Answer Key—Tests
Chapter 1—Test A
flipper helps the whale swim through water. The
human arm has many functions including grasping
things, moving objects, and helping move the human
body around. The structures have similar bone
arrangements and are located at approximately the
same place on each organism’s body. However, the
structures are not completely identical. For example,
bone lengths are different and joints are located in
different places. 35. A population is a group of one
type of organisms that live in an area. Examples
might include a herd of bison on a prairie; all of the
clover plants in a field; all of the aphids on a plant; all
of the earthworms in a particular plot of ground.
Accept any two answers that correctly identify a
population with one type of organism in one location.
Multiple Choice 1. b 2. d 3. b 4. c 5. b 6. b 7. c 8. d
9. b 10. b 11. b 12. a 13. c 14. d 15. b Completion
16. controlled 17. open-minded; skeptical; objective
18. peer review 19. function 20. 3 Short Answer
21. Sample answer: Reviewers must be anonymous
and independent so that they are not biased or
influenced by the ideas in the papers or the scientists
who wrote the papers. 22. Saying “just a theory”
implies that the idea is just a hunch. Scientific
theories like evolution are much stronger than a
hunch—they are well– tested and well–accepted
explanations supported by a large body of evidence.
23. A bias is a particular preference or point of view
that is personal rather than scientific. 24. Student
answers may include any science-based question that
affects society but is not a question that involves
morals, ethics, or making judgements based on
personal opinion. Using Science Skills 25.
Reproduction is important to maintaining a group of
animals. An individual member of the group can
survive without reproduction, but the entire group
would die out if none of its members reproduced. 26.
Rabbit B is the control. 27. Ice (temperature) is the
variable. 28. The fur color of the Himalayan rabbit
changes with the temperature. 29. Rabbit B is the
control. Without a control, the cause of any observed
change cannot be determined. 30. When the body of a
Himalayan rabbit is cool, the rabbit’s fur will grow in
dark. When the rabbit’s body is warm, the fur will
grow in white. Essay 31. One goal of science is to
investigate and understand the natural world, to
explain events in the natural world, and to use those
explanations to make useful predictions. 32. A theory
can change over time. No theory is considered
absolute truth. As new evidence is uncovered, a
theory may be revised or replaced by a more useful
explanation. 33. Anything lacking one or more of the
following characteristics of life is nonliving: made up
of cells; reproduces; based on a universal genetic
code; grows and develops; obtains and uses materials
and energy; responds to its environment; maintains a
stable internal environment; and, taken as a group,
changes over time. 34. The functions of the structures
are different. The bird wing and the bat wing allow
those animals to fly and the
Chapter 1 —Test B
Multiple Choice 1. b 2. b 3. d 4. b 5. c 6. c 7. c 8. a
9. b 10. b 11. a 12. d 13. b 14. c 15. d Completion
16. predictions 17. curiosity 18. theory 19.
metabolism 20. energy Short Answer 21. Science is
always changing and advancing so the facts may
change over time. 22. Sample answer: The missing
mineral in the diet is needed for the health of the rats.
23. Sample answer: The paper may contain mistakes,
unfair influences, or fraud. 24. Saying that an idea is
“just a theory” implies that the idea is just a hunch.
Scientific theories like evolution are much stronger
than a hunch—they are well-tested and well-accepted
explanations supported by a large body of evidence.
25. Global ecologists study how humans impact the
Earth and the other living things on Earth. Using
Science Skills 26. meter, centimeter, millimeter,
kilometer 27. Milliliters and cubic centimeter are
equal units. 1000 mL = 1 L = 1000 cm3. 28. The
boiling point of water in degrees Celsius is 100°C. 29.
The prefix kilo- means 1000. 30. 2 L of water is equal
to 2000 mL.
Chapter 2 —Test A
Multiple Choice 1. c 2. b 3. d 4. b 5. d 6. b 7. a 8. c
9. a 10. b 11. d 12. c 13. a 14. d 15. b Completion
16. electrons 17. electrons 18. monomers 19.
reactants Short Answer 20. activation energy 21.
No. The properties of a compound are usually
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Answer Key—Tests • Chapter 2
different from the properties of the elements that
make up the compound. 22. The sodium atom loses
an electron and becomes positively charged. The
chlorine atom gains an electron and becomes
negatively charged. The two charged ions then form
an ionic bond. 23. The atoms in H2 gas and O2 gas are
rearranged into water molecules. Covalent bonds are
formed between the H and O atoms. 24. The ability of
water to form multiple hydrogen bonds accounts for
water’s properties of adhesion and cohesion. 25. A
mixture is a material composed of two or more
elements or compounds that are physically mixed
together but not chemically combined. Using
Science Skills 26. enzyme Y 27. about 45°C 28.
Enzyme X’s optimum temperature is 40ºC and
enzyme Y’s optimum temperature is about 80ºC. 29.
enzyme X 30. enzyme Y Essay 31. Isotopes of an
element have the same number of protons but
different numbers of neutrons. Because the mass
number is the sum of the atomic number (number of
protons) and the number of neutrons, isotopes of the
same element have different mass numbers. 32. The
pH of pure water is 7, or neutral. Tomato juice, with a
pH of 4, contains higher concentrations of H+ ions
than pure water and is an acidic solution. Soap, with a
pH of 10, contains lower concentrations of H+ ions
than pure water and is a basic solution. 33. First,
organic compounds contain carbon atoms, each of
which has four valence electrons. Each electron can
join with an electron from another atom to form a
covalent bond. Carbon can bond with many elements,
including hydrogen, oxygen, phosphorus, and
nitrogen. Second, a carbon atom can bond to other
carbon atoms, which gives carbon the ability to form
chains that are of great length. These carbon–carbon
bonds can be single, double, or triple bonds. Chains
of carbon atoms can even close upon themselves to
form rings and loops. Carbon thus has the ability to
form millions of different large and complex
structures. 34. Carbohydrates, nucleic acids, and
proteins are polymers because each is made up of
different monomers. Simple sugars
(monosaccharides), nucleotides, and amino acids are
the monomers that make up those polymers. Some
lipids are made up of a glycerol molecule and three
fatty acids. These are not polymers because they are
not made up of monomers. 35. During a chemical
reaction, chemical bonds in the reactants are broken
and chemical bonds are formed to make the products.
Energy is released or absorbed whenever bonds are
broken or formed.
Chapter 2 —Test B
Multiple Choice 1. d 2. b 3. c 4. a 5. b 6. a 7. d 8. b
9. a 10. c 11. a 12. b 13. c 14. b 15. d Modified
True/False 16. T 17. T 18. T Completion 19.
chemical Short Answer 20. ionic 21. The sodium
atom loses an electron and becomes positively
charged. The chlorine atom gains that electron and
becomes negatively charged. The two charged ions
then form an ionic bond. 22. Add some salt—the
solute—to a container of water—the solvent—to
produce a salt solution. 23. Atoms have equal
numbers of negative electrons and positive protons.
24. The energy comes from chemical reactions that
release energy stored in food. 25. Answer should
include two of the following: regulating chemical
pathways, making materials that cells need, releasing
energy, and transferring information. Using
Science Skills 26. hydrochloric acid 27. 6.2 28.
13.0 29. The H+ ion concentration of sea water is
lower than the H+ ion concentration of pure water. 30.
Yes. According to Figure 2–2, some foods such as
tomatoes are acidic, yet are safe to eat.
Unit 1 —Test A
Multiple Choice 1. c 2. b 3. c 4. a 5. d 6. a 7. b 8. a
9. a 10. c 11. b 12. b 13. d 14. b 15. c Completion
16. independent or manipulated 17. compound 18.
enzyme 19. hypothesis 20. asexual Short Answer
21. Students should list five of these eight
characteristics: made up of units called cells, ability
to reproduce, based on a universal genetic code,
ability to grow and develop, ability to obtain and use
materials and energy, ability to respond to the
environment, ability to maintain a stable internal
environment, and tendency as a group to change over
time. 22. Isotopes of an element all have the same
chemical properties because they have the same
number of electrons. 23. An acidic solution contains a
higher concentration of H+ ions than pure water and
has a pH value above 7. A basic solution contains a
lower concentration of H+ ions than pure water and
has a pH value above 7. 24. A chemical reaction is a
process that changes one set of chemicals into another
set of chemicals. 25. Cell cultures can be used to test
cell responses under controlled conditions, to study
interactions between cells, and to select specific cells
for further study.
