BIOL 212 EXAM 1 (CH 2 - 8) QUESTIONS AND
ANSWERS
What percent of the 92 elements are essential to life? - Answers - 20-25%
Trace element - Answers - Elements that only required in minute quantities.
What element is required by all forms of life? - Answers - Iron
What makes up the atomic nucleus? - Answers - Protons & Neutrons
Protons and __________ have almost the same mass. - Answers - Neutrons
How do radioactive isotopes decay? - Answers - Radioactive isotopes decay
spontaneously, giving off particles and energy.
How are radioactive tracers used in medicine? - Answers - Track atoms through
metabolism. Energy being emitted is captured by sophisticated imaging instruments.
What is used in radiometric dating? - Answers - Half-lives of isotopes
When do electrons have more potential energy? - Answers - Electrons have more
potential energy the farther they are from the nucleus.
What determines the chemical behavior of an atom? - Answers - The distribution of
electrons in electron shells.
Non-Polar Covalent Bond - Answers - Atoms have similar or identical electronegativities
and share the electrons equally.
Polar Covalent Bond - Answers - One atom is more electronegative than the other, and
the atoms do not share the electrons equally. The more electronegative atom pulls the
shared electrons closer to itself.
Ionic Bond - Answers - An ionic bond is an attraction between an anion (-) and a cation
(+).
What are the strongest chemical bonds? - Answers - Covalent Bonds & Ionic Bonds
Why are weak chemical bonds important in biology? - Answers - They are reversible,
which can be a functional advantage.
What are the three types of weak chemical bonds? - Answers - Hydrogen Bonds, van
der Waals interactions, and bonds between ionic compounds dissolved in water
,Hydrogen Bond - Answers - Forms when a hydrogen atom, present in a polar covalent
bond, is attracted to a highly electronegative atom (N, O, or F).
Van der Waals Interactions - Answers - Interactions are attractions between molecules
that are close together.
What is an orbital? - Answers - The 3D space where an electron is found 90% of the
time.
Why is molecular shape important in biology? - Answers - It determines how biological
molecules interact.
What are the four emergent properties of water? - Answers - 1. Cohesion & Adhesion
2. Moderation of Temperature
3. Expansion Upon Freezing
4. Versatility as a Solvent
Cohesion - Answers - Hydrogen bonding between two water molecules.
Adhesion - Answers - An attraction between a water molecule and a molecule of a
different substance.
Surface Tension - Answers - A measure of how hard it is to break the surface of a liquid.
Why does water have an ususally high surface tension? - Answers - Because of the
hydrogen bonding between the molecules at the air-water interface.
Water ___ heat from warmer air and ___ stored heat to cooler air. - Answers - Water
absorbs heat from warmer air and releases stored heat to cooler air.
Heat - Answers - Thermal energy transferred from one body of matter to another.
Kinetic Energy - Answers - The energy of motion
Thermal Energy - Answers - Kinetic energy associated with random motion.
Temperature - Answers - The average kinetic energy of the molecules in a body of
matter regardless of volume.
What is the difference between temperature and thermal energy? - Answers - Thermal
energy is dependent on volume (total kinetic energy).
Heat always transfers from ______ to ______. - Answers - Heat always transfers from
warmer to colder.
, Specific Heat - Answers - The amount of heat that must be absorbed or lost for 1 g of
material to change by 1*C.
Why can water resist changes in temperature? - Answers - Because of its high specific
heat (1 cal/g/*C).
What causes water's high specific heat? - Answers - Hydrogen Bonding
Evaporation - Answers - Transformation from liquid to gas.
Heat of Vaporization - Answers - The heat a liquid must absorb for 1 g to be converted
to gas.
Evaporative Cooling - Answers - Water molecules with the greatest kinetic energy leave
as gas, making the remaining liquid water cooler.
Solution - Answers - A liquid that is a completely homogeneous mixture of substances.
Solvent - Answers - The dissolving agent of a solution.
Solute - Answers - The substance that is dissolved.
Aqueous Solution - Answers - A solution in which water is the solvent.
What happens when an ionic compound is dissolved in water? - Answers - Each ion is
surrounded by a hydration shell.
Hydrophilic Substance - Answers - A substance that has an affinity for water.
Hydrophobic Substance - Answers - A substance that does not have an affinity for
water.
Concentrations of H+ and OH- are ______ in pure water. - Answers - Equal
Hydrogen in hydrogen bonds can ____ from _____ to the _____. - Answers - Hydrogen
in hydrogen bonds can shift from one H2O to the other.
Acid - Answers - A substance that increases the H+ concentration of a solution.
Base - Answers - Any substance that reduces the H+ concentration of a solution.
In any aqueous solution at 25*C, the product of H+ and OH- is constant and can be
written... - Answers - [H+][OH-] = 10^-14
The pH of a solution is defined by the negative logarithm of H+ concentration, written
as... - Answers - pH = -log[H+]
ANSWERS
What percent of the 92 elements are essential to life? - Answers - 20-25%
Trace element - Answers - Elements that only required in minute quantities.
