The Chemistry of Life
Assessments
Douglas Wilkin, Ph.D. (DougW)
Say Thanks to the Authors
Click http://www.ck12.org/saythanks
(No sign in required)
To access a customizable version of this book, as well as other
interactive content, visit www.ck12.org
CK-12 Foundation is a non-profit organization with a mission to
reduce the cost of textbook materials for the K-12 market both
in the U.S. and worldwide. Using an open-content, web-based
collaborative model termed the FlexBook®, CK-12 intends to
pioneer the generation and distribution of high-quality educational
content that will serve both as core text as well as provide an
adaptive environment for learning, powered through the FlexBook
Platform®.
Copyright © 2014 CK-12 Foundation, www.ck12.org
The names “CK-12” and “CK12” and associated logos and the
terms “FlexBook®” and “FlexBook Platform®” (collectively
“CK-12 Marks”) are trademarks and service marks of CK-12
Foundation and are protected by federal, state, and international
laws.
Any form of reproduction of this book in any format or medium,
in whole or in sections must include the referral attribution link
http://www.ck12.org/saythanks (placed in a visible location) in
addition to the following terms.
Except as otherwise noted, all CK-12 Content (including CK-12
Curriculum Material) is made available to Users in accordance
with the Creative Commons Attribution-Non-Commercial 3.0
Unported (CC BY-NC 3.0) License (http://creativecommons.org/
licenses/by-nc/3.0/), as amended and updated by Creative Commons from time to time (the “CC License”), which is incorporated
herein by this reference.
Complete terms can be found at http://www.ck12.org/terms.
Printed: October 6, 2014
AUTHOR
Douglas Wilkin, Ph.D. (DougW)
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
C HAPTER
1
The Chemistry of Life
Assessments
C HAPTER O UTLINE
1.1
Matter and Organic Compounds
1.2
Biochemical Reactions
1.3
Water, Acids, and Bases
1.4
The Chemistry of Life
1
1.1. Matter and Organic Compounds
www.ck12.org
1.1 Matter and Organic Compounds
Lesson Quiz
Name___________________ Class______________ Date________
Multiple Choice
Circle the letter of the correct choice.
1. Which of the following are functions of nucleic acids?
a.
b.
c.
d.
They help make proteins.
They contain instructions for proteins.
They pass instructions from parents to offspring.
all of the above
2. Types of lipids include:
a.
b.
c.
d.
triglycerides.
polysaccharides.
amino acids.
nucleotides.
3. The characteristics of DNA include which of the following?
a.
b.
c.
d.
DNA is made of nucleotides consisting of a sugar, a phosphate group, and a carbon base.
DNA is made of a single polynucleotide chain, which winds into a double helix.
DNA is how inherited characteristics are passed from one generation to the next.
all of the above
4. Differences between DNA and RNA include all of the following, except that
a.
b.
c.
d.
thymine is a base in DNA, uracil is a base in RNA.
RNA consists of just one polynucleotide chain, DNA consists of two chains.
DNA uses the information in RNA to assemble the correct amino acids and help make proteins.
All of the above are correct.
5. A(n) ____________ cannot be broken down into other types of substances.
a.
b.
c.
d.
element
compound
molecule
metal
6. Functions of proteins include
a.
b.
c.
d.
giving cells their shape.
targeting foreign substances for destruction.
speeding up biochemical reactions.
all of the above.
7. In a DNA molecule, adenine always pairs with
a. cytosine.
2
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
b. guanine.
c. thymine.
d. nucleotide.
8. DNA nucleotides contain all of the following, except
a.
b.
c.
d.
uracil.
a phosphate group.
a sugar.
thymine.
9. The main difference between saturated and unsaturated fatty acids is
a.
b.
c.
d.
the amount of energy found in the fatty acid.
saturated fatty acids are liquids.
unsaturated fatty acids can be packed together very tightly.
the number of hydrogen atoms bonded to the carbon atoms.