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Answer Key—Tests • Chapter 3
Chapter 3—Test A
26. Adhesion is the attraction between molecules of
different substances, whereas cohesion is the
attraction between molecules of the same substance.
27. Whenever possible, a hypothesis should be tested
by an experiment in which only one variable is
changed at a time. Using Science Skills 28.
milligram, gram, kilogram, metric ton 29. 0°C 30. one
hundredth 31. 5000 32. Because metric units are
scaled on multiples of 10, converting meters to
centimeters entails multiplying by 1000, a multiple of
10. Converting yards to inches, however, would entail
multiplying the number of yards by 36, which is the
number of inches in each yard. Essay 33. A
hypothesis is a proposed scientific explanation for a
set of observations. A particular hypothesis may
become so well supported that scientists consider it a
theory. A theory applies to a well-tested explanation
that unifies a broad range of observations. 34. An
ionic bond is formed when one or more electrons are
transferred from one atom to another. A covalent
bond forms when electrons are shared between atoms.
35. In an enzyme-catalyzed reaction, the substrates
bind to the site on the enzyme called the active site.
The active site and the substrates have
complementary shapes. The enzyme and the
substrates form an enzyme-substrate complex, and
they remain bound until the reaction is done.
Multiple Choice 1. c 2. b 3. c 4. a 5. c 6. d 7. d 8. b
9. c 10. d 11. d 12. b 13. a 14. a 15. d Modified
True/False 16. F; oxygen 17. T 18. T 19. T
Completion 20. decomposers 21. 50 22. biotic
Short Answer 23. Organisms interact with each
other and their environments. These interactions
produce a web of interdependence among individual
organisms, species, populations, communities, and
the environments in which they live at every level of
organization in the biosphere. 24. The two producers
are alike because they both produce carbohydrates
and oxygen and are essential to the flow of energy
through the biosphere. They are different because
they get their energy from different sources. 25.
Sometimes consumers are much less massive than the
organisms they feed upon. For example, thousands of
insects may graze on a single tree. The tree has a lot
of biomass, but it is only one organism. So the “base”
of the pyramid will be small and the next level up will
be wider. Using Science Skills 26. Figure 3–8 is
an example of a model. 27. The deer is on the second
trophic level, so it is two steps away from the sun.
You can tell because there is only one arrow between
it and a producer that relies on the sun. 28. An
ecosystem is a collection of all the organisms that live
in a particular place, together with their nonliving, or
physical, environment. A food web shows only the
living parts of an ecosystem. It does not show the
nonliving parts of the ecosystem. 29. There is one
first-level consumer for corn, three for carrots, four
for flowering shrubs, and one for trees. 30. The
mouse population would be the most directly
affected. The mice are the only consumers who eat
corn. Essay 31. Ecologists use observation,
experimentation, and modeling. Observation involves
asking questions and using senses to gather
information. Experimentation is used to test
hypotheses. Ecologists might set up artificial
environments or carefully change parts of natural
ecosystems to do experiments. Ecologists use
modeling to understand phenomena that are difficult
to study directly. Some models are mathematical
models based on data gathered through observation
and experimentation. 32. Students’ answers will vary.
All answers should describe at least one biotic factor
affecting more than one abiotic factor. Sample
answer: Trees around a pond can shade the pond,
thereby reducing the amount of sunlight
Unit 1 —Test B
Multiple Choice 1. b 2. b 3. c 4. a 5. c 6. d 7. a 8. d
9. c 10. c 11. b 12. a 13. d 14. b 15. d Completion 16.
sexual 17. enzyme 18. asexual 19. protons 20.
carbohydrates Short Answer 21. An acidic solution
contains a higher concentration of H+ ions than pure
water and has a pH value above 7. A basic solution
contains a lower concentration of H+ ions than pure
water and has a pH value above 7. 22. A chemical
reaction is a process that changes one set of chemicals
into another set of chemicals. 23. Adhesion is the
attraction between molecules of different substances,
whereas cohesion is the attraction between molecules
of the same substance. 24. In a saltwater solution, the
sodium and chloride ions that make up the salt
gradually become dispersed in the water, becoming
evenly distributed throughout the solution. 25. An
enzyme speeds up a chemical reaction by lowering
the activation energy. Using Science Skills 26.
coffee 27. 12.0 28. Blood is a base. 29. Lemon juice
has more H+ ions than OH– ions. 30. 200 times
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Answer Key—Tests • Chapter 4
that reaches the pond. The temperature of the pond
water will not be as high as the temperature would be
if more sunlight hit the water. 33. Unlike most other
organisms, certain types of bacteria are able to use
nitrogen gas from the atmosphere directly. These
bacteria, which live in the soil and on the roots of
legumes, convert nitrogen gas to ammonia during the
process of nitrogen fixation. Decomposer bacteria in
the soil convert ammonia into nitrates and nitrites,
which are also used by producers. Still other soil
bacteria obtain energy by converting nitrates into
nitrogen gas during the process of denitrification,
returning the nitrogen to the atmosphere. 34. The
growth of crop plants is usually limited by one or
more nutrients that the plants need. Fertilizers add
large amounts of nitrogen, phosphorus, and
potassium, which help plants grow better in soil that
is low in those nutrients. Some fertilizers also contain
other nutrients, such as calcium, magnesium, and
sulfur, in small amounts. Adding all these nutrients in
fertilizers makes the soil more productive. In that
way, farmers can grow better, larger crops and make
more money. 35. A pyramid of energy shows the
relative amount of energy available at each trophic
level of a food chain or a food web. A pyramid of
biomass shows the relative amount of living organic
matter available at each trophic level in an ecosystem.
A pyramid of numbers shows the relative number of
individual organisms at each tropic level in an
ecosystem.
25. The first-level consumers would provide 10
percent (one tenth) of 1500 calories, or 150 calories,
of energy to the second-level consumers. The secondlevel consumers would provide one tenth of 150
calories, or 15 calories, of energy to the third-level
consumer. Using Science Skills 26. Grass,
caterpillar, robin, fox, and mountain lion is the
longest food chain in Figure 3–4. 27. Trees and
grasses are the primary producers in Figure 3–4. 28.
There are no omnivores in Figure 3–4. No consumer
shown eats both plants and animals. 29. The deer
would be the most affected. They are the only species
that feeds exclusively on trees. Caterpillars would
also be affected but not as much as the deer. The
caterpillars feed on trees, but they also feed on grass.
30. The snake would obtain more energy after eating
a grasshopper. When the snake eats a grasshopper, the
snake is a second-level consumer. When the snake
eats a frog, it is a third-level consumer. A greater
percentage of energy from the grass is still available
from the grasshopper than from the frog.
Chapter 4—Test A
Multiple Choice 1. d 2. a 3. a 4. c 5. b 6. d 7. b 8. b
9. b 10. c 11. b 12. c 13. c 14. a 15. b Completion
16. competitive exclusion 17. plant 18.
commensalism 19. secondary 20. wetland Short
Answer 21. An area’s climate is made up of the
average conditions for that area over long periods. A
climate area can be divided into several
microclimates because environmental conditions can
vary over small distances. 22. Accept any response
that is properly supported by an explanation. Sample
answer: Conditions on Earth would be worse if the
concentration of greenhouse gases increased because
the amount of heat trapped by the gases would
increase. This increase in global temperature would
change climates on Earth. Alternate answer:
Conditions on Earth would be worse if the
concentration of greenhouse gases decreased because
the amount of heat escaping into space would
increase. This increased loss of heat would decrease
global temperature and would change the climates on
Earth. 23. Predators keep the population of their prey
from getting too large by eating the prey animals. 24.
A desert biome is defined as having less than 25 cm
of annual rainfall. 25. The circulation distributes heat,
oxygen, and nutrients. Using Science Skills 26.
No, sea cucumbers are not photosynthetic. They live
in the open ocean aphotic zone. No
Chapter 3 —Test B
Multiple Choice 1. d 2. c 3. b 4. a 5. c 6. d 7. d 8. c
9. c 10. d 11. c 12. a 13. a 14. a 15. d Completion
16. ecology 17. condensation 18. algae 19. four 20.
biotic Short Answer 21. Sharks are the top
consumer in a food chain that begins with algae.
Algae are producers that get their energy from the
sun. Energy from the sun eventually is passed on to
the shark through the food chain that begins with the
algae. 22. Students’ answers should include most of
the following: Biotic factors: trees, grasses, deer,
ducks/birds, frog, cattails (the tall plants on the left);
Abiotic factors: water, rock, air, sunlight, soil 23. The
cycling of oxygen, carbon, nitrogen, and hydrogen
make these materials available to living organisms in
a form that cells can use. 24. A large input of a
limiting nutrient, such as nitrogen or phosphorus, can
cause the algae to grow and reproduce more quickly.
