Name:______________________________ Class: _________________ Date: _________________
Chemistry of Life
Chapter Test A
Answer Key
Multiple Choice
1. b
2. d
3. a
4. b
5. a
6. a
7. b
8. d
9. b
10. b
11. d
12. c
13. a
14. c
15. b
Short Answer
16. The pair in part B.
17. Magnesium has lost electrons to oxygen and
both are now ions that are electrically
attracted to each other.
18. It is positively charged because it has lost
electrons.
19. The ions have full outer energy levels.
Before, magnesium had two electrons in its
outer energy level that it was likely to lose,
and oxygen needed two electrons to fill its
outer energy level.
20. The illustration would show a sharing of
electron pairs rather than magnesium losing
electrons to oxygen.
21. a protein
22. the nitrogen bonded to the two carbon atoms
23. The four lines surrounding the “C” represent
the four bonds that carbon can form. By
forming bonds with many other elements,
carbon can form large, complex molecules
like proteins.
24. a polypeptide.
25. A protein is a polymer made of monomers
called amino acids. A polymer is a large
molecule made of many monomers, which
are smaller, repeating molecules that are
bonded together.
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
1
Chemistry of Life
Name:______________________________ Class: _________________ Date: _________________
Chemistry of Life
Chapter Test A
MULTIPLE CHOICE
Choose the letter of the best answer. (15 credits)
_____ 1. The smallest basic unit of
matter is the
a. molecule.
b. atom.
c. compound.
d. cell.
_____ 6. What is unique about
carbon?
a. bonding properties
b. ability to bond with
oxygen
c. properties as a reactant
d. properties as an enzyme
_____ 2. Which of the following is
formed when an atom gains
or loses electrons?
a. element
b. compound
c. molecule
d. ion
_____ 7. Which substance
represented in Figure 2.1
(A or B) is the solvent?
_____ 3. Atoms in molecules share
pairs of electrons when they
make
a. covalent bonds.
b. ionic bonds.
c. hydrogen bonds.
d. polymers.
_____ 4. What gives water many
properties that are important
to living things?
a. temperature
b. hydrogen bonds
c. density
d. specific heat
FIG. 2.1
a.
b.
c.
d.
both A and B
substance A
substance B
neither A nor B
_____ 5. Which of the following
solutions has the highest H
ion concentration?
a. a solution with a pH of 1
b. a solution with a pH of 4
c. a solution with a pH of 7
d. a solution with a pH of 10
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
2
Chemistry of Life
Name:______________________________ Class: _________________ Date: _________________
Chapter Test A, continued
_____ 8. The four main types of
carbon-based molecules in
organisms are
carbohydrates, lipids,
nucleic acids, and
a. starches.
b. fatty acids.
c. monosaccharides.
d. proteins.
_____ 13. The activation energy
needed for a chemical
reaction is decreased by a
a. catalyst.
b. reactant.
c. product.
d. substrate.
_____ 14. In the lock-and-key model
of enzyme function shown
in Figure 2.2, what is
happening in step 2?
_____ 9. Both animal fats and plant
oils are made up of glycerol
and
a. phospholipids.
b. fatty acids.
c. polar molecules.
d. saturated fats.
_____ 10. Substances are changed into
different substances when
bonds break and form
during
a. chemical equilibrium.
b. chemical reactions.
c. ion formation.
d. hydrogen bonding.
FIG. 2.2
a. The catalyzed reaction is
releasing a product.
b. The active sites are
restructuring the enzyme.
c. The enzyme is causing
new bonds to form
between the substrates.
d. The substrates are
beginning to bind to the
enzyme.
_____ 11. Identify the products in this
reaction: 6H2O  6CO2 
C6H12O6+ 6O2.
a. 6H2O and 6CO2
b. 6CO2 and C6H12O6
c. 6H2O, C6H12O6, and 6O2
d. C6H12O6 and 6O2
_____ 15. Which aspect of a chemical
reaction is affected by
enzymes?
a. direction
b. rate
c. equilibrium
d. pH
_____ 12. Chemical reactions that
absorb more energy than
they release are called
a. exothermic.
b. catalyzed.
c. endothermic.
d. activated.
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
3
Chemistry of Life
Name:______________________________ Class: _________________ Date: _________________
Chapter Test A, continued
Short Answer Use the diagram below to answer items 16–20. (5 credits)
FIG. 2.3
16. Which pair of atoms are ions?
_______________________________________________________________
17. How can you tell that an ionic bond is formed between magnesium and
oxygen?
_______________________________________________________________
_______________________________________________________________
18. Remembering that electrons are negatively charged, is magnesium in part B
positively or negatively charged? Why?
_______________________________________________________________
19. Why is the compound magnesium oxide more stable than its separate
components, magnesium and oxygen?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
20. How would the illustration be different if magnesium and oxygen formed
covalent bonds?
_______________________________________________________________
_______________________________________________________________
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
4
Chemistry of Life
Name:______________________________ Class: _________________ Date: _________________
Chapter Test A, continued
Use the diagram below to answer items 21–25. (5 credits)
FIG. 2.4
21. Figure 2.4 shows the basic molecular structure of amino acids and how they
bind together. What type of molecule is formed by amino acids?
_______________________________________________________________
22. What part of the amino acid in the center of the diagram is the amino group?
_______________________________________________________________
23. At the center of the diagram is a carbon molecule. What do the four lines that
surround the “C” illustrate about carbon?
_______________________________________________________________
24. The arrows point to peptide bonds between amino acids. What is the name of a
chain of amino acids linked by peptide bonds?
_______________________________________________________________
25. Is a protein a monomer or a polymer? Define these terms in your answer.
_______________________________________________________________
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
5
Chemistry of Life