Mastering Concepts
1.1
1. What characteristics distinguish the living from the nonliving?
Living things display all of these characteristics: they reproduce and grow, use energy,
have levels of organization, maintain constant internal conditions, and evolve.
2. List the levels of life’s organizational hierarchy from smallest to largest, starting with
atoms and ending with the biosphere.
Atoms, molecules, organelles, cells, tissues, organs, organ systems, organism, population,
community, ecosystem, biosphere
3. What are the roles of natural selection and mutations in evolution?
Natural selection leads to adaptations which help populations to survive, and mutations
generate the variation needed by natural selection.
1.2
1. What are the goals of taxonomy?
The goals of taxonomy are to name species and classify them based on evolutionary
relationships.
2. How are domains related to kingdoms?
Domains are larger, more encompassing taxonomic categories than kingdoms. Each
domain may contain one or several kingdoms.
3. List and describe the four main groups of eukaryote.
Protista – multi- or single- celled, independently mobile, both autotrophs and
heterotrophs
Fungi – not independently mobile, decomposers, heterotrophs
Plants – multicellular, photosynthetic life, producers, autotrophs
Animals – multicellular, no photosynthesis and independently mobile, consumers,
heterotrophs
1.3
1. What are the components of scientific inquiry?
The components of the scientific method are making observations, asking questions,
consulting prior knowledge, forming a hypothesis, testing the hypothesis (often with a
controlled experiment), collecting and interpreting data in light of prior knowledge, and
forming a conclusion.
2. Identify the elements of the experiment summarized in the Apply It Now box.
Sample size = 200 rats; variables: independent = saccharin treatment, dependent =
number of tumors, standardized = brand of chow; controls = 1 group with no saccharin
added to chow; statistical analysis = calculating percentages of tumors between the
different groups; creativity and logic = went into the choice of rats as a test subject.
3. What is the difference between a hypothesis and a theory?
Hypotheses are untested tentative explanations, while theories have a great deal of
independent supporting evidence. Theories are also much more comprehensive in nature.
4. What are some limitations of scientific inquiry?
Scientific inquiry cannot answer subjective questions related to beauty, morality, ethics,
or religion. And it can only test hypotheses that can be falsified.
1.4
1. What observations led Darwin and Wallace to predict the existence of a long-tongued
moth in Madagascar?
The observations were of orchids with long nectar tubes.
2. How does this story illustrate discovery science?
The relationship between the moth and the orchid was determined through observations
and not experimentation.
Write It Out
1. Describe each of the five characteristics of life, and list several nonliving things that
possess at least two of these characteristics.
a) Organization – a hierarchical pattern from atoms to the biosphere; b) requires energy –
metabolic reactions acquire and use energy; c) maintains internal constancy – in the face
of a changing environment the inside of cells and living organisms remain within a
constant range; d) Reproduction, growth, and development – organisms make new
organisms similar to themselves, and those organisms change into adult form; e)
evolution – the genetic makeup of a population changes over time, often as it adapts to
the environment through natural selection. Examples of nonliving things: a house is
structurally organized and maintains a constant range of temperatures; automobiles are
organized and require energy; crystal formations are organized and grow; viruses are
organized and evolve.
2. Draw and explain the relationship between producers and consumers (including
decomposers).
Answers will be visual based on Fig. 1.4
3. What is homeostasis? Give an example other than those mentioned in the book.
Homeostasis is a state of internal constancy. An example is the human body’s ability to
maintain a constant internal temperature of 37 degrees Celsius.
4. Describe the main differences between asexual and sexual reproduction. Why are both
types of reproduction common?
In asexual reproduction all the genetic information comes from one parent, so organisms
are almost identical. In sexual reproduction the genetic information comes from two
parents, generating variation. Asexual reproduction is quicker and works in habitats that
are stable. Sexual reproduction allows populations to adapt to changing environmental
conditions.
5. Describe a specific adaptation in an organism familiar to you, and explain how the
environment could have selected for that adaptation.
[Answers will vary]
6. How are the members of the three domains similar? How are they different?
The members of all three domains are made of at least one cell and contain DNA. The
domains are different, however, since DNA sequences differ between bacteria and
archaea. Eukaryotes have a nucleus and can be multicellular.
7. Find an example of a news story that describes an experiment. Which components of
the scientific method can you identify in the article?
[Answers will vary]
8. Give two examples of questions that you cannot answer using the scientific method.
Explain your reason for choosing each example.
Science cannot answer questions regarding moral, ethical, aesthetic, and religious issues.
Two examples of questions that science cannot answer are “Is a rattlesnake or a peacock
more beautiful?” and “Is it ethical to use animals in cosmetics research?”
9. If you dissect and label the parts of an earthworm, are you “doing science”? Why or
why not? Give an example of a testable hypothesis that could result from a dissection.
The act of dissecting and identifying the parts of an earthworm is not science, but it
provides investigators with the anatomical knowledge needed to ask questions and
develop hypotheses. A testable hypothesis resulting from such an activity could address
the relationship between the size of an earthworm and the number of segments.
10. Studies show that drug company-funded research is more favorable to new drugs than
is publicly funded research. How can scientists avoid such systematic biases?
Double-blind experiments and the freedom to publish all results, both positive and
negative, would help scientists to avoid bias.
