,OpenStax Biology 2e Instructor Answer Guide
Biology 2e
Unit 1: The Chemistry of Life
Chapter 1: The Study of Life
Visual Connection Questions
1. In the example below, the scientific method is used to solve an everyday problem. Order the
scientific method steps (numbered items) with the process of solving the everyday problem
(lettered items). Based on the results of the experiment, is the hypothesis correct? If it is
incorrect, propose some alternative hypotheses.
1. Observation: C. My toaster doesn’t toast my bread.
2. Question: F. Why doesn’t my toaster work?
3. Hypothesis: A. There is something wrong with the electrical outlet.
4. Prediction: B. If something is wrong with the outlet, my coffeemaker also won’t work when
plugged into it.
5. Experiment: D. I plug my coffee maker into the outlet.
6. Result: E. My coffeemaker works.
The original hypothesis is incorrect, as the coffeemaker works when plugged into the outlet.
Alternative hypotheses include that the toaster might be broken or that the toaster wasn’t
turned on.
,OpenStax Biology 2e Instructor Answer Guide
2. Decide if each of the following is an example of inductive or deductive reasoning.
1: inductive
2: deductive
3: deductive
4: inductive
3. Which of the following statements is false?
b. Communities exist within populations which exist within ecosystems.
,OpenStax Biology 2e Instructor Answer Guide
Review Questions
4. The first forms of life on Earth were ____.
b. microorganisms
5. A suggested and testable explanation for an event is called a ___.
a. hypothesis
6. Which of the following sciences is not considered a natural science?
d. computer science
7. The type of logical thinking that uses related observations to arrive at a general conclusion is
called ____.
d. inductive reasoning
8. The process of ____ helps to ensure that a scientist’s research is original, significant, logical,
and thorough.
c. peer review
9. A person notices that her houseplants that are regularly exposed to music seem to grow
more quickly than those in rooms with no music. As a result, she determines that plants grow
better when exposed to music. This example most closely resembles which type of reasoning?
a. inductive reasoning
10. The smallest unit of biological structure that meets the functional requirements of “living” is
the ____.
c. cell
11. Viruses are not considered living because they ____.
a. are not made of cells
12. The presence of a membrane-enclosed nucleus is a characteristic of _____.
b. eukaryotic cells
13. A group of individuals of the same species living in the same area is called a(n) _____.
c. population
14. Which of the following sequences represents the hierarchy of biological organization from
the most inclusive to the least complex level?
d. biosphere, ecosystem, community, population, organism
15. Where in a phylogenetic tree would you expect to find the organism that had evolved most
recently?
d. at the branch tips
,OpenStax Biology 2e Instructor Answer Guide
Critical Thinking Questions
16. Although the scientific method is used by most of the sciences, it can also be applied to
everyday situations. Think about a problem that you may have at home, at school, or with your
car, and apply the scientific method to solve it
Answers will vary, but should apply the steps of the scientific method. One possibility could be a
car which doesn’t start. The hypothesis could be that the car doesn’t start because the battery
is dead. The experiment would be to change the battery or to charge the battery and then
check whether the car starts or not. If it starts, the problem was due to the battery, and the
hypothesis is accepted.
17. Give an example of how applied science has had a direct effect on your daily life.
Answers will vary. One example of how applied science has had a direct effect on daily life is the
presence of vaccines. Vaccines to prevent diseases such polio, measles, tetanus, and even
influenza affect daily life by contributing to individual and societal health.
18. Name two topics that are likely to be studied by biologists, and two areas of scientific study
that would fall outside the realm of biology.
Answers will vary. Topics that fall inside the area of biological study include how diseases affect
human bodies, how pollution impacts a species’ habitat, and how plants respond to their
environments. Topics that fall outside of biology (the “study of life”) include how metamorphic
rock is formed and how planetary orbits function.
19. Thinking about the topic of cancer, write a basic science question and an applied science
question that a researcher interested in this topic might ask.
Answers will vary. Basic science: What evolutionary purpose might cancer serve? Applied
science: What strategies might be found to prevent cancer from reproducing at the cellular
level?
20. Select two items that biologists agree are necessary in order to consider an organism
“alive.” For each, give an example of a nonliving object that otherwise fits the definition of
“alive.”
Answers will vary. Layers of sedimentary rock have order but are not alive. Technology is
capable of regulation but is not, of itself, alive.
21. Consider the levels of organization of the biological world, and place each of these items in
order from smallest level of organization to most encompassing: skin cell, elephant, water
molecule, planet Earth, tropical rainforest, hydrogen atom, wolf pack, liver.
Smallest level of organization to largest: hydrogen atom, water molecule, skin cell, liver,
elephant, wolf pack, tropical rainforest, planet Earth.