10. Complex carbohydrates are made out of subunits called ____________.
a.
b.
c.
d.
starch
monosaccharides
amino acids
nucleotides
11. Proteins are made out of subunits called ____________.
a.
b.
c.
d.
polypeptides
monosaccharides
amino acids
nucleotides
12. Nucleic acids are made out subunits called ____________.
a.
b.
c.
d.
DNA
monosaccharides
amino acids
nucleotides
True or False
Write true if the statement is true or false if the statement is false.
_______ 13. Carbon is the main element in organic compounds.
_______ 14. Starch is a monosaccharide, a type of carbohydrate.
_______ 15. Lipids are the major components of cell membranes.
_______ 16. The four major types of organic compounds include carbohydrates, lipids, proteins, and amino acids.
_______ 17. An element cannot be broken down into other types of substances.
Fill in the Blanks
Fill in the blank with the term that best completes the sentence.
18. There are just ____________ different amino acids commonly found in the proteins of living things.
19. A chemical ____________ is a process that changes some chemical substances into others.
20. The Periodic Table of the Elements arranges elements in groups based on their ____________.
21. ____________ consist of repeating units called fatty acids.
22. An alpha helix describes the secondary structure of a ____________.
3
1.1. Matter and Organic Compounds
www.ck12.org
23. ____________ and ____________ are two examples of nucleic acids.
24. The shape of DNA can be described as a ____________.
25. Matter is anything that takes up space and has ____________.
Short Answer
Answer each question in the space provided.
26. Discuss why carbon is essential to life on Earth.
27. Describe the structures of proteins and nucleic acids, and discuss the functional relationship between these two
types of organic compounds.
4
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
1.2 Biochemical Reactions
Lesson Quiz
Name___________________ Class______________ Date________
Multiple Choice
Circle the letter of the correct choice.
1. CH4 + 2O2 → CO2 + 2H2 O. The products in this reaction include
a.
b.
c.
d.
methane and oxygen.
carbon dioxide and water.
carbon dioxide and oxygen.
methane and water.
2. The “push” needed to start a chemical reaction is the
a.
b.
c.
d.
enzymatic energy.
endothermic energy.
activation energy.
reactant energy.
3. Enzymes are
a.
b.
c.
d.
carbohydrates that store biological energy.
lipids that form biological membranes.
proteins that speed up biochemical reactions.
nucleic acids that have the information to make proteins.
4. In the photosynthesis reaction, 6CO2 + 6H2 0 → C6 H12 O6 + 602 , there are 18 oxygen atoms in the reactants.
How many oxygen atoms are in the products?
a.
b.
c.
d.
6
12
18
24
5. Organisms need enzymes because
a.
b.
c.
d.
temperatures may too low inside organisms for reactions to occur without enzymes.
the levels of reactants may be too low for them to react without assistance from enzymes.
they need biochemical reactions to speed up to occur quickly enough to maintain life.
all of the above
6. An example of a catabolic reaction is
a.
b.
c.
d.
making starch from monosaccharides.
the formation of proteins from amino acids.
the breakdown of glucose to release energy.
the joining of nucleotides in the copying of DNA.
7. Without enzymes, you could not
5
1.2. Biochemical Reactions
a.
b.
c.
d.
www.ck12.org
burn methane into carbon dioxide and water.
photosynthesize and make glucose from carbon dioxide and water.
break down glucose into carbon dioxide and water.
You could do all of the above without enzymes.
8. Activation energy is required in which of the following reactions?
a.
b.
c.
d.
biochemical reactions only
only endothermic reactions
only exothermic reactions
all chemical reactions
9. The action of enzymes is crucial to life. Enzymes act by
a.
b.
c.
d.
lowering the activation energy needed to start the reaction.
reducing the amount of energy absorbed during a biochemical reaction.
reducing the amount of heat released during a biochemical reaction.
conserving matter in a biochemical reaction, such that the number of atoms in the reactants equals the
number in the products.
10. Which represents the correct depiction of a exothermic reaction?
a.
b.
c.
d.
Reactants + Heat → Products
Reactants → Products + Heat
Reactants + Products → Heat
Products + Heat → Reactants
11. The activities of enzymes depend on
a.
b.
c.
d.
temperature.
ionic conditions.
pH of the surroundings.
all of the above.