What element is required by all forms of life? - Answers - Iron
What makes up the atomic nucleus? - Answers - Protons & Neutrons
Protons and __________ have almost the same mass. - Answers - Neutrons
How do radioactive isotopes decay? - Answers - Radioactive isotopes decay
spontaneously, giving off particles and energy.
How are radioactive tracers used in medicine? - Answers - Track atoms through
metabolism. Energy being emitted is captured by sophisticated imaging instruments.
What is used in radiometric dating? - Answers - Half-lives of isotopes
When do electrons have more potential energy? - Answers - Electrons have more
potential energy the farther they are from the nucleus.
What determines the chemical behavior of an atom? - Answers - The distribution of
electrons in electron shells.
Non-Polar Covalent Bond - Answers - Atoms have similar or identical electronegativities
and share the electrons equally.
Polar Covalent Bond - Answers - One atom is more electronegative than the other, and
the atoms do not share the electrons equally. The more electronegative atom pulls the
shared electrons closer to itself.
Ionic Bond - Answers - An ionic bond is an attraction between an anion (-) and a cation
(+).
What are the strongest chemical bonds? - Answers - Covalent Bonds & Ionic Bonds
Why are weak chemical bonds important in biology? - Answers - They are reversible,
which can be a functional advantage.
What are the three types of weak chemical bonds? - Answers - Hydrogen Bonds, van
der Waals interactions, and bonds between ionic compounds dissolved in water
,Hydrogen Bond - Answers - Forms when a hydrogen atom, present in a polar covalent
bond, is attracted to a highly electronegative atom (N, O, or F).
Van der Waals Interactions - Answers - Interactions are attractions between molecules
that are close together.
What is an orbital? - Answers - The 3D space where an electron is found 90% of the
time.
Why is molecular shape important in biology? - Answers - It determines how biological
molecules interact.
What are the four emergent properties of water? - Answers - 1. Cohesion & Adhesion
2. Moderation of Temperature
3. Expansion Upon Freezing
4. Versatility as a Solvent
Cohesion - Answers - Hydrogen bonding between two water molecules.
Adhesion - Answers - An attraction between a water molecule and a molecule of a
different substance.
Surface Tension - Answers - A measure of how hard it is to break the surface of a liquid.
Why does water have an ususally high surface tension? - Answers - Because of the
hydrogen bonding between the molecules at the air-water interface.
Water ___ heat from warmer air and ___ stored heat to cooler air. - Answers - Water
absorbs heat from warmer air and releases stored heat to cooler air.
Heat - Answers - Thermal energy transferred from one body of matter to another.
Kinetic Energy - Answers - The energy of motion
Thermal Energy - Answers - Kinetic energy associated with random motion.
Temperature - Answers - The average kinetic energy of the molecules in a body of
matter regardless of volume.
What is the difference between temperature and thermal energy? - Answers - Thermal
energy is dependent on volume (total kinetic energy).
Heat always transfers from ______ to ______. - Answers - Heat always transfers from
warmer to colder.
, Specific Heat - Answers - The amount of heat that must be absorbed or lost for 1 g of
material to change by 1*C.
Why can water resist changes in temperature? - Answers - Because of its high specific
heat (1 cal/g/*C).
What causes water's high specific heat? - Answers - Hydrogen Bonding
Evaporation - Answers - Transformation from liquid to gas.
Heat of Vaporization - Answers - The heat a liquid must absorb for 1 g to be converted
to gas.
Evaporative Cooling - Answers - Water molecules with the greatest kinetic energy leave
as gas, making the remaining liquid water cooler.
Solution - Answers - A liquid that is a completely homogeneous mixture of substances.
Solvent - Answers - The dissolving agent of a solution.
Solute - Answers - The substance that is dissolved.
Aqueous Solution - Answers - A solution in which water is the solvent.
What happens when an ionic compound is dissolved in water? - Answers - Each ion is
surrounded by a hydration shell.
Hydrophilic Substance - Answers - A substance that has an affinity for water.
Hydrophobic Substance - Answers - A substance that does not have an affinity for
water.
Concentrations of H+ and OH- are ______ in pure water. - Answers - Equal
Hydrogen in hydrogen bonds can ____ from _____ to the _____. - Answers - Hydrogen
in hydrogen bonds can shift from one H2O to the other.
Acid - Answers - A substance that increases the H+ concentration of a solution.
Base - Answers - Any substance that reduces the H+ concentration of a solution.
In any aqueous solution at 25*C, the product of H+ and OH- is constant and can be
written... - Answers - [H+][OH-] = 10^-14
The pH of a solution is defined by the negative logarithm of H+ concentration, written
as... - Answers - pH = -log[H+]
