Biology 12:
Biological Molecules and Water Review
Review Questions:
1. Why is water considered to be a polar molecule? What type of bond occurs between
water molecules?
2. Explain why ice floats on liquid water. What value does this have?
3. Distinguish between an acid and a base. Give an example of each.
4. Solutions with a pH of less than 7 are termed
whereas those solutions with
a pH greater than 7 are termed
. As the pH scale decreases, there is a
- fold increase in hydrogen ion concentration for every pH unit.
5. Define a buffer. What is the function of a buffer solution?
6. Distinguish between dehydration synthesis and hydrolysis.
7. What is the function(s) of proteins?
8. What are the 2 functional groups in amino acids? How do amino acids differ?
9. What type of bond joins 2 amino acids together? Describe which parts are joined.
10. Compare a dipeptide, a polypeptide, and a protein molecule.
11. Distinguish between the primary, secondary, tertiary and quaternary structure of a
protein.
12. What is the difference among monosaccharides, disaccharides, and
polysaccharides.
13. List 2 sugars each for monosaccharides, disaccharides, and polysaccharides.
14. What is the role of starch, glycogen, and cellulose in cells?
15. Are lipids soluble in water? Distinguish between fats and oils as types of lipid. How
are they formed?
16. Explain the difference between a saturated and an unsaturated fatty acid.
17. What is a soap? Why does soap cause oil to disperse in water? What is meant by
emulsification?
18. How is the phospholipid bilayer arranged in the cell membrane?
19. What is unique about the structure of steroids? List several examples of steroids.
20. List 2 types of nucleic acids. Human genes are composed of which type?
21. Give the components of every nucleotide. What distinguishes DNA from RNA?
Objectives Test
Completion and Short Answer Questions
1. Define an acid, base, and salt.
a. acid
solution that contributes H+ions; pH less than 7
b. base
solution that donates 0H—ions; pH greater than 7
c. salt
a compound formed by the neutralization of an acid; the hydrogen is
often replaced by a metal.
1
Biology 12:
Biological Molecules and Water Review
2. If the hydrogen ion concentration [H+] of 10-7 has a pH of 7, what is the pH of the
following concentrations?
[H+]
-4
a. 10
b. 10_6
c. 10_10
d. 10_ 14
pH
4
6
10
14
Acid or Base?
acid
Acid
Base
Base
3. Which of the numbers above represents the largest [H+] ? 10-4
4. What is the importance of pH to biological systems?
pH is important for the
optimal conditions for enzymes. Acidic conditions are also able to activate some
enzymes, or deactivate them, where desired.
5. How do living things prevent rapid and drastic changes in pH? Living things
produce buffers (often NaHCO3) that help control rapid changes. We also have
excretory systems that help to regulate the [H+] in our blood
6. What are the 4 classes of biological (organic) molecules?
Carbohydrates, lipids, proteins and nucleic acids
7. of the classes in answer 17, which:
a. are MOST concerned with energy?
Carbohydrates, lipids, and nucleic acids
b. one forms most enzymes?
proteins
c. one makes up genes?
Nucleic acids
d. are long-term energy storage?
Lipids
8. Write the word saturated and the word unsaturated beneath the appropriate structure.
2
Biology 12:
Biological Molecules and Water Review
3
9. Label the diagram with the following terms: synthesis, hydrolysis, macromolecule,
monomers.
10. Which 5 molecules in question 9 would be associated with part (a) in this diagram?
Fatty acids + glycerol, amino acids, nucleotides, monosaccharides
11. Which 4 molecules would be associated with part (c) in this diagram?
Lipids, Proteins, Nucleic acids, Carbohydrates
12. When many glucose molecules are joined, the macromolecule starch or glycogen
results. When many amino acids are joined, the macromolecule
results. When glycerol and fatty acids are joined,
Lipids
protein
result. When
nucleotides join, the macromolecule Nucleic Acids (DNA or RNA or ATP) results.
13. In this hydrolytic reaction, write in the name of the molecule required on the left and
the atoms required on the right.
Biology 12:
Biological Molecules and Water Review
14. The diagram below is an amino acid. Write the word amino and the work acid on the
appropriate line.
15. The diagram below is a dipeptide. Circle the peptide bond.
16. Levels of protein structure.
The linear sequence of amino acids in a protein constitutes the
primary
structure. The type of bond that links the amino acids is a(n)
peptide
bond. The functional groups on a amino acid that will join to form this bond are termed
amino and carboxylic acid . The group that represents the side chains on the protein
molecule is the
remainder group.
17. The diagram below represents the structure of a nucleotide. Write the words, base,
sugar, and phosphoic acid beside the appropriate structures.
4
Biology 12:
Biological Molecules and Water Review
18.
a. this is the primary structure of a
DNA
Which letters represents the backbone?
5
strand.
S&P
Which letter(s) represent(s) the nitrogenous base? B
b. Which molecule would the letter s stand for?
What specific molecule is S in DNA?
Deoxyribose
ribose
Deoxyribose
What specific molecule is S in RNA?
Ribose
Which nucleic acid would require a double strand? DNA
19. Acids have a pH that is
than 7.
less than 7, whereas bases have a pH that is greater
20. At pH 7, [H+] = [OH_]. Below pH 7, which of these is greater?
[H+]
21. An unsaturated fatty acid contains less hydrogen
than a saturated fatty acid.
22. When glycerol combines with 3 fatty acids, a
molecule results.
Lipid
23.
Phospholipids are lipids containing phosphorous that are very important in cell
membranes.
24. Hydrolysis is the splitting of a bond within a larger molecule by the addition of
water.
25.
Emulsifying
is the act of dispersing one liquid in another, as fat in water.
Matching: Match the following answers to one or more of the words below.
a. amino acid (or more than one)
b. glycerol
c. glucose (or more than one)
d. fatty acid
e. nucleotide (or more than one)
f. both glycerol and fatty acids
Biology 12:
Biological Molecules and Water Review
A.
nucleic acid
e
disaccharide c
B.
,
,
quick energy ,c
protein a
polysaccharide c
cellulose c
.
gene
,
e
long-term stored energy f
C.
,
enzyme a
,
plant cell wall c
peptide bond a
unsaturated
Glycogen
hydrogen bond e
c
6
hydrocarbon (only hydrogen and carbon)
d
ribose e
d
Matching. Match the following answers to the diagrams below.
a. amino acid (or more than one)
b. glycerol
c. glucose (or more than one)
d. fatty acid
e. nucleotide (or more than one)
f. both glycerol and fatty acids
Biology 12:
Biological Molecules and Water Review
7