12. What is the main difference between an endothermic reaction and an exothermic reaction?
a.
b.
c.
d.
An endothermic reaction gives off energy and an exothermic reaction absorbs energy.
An exothermic reaction gives off energy and an endothermic reaction absorbs energy.
An endothermic reaction does not need activation energy.
Only an endothermic reaction involves enzymes.
True or False
Write true if the statement is true or false if the statement is false.
_______ 13. An enzyme speeds up biochemical reactions by lowering the activation energy.
_______ 14. The number of atoms in the reactants of a chemical reaction is always the same as the number of atoms
in the products.
_______ 15. Not all chemical reactions involve energy.
_______ 16. The joining of amino acids to form a protein is a catabolic reaction, building up bigger molecules from
smaller ones.
_______ 17. Enzymes are necessary for life.
Fill in the Blanks
Fill in the blank with the term that best completes the sentence.
18. ____________ reactions are chemical reactions that take place inside cells.
19. ____________ reactions in organisms are called catabolic reactions.
6
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
20. ____________ energy is the energy needed to start a chemical reaction.
21. The sum of all the ____________ in an organism is called metabolism.
22. In a reaction involving sodium and chlorine, table salt (sodium chloride) is the ____________ .
23. During a chemical reaction, ____________ is always conserved.
24. A(n) ____________ is a protein that speeds up a biochemical reaction.
25. A substance that is used to start a chemical reaction is called a ____________.
Short Answer
Answer each question in the space provided.
26. What is a chemical reaction? Use correct vocabulary in your response, and provide an example.
27. Discuss enzymes. Include a definition, a description of the role of enzymes, and a discussion of how an enzyme
works.
7
1.3. Water, Acids, and Bases
1.3 Water, Acids, and Bases
Lesson Quiz
Name___________________ Class______________ Date________
Multiple Choice
Circle the letter of the correct choice.
1. The oxygen in a water molecule
a.
b.
c.
d.
attracts electrons more strongly than the hydrogen atoms.
has a slight negative charge.
binds to a hydrogen of another water molecule through a hydrogen bond.
all of the above
2. Most of the water on Earth can be found as
a.
b.
c.
d.
freshwater in icecaps, glaciers and the inland seas.
freshwater in lakes, the atmosphere and as moisture in soil.
saltwater in lakes, the atmosphere and as moisture in soil.
saltwater in the oceans.
3. Acids have a pH
a.
b.
c.
d.
less than 14.
between 0 and 14.
between 0 and 7.
between 7 and 14.
4. Ice floats on water because
a.
b.
c.
d.
ice has a lower density than water.
water contracts when it freezes.
of the boiling point of water.
all of the above
5. How do hydrogen bonds affect water’s properties?
a.
b.
c.
d.
Hydrogen bonds explain why water molecules stick together.
Hydrogen bonds cause water to have a relatively high boiling point.
Hydrogen bonds also cause water to expand when it freezes.
all of the above
6. Which is the strongest base?
a.
b.
c.
d.
lemon juice
soda pop
eggs
ammonia
7. Which is the strongest acid?
a. lemon juice
8
www.ck12.org
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
b. orange juice
c. milk
d. soap
8. Which of the following is an example of a solution?
a.
b.
c.
d.
a pepperoni pizza
a box of Lucky Charms cereal
a glass of orange juice
a hot fudge sundae
True or False
Write true if the statement is true or false if the statement is false.
_______ 9. Water is a chemical.
_______ 10. Water is a product of photosynthesis.
_______ 11. Water is a polar molecule —it has regions with different charges.
_______ 12. Pure water has a pH of 7.
_______ 13. The inside of your stomach has a low pH.
_______ 14. Most of the water on Earth consists of freshwater in the oceans.
_______ 15. The hydrogen bonds that hold water molecules together are very strong bonds.
_______ 16. Ammonia is a very strong acid.
_______ 17. The oxygen atom in a water molecule attracts electrons more strongly than the hydrogen atoms.
Fill in the Blanks
Fill in the blank with the term that best completes the sentence.