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Answer Key—Tests • Chapter 4
light penetrates that part of the ocean. Therefore, sea
cucumbers would not have light to perform
photosynthesis. 27. Student answers should list at
least three organisms listed in the intertidal zone
column aside from birds. The intertidal zone is
covered by water during high tide but is exposed to
the air during low tide. So organisms that stay in this
area are sometimes underwater and sometimes
exposed to the air. 28. At 6000 meters, in the area of
the deep-sea vent, chemosynthetic bacteria are the
producers, providing energy for organisms that
inhabit the area. Other benthos feed on dead organic
materials that drift down from the surface. At 100
meters, algae are probably the producers because this
is probably within the photic zone. Complex food
webs exist in this upper area of the ocean. 29. The
intertidal zone (sea urchins, snails), the coastal ocean
zone (dolphins, jellyfish, plankton, sea urchins,
sharks, snails, whales), and the open ocean photic
zone (dolphins, jellyfish, plankton, sharks, whales) all
have some organisms in common. The factor that all
three of these zones have in common is the amount of
light. All of these zones are shallow enough to have
enough light for photosynthesis. 30. At high tide, sea
water is an abiotic factor because the intertidal
organisms are submerged. At low tide, the abiotic
factors are exposure to air, sunlight, heat, battering
waves, and strong currents. Essay 31. Cold water
near the poles sinks and then flows parallel to the
ocean bottom, eventually rising again in warmer
regions through a process called upwelling.
Meanwhile, surface water is moved by winds. In both
cases, the water flow creates ocean currents. Like air
currents, ocean currents transport heat within the
biosphere. Surface ocean currents warm or cool the
air above them, thus affecting the weather and climate
of nearby landmasses. 32. Primary succession occurs
on newly exposed surfaces, such as a fresh lava flow
that has destroyed the previous ecosystem. The first
organisms to appear are lichens that colonize the
newly formed volcanic rock. Over time, lichens break
down the rock, fix atmospheric nitrogen, and add
organic material as they decompose, creating soil.
Various types of plants, including mosses and
grasses, can then take root in the thin layer of soil. As
the soil gets thicker and richer from decomposing
organisms, seeds of shrubs and trees may take root. A
characteristic ecological community may eventually
dominate the area. 33. Competition between deer
probably caused the population decline. The deer
population grew so much that there were not enough
resources to support all the deer. The deer had to
compete for resources and many died. 34. Temperate
grasslands in the United States, Central Asia, and
Argentina belong to the same biome. They share the
abiotic characteristics of hot, dry summers, cold
winters, moderate precipitation, fertile soils, drought,
and susceptibility to wildfires. They share the biotic
characteristics of lush perennial grasses adapted to
cold and fire. All of these grasslands are found in
temperate biomes, even though they are far from one
another, because the angle at which the sun strikes
Earth in these areas is similar. Since they are in the
same biome, these areas have similar climates. Plants
and animals in all these locations display similar
characteristics, since they have adaptations enabling
them to survive in similar climates. 35. A river
ecosystem at its source flows rapidly and contains
little sediment, so few plants can become established.
As the water flows, it slows down and picks up
sediments. Where sediments build up, and the flow
slows, plants are able to establish themselves. The
water flows more slowly farther downstream, and the
plants and animals grow more diverse.
Chapter 4 —Test B
Multiple Choice 1. d 2. b 3. a 4. b 5. c 6. b 7. b 8. b
9. b 10. c 11. c 12. a 13. b 14. a 15. c Modified
True/False 16. F; competition 17. T 18. T
Completion 19. 23.5°N, 23.5°S 20. plant 21. climax
community 22. elevation 23. wetland 24. An area’s
climate is made up of the average conditions for that
area over long periods. A climate area can be divided
into several microclimates because environmental
conditions can vary over small distances. 25. Answers
should include at least three of the following: water,
light, nutrients, and space to grow 26. The two
species would be in competition, and the competitive
exclusion principle would apply. One species would
win out over the other, and the population of the
losing species would die out. 27. Predators keep the
population of their prey from getting too large by
eating the prey animals. 28. Near the source of a river
and stream the water flows quickly and few sediments
build up. Plants need sediments in which to establish
themselves. Using Science Skills 29. Tropical rain
forests, deserts, temperate forests, boreal forests, and
the tundra have relatively stable amounts of
precipitation all year long. 30. Trop513
Answer Key—Tests · Chapter 5
ical rain forests, tropical dry forests, tropical
grasslands/savannas/shrublands, and northwestern
coniferous forests have little seasonal variation in
temperatures.
last stage of demographic transition occurs when the
birth-rate equals the death rate. The model of age
structure for the United States shows fewer children
in the younger age categories, indicating a declining
birthrate. Essay 31. Population density is calculated
by dividing the number of individuals in a population
by the unit area. If one population has more members
than another population in areas of the same size, the
larger population will have a greater density per unit
area. For example, if there are 10 members of one
population who live in an area covering 2-square
kilometers, the population density is 5 members per
square kilometer. If there are 100 members of another
population that live in the same 2-square-kilometer
area, the population density is 50 members per square
kilometer. 32. A population will increase or decrease
in size depending on how many individuals are added
to it or removed from it. There are two ways
individuals can be added to a population. Individuals
can be born into the population or they can move into
it from outside the population, or immigrate. There
are two ways individuals can be removed from a
population. They can die or they can move out of the
population, or emigrate. 33. Exponential growth
occurs when the size of each generation of offspring
will be larger than the generation before it. At first,
the size of the population increases slowly; then, it
increases more and more rapidly until it approaches
an infinitely large size. Under ideal conditions with
unlimited resources, a population will grow
exponentially. Exponential growth does not continue
in natural populations for very long. As resources
become less available as the population grows, the
rate of population growth slows down. Logistic
growth occurs when a population’s growth slows or
stops following a period of exponential growth. 34.
Under ideal conditions, populations will continue to
grow if there are no factors that limit their growth.
Some factors in a population’s environment that can
limit growth are predation, competition, parasitism,
and disease. Other limiting factors are climate
extremes and human activities. 35. The predator/prey
relationship is one of the best-known mechanisms of
population control. As the predators feed on the prey,
the prey population falls. The decline in the prey
population is followed, sooner or later, by a decline in
the predator population, because there is less for the
predators to feed on. A decline in
Chapter 5—Test A
Multiple Choice 1. d 2. d 3. c 4. d 5. b 6. a 7. a 8. a
9. d 10. c 11. c 12. c 13. a 14. b 15. a Modified
True/False 16. T 17. T Completion 18. exponential
19. dependent. 20. high Short Answer 21. Drought
will affect a population in the same way regardless of
the population’s size or density 22. The population
that has 25 pine trees in 2 square kilometers has the
higher density because it has the same population size
in a smaller area than the population with 25 trees in
5 square kilometers. 23. Exponential growth of both
organisms will both produce a J-shaped curve on a
graph because each generation of off spring will be
larger than the generation before. However, the
organisms that reproduce slowly will take longer to
show as much growth. 24. People want to get rid of
introduced species regardless of the population
density. A density-independent limiting factor would
wipe out all members of a species in an area no
matter how densely populated the area is. 25. A
demographer can predict how a population will
change by studying factors such as its birthrates,
death rates, and age structure. Using Science Skills
26. Sample answer: One possible reason why the
diagrams have different shapes is that the birthrate in
Guatemala is higher than the birthrate in the United
States. This difference would make the bottom of
Guatemala’s diagram wider. Another possible reason
is that the death rate in the United States is lower than
the death rate in Guatemala. Fewer people dying
means that they live longer, which causes the top of
the US diagram to be fatter. 27. The population
growth in the United States will show a slight
increase in the older population and a slight decrease
in the younger population. This indicates a slow but
steady growth rate for the near future. 28. Guatemala
is experiencing a rapid growth rate because there are
more children than adults indicated. The birthrate is
high, and if the death rate fell, Guatemala would be in
an early stage of demographic transition. 29. The 80+
age group has a higher number of females than males
in the United States. This difference most likely
happens because women tend to have a longer lifeexpectancy than men in the United States. 30. The
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Answer Key—Tests • Chapter 6
the predator population means that the prey have
fewer enemies, so the prey population rises again.