11. For each of the following examples, state whether each of the following faults
occurred: (I) experimental evidence does not support conclusions; (II) inadequate
controls; (III) biased sampling; (IV) inappropriate extrapolation from the experimental
group to the general population; (V) sample size too small. a) “I ran 4 miles every
morning when I was pregnant with my first child,” the woman told her physician, “and
Jamie weighed only half as much as a normal baby. This time, I didn’t exercise at all, and
Jamie’s sister had normal birth weight. Therefore, running during pregnancy must cause
low birth weight.” b) Eating foods high in cholesterol was found to be dangerous for a
large sample of individuals with hypercholesterolemia, a disorder of the heart and blood
vessels. It was concluded from this study that all persons should limit dietary cholesterol
intake. c) Osteogenesis imperfecta (OI) is an inherited condition that causes easily
fractured bones. In a clinical study, 30 children with OI were given a new drug for 3
years. The children all showed less fatigue, improved bone density, and a lowered
incidence of fractures compared with before treatment began. The conclusion: the drug is
effective in treating OI. d) Researchers studied HIV in blood and semen from 11 HIVinfected men. In eight of the men, the virus was resistant to several medications. In two
men, virus from the blood was resistant to the class of drugs called protease inhibitors,
but virus from semen was not resistant. The researchers concluded that protease
inhibitors do not reach the male reproductive organs.
Scenario A: the evidence supports the conclusion, but faults (II), (IV), and (V) mean that
the evidence is unreliable. Scenario B: Without more information, it is not possible to
determine whether fault (II) occurred; fault (IV) is the main problem. Scenario C: The
main faults are (II) and (V). Scenario D: Fault (V) certainly occurred; faults (I) and (IV)
are possible; without more information, it is not possible to determine whether faults (II)
or (III) occurred.
12. Design an experiment to test the following hypothesis: “Eating chocolate causes zits.”
Include sample size, independent variable, dependent variable, the most important
variables to standardize, and an experimental control.
Overall, the experiment would require dividing a population into two groups, one of
which received chocolate and the other not receiving chocolate. After some
predetermined amount of time, the researchers would measure the density of pimples in
each group. The independent variable in this experiment is the treatment group
(chocolate or no chocolate), and the dependent variable is the density of zits. The
experiment should include a large sample size (hundreds of people at minimum). The
variables to standardize include: other components of the diet, the age group of the
subjects, and the subjects’ history of skin problems. The control group would consist of
individuals not consuming chocolate.
13. Morgellons syndrome is a medical mystery. Patients experience sensations of
stinging, biting, or crawling skin; they may also have rashes or sores that are slow to heal.
Scientists have proposed several hypotheses to explain the symptoms: the patients may be
imagining the disorder and creating the sores by picking at their skin; “Morgellons
syndrome” may simply be a new name for a recognized skin disorder such as dermatitis
or a bacterial infection; or exposure to toxins in the environment may cause the
symptoms. If you had unlimited resources, what data might you collect to test each
hypothesis?
Some possible data to collect could include the following: Hypothesis 1 – video
observations or 24-hour surveillance to check for picking sores; Hypothesis 2 – collect
samples from all infected individuals and test for the presence of bacteria; Hypothesis 3 –
test the home and work environments of all patients for toxin levels.
14. Review “The Saccharin Scare” box on page 14. If you were investigating a possible
saccharin-cancer link today, how would you improve on the design of the experiments
conducted in the 1970s? Also, develop a hypothesis that could explain why more male
than female rats developed tumors. Design an experiment that would help you test your
hypothesis.
Improvements could include multiple treatment levels for saccharin dosage, larger
sample sizes in each treatment group, and tests comprised of multiple treatments over
several animal models maintaining a consistent experimental design. Potential
hypotheses and experimental design will vary, but experiments should have a large
sample size for the control and experimental groups, state specific standardized variables,
include a measurable outcome, and have a manipulated variable that differs between the
groups.
Pull It Together
1. What are the elements of a controlled experiment?
A controlled experiment consists of a control group and experimental group. There
should only be one difference between the groups and this difference is one of the
independent variables in the experiment. The control group is one that is considered
“normal” for the variable being tested. It could be a healthy population compared to a
diseased population or it could be a population receiving no treatments compared to a
population receiving treatments.
2. Name and briefly describe the three domains of life.
The three domains of life are Eukarya, Bacteria and Archaea. Domain Bacteria consists
of single-celled organisms with a simple cellular structure. Domain Archaea consists of
archaebacteria and single-celled organisms similar to bacteria. Some live in extreme
environments where no other forms of life can survive. Domain Eukarya consists of
organisms made of more complex cellular structures containing many internal organelles,
such as chloroplasts or mitochondria.
3. What is the relationship between natural selection and evolution?
Natural selection is the driving force for evolution. A huge variety of characteristics can
make some organisms stronger, better able to survive environmental stress, more able to
find resources, more able to avoid predation, and ultimately more likely to reproduce.
The process of natural selection is one of several forces that casues the genetic makeups
of a population to change from generation to generation.
4. List the levels of biological organization, from atoms to the biosphere, and describe the
relationships among them.
Atoms are assembled into molecules. Molecules are assembled into cells. Cells are the
“building blocks” of organisms. Organisms of the same type live together in populations.
Many different populations that live together and rely on each other make up a
community. The non-living environments filled by specific community types make
biomes. All the biomes on the planet and their interrelation make the biosphere.
(note: ecosystems not mentioned)