18. Water’s ____________ gives it unique properties that are important to understand its importance.
19. The positive end of one water molecule is attracted to the ____________ end of a nearby water molecule.
20. A ____________ is a mixture of two or more substances with the same composition throughout.
21. The ____________ point of water is 100°C.
22. The pH scale ranges from ____________ to ____________.
23. A difference in electrical charge between different parts of the same molecule is called ____________.
24. Your stomach is a very ____________ environment.
25. ____________ bonds form between adjacent water molecules.
Short Answer
Answer each question in the space provided.
26. Discuss why water is a polar molecule.
9
1.3. Water, Acids, and Bases
27. What are the main differences between an acid and a base? Give examples of each.
10
www.ck12.org
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
1.4 The Chemistry of Life
Chapter Test
Name___________________ Class______________ Date________
Multiple Choice
Circle the letter of the correct choice.
1. Which statement about atoms is false?
a.
b.
c.
d.
An atom is the smallest type of particle.
An atom consists of smaller particles.
An atom has the properties of an element.
none of the above
2. Which of the following chemical substances is a compound?
a.
b.
c.
d.
oxygen
water
iron
hydrogen
3. Organic compounds are
a.
b.
c.
d.
found mainly in living things.
needed for life processes.
made mostly of carbon.
all of the above
4. Sugar and starch are the type of organic compounds called
a.
b.
c.
d.
proteins.
lipids.
carbohydrates.
fats.
5. Which statement is true about saturated fatty acids?
a.
b.
c.
d.
They are found mainly in plants.
They have bent chains.
They are liquids at room temperature.
They have as many hydrogen atoms as possible.
6. The basic building blocks of proteins are
a.
b.
c.
d.
amino acids.
fatty acids.
nucleotides.
saccharides.
7. Nucleic acids carry the genetic code in the sequence of their
a. sugars.
11
1.4. The Chemistry of Life
www.ck12.org
b. phosphate groups.
c. nitrogen bases.
d. backbones.
8. Which chemical reactions require activation energy to occur?
a.
b.
c.
d.
only endothermic reactions
only exothermic reactions
all chemical reactions
only chemical reactions in living things
9. What ions determine the acidity of a solution?
a.
b.
c.
d.
H2 O
H3 O+
OH−
H+
10. All of the following statements are true about bases, except:
a.
b.
c.
d.
Bases have a pH lower than 7.
Bases taste bitter.
Strong bases can be harmful.
Bases play important roles in living things.
True or False
Write true if the statement is true or false if the statement is false.
_______ 11. Organisms use carbohydrates and lipids to store energy.
_______ 12. Adenine always binds with guanine.
_______ 13. The primary structure of proteins is a double helix.
_______ 14. Proteins have many functions.
_______ 15. The burning of methane is an endothermic reaction.
_______ 16. Most of Earth’s water is found in lakes and large rivers.
_______ 17. A solution has the same composition throughout.
_______ 18. Bleach is an example of a strong acid.
_______ 19. Enzymes need acids and bases in order to work.
_______ 20. Water is involved in most biochemical reactions.
Fill in the Blanks
Fill in the blank with the term that best completes the sentence.
21. A chemical ____________ is a force that holds together the atoms in a molecule.
22. A chemical ____________ is a process that changes some chemical substances into others.
23. A substance that starts a chemical reaction is a(n) ____________.
24. A substance that results from a chemical reaction is a(n) ____________.
25. Exothermic reactions in organisms are called ____________ reactions.
26. Endothermic reactions in organisms are called ____________ reactions.
27. A(n) ____________ is a protein that speeds up a biochemical reaction.
28. A difference in electrical charge between two parts of the same molecule is termed ____________.
12
www.ck12.org
Chapter 1. The Chemistry of Life Assessments
29. The type of bond that forms between water molecules is a(n) ____________ bond.
30. The pH of water is ____________.
Short Answer
Answer each question in the space provided.
31. Why is carbon essential to life on Earth?
32. Explain the importance of enzymes to living things.
33. Relate water’s structure to its properties.
13