BIOLOGY MCRAW HILL 02

  1. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    1. The property that distinguishes an atom of one element (carbon,for example) from an
    atom of another element (oxygen, for example) is

    the number of electrons.

    the number of protons.

    the number of neutrons.

    the combined number of protons and neutrons.
    b. the number of protons.
  2. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    2. If an atom has one valence electron—that is, a single electron in its outer energy level—it will most likely form

    one polar, covalent bond.

    two nonpolar, covalent bonds.

    two covalent bonds.

    an ionic bond.
    d. an ionic bond.
  3. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    3. An atom with a net positive charge must have more

    protons than neutrons.

    protons than electrons.

    electrons than neutrons.

    electrons than protons.
    protons than electrons.
  4. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    4. The isotopes carbon-12 and carbon-14 differ in

    the number of neutrons.

    the number of protons.

    the number of electrons.

    Both b and c are correct.
    the number of neutrons.
  5. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    5. Which of the following is NOT a property of the elements most commonly found in living organisms?

    The elements have a low atomic mass.

    The elements have an atomic number less than 21.

    The elements possess eight electrons in their outer energy level.

    The elements are lacking one or more electrons from their outer energy level.
    The elements possess eight electrons in their outer energy level.
  6. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    6. Ionic bonds arise from

    shared valence electrons.

    attractions between valence electrons.

    charge attractions between valence electrons.

    attractions between ions of opposite charge.
    attractions between ions of opposite charge.
  7. BIOLOGY MCRAW HILL 02
    UNDERSTAND
    7. A solution with a high concentration of hydrogen ions

    is called a base.

    has a high pH.

    is called an acid.

    Both b and c are correct.
    is called an acid.
  8. BIOLOGY MCRAW HILL 02
    APPLY
    1. Using the periodic table on page 22, which of the following atoms would you predict should form a positively charged ion (cation)?

    Fluorine (F)

    Potassium (K)

    Neon (Ne)

    Sulfur (S)
    c. Potassium (K)
  9. BIOLOGY MCRAW HILL 02
    APPLY
    2. Refer to the element pictured. How many covalent bonds could this atom form?

    Two

    Three

    Four

    None
    b. Three
  10. BIOLOGY MCRAW HILL 02
    APPLY
    3. A molecule with polar covalent bonds would

    be soluble in water.

    not be soluble in water.

    contain atoms with very similar electronegativity.

    Both b and c are correct.
    a. be soluble in water.
  11. BIOLOGY MCRAW HILL 02
    APPLY
    4. Hydrogen bonds are formed

    between any molecules that contain hydrogen.

    only between water molecules.

    when hydrogen is part of a polar bond.

    when two atoms of hydrogen share an electron.
    c. when hydrogen is part of a polar bond.
  12. BIOLOGY MCRAW HILL 02
    APPLY
    5. If you shake a bottle of oil and vinegar then let it sit, it will separate into two phases because

    the nonpolar oil is soluble in water.

    water can form hydrogen bonds with the oil.

    polar oil is not soluble in water.

    nonpolar oil is not soluble in water.
    d. nonpolar oil is not soluble in water.
  13. BIOLOGY MCRAW HILL 02
    APPLY
    6. The decay of radioactive isotopes involves changes to the nucleus of atoms.
    Explain how this differs from the changes in atoms that occur during chemical reactions.
    • Chemical reactions involve changes in the electronic configuration of atoms.
    • Radioactive decay involves the actual decay of the nucleus itself, producing another atom and emitting radiation.
  14. BIOLOGY MCRAW HILL 02
    SYNTHESIZE
    1. Elements that form ions are important for a range of biological processes. You have learned something about the cations
    sodium Na+, calcium Ca2+, and potassium K+
    Use your knowledge of the definition of a cation to identify other examples from the periodic table.
    • A cation is an element that tends to lose an electron from its outer energy level,
    • leaving behind a net positive charge due to the presence of the protons in the atomic nucleus.
    • Electrons are only lost from the outer energy level if that loss is energetically favorable;
    • that is, if it makes the atom more stable by virtue of obtaining a
    • filled outer energy level (the octet rule).
    • The atoms that fall into this category will be those in the first two columns.
    • Examples include lithium (Li), magnesium (Mg), and beryllium (Be).
  15. BIOLOGY MCRAW HILL 02
    SYNTHESIZE
    2. A popular theme in science fiction literature has been the idea of silicon-based life-forms in contrast to our carbon-based life.
    Evaluate the possibility of silicon-based life based on the chemical structure and potential for chemical bonding of a silicon atom.
    • 2. Silicon has an atomic number of 14. This means that there are four unpaired electrons in its outer energy level (comparable to carbon).
    • Based on this fact, you can conclude that silicon, like carbon, could form four covalent bonds.
    • Silicon also falls within the group of elements with atomic masses less than 21,
    • a property of the elements known to participate in the formation of biologically important molecules.
    • Interestingly, silicon is much more prevalent than carbon on Earth.
    • Although silicon dioxide is found in the cell walls of plants and single-celled organisms called
    • diatoms, silicon-based life has not been identified on this planet.
    • Given the abundance of silicon on Earth you can conclude that some other aspect of the chemistry of this atom makes it incompatible with the formation of
    • molecules that make up living organisms.
  16. BIOLOGY MCRAW HILL 02
    SYNTHESIZE
    3. Efforts by NASA to search for signs of life on Mars have focused on the search for evidence of
    liquid water rather than looking directly for biological organisms (living or fossilized).
    Use your knowledge of the influence of water on life on Earth to construct
    an argument justifying this approach.
    • 3. Water is considered to be a critical molecule for the evolution of life on
    • Earth. It is reasonable to assume that water on other planets could play a
    • similar role. The key properties of water that would support its role in the
    • evolution of life are:
    • ∙ The ability of water to act as a solvent. Molecules dissolved in water
    • could move and interact in ways that would allow for the formation
    • of larger, more complex molecules such as those found in living
    • organisms.
    • ∙ The high specific heat of water. Water can modulate and maintain its
    • temperature, thereby protecting the molecules or organisms within it
    • from temperature extremes—an important feature on other planets.
    • A-2 appendix A
    • ∙ The difference in density between ice and liquid water. The fact that
    • ice floats is a simple, but important feature of water environments
    • since it allows living organisms to remain in a liquid environment
    • protected under a surface of ice. This possibility is especially
    • intriguing, given recent evidence of ice-covered oceans on Europa,
    • a moon of the planet Jupiter.
    • knowledge of the influence of water on life on Earth to construct
    • an argument justifying this approach.
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ianquinto
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351864
Card Set
BIOLOGY MCRAW HILL 02
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BIOLOGY MCRAW HILL 02
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