,OpenStax Biology 2e Instructor Answer Guide
22. You go for a long walk on a hot day. Give an example of a way in which homeostasis keeps
your body healthy.
During your walk, you may begin to perspire, which cools your body and helps your body to
maintain a constant internal temperature. You might also become thirsty and pause long
enough for a cool drink, which will help to restore the water lost during perspiration.
23. Using examples, explain how biology can be studied from a microscopic approach to a
global approach.
Researchers can approach biology from the smallest to the largest, and everything in between.
For instance, an ecologist may study a population of individuals, the population’s community,
the community’s ecosystem, and the ecosystem’s part in the biosphere. When studying an
individual organism, a biologist could examine the cell and its organelles, the tissues that the
cells make up, the organs and their respective organ systems, and the sum total—the organism
itself.
This file is copyright 2018, Rice University. All Rights Reserved.
,OpenStax Biology 2e Instructor Answer Guide
Biology 2e
Unit 1: The Chemistry of Life
Chapter 2: The Chemical Foundation of Life
Visual Connection Questions
1. How many neutrons do carbon-12 and carbon-13 have, respectively?
Carbon-12 has six neutrons. Carbon-13 has seven neutrons.
2. Figure 2.7 An atom may give, take, or share electrons with another atom to achieve a full
valence shell, the most stable electron configuration. Looking at this figure, how many electrons
do elements in group 1 need to lose in order to achieve a stable electron configuration? How
many electrons do elements in groups 14 and 17 need to gain to achieve a stable
configuration?
Elements in group 1 need to lose one electron to achieve a stable electron configuration.
Elements in groups 14 and 17 need to gain four and one electrons, respectively, to achieve a
stable configuration.
,OpenStax Biology 2e Instructor Answer Guide
3. Which of the following statements is false?
c. To be enantiomers, a molecule must have at least three different atoms or groups connected
to a central carbon.
Review Questions
4. If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it
have?
a. 54
5. Atoms that vary in the number of neutrons found in their nuclei are called ________.
d. isotopes
6. Potassium has an atomic number of 19. What is its electron configuration?
c. shells 1, 2 and 3 are full and shell 4 has one electron
7. Which type of bond represents a weak chemical bond?
a. hydrogen bond
8. Which of the following statements is not true?
d. Water is the most abundant molecule in the Earth’s atmosphere.
9. When acids are added to a solution, the pH should ________.
a. decrease
,OpenStax Biology 2e Instructor Answer Guide
10. We call a molecule that binds up excess hydrogen ions in a solution a(n) ________.
c. base
11. Which of the following statements is true?
b. Acids and bases will neutralize each other
12. Each carbon atom can bond with as many as ________ other atom(s) or molecule(s).
d. four
13. Which of the following is not a functional group that can bond with carbon?
a. sodium
Critical Thinking Questions
14. What makes ionic bonds different from covalent bonds?
Ionic bonds are created between ions. The electrons are not shared between the atoms, but
rather are associated more with one ion than the other. Ionic bonds are strong bonds, but are
weaker than covalent bonds, meaning it takes less energy to break an ionic bond compared
with a covalent one.
15. Why are hydrogen bonds and van der Waals interactions necessary for cells?
Hydrogen bonds and van der Waals interactions form weak associations between different
molecules or within different regions of the same molecule. They provide the structure and
shape necessary for proteins and DNA within cells so that they function properly
16. Discuss how buffers help prevent drastic swings in pH.
Buffers absorb the free hydrogen ions and hydroxide ions that result from chemical reactions.
Because they can bond these ions, they prevent increases or decreases in pH. An example of a
buffer system is the bicarbonate system in the human body. This system is able to absorb
hydrogen and hydroxide ions to prevent changes in pH and keep cells functioning properly.
17. Why can some insects walk on water?
Some insects can walk on water, although they are heavier (denser) than water, because of the
surface tension of water. Surface tension results from cohesion, or the attraction between
water molecules at the surface of the body of water (the liquid-air/gas interface).
18. What property of carbon makes it essential for organic life?
Carbon is unique and found in all living things because it can form up to four covalent bonds
between atoms or molecules. These can be nonpolar or polar covalent bonds, and they allow
for the formation of long chains of carbon molecules that combine to form proteins and DNA.
, OpenStax Biology 2e Instructor Answer Guide
19. Compare and contrast saturated and unsaturated triglycerides.
Saturated triglycerides contain no double bonds between carbon atoms; they are usually solid
at room temperature. Unsaturated triglycerides contain at least one double bond between
carbon atoms and are usually liquid at room temperature.
This file is copyright 2018, Rice University. All Rights Reserved.
