Raven/Johnson Biology 8e
Chapter 01 - Answers
1. Which of the following is NOT a property of life?
a. Energy utilization
b. Movement
c. Order
d. Homeostasis
The correct answer is b—
A. Answer a is incorrect. All living organisms must use energy to support themselves.
The correct answer is b—Movement
B. Answer b is correct. Although many things that are alive move, not all things that move
are alive.
The correct answer is b—
C. Answer c is incorrect. Order and organization are important properties of all living things.
The correct answer is b—
D. Answer d is incorrect. Homeostasis, or the ability to maintain a fairly constant internal
environment, is important for organisms ranging from single cells to complex
multicellular organisms such as you.
2. Which is the correct order of hierarchical levels of living systems?
a. Cellular, molecular, population, ecosystem, biosphere
b. Cellular, organelle, organs, ecosystems, populations
c. Cellular, organismal, population, community, ecosystem
d. Species, community, population, ecosystem, biosphere
The correct answer is c—
A. Answer a is incorrect. Although a molecular level underlies the cellular level of life,
molecules are not considered to be alive.
The correct answer is c—
B. Answer b is incorrect. Organelles are found within cells and do not represent their
own independent level of life.
The correct answer is c—Cellular, organismal, population, community, ecosystem
C. Answer c is correct. Each level represents increasing complexity and encompasses the
preceding level.
The correct answer is c—
D. Answer d is incorrect. The order of these levels is incorrect. Populations represent a
lower hierarchical level than either species or communities.
3. The process of inductive reasoning involves—
a. the use of general principles to predict a specific result
b. the generation of specific predictions based on a belief system
c. the use of specific observations to develop general principles
d. the use of general principles to support a hypothesis
Raven/Johnson Biology 8e
Chapter 01 - Answers
The correct answer is c—
A. Answer a is incorrect. Deductive reasoning involves the use of general principles to
make predictions about specific results.
The correct answer is c—
B. Answer b is incorrect. Science is based on observations and experiments, not belief
systems.
The correct answer is c—The use of specific observations to develop general principles
C. Answer c is correct. Inductive reasoning represents the synthesis of information to
form a possible explanation (hypothesis) that will apply to all cases.
The correct answer is c—
D. Answer d is incorrect. A hypothesis represents a possible explanation of a set of
specific observations and is supported by experimental testing of predictions.
4. A hypothesis in biology is best described as—
a. a possible explanation of an observation
b. an observation that supports a theory
c. a general principle that explains some aspect of life
d. an unchanging statement the correctly predicts some aspect of life
The correct answer is a—a possible explanation of an observation
A. Answer a is correct. A hypothesis represents a scientist’s “best guess” about how the
world works.
The correct answer is a—
B. Answer b is incorrect. A theory represents the collective understanding of a
phenomenon based on well-tested hypotheses.
The correct answer is a—
C. Answer c is incorrect. A hypothesis is a possible explanation. Without experimental
tests it cannot be considered a principle.
The correct answer is a—
D. Answer d is incorrect. A hypothesis is always open to change. The process of
scientific experimentation tests the validity of hypotheses and drives our
understanding of the biological world by challenging old ideas with new information.
5. What is the significance of Pasteur’s experiment to test the germ hypothesis?
a. It proved that heat can sterilize a broth.
b. It demonstrated that cells can arise spontaneously.
c. It demonstrated that some cells are germs.
d. It demonstrated that cells can only arise from other cells.
The correct answer is d—
A. Answer a is incorrect. Although the ability to sterilize a liquid using heat is an
important aspect of this experiment, it is not the major result.
Raven/Johnson Biology 8e
Chapter 01 - Answers
The correct answer is d—
B. Answer b is incorrect. The result of this experiment disproved the hypothesis that life
could arise spontaneously since no cells grew in the unbroken flask.
The correct answer is d—
C. Answer c is incorrect. The term germ is used here in its sense of origin not in the
sense of pathogen as we typically think of it.
The correct answer is d—It demonstrated that cells can only arise from other cells.
D. Answer d is correct. The germ hypothesis proposed that life only comes from life—or
in this case, cells come from preexisting cells.
6. Which of the following is NOT an example of reductionism?
a. Analysis of an isolated enzyme’s function in an experimental assay
b. Investigation of the effect of a hormone on cell growth in a petri dish
c. Observation of the change in gene expression in response to specific stimulus
d. An evaluation of the overall behavior of a cell
The correct answer is d—
A. Answer a is incorrect. Reductionism involves looking at individual molecules and
proteins.
The correct answer is d—
B. Answer b is incorrect. Reductionism involves looking at specific pathways or
interactions.
The correct answer is d—
C. Answer c is incorrect. Reductionism involves examination of specific reactions.
The correct answer is d—An evaluation of the overall behavior of a cell
D. Answer d is correct. Trying to understand a complex system as a functioning whole is
not part of a reductionist approach.