This cycle of predator and prey populations can be
repeated indefinitely.
can be a renewable resource only if harvested
sustainably. 27. Sample answer: Fish make up a large
part of the human diet around the world. 28. About
27% 29. Sample answer: Because of overfishing, the
world fish stocks are being depleted. Marine habitats
are being destroyed. 30. Sample answer: Many fish
species may become extinct. Essay 31. The
sustainable development of water resources involves
protection of the natural systems involved in the
water cycle. For example, wetlands help to purify the
water running through them. As water flows slowly
through a wetland, densely growing plants filter
certain pollutants out of the water. Similarly, forests
and other vegetation help to purify the water that
seeps into the ground or runs off into rivers and lakes.
Water conservation is an important aspect of
sustainable development because the demand for
water is growing rapidly in many parts of the United
States. Measures such as drip irrigation reduce water
lost to evaporation, conserving the resource and
protecting the natural system, a key to sustainable
resource use. 32. Biodiversity is one of Earth’s
greatest natural resources. Species of many kinds
have provided us with medicines—including
painkillers, antibiotics, heart drugs, antidepressants,
and anticancer drugs. For example, the foxglove plant
contains compounds called digitalins that are used to
treat heart disease. When biodiversity is reduced,
potential sources of new medicines may be lost. 33.
Some zoos have established captive breeding
programs, in which animals are bred and raised in
protected surroundings in the hopes that a population
can someday be returned to the wild. Today,
conservation efforts include the protection of entire
ecosystems as well as single species. Protecting an
ecosystem will ensure that the natural habitats and the
interactions of many different species are preserved at
the same time. Governments and conservation groups
world-wide are working to set aside land or expand
existing areas as parks and reserves. 34. A person’s
ecological footprint is the total area of land and water
ecosystems needed to provide the resources the
person needs and to absorb and make harmless the
waste the person produces. Resources the person
needs include energy, food, water, and shelter. The
waste the person produces includes sewage and
green-house gases. 35. Damage to the ozone layer by
chlorofluorocarbons (CFCs) has left a vast area over
Antarctica that is thin enough every winter.
Chapter 5—Test B
Multiple Choice 1. d 2. b 3. a 4. c 5. d 6. c 7. a 8. c
9. c 10. a 11. b 12. a 13. c 14. b 15. b Modified
True/False 16. T 17. F; predator-prey 18. F;
dependent 19. F; nineteenth Completion 20. age
structure 21. exponentially 22. dependent Short
Answer 23. A limiting factor is a factor that causes
population growth to decrease, such as competition,
drought, predation, or disease. 24. Drought will affect
a population in the same way regardless of the
population’s size or density. 25. Population growth
has slowed in the United States, but China and India
are only in the beginning stage of demographic
transition where the population is still growing
rapidly. Using Science Skills 26. 1900 27. The
deaths per thousand is the same in 1960 and 1970. 28.
1990 (6.9) 29. The number of births over deaths since
1950 steadily decreases from 14.5 in 1950 to 6.9 in
1990. 30. Figure 5–4 shows that as the life
expectancy at birth increases, the deaths per thousand
decreases. Increased life expectancy means that
people live longer. Because they live longer, fewer
people die in a certain period of time.
Chapter 6 —Test A
Multiple Choice 1. b 2. a 3. d 4. b 5. c 6. c 7. c 8. d
9. b 10. b 11. c 12. d 13. d 14. a 15. c Completion
16. monoculture 17. renewable 18. water shed 19.
species diversity; biodiversity 20. invasive Short
Answer 21. Industrial growth results in increased
burning of fossil fuels and increased production of
waste and pollution. 22. Sustainable development
aims to provide for human needs while preserving the
ecosystems that produce natural resources. 23. Soil
erosion is the removal of soil by water or wind. 24.
Species of many kinds provide us with food and
medicines. In addition, diverse ecosystems are
healthy ecosystems and their stability and
productivity are beneficial to humans. 25. Animals,
such as the carrier pigeon, have often been hunted to
extinction. Populations of rare animals are hunted for
fur, hides, meat, horns, and other body parts, which
makes them vulnerable to extinction. Using
Science Skills. 26. Fish, an ocean resource; the fish
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Answer Key—Tests • Chapter 6
to allow higher than normal amounts of UV radiation
to strike Earth. UV radiation causes sunburn, and
excess exposure to UV can cause cancer, damage
eyes, and decrease organisms’ resistance to disease.
Intense UV can damage tissue in plant leaves and
phytoplankton. The United States and many other
nations have an international agreement to phase out
the use of CFCs.
are energy pyramids, biomass pyramids, and numbers
pyramids. Using Science Skills. 26. From 1880 to
1980, the acidity increased from a pH of about 6.8 to
a pH of about 4.8. The likely cause of the change is
acid rain. 27. Mussels are least tolerant of increased
acidity. Lake trout are most tolerant. 28. The survival
of smallmouth bass is first affected by increasing
acidity at a pH of about 5.8. 29. Mussels are most
likely to be threatened by extinction if the above trend
continues. 30. The change in acidity is a densityindependent factor, because it is caused by human
activities and not by the size of mussel and fish
populations. Essay 31. A predator-prey relationship
is one of the best-known mechanisms of population
control. Increases in the prey population are followed
by increases in the predator population. As the
predators kill the prey, the prey population falls. The
decline in the prey population is followed by a
decline in the predator population because there are
fewer prey for the predators to feed upon. This cycle
of predator and prey populations can be repeated
indefinitely. 32. The unequal heating of Earth’s
surface drives winds and ocean currents, which
transport heat throughout the biosphere. Winds form
because warm air tends to rise and cool air tends to
sink. The upward movement of warm air near the
equator and the downward movement of cold air over
the poles create winds. The winds move heat
throughout the atmosphere, from regions of sinking
air to regions of rising air. Similar patterns of heating
and cooling occur in Earth’s oceans and create ocean
currents. 33. For most of human existence, the
population grew slowly. Life was harsh, and limiting
factors, such as diseases and lack of food, kept
population sizes low. About 500 years ago, the human
population began growing more rapidly. Agriculture
and industry made life easier and safer. The food
supply increased, and improved sanitation and
medicine reduced the death rate. At the same time,
birthrates in most places remained high, causing the
human population to experience exponential growth.
Over the past century, population growth in the
United States and some other countries has slowed
dramatically, as both birth and death rates have fallen
with increasing education and standards of living. 34.
Habitat fragmentation refers to the splitting of
ecosystems into pieces. As a result, remaining pieces
of habitat become biological “islands.” For example,.
Chapter 6—Test B
Multiple Choice 1. a 2. d 3. a 4. b 5. b 6. d 7. b 8. d
9. c 10. d 11. c 12. b 13. b 14. a 15. b Modified
True/False 16. F; oxygen 17. F; hot spots 18. T
Completion 19. sustainable development 20.
biological magnification 21. particulates 22. captive
breeding 23. greenhouse Short Answer 24.
Sustainable development aims to provide for human
needs while preserving the eco systems that produce
natural resources. 25. Soil erosion is the removal of
soil by water or wind. 26. Answers will vary. Sample
answer: Waste material dumped into a lake by a
factory is an example of point source water pollution.
Oil and grease washed off streets and into the water
supply is an example of nonpoint source water
pollution. Using Science Skills 27. The most
diverse group of species is insects, with more than
1,000,000 species. 28. The group “flowering plants”
has the highest number of species on the list, with 565
endangered species. 29. Table II. 30. The list will
likely have a lower number of endangered species.
Unit 2 —Test A
Multiple Choice 1. a 2. d 3. c 4. a 5. b 6. d 7 d 8. c
9. c 10. d 11. c 12. c 13. a 14. b 15. c Completion
16. ten 17. denitrification 18. tundra 19. exponential
20. monoculture Short Answer 21. Possible
answer: A sustainable strategy for protecting land
resources is contour plowing; for protecting forest
resources, replanting trees; for protecting fishery
resources, regulating the number and size of fish
caught. 22. Biological magnification is the process in
which increasing concentrations of toxic substances
accumulate at higher trophic levels of food chains and
food webs. 23. Aquatic ecosystems are determined
primarily by the depth, flow, temperature, and
chemistry of the overlying water. 24. Four important
characteristics of populations are geographic
distribution, density, growth rate, and age structure.