Biology 2e
Unit 1: The Chemistry of Life
Chapter 1: The Study of Life
Visual Connection Questions
1. In the example below, the scientific method is used to solve an everyday problem. Order the
scientific method steps (numbered items) with the process of solving the everyday problem
(lettered items). Based on the results of the experiment, is the hypothesis correct? If it is
incorrect, propose some alternative hypotheses.
1. Observation: C. My toaster doesn’t toast my bread.
2. Question: F. Why doesn’t my toaster work?
3. Hypothesis: A. There is something wrong with the electrical outlet.
4. Prediction: B. If something is wrong with the outlet, my coffeemaker also won’t work when
plugged into it.
5. Experiment: D. I plug my coffee maker into the outlet.
6. Result: E. My coffeemaker works.
The original hypothesis is incorrect, as the coffeemaker works when plugged into the outlet.
Alternative hypotheses include that the toaster might be broken or that the toaster wasn’t
turned on.
,OpenStax Biology 2e Instructor Answer Guide
2. Decide if each of the following is an example of inductive or deductive reasoning.
1: inductive
2: deductive
3: deductive
4: inductive
3. Which of the following statements is false?
b. Communities exist within populations which exist within ecosystems.
,OpenStax Biology 2e Instructor Answer Guide
Review Questions
4. The first forms of life on Earth were ____.
b. microorganisms
5. A suggested and testable explanation for an event is called a ___.
a. hypothesis
6. Which of the following sciences is not considered a natural science?
d. computer science
7. The type of logical thinking that uses related observations to arrive at a general conclusion is
called ____.
d. inductive reasoning
8. The process of ____ helps to ensure that a scientist’s research is original, significant, logical,
and thorough.
c. peer review
9. A person notices that her houseplants that are regularly exposed to music seem to grow
more quickly than those in rooms with no music. As a result, she determines that plants grow
better when exposed to music. This example most closely resembles which type of reasoning?
a. inductive reasoning
10. The smallest unit of biological structure that meets the functional requirements of “living” is
the ____.
c. cell
11. Viruses are not considered living because they ____.
a. are not made of cells
12. The presence of a membrane-enclosed nucleus is a characteristic of _____.
b. eukaryotic cells
13. A group of individuals of the same species living in the same area is called a(n) _____.
c. population
14. Which of the following sequences represents the hierarchy of biological organization from
the most inclusive to the least complex level?
d. biosphere, ecosystem, community, population, organism
15. Where in a phylogenetic tree would you expect to find the organism that had evolved most
recently?
d. at the branch tips
,OpenStax Biology 2e Instructor Answer Guide
Critical Thinking Questions
16. Although the scientific method is used by most of the sciences, it can also be applied to
everyday situations. Think about a problem that you may have at home, at school, or with your
car, and apply the scientific method to solve it
Answers will vary, but should apply the steps of the scientific method. One possibility could be a
car which doesn’t start. The hypothesis could be that the car doesn’t start because the battery
is dead. The experiment would be to change the battery or to charge the battery and then
check whether the car starts or not. If it starts, the problem was due to the battery, and the
hypothesis is accepted.
17. Give an example of how applied science has had a direct effect on your daily life.
Answers will vary. One example of how applied science has had a direct effect on daily life is the
presence of vaccines. Vaccines to prevent diseases such polio, measles, tetanus, and even
influenza affect daily life by contributing to individual and societal health.
18. Name two topics that are likely to be studied by biologists, and two areas of scientific study
that would fall outside the realm of biology.
Answers will vary. Topics that fall inside the area of biological study include how diseases affect
human bodies, how pollution impacts a species’ habitat, and how plants respond to their
environments. Topics that fall outside of biology (the “study of life”) include how metamorphic
rock is formed and how planetary orbits function.
19. Thinking about the topic of cancer, write a basic science question and an applied science
question that a researcher interested in this topic might ask.
Answers will vary. Basic science: What evolutionary purpose might cancer serve? Applied
science: What strategies might be found to prevent cancer from reproducing at the cellular
level?
20. Select two items that biologists agree are necessary in order to consider an organism
“alive.” For each, give an example of a nonliving object that otherwise fits the definition of
“alive.”
Answers will vary. Layers of sedimentary rock have order but are not alive. Technology is
capable of regulation but is not, of itself, alive.
21. Consider the levels of organization of the biological world, and place each of these items in
order from smallest level of organization to most encompassing: skin cell, elephant, water
molecule, planet Earth, tropical rainforest, hydrogen atom, wolf pack, liver.
Smallest level of organization to largest: hydrogen atom, water molecule, skin cell, liver,
elephant, wolf pack, tropical rainforest, planet Earth.