7. A scientific theory is—
a. a guess about how things work in the world
b. a statement of how the world works that is supported by experimental data
c. a belief held by many scientists
d. both a and c
The correct answer is b—
A. Answer a is incorrect. A hypothesis might be categorized as a guess, but a theory is
supported by data.
The correct answer is b—a statement of how the world works that is supported by experimental
data
B. Answer b is correct. Scientific theories are based on evidence and are open to revision
as new evidence is gathered through the process of scientific discovery.
The correct answer is b—
Raven/Johnson Biology 8e
Chapter 01 - Answers
C. Answer c is incorrect. Scientific theories must be based on experimental evidence.
Just believing something to be true is not enough to make a theory.
The correct answer is b—
D. Answer d is incorrect. A scientific theory is the product of research and testing of
many competing hypotheses. Only when the evidence from many experiments
supports a hypothesis is it labeled a theory.
8. How is the process of natural selection different from that of artificial selection?
a. Natural selection produces more variation.
b. Natural selection makes an individual better adapted.
c. Artificial selection is a result of human intervention.
d. Artificial selection results in better adaptations.
The correct answer is c—
A. Answer a is incorrect. Natural selection does produce variation, but not any more than
artificial selection. In fact, organisms that undergo artificial selection may be more
diverse since humans would protect them from other selective pressures.
The correct answer is c—
B. Answer b is incorrect. Natural selection works on populations, not on individuals. An
individual organism can adapt to its environment, but only those adaptations encoded
within its genome will be transferred to the next generation of individuals within the
population.
The correct answer is c—Artificial selection is a result of human intervention.
C. Answer c is correct. Artificial selection occurs when humans control the breeding and
survival of organisms with the goal of enhancing one or more desirable traits.
The correct answer is c—
D. Answer d is incorrect. Artificial selection can produce adaptations or traits that are
better from a human’s perspective, but often these organisms would not survive or
reproduce in the wild.
9. How does the fossil record help support the theory of evolution by natural selection?
a. It demonstrates that simple organisms predate more complex organisms.
b. It provides evidence of change in the form of organisms over time.
c. It shows that diversity existed millions of years ago.
d. Both a and b.
The correct answer is a—It demonstrates that simple organisms predate more complex
organisms.
A. Answer a is correct. The fossil record does show the change from simpler to more
complex forms over time. This supports a prediction of evolution by natural selection.
The correct answer is a—
B. Answer b is incorrect. The fossil record does demonstrate a change in form of
organisms over time; however, it does not provide any evidence of the mechanism of
change.
Raven/Johnson Biology 8e
Chapter 01 - Answers
The correct answer is a—
C. Answer c is incorrect. Although the fossil record indicates that diverse forms of life
existed millions of years ago, this observation does not support the theory of
evolution.
The correct answer is a—
D. Answer d is incorrect. Although changes in form in the fossil record are evidence for
evolution, natural selection predicts that simpler forms will precede more complex
forms in time.
10. The theory of evolution by natural selection is a good example of how science proceeds
because—
a. it rationalizes a large body of observations
b. it makes predictions that have been tested by a variety of approaches
c. it represents Darwin’s belief of how life has changed over time
d. Both a and b
The correct answer is d—
A. Answer a is incorrect. Evolution explains a large body of observations, but is not the
only option that is true.
The correct answer is d—
B. Answer b is incorrect. Evolution makes a prediction that has been tested in a variety
of ways, but is not the only option that is true.
The correct answer is d—
C. Answer c is incorrect. The theory of evolution by natural selection is not a system of
belief held by Darwin or anyone else.
The correct answer is d—Both a and b
D. Answer d is correct. Both option a and option b correctly complete the sentence.
11. How does the field of molecular genetics help support the concept of evolution?
a. Comparisons of genes demonstrate a relationship between all living things.
b. Different organisms have different genomes.
c. Sequencing allows for the identification of unique genes.
d. The number of genes in an organism increase with the complexity of the
organism.
The correct answer is a—Comparisons of genes demonstrate a relationship between all living
things.
A. Answer a is correct. The evolutionary distance between organisms is reflected in the
divergence in the DNA sequence of certain important genes.
The correct answer is a—
B. Answer b is incorrect. All living things have certain critical genes in common.
Changes in the DNA sequence of these genes, rather than differences in the overall
collection of genes, is an indicator of the process of evolution.
Raven/Johnson Biology 8e
Chapter 01 - Answers
The correct answer is a—
C. Answer c is incorrect. It is the changes in genes found in common with all living
organisms that give the most useful picture of evolution.
The correct answer is a—
D. Answer d is incorrect. The absolute number of genes within an organism’s genome
does not seem to be correlated to evolution.