25. The three different types of ecological pyramids
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Answer Key—Tests • Chapter 7
Multiple Choice 1. b 2. d 3. c 4. a 5. b 6. c 7. a 8. d
9. d 10. d 11. b 12. a 13. d 14. c 15. d Completion
16. transmission 17. chromosomes 18. chloroplasts,
mitochondria 19. active transport 20. homeostasis
Short Answer 21. This cell is a prokaryote. It has a
cell wall, indicated by the letter B, and its DNA,
indicated by the letter C, is not enclosed in a nucleus.
22. Cell walls protect the plant cells from expanding
even under tremendous osmotic pressure. 23. Because
the concentration of water in the cup is greater than
the concentration of water in the raisin, water will
flow from the cup into the raisin. 24. (A) rough
endoplasmic reticulum; (B) cytoplasm; (C) smooth
endoplasmic reticulum; (D) nucleolus; (E) nucleus;
(F) mitochondrion; (G) Golgi apparatus; (H)
ribosome; (I) cell membrane 25. Both are forms of
active transport of large molecules carried out by
movements of the cell membrane. Endocytosis
involves taking material into the cell, whereas
exocytosis involves moving material out of the cell.
Using Science Skills 26. The experimental setup
shows a solution with differing concentrations of
solute separated by a selectively permeable
membrane. The membrane is permeable to water but
not the solute. 27. The solution on Side A has fewer
solute particles than the solution on Side B. Both
solutions have the same amount of water, so the
solution on Side A is hypotonic compared to the
solution on Side B. 28. The membrane is permeable
to water so water can cross the membrane in both
directions. Over time, there will be a net movement of
water toward Side B, which has a higher
concentration of solute particles. 29. At equilibrium,
Side A will have less water than Side B and the
concentration of solute molecules will be equal on
either side of the selectively permeable membrane.
30. Yes, the water molecules will continue to move
across the membrane; however, there will not be a net
movement from one side to the other. Essay 31. The
cell theory states that all living things are composed
of cells. It also says that cells are the basic units of
structure and function in living things, and that new
cells come from existing cells. The cell theory is
significant to biology because all living thing are
made of cells. Differences in the structure and
function of different life forms are reflected in
differences in their cell structures. 32. The cell
membrane is a thin, flexible barrier around the cell.
The cell
in suburbs, patches of forest can be surrounded by
farms, houses, and shopping malls. The smaller the
“island,” the fewer species can live there, the smaller
their populations can be, and the more vulnerable
they are to further disturbance or climate change. 35.
Population growth depends, in part, on how many
people of different ages make up a given population.
In a population with similar numbers of people in
each age group, the population growth rate is likely to
be low. There are relatively few people of
reproductive age to produce children, and there are
relatively great numbers of people in the older ages at
high risk of dying. In populations in which there are
many more young people than middle-aged and
elderly people, the population growth rate is likely to
be high. Many people are of reproductive age, and
there are relatively few people in the older ages at
high risk of dying.
Unit 2 —Test B
Multiple Choice 1. c 2. b 3. d 4. d 5. a 6. c 7. c 8. b
9. d 10. a 11. c 12. b 13 b 14. a 15. c 16. b
Completion 17. biosphere 18. sunlight 19. niche 20.
logistic 21. biological magnification Short Answer
22. Photosynthesis depends on light energy;
chemosynthesis relies on the energy within inorganic
molecules 23. Energy flows in one direction: first
from sunlight to producers and then from producers to
consumers. 24. Foreign species in new habitats often
become invasive because they lack parasites and
predators in the new habitats. 25. Latitude determines
the angle at which sunlight strikes Earth’s surface.
This, in turn, determines how much the surface is
heated and, thus, climate. 26. The three different
types of ecological pyramids are energy pyramids,
biomass pyramids, and numbers pyramids. Using
Science Skills 27. The graph represents the
interaction between a predator population and a prey
population. 28. The wolf population generally rises
whenever the moose population increases, because
there are more moose for the wolves to feed upon. 29.
An increase in the number of wolves usually is
followed by a decline in the moose population,
because the large number of wolves feeds upon
moose until they are reduced in number. 30. There are
almost always fewer wolves than moose, because
wolves are at a higher trophic level than moose, and
fewer organisms generally can be supported at a
higher trophic level.
Chapter 7—Test A
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Answer Key—Tests • Chapter 8
wall is a strong layer that surrounds the cell
membrane in some cells. The nucleus is a large
structure found in some cells. It contains the cell’s
genetic material and controls the cell’s activities. The
fluid portion of the cell outside the nucleus (if
present), is the cytoplasm. All cells have a cell
membrane and cytoplasm. Only eukaryotes have a
nucleus. Animal cells do not have a cell wall, but
plant cells and some prokaryotes do. 33. Microtubules
are hollow tubes of protein that help maintain the
shape of a cell. Microtubules also make up cilia and
flagella, which function in cell movement.
Microfilaments are long, thin fibers that are narrower
than microtubules. Microfilaments function in the
movement and support of the cell. 34. Facilitated
diffusion involves the movement of molecules across
a membrane through protein channels. The molecules
move from an area of high concentration to an area of
lower concentration. Facilitated diffusion does not
require additional energy. Active transport is the
movement of particles across the cell membrane
using energy. Molecules can move from an area of
low concentration to an area of higher concentration
in active transport. Osmosis is an example of
facilitated diffusion. 35. The cell from the unicellular
organism carries out all the life processes of the
organism. It is not specialized. The cell from the
multicellular organism is specialized and carries out
only certain functions in the organism, while relying
on other cells in the multicellular organism to
complete other life processes.
into chemical energy. The structures identified with
the letter D are mitochondria, which convert chemical
energy into compounds more convenient for the cell
to use. The cell with the chloroplasts is a plant cell.
26. Diffusion is the movement of molecules from an
area of higher concentration to an area of lower
concentration. 27. Both are forms of active transport
of large molecules carried out by movements of the
cell membrane. Endocytosis involves taking material
into the cell, whereas exocytosis involves moving
material out of the cell. Using Science Skills 28.
Drawing II—a plant cell—contains the structure
described (a chloroplast). The structure is labeled N.
29. The organelle labeled K is the nucleus. The
nucleus stores DNA and directs the activities of the
cell. 30. Both drawings represent eukaryotes, as
shown by the presence of a nucleus.
Chapter 8—Test A
Multiple Choice 1. d 2. d 3. d 4. a 5. c 6. c 7. c 8. b
9. d 10. d 11. d 12. b 13. d 14. a 15. c Completion
16. grana 17. stroma 18. ATP synthase 19. carbon
dioxide 20. decreases Short Answer 21. Pond
plants and phytoplankton are autotrophs. Ducks,
turtles, snails, insects, and fish are heterotrophs. 22.
Each carbon dioxide molecule contains one carbon
atom, and a glucose molecule contains six carbon
atoms. 23. Sample answer: Both are found in the
electron transport chain within the thylakoid
membranes. They both absorb light and use the
light’s energy to excite electrons. 24. The two cellular
regions must have a difference in concentration of
hydrogen ions in order for ions to flow through the
protein and cause it to turn ADP into ATP. Without
the membrane separating these regions, there could
not be a concentration gradient. 25. The lightdependent reactions use energy from the sun to
produce ATP and NADPH, and the light-independent
reactions (Calvin cycle) use ATP and NADPH from
the light-dependent reactions to produce high-energy
sugars Using Science Skills 26. The student is
varying the concentration of carbon dioxide in the
environment of two similar plants. The student is
probably trying to test the effect of carbon dioxide
concentration on plants. 27. The student might set up
a similar geranium plant under a bell jar with a tube
that allows air to enter and leave the plant’s
environment freely. 28. Plant A is being grown with a
carbon dioxide absorbant.
Chapter 7 —Test B
Multiple Choice 1. c 2. b 3. c 4. c 5. a 6. a 7. c 8. d
9. c 10. b 11. c 12. b 13. d 14. b 15. c Completion
16. cells 17. nucleolus 18. ribosomes 19. cell
membrane 20. active transport 21. cells, organs
Short Answer 22. The cell theory says that all
living things are composed of cells. It also says that
cells are the basic units of structure and function in
living things and that new cells come from existing
cells. 23. Prokaryotes are generally simpler and
smaller than eukaryotes, whereas eukaryotes enclose
their DNA in a nucleus and have other specialized
organelles. 24. The cytoskeleton helps the cell
maintain its shape and internal organization. It is also
involved in many forms of cell movement. 25. The
structure identified with the letter E is a chloroplast,
which captures energy from sunlight and converts it
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Answer Key—Tests • Chapter 9
A plant grown in an environment with depleted
carbon dioxide would not be able to carry out the
Calvin cycle—its rate of photosynthesis would likely
be slower than that of a plant grown under normal
contitions. Photosynthesis may even stop all together.
