Transcript Chapter 2 - FacultyWeb

How is it possible for two samples of hydrogen
to contain the same number of atoms, yet one
sample weighs more than the other?
1. One sample has more bonds.
2. One sample contains fewer electrons,
decreasing weight.
3. One sample contains more of
hydrogen’s heavier isotope(s).
4. One sample includes more protons,
increasing weight.
What is a mole and why is it useful to describe
elements in terms of moles?
1.
2.
3.
4.
6.023 x 1023/easier to keep track of relative
numbers of atoms in chemical samples
Is a quantity with a weight in grams equal to that
element’s atomic weight/because one mole of a
given element always contains the same number of
atoms as one mole of any other element
The total number of neutrons and protons in the
nucleus/nuclei sometimes emit subatomic particles
or radiation in measurable amounts
A and B are correct
Which kind of bond holds atoms in a water
molecule together?
What attracts water molecules to one
another?
1.
2.
3.
4.
Polar covalent bonds; hydrogen bonds
Ionic bonds; charge interactions
Hydrogen bonds; charge interactions
Covalent bonds; hydrogen bonds
Both oxygen and neon are gases at room
temperature.
Oxygen combines readily with other
elements, but neon does not. Why?
1. Neon has 8 electrons in its valence
shell, oxygen has only 6.
2. Neon cannot undergo bonding due to
its polarity.
3. Neon is exergonic.
4. Neon’s molecular weight is too low to
allow bonding.
The chemical shorthand used to describe chemical
compounds and reactions effectively is known as__.
1.
2.
3.
4.
Molecular formula
Chemical notation
Molecular weight
Mass number
Which of these notations describes dehydration
synthesis and why?
1.
2.
3.
4.
A-B-C-H + HO-DE  A-B-C-D-E + H2O; formation of
a complex molecule by removal of a water molecule
A-B-C-D-E + H2O  A-B-C-H + HO-D-E; a chemical
bond was broken through the addition of a water
molecule
AB  A + B; a molecule is broken into smaller
fragments
AB + CD  AD + CB; molecules are shuffled around
to produce a new product
In cells, glucose, a six-carbon molecule, is
converted into two three-carbon molecules by a
reaction that releases energy. How would you
classify this reaction?
1.
2.
3.
4.
Endergonic
Exergonic
Decomposition
B and C are correct
Why are enzymes needed in our cells?
1. To promote chemical reactions
2. For chemical reactions to proceed
under conditions compatible with life
3. To lower activation energy requirements
4. All of the above
Which property of water accounts for the cooling
effect of perspiration?
1.
2.
3.
4.
Solubility; solutes easily break up in water
Reactivity; hydrolysis causes salt crystals to form on
the skin
High heat capacity; water carries away heat when it
changes from a liquid to a gas
Lubrication; there is little friction between molecules
Wine has a pH of 3. This means that compared to
tomatoes that have a pH of 4….
1.
2.
3.
4.
Wine is closer to neutral pH than tomatoes.
The concentration of hydrogen ions is 10 times as
great in the wine as in a tomato and both are acidic.
The concentration of hydroxide ions is ten times as
great in the tomato as in the wine and both are basic.
The concentration of hydrogen ions is 100 times as
great in the wine as the tomato and both are acidic.
How does an antacid help decrease
stomach discomfort?
1. By reducing buffering capacity of the
stomach
2. By decreasing pH of stomach contents
3. By reacting a weak acid with a stronger one
4. By neutralizing acid using a weak base
Why does a solution of table salt conduct
electricity, but a sugar solution does not?
1.
2.
3.
4.
Electrical conductivity requires ions.
Sugar forms a colloid, salt forms a
suspension.
Electricity is absorbed by glucose
molecules.
Table salt is hydrophobic, sugar is
hydrophilic.
A food contains organic molecules with the elements
C, H, and O in a ratio of 1:2:1. What class of
compounds do these molecules belong to, and what
are their major functions in the body?
1. Lipids; energy source
2. Proteins; support and movement
3. Nucleic acids; determining inherited
characteristics
4. Carbohydrates; energy source
Which lipids would you find in human cell
membranes?
1.
2.
3.
4.
Cholesterol
Glycolipids
Phospholipids
All of the above
Why is cholesterol important in the
human body?
1.
2.
3.
4.
It transforms into prostaglandins, which are
released by damaged tissues causing pain.
Cells need it to maintain their membranes and
for growth and division.
It is an essential component of eicosanoids
It is the only site of storage for lipid soluble
vitamins.
What are structural and functional
similarities of phospholipids and
glycolipids?
1.
2.
3.
4.
Their hydrocarbon tails are hydrophobic.
They help form and maintain intracellular
structures.
They are primarily composed of phosphate and
glycogen, respectively.
A and B are correct
When two monosaccharides undergo a
dehydration synthesis reaction, which type of
molecule is formed?
1.
2.
3.
4.
Polypeptide
Disaccharide
Eicosanoid
Polysaccharide
Proteins are chains of which small
organic molecules?
1.
2.
3.
4.
Saccharides
Fatty acids
Amino acids
Nucleic acids
Which level of protein structure would be
affected by an agent that breaks hydrogen
bonds?
1. The primary level of protein structure
2. The secondary level of protein
structure
3. The tertiary level of protein structure
4. The protein structure would NOT be
affected by this agent
How does boiling a protein affect its
structural and functional properties?
1. Heat denatures the protein, causing
unfolding.
2. Heat causes the formation of
additional quaternary structure.
3. Heating rearranges the primary
structure of the protein.
4. Heat alters the radical groups on the
amino acids.
Why is it significant that keratin and collagen
are fibrous proteins and myoglobin and
hemoglobin are globular proteins?
1.
2.
3.
4.
Fibrous proteins are tough and insoluble in
water; they play structural roles
Fibrous proteins are only functional when
they are in solution
Globular proteins readily enter aqueous
solutions and function only when they are in
solution
A and C are correct
How might a change in an enzyme’s
active site affect its functions?
1. Increased activity due to a better fit
with the substrate
2. Decreased activity due to a poor
substrate fit
3. Inhibited activity due to no substrate
fit
4. All of the above
A large organic molecule composed of the
sugar ribose, nitrogenous bases, and
phosphate groups is which kind of nucleic
acid?
1.
2.
3.
4.
DNA
ATP
tRNA
RNA
All of the following except __ are functions of DNA.
1.
2.
3.
4.
Encoding information needed to build
proteins.
Controlling physical characteristics of our
bodies.
Manufacturing specific proteins.
Regulating all aspects of cellular metabolism.
What molecule is produced by the
phosphorylation of ADP?
1.
2.
3.
4.
ATPase
ATP
Adenosine Diphosphate
Uridine Triphosphate
Metabolic turnover refers to ____. The rate at which
this happens to glycogen in the liver is about ___.
1.
2.
3.
4.
The conversion of diglycerides to
triglycerides/once in a lifetime
The method by which a disaccharide
becomes a polysaccharide/every few minutes
Continuous removal and replacement of
organic molecules/every 1–2 days
The rate at which ATP is synthesized/every
1–2 weeks