12. The cell theory states—
a. cells are small
b. cells are highly organized
c. there is only one basic type of cell
d. all living things are made up of cells
The correct answer is d—
A. Answer a is incorrect. Cells are small; however, this is not the idea represented by the
cell theory.
The correct answer is d—
B. Answer b is incorrect. The organization of cells is a property of life, but it is not part
of the cell theory.
The correct answer is d—Answer c is incorrect. At least three different basic cell types are
represented by the three domains of life: Bacteria, Archaea, and Eukarya.
The correct answer is d—all living things are made up of cells
C. Answer d is correct. The cell theory holds that a cell is the smallest unit of life and
that all living things are made up of one or more cells.
13. The molecule DNA is important to biological systems because—
a. it can be replicated
b. it encodes the information for making a new individual
c. it forms a complex, double-helical structure
d. nucleotides form genes
The correct answer is b—
A. Answer a is incorrect. The ability of DNA to replicate is important; however, this
property is not the most important aspect of the molecule.
The correct answer is b—it encodes the information for making a new individual
B. Answer b is correct. The transfer of information between generations is critical for the
continuity of life.
The correct answer is b—
C. Answer c is incorrect. The ability of DNA to form a double helix is a property of the
molecules that make it up.
The correct answer is b—
Raven/Johnson Biology 8e
Chapter 01 - Answers
D. Answer d is incorrect. Genes are important for biological systems, but only because
they encode information, not because they are composed of nucleotides.
14. In which domain of life would you find only single-celled organisms?
a. Eukarya
b. Bacteria
c. Archaea
d. Both b and c
The correct answer is d—
A. Answer a is incorrect. The domain Eukarya includes many single-celled organisms;
however, it also includes multicellular plants, animals, and fungi.
The correct answer is d—
B. Answer b is incorrect. The domain Bacteria includes single-celled organisms, but this
is not the only domain for which this is true.
The correct answer is d—
C. Answer c is incorrect. The domain Archaea includes single-celled organisms, but this
is not the only domain for which this is true.
The correct answer is d—Both b and c
D. Answer d is correct. Both domains Bacteria and Archaea include single-celled
organisms. These two domains constitute the prokaryotic cellular world.
15. Evolutionary conservation occurs when a characteristic is—
a. important to the life of the organism
b. not influenced by evolution
c. reduced to its least complex form
d. found in more primitive organisms
The correct answer is a—important to the life of the organism
A. Answer a is correct. If the loss of a particular characteristic will result in the death of
the organism, then natural selection works to preserve that trait.
The correct answer is a—
B. Answer b is incorrect. All characteristics of an organism can be affected by evolution;
however, when changing the characteristic results in the death or maladaptation of the
organism, then natural selection will eliminate it.
The correct answer is a—
C. Answer c is incorrect. Evolutionary conservation works to maintain those
characteristics that are vital of the life of an organism. Complexity is unimportant.
The correct answer is a—
D. Answer d is incorrect. Evidence for evolutionary conservation is found by comparing
diverse organisms, not just looking at what appears to be more primitive forms.
Raven/Johnson Biology 8e
Chapter 01 - Answers
Challenge Questions
1. Exobiology is the study of life on other planets. In recent years, scientists have sent
various spacecraft out into the galaxy in search for extraterrestrial life. Assuming that
all life shares common properties, what should exobiologists be looking for as they
explore other worlds?
Answer—For something to be considered living it would demonstrate organization, possibly
including a cellular structure. The organism would gain and use energy to maintain homeostasis,
respond to its environment, and to grow and reproduce. These latter properties would be difficult
to determine if the evidence of life from other planets comes from fossils. Similarly, the ability of
an alien organism to evolve could be difficult to establish.
2. The classic experiment by Pasteur (see figure 1.4) tested the hypothesis that cells arise
from other cells. In this experiment cell growth was measured following sterilization
of broth in a swan-neck flask or in a flask with a broken neck.
a. Which variables were kept the same in these two experiments?
Answer—The variables that were held the same between the two experiments include the broth,
the flask, and the sterilization step.
b. How does the shape of the flask affect the experiment?
Answer—The shape of the flask influences the experiment because any cells present in the air
can enter the flask with the broken neck, but they are trapped in the neck of the other flask.
c. Predict the outcome of each experiment based on the two hypotheses.
Answer—If cells can arise spontaneously, then cell growth will occur in both flasks. If cells can
only arise from preexisting cells (cells in the air), then only the flask with the broken neck will
grow cells. Breaking the neck exposes the broth to a source of cells.
d. Some bacteria (germs) are capable of producing heat-resistant spores that
protect the cell and allow it to continue to grow after the environment cools.
How would the outcome of this experiment have been affected if sporeforming bacteria were present in the broth?
Answer—If the sterilization step did not actually remove all cells, then growth would have
occurred in both flasks. This result would seem to support the hypothesis that life can arise
spontaneously.