29. This plant has been in a carbon-dioxide-rich
environment. It will probably have a higher rate of
photosynthesis than a plant under normal conditions
because carbon dioxide is plentiful. 30. Plants require
carbon dioxide to produce starches. A higher
concentration of carbon dioxide surrounding a plant
can increase the production of starches. If the area
surrounding a plant is depleted of carbon dioxide, a
plant may not be able to produce any starches. Essay
31. A glucose molecule can store more than 90 times
the energy of an ATP molecule. Glucose is used by
cells to store large amounts of energy for long periods
of time. In contrast, ATP is used to store smaller
amounts of energy that will be used in the next few
seconds. Cells can regenerate ATP from ADP as
needed by using the energy from glucose. 32.
Chlorophyll absorbs light especially well in the red
and blue regions of the visible light spectrum
(reflecting green). Carotenes absorb light in the bluegreen parts of the visible spectrum (reflecting yellow,
orange, and red). Having more than one kind of
pigments increases the range of light from which a
plant can harvest energy. 33. The reactions that take
place within the photosystems and electron transport
chain require light in order to take place. ATP
synthesis is dependent on the products of these
reactions. Thus, the nickname “light reactions” for
these reactions is not misleading. However, the lightindependent reactions can take place under both light
and dark conditions. They do not require darkness, so
it is misleading to call them dark reactions. 34. Three
of the factors that affect the rate of photosynthesis are
light intensity, temperature, and water. The rate of
photosynthesis increases with light intensity up to a
certain point, then levels off . Photosynthesis slows at
extreme temperatures and usually has an optimal
temperature for each kind of plant. A lack of water
also slows down photosynthesis. 35. CAM plants do
not take in carbon dioxide through their leaves all the
time, as do other plants. Instead, CAM plants take it
in only at night, when temperatures are cooler. Their
leaves close up during the day so that water is not lost
to the warm air. Aquatic plants are not at risk from
drying out during the warm day, because they live in
water. Therefore, they do not need to close their
leaves during the day to prevent water loss.
Chapter 8—Test B
Multiple Choice 1. c 2. d 3. a 4. a 5. d 6. c 7. a 8. c
9. a 10. d 11. c 12. b 13. b 14. c 15. a Modified
True/False 16. T 17. T 18. F; Calvin cycle; lightindependent reactions 19. F; an H+ ion; a hydrogen
ion Completion 20. heterotrophs; consumers 21.
stroma 22. granum 23. ATP synthase 24. carbon
dioxide Short Answer. 25. Electron carriers accept
pairs of high-energy electrons and transfer them,
along with their energy, to other molecules. NADP+ is
one example of an electron carrier. 26. The lightdependent reactions use energy from the sun to
produce ATP and NADPH, and the light-independent
reactions (Calvin cycle) use ATP and NADPH from
the light-dependent reactions to produce high-energy
sugars. 27. water, light intensity, temperature. Using
Science Skills 28. The beaker she placed in the
shade is the control. 29. The bubbles are probably
oxygen gas, which is a product of photosynthesis. 30.
5 cm 31. The student’s data show that as the water
plant gets closer to the light, the water plant gives off
more bubbles.
Chapter 9 —Test A
Multiple Choice 1. c 2. a 3. c 4. c 5. b 6. a 7. a 8. d
9. a 10. a 11. d 12. c 13. a 14. b 15. a Completion
16. cellular respiration 17. pyruvic acid 18. H+ ions
19. 2 20. oxygen Short Answer 21. Arrow B
represents cellular respiration, because it shows the
flow of energy from plants to animals. Plants produce
food (sugars), which animals use to fuel cellular
respiration. 22. Photosynthesis releases oxygen into
the atmosphere as a product, whereas cellular
respiration uses oxygen as a reactant to release energy
from food. 23. The movement of H+ ions back across
the inner mitochondrial membrane through ATP
synthase converts ADP into ATP. 24. Oxygen is the
final electron acceptor in the electron transport chain,
which means that it is needed to get rid of low-energy
electrons and H+ ions. 25. Pathway A and pathway B
can both take place when there is no oxygen. When
cells run out of oxygen, they can still produce some
energy, even though they do so inefficiently. 26.
Using Science Skills 26. Sample answer: When
exposed to light, the
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Answer Key—Tests • Chapter 8
aquatic plants will carry out both cellular respiration
and photosynthesis. After a time in the dark, the
plants will carry out only cellular respiration. 27. The
purpose of the indicator is to detect the presence of
carbon dioxide. The plants will give off oxygen and
take in carbon dioxide when they are carrying out
photosynthesis. They will give off carbon dioxide and
take in oxygen when they are carrying out cellular
respiration. If the plants produce more carbon dioxide
in cellular respiration than they are able to use, the
indicator will change from blue to yellow. If the
plants produce and consume the same amount of
carbon dioxide, no new carbon dioxide will be
produced and the indicator will not change color. 28.
The solution in test tubes 2 and 3 will turn yellow
because the plants will give off CO2 from cellular
respiration but will not use it up through
photosynthesis. 29. After another 24 hours, test tube 2
will still be yellow. Test tube 3 will be blue again. 30.
Sample answer: The plant in test tube 2 remained in
the dark and was not able to carry out photosynthesis,
so it did not use up carbon dioxide. The carbon
dioxide keeps the bromthymol blue yellow. However,
the plant in test tube 3 was in the light, where it could
carry out photosynthesis. This plant used up the
carbon dioxide, and without carbon dioxide the color
of the bromthymol blue turned back to blue. Essay
31. If the energy in glucose were released in just one
step, most of the energy would be lost as heat. The
gradual process of cellular respiration allows the cell
to control the release of energy into packages of ATP
that can be used more efficiently for cell activities.
32. Sample answer: During the Krebs cycle, pyruvic
acid is broken down into carbon dioxide in a series of
energy-extracting reactions. Coenzyme A forms
acetyl-CoA, which later becomes citric acid. Citric
acid is then broken down, CO2 is released, and
electrons are transferred to energy carriers. One
molecule of pyruvic acid gives 4 molecules of
NADH, 1 molecule of FADH2, and 1 molecule of
ATP. 33. Sample answer: The electron carriers of
cellular respiration are NAD+ and FAD. These
molecules accept high-energy electrons (thus
becoming NADH and FADH2) and move to the
electron transport chain. The energy stored in these
electron carriers is transferred to the electron
transport chain. The electron transport chain, in turn,
uses the energy to move hydrogen ions across the
inner mitochondrial membrane, which creates a
charge difference across the membrane. 34. Lactic
acid is an indication that lactic acid fermentation is
occurring in muscle cells. Lactic acid fermentation
occurs only in the absence of oxygen. Thus, the heart
cells with more lactic acid may not have been
receiving enough oxygen, a factor that could
contribute to the occurrence of a heart attack. The
level of lactic acid could be measured in certain parts
of the heart as an indication of risk of heart attack. 35.
During brief periods of intense activity, muscle cells
may use oxygen faster than it can be supplied by the
body. When the oxygen supply gets very low, the
electron transport chain cannot function because
oxygen serves as its final electron acceptor. This
forces the Krebs cycle to stop. In this anaerobic
situation, the muscle cells can produce ATP only by
means of lactic acid fermentation.
Chapter 9—Test B
Multiple Choice 1. c 2. c 3. b 4. b 5. d 6. d 7. d 8. b
9. c 10. a 11. b 12. d 13. c 14. d 15. b Modified
True/False 16. F; oxygen 17.F; products 18. T 19. T
20. F; ATP Completion 21. the sun 22. 2 23. 2 24.
C Short Answer 25. Photosynthesis releases
oxygen into the atmosphere as a product, whereas
cellular respiration uses oxygen as a reactant to
release energy from food. 26. Citric acid is the first
compound formed in the process. 27. Alcoholic
fermentation produces carbon dioxide, alcohol, and
NAD+, whereas lactic acid fermentation produces
lactic acid and NAD+. Using Science Skills 28.
Sample answer: The equation for cellular respiration
is 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy. The
mouse should give off CO2 and H2O. 29. Sample
answer: The mouse requires oxygen and sugar from
food (glucose) to carry out cellular respiration. Fresh
air containing oxygen flows in through the tubes from
outside the flasks into flasks B, C, and D. Air mixed
with whatever the mouse gives off flows from flask B
into flask A. The mouse receives fresh air and should
be able to survive in the chamber for the duration of
the experiment. 30. Sample answer: If the mouse is
carrying out cellular respiration, it will give off CO2.