,OpenStax Biology 2e Instructor Answer Guide
22. You go for a long walk on a hot day. Give an example of a way in which homeostasis keeps
your body healthy.
During your walk, you may begin to perspire, which cools your body and helps your body to
maintain a constant internal temperature. You might also become thirsty and pause long
enough for a cool drink, which will help to restore the water lost during perspiration.
23. Using examples, explain how biology can be studied from a microscopic approach to a
global approach.
Researchers can approach biology from the smallest to the largest, and everything in between.
For instance, an ecologist may study a population of individuals, the population’s community,
the community’s ecosystem, and the ecosystem’s part in the biosphere. When studying an
individual organism, a biologist could examine the cell and its organelles, the tissues that the
cells make up, the organs and their respective organ systems, and the sum total—the organism
itself.
This file is copyright 2018, Rice University. All Rights Reserved.
,OpenStax Biology 2e Instructor Answer Guide
Biology 2e
Unit 1: The Chemistry of Life
Chapter 2: The Chemical Foundation of Life
Visual Connection Questions
1. How many neutrons do carbon-12 and carbon-13 have, respectively?
Carbon-12 has six neutrons. Carbon-13 has seven neutrons.
2. Figure 2.7 An atom may give, take, or share electrons with another atom to achieve a full
valence shell, the most stable electron configuration. Looking at this figure, how many electrons
do elements in group 1 need to lose in order to achieve a stable electron configuration? How
many electrons do elements in groups 14 and 17 need to gain to achieve a stable
configuration?
Elements in group 1 need to lose one electron to achieve a stable electron configuration.
Elements in groups 14 and 17 need to gain four and one electrons, respectively, to achieve a
stable configuration.
,OpenStax Biology 2e Instructor Answer Guide
3. Which of the following statements is false?
c. To be enantiomers, a molecule must have at least three different atoms or groups connected
to a central carbon.
Review Questions
4. If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it
have?
a. 54
5. Atoms that vary in the number of neutrons found in their nuclei are called ________.
d. isotopes
6. Potassium has an atomic number of 19. What is its electron configuration?
c. shells 1, 2 and 3 are full and shell 4 has one electron
7. Which type of bond represents a weak chemical bond?
a. hydrogen bond
8. Which of the following statements is not true?
d. Water is the most abundant molecule in the Earth’s atmosphere.
9. When acids are added to a solution, the pH should ________.
a. decrease
,OpenStax Biology 2e Instructor Answer Guide
10. We call a molecule that binds up excess hydrogen ions in a solution a(n) ________.
c. base
11. Which of the following statements is true?
b. Acids and bases will neutralize each other
12. Each carbon atom can bond with as many as ________ other atom(s) or molecule(s).
d. four
13. Which of the following is not a functional group that can bond with carbon?
a. sodium
Critical Thinking Questions
14. What makes ionic bonds different from covalent bonds?
Ionic bonds are created between ions. The electrons are not shared between the atoms, but
rather are associated more with one ion than the other. Ionic bonds are strong bonds, but are
weaker than covalent bonds, meaning it takes less energy to break an ionic bond compared
with a covalent one.
15. Why are hydrogen bonds and van der Waals interactions necessary for cells?
Hydrogen bonds and van der Waals interactions form weak associations between different
molecules or within different regions of the same molecule. They provide the structure and
shape necessary for proteins and DNA within cells so that they function properly
16. Discuss how buffers help prevent drastic swings in pH.
Buffers absorb the free hydrogen ions and hydroxide ions that result from chemical reactions.
Because they can bond these ions, they prevent increases or decreases in pH. An example of a
buffer system is the bicarbonate system in the human body. This system is able to absorb
hydrogen and hydroxide ions to prevent changes in pH and keep cells functioning properly.
17. Why can some insects walk on water?
Some insects can walk on water, although they are heavier (denser) than water, because of the
surface tension of water. Surface tension results from cohesion, or the attraction between
water molecules at the surface of the body of water (the liquid-air/gas interface).
18. What property of carbon makes it essential for organic life?
Carbon is unique and found in all living things because it can form up to four covalent bonds
between atoms or molecules. These can be nonpolar or polar covalent bonds, and they allow
for the formation of long chains of carbon molecules that combine to form proteins and DNA.
, OpenStax Biology 2e Instructor Answer Guide
19. Compare and contrast saturated and unsaturated triglycerides.
Saturated triglycerides contain no double bonds between carbon atoms; they are usually solid
at room temperature. Unsaturated triglycerides contain at least one double bond between
carbon atoms and are usually liquid at room temperature.
This file is copyright 2018, Rice University. All Rights Reserved.
