 moles of H+ in it.
E)It doesn't hurt sensitive tissues of the mouth or digestive tract when consumed.
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