The CO2 will flow into flask A, and the
phenolphthalein in flask A will change from pink to
clear.
Chapter 10—Test A
Multiple Choice 1. c 2. c 3. c 4. b 5. c 6. b 7. c 8. a
9. c 10. c 11. c 12. d 13. b
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Answer Key—Tests • Chapter 10
14. c 15. c Modified True/False 16. T 17. F;
nuclear envelope Completion 18. 10 19. G1 phase,
Interphase 20. apoptosis 21. differentiation 22. adult
Short Answer 23. As a cell grows larger, more
demands are placed on its DNA, and the cell has
more trouble moving enough nutrients and wastes
across the cell membrane. 24. Because the offspring
of asexual reproduction are genetically identical to
parents, they have the characteristics that help them
survive in the conditions in which the parent cells
survived. They might not have characteristics to
survive should the conditions change. 25. A cell that
lacked cyclins would probably not undergo mitotic
division, and then it would continue to grow, have
DNA overload, and exchange materials inefficiently
until it dies. Using Science Skills 26. Diagram A
shows cancer cells because it shows cells that are not
growing in a controlled way. They have formed a
tumor. 27. Cancer cells do not respond to the signals
that control the growth of most cells. As a result,
cancer cells form masses (tumors). These signals
include growth factors that stimulate cell division at a
proper rate and signals that prevent excessive growth
so that tissues do not disrupt each other. Diagram A
shows cells that have divided until they have formed
a tumor. These cells are dividing more quickly than
normal cells do. They have started disrupting adjacent
cells. 28. They can break loose from the mass they are
now a part of and spread throughout the body,
disrupting normal activities, forming secondary
tumors, and causing serious medical problems. 29.
Diagram A: These cells might have a defect in the
p53 gene, which has allowed the cells to multiply
more quickly and chaotically than the normal cells.
Diagram B: These cells probably have a healthy copy
of the p53 gene, which has stopped the cell cycle until
the genetic material in these cells has been properly
replicated. 30. Students may suggest removing the
cancerous cells in hopes of preventing their continued
division, growth, and spread throughout the body,
treating them with radiation or chemicals that will
destroy the cells, etc. Essay 31 During growth, a
cell’s volume increases more rapidly than does its
surface area, causing its ratio of surface area to
volume to decrease with increasing size. As a cell’s
ratio of surface area to volume decreases, it becomes
more difficult for a cell to move needed materials in
and wastes out. Thus, a normal growing cell will
usually divide into two daughter cells before it
becomes too large. 32. Interphase consists of the G1
phase, S phase, and the G2 phase. During the G1
phase, the cell grows; during the S phase, the DNA
replicates; during the G2 phase, the cell prepares for
mitosis. The M phase or cell division includes mitosis
and cytokinesis. 33. Mitosis is the division of the
nucleus. Cytokinesis is the division of the cytoplasm.
If mitosis occurred without cytokinesis, the cell
would contain two nuclei and twice the DNA. If
cytokinesis occurred without mitosis, one of the new
cells would lack DNA and a nucleus altogether. 34.
Some people are opposed to stem cell research
because the harvesting of embryonic stem cells can
cause the destruction of embryos. They feel that
embryos are entitled to the same rights as adults.
People who believe that stem cell research should
continue argue that embryos do not have the same
rights as fully formed humans and that scientists must
do all they can to save lives. They feel that it is
unethical to restrict research. Student answers should
include their own opinion on the subject. 35.
Prophase: the chromatin condenses into
chromosomes, the centrioles separate (in animal
cells), and the nuclear membrane breaks down;
metaphase: the chromosomes line up across the
midline of the cell and each chromosome is attached
to a spindle fiber and centromere; anaphase: sister
chromatids separate into individual chromosomes;
telophase: chromosomes move to opposite sides of
the dividing cell, and two new nuclear envelopes
form.
Chapter 10—Test B
Multiple Choice 1. d 2. c 3. a 4. c 5. d 6. a 7. c 8. b
9. c 10. c 11. b 12. c 13. c 14. d 15. b Completion
16. sexual, asexual 17. 92 18. interphase 19.
metaphase 20. apoptosis 21. pluripotent Short
Answer 22. Because the offspring of asexual
reproduction are genetically identical to parents, they
have the characteristics that help them survive in the
conditions in which the parent cells survived. They
might not have characteristics to survive should the
conditions change. 23. Packaging genetic material
into chromosomes helps the cell separate the DNA
precisely during cell division. If the genetic material
was spread out into smaller pieces, some of the
material might get lost more easily when the cell
divided into two cells. 24. Chromatids are two
identical DNA strands joined by a centromere, and
chromatin is
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Answer Key—Tests • Chapter 10
the material (DNA and proteins) that makes up
chromosomes. 25. A: G1 phase, cell growth; B: S
phase, DNA replication; C: G2 phase, preparation for
mitosis; D: M phase, cell division (mitosis and
cytokinesis). 26. In metaphase the sister chromatids
are still attached to one another and are found in the
middle of the cell, whereas in anaphase the sister
chromatids have separated and are beginning to move
to opposite sides of the cell. Using Science Skills
27. Four 28. X is a centriole; Y is a spindle fiber. 29.
D, A, C, B 30. The next step would be cytokinesis. It
would show two daughter cells forming. Also accept
interphase or G1.
the light-dependent reactions to convert ADP and
NADP+ into the energy carriers ATP and NADPH.
They provide the energy to build high-energy sugars
in the Calvin cycle. 33. The process of releasing
energy from glucose is begun with glycolysis, which
yields 2 molecules of ATP. When oxygen is not
available, glycolysis is followed by fermentation,
which produces no more ATP molecules. When
oxygen is available, cellular respiration can occur.
That pathway results in the production of 34 more
ATP molecules, for a total of 36 ATP molecules from
a single molecule of glucose. 34. In the process of
photosynthesis, the light-dependent reactions convert
the electron carrier NADP+ into NADPH, which
provides energy to build high-energy sugars in the
Calvin cycle. In cellular respiration, the electron
carriers NADP+ and FAD+ are used to make NADPH
and FADH2. The electrons in those compounds are
used in the electron transport chain to convert ADP to
ATP. 35. During prophase, the chromatin condenses
into chromosomes. The centrioles separate, and a
spindle begins to form. The nuclear envelope breaks
down. During metaphase, the chromosomes line up
across the center of the cell. Each chromosome is
connected to a spindle fiber at its centromere. During
anaphase, the sister chromosomes separate into
individual chromosomes and are moved apart. During
telophase, the chromosomes gather at opposite ends
of the cell and lose their distinct shapes. Two new
nuclear envelopes form.
Unit 3 —Test A
Multiple Choice 1. a 2. a 3. c 4. b 5. a 6. a 7. c 8. b
9. a 10. d 11. d 12. b 13. a 14. d 15. b Completion
16. cell membrane 17. sunlight 18. osmosis 19.
glycolysis 20. mitosis Short Answer 21. All living
things are composed of cells. Cells are the basic units
of structure and function in living things. New cells
are produced from existing cells. 22. ATP, or
adenosine triphosphate, is one of the principal
compounds that cells use to store and release energy.
Energy is released when the chemical bond between
the second and third phosphates is broken. 23. 6CO2
+ 6H2O
C6H12O6 + 6O2 carbon dioxide + water
sugars + oxygen 24. Cell division causes the
ratio of surface area to volume to become greater in
the daughter cells. 25. An autotroph makes its own
food, whereas a heterotroph obtains energy from the
foods it eats. Using Science Skills 26. Structure G
is a centriole. 27. Structure M is a mitochondrion. 28.
Structure J is a vacuole. Its function is to store
materials. 29. Structure O is a chloroplast. There is no
corresponding structure in Diagram I because animal
cells do not contain chloroplasts 30. They represent
eukaryotic cells, because each of the two cells has a
nucleus. Essay 31 They are similar in that both
involve the movement of materials across a
membrane. Facilitated diffusion involves movement
of particles across the membrane through protein
channels. Yet, this process does not require use of the
cell’s energy because it is still diffusion. Active
transport, by contrast, does require use of the cell’s
energy because it is the movement of materials
against a concentration difference. 32. When
pigments in photosystem II absorb light, the light
energy is absorbed by electrons, increasing their
energy level. These high-energy electrons are used in
Unit 3 —Test B
Multiple Choice 1. b 2. c 3. c 4. c 5. c 6. b 7. c 8. a
9. a 10. b 11. a 12. a 13. b 14. c 15. b Completion 16.
tissue 17. oxygen 18. chromatids 19. osmosis 20.
glycolysis Short Answer 21. All living things are
composed of cells. Cells are the basic units of
structure and function in living things. New cells are
produced from existing cells. 22. carbon dioxide +
water
sugars + oxygen 23. Prophase,
metaphase, anaphase, telophase 24. ATP, or
adenosine triphosphate, is one of the principal
compounds that cells use to store and release energy.
Energy is released when the chemical bond between
the second and third phosphates is broken. 25. 6O2 +
C6H12O6
6CO2 + 6H2O + energy, oxygen +
glucose
carbon dioxide + water + energy Using
Science Skills 26. Structure G is a centriole. 27.
Structure M is
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Answer Key—Tests • Chapter 12
a mitochondrion. 28. Structure J is a vacuole. Its
function is to store materials. 29. Structure O is a
chloroplast. There is no corresponding structure in
Diagram I because animal cells do not contain
chloroplasts 30. They represent eukaryotic cells,
because each of the two cells has a nucleus.
and therefore had green seeds. 33. The kinds of off
spring produced by genetic crosses are the results of
chance. For example, the number of gametes
produced that contain particular alleles is not certain.
Likewise, the fusion of two gametes with particular
alleles is not certain. Thus, the results of genetic
crosses shown in Punnett squares are just probable
results. 34. The alleles that determine flower color in
four o’clock plants show incomplete dominance. She
should use pollen from white-flowered four o’clock
plants to pollinate red-flowered four o’clock plants, or
vice versa. She should then collect seeds from the off
spring. All of these hybrid seeds will produce only
pink-flowered four o’clock plants. 35. Both meiosis I
and meiosis II contain a prophase, a metaphase, and
an anaphase. However, chromosomes replicate prior
to meiosis I but not prior to meiosis II. Also, during
meiosis I, tetrads form and align along the center of
the cell. Then, the homologous chromosomes are
separated and two haploid daughter cells form.
During meiosis II, sister chromatids align along the
center of the cell and are then separated. Four haploid
daughter cells form.
Chapter 11 —Test A
Multiple Choice 1. c 2. c 3. d 4. a 5. a 6. c 7. b 8. c 9.
c 10. b 11. d 12. a 13. a 14. a 15. b Completion 16.
gametes, sex cells 17. round yellow seeds only 18.
polygenic trait Short Answer 19. Segregation
happens when the alleles for each gene separate. Each
gamete gets only one allele for each gene. The
principle of independent assortment states that the
way alleles for one pair of genes segregate does not
affect the segregation of other alleles. 20. Thirty of
the off spring are expected to be tall and have yellow
seeds. 21. 100% 22. Keep an arctic fox warm when
its native environment would be cool. 23.
Homologous chromosomes are the two sets of
chromosomes found in a body cell—one set inherited
from the male parent and the other inherited from the
female parent. 24. The genes that Mendel studied
were located on different chromosomes or were
located far apart on the same chromosome. 25.
Crossing-over occurs most frequently between the
star eye gene and the black body gene. Using Science
Skills 26. The structure is a tetrad. 27. New allele
combinations might form during stage A, which is
prophase I. 28. Generally, one egg would result. One
of the four haploid cells would form an egg. 29. The
cells in stages A, B, and C are 2N. The cells in stages
D, E, F, and G are N. 30. Each cell in stage G,
telophase II, has a single copy of each gene. Essay
31. The tall pea plant should be crossed with a short
pea plant. If the tall pea plant is homozygous, all of
the off spring will be tall. If the tall pea plant is
heterozygous, it is likely that about half of the off
spring will be tall and half will be short. 32. When the
heterozygous yellow-seed F1 plants produced
gametes, their dominant allele for yellow seeds
segregated from their recessive allele for green seeds.
As a result, some of their gametes had the dominant
allele, and others had the recessive allele. When the
F1 plants self-pollinated, some male gametes with the
recessive allele fused with female gametes with the
recessive allele during fertilization. Some of the off
spring that resulted had two alleles for green seeds
Chapter 11 —Test B
Multiple Choice 1. d 2. d 3. a 4. b 5. b 6. b 7. a 8. c 9.
b 10. b 11. c 12. b 13. b 14. c 15. a Modified
True/False 16. F; 50% 17. T 18. T Completion 19. P
20. TT and Tt 21. genes and environmental conditions
22. half 23. gene Short Answer 24. Garden pea
plants produce many off spring, they have traits that
come in only two forms, and crosses between the
plants can be controlled easily. 25. The phenotype
ratio is 9 round, yellow seeds : 3 round, green seeds :
3 wrinkled, yellow seeds : 1 wrinkled, green seed. 26.
A diploid cell has two sets of chromosomes. 27.
Homologous chromosomes are the two sets of
chromosomes found in a body cell—one set inherited
from the male parent and the other inherited from the
female parent. Using Science Skills 28. The genotype
of the off spring is bbRR. 29. The phenotype of the
off spring is white, rough hair. 30. The phenotypes of
the off spring are black, rough hair; black, smooth
hair; white, rough hair; and white, smooth hair.
Chapter 12 —Test A
Multiple Choice 1. a 2. d 3. b 4. c 5. b 6. d 7. d 8. c 9.
a 10. c 11. c 12. c 13. a
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Answer Key—Tests • Chapter 13
14. b 15. a Completion 16. AGCT 17. Hydrogen
bonds 18. histones 19. enzymes 20. telomeres Short
Answer 21. The circles are the phosphate group, the
pentagons are deoxyribose, and the A and T
(adenosine and thymine) are the bases. 22. Avery
repeated Griffith’s experiment, and identified the
component of the cell that caused transformation. 23.
Hershey and Chase labeled the DNA of a
bacteriophage with 32P, and found that after the
bacteria were infected with the bacteriophage, the 32P
was in the bacteria. 24. The hydrogen bonds between
the base pairs must be broken, and the molecule must
unwind. 25. In prokary-otes, DNA replication starts in
one place, and in eukaryotes DNA replication starts in
many places. Using Science Skills 26. Bacterial
transformation 27. The mice live in experiments 2
and 3. 28. The harmless bacteria were trans-formed
by the heat-killed bacteria, making the harmless
bacteria deadly. The mice that were injected with the
mixture died. 29. The harmless bacteria would be
transformed into disease-causing bacteria. To test this
hypothesis, he could inject the bacteria in to mice and
see if the mice develop pneumonia, or he could grow
them on plates and observe the colonies that grow.
30. The bacterial cell membrane can somehow permit
very large molecules like DNA to enter the cell.
Essay 31. Griffith killed disease-causing bacteria and
mixed them with live, harmless bacteria. The
harmless bacteria transformed into disease-causing
bacteria. Because the ability to cause disease was an
inherited by the off spring of the transformed
bacteria, Griffith concluded that the transforming
factor had to be a gene. 32. DNA has three functions:
to store, copy, and transmit information. DNA is like
a book because books also have those functions. They
hold information until the information is needed. The
information in the books can be copied, and each
copy of the book has the same information as the
original book. 33. Each nucleotide is made of three
parts: a phosphate group, deoxyribose, and a base.
Covalent bonds between the phosphate and the
deoxyribose molecules gives DNA stability. There
are two long bases (adenine and guanine), and two
short bases (thymine and cytosine). There is always a
long base and a short base in each pair: adenine
always pairs with thymine, and guanine always pairs
with cytosine. Because a long and a short base are
always together, the backbones of the DNA molecule
can be parallel and uniform and hydrogen bonds can
form between the base pairs. This hydrogen bond is
easily broken so DNA can “unzip” for replication,
and the individual strands stay securely intact. 34. Oft
en, the two chromosomes in a prokaryotic cell attach
to different points inside the cell membrane and are
separated when the cell splits to form two new cells.
In eukaryotic cells, the chromosomes separate from
each other during anaphase of mitosis. 35. The
chromosome would first unravel into supercoiled
strands of nucleosomes, which would unravel into
looser coils. Then, the coils would unravel into
strands of nucleosomes. The nucleosomes would
unravel into clusters of histones and a single DNA
molecule.
Chapter 12 —Test B
Multiple Choice 1. a 2. b 3. b 4. a 5. b 6. d 7. c 8. b 9.
d 10. b 11. c 12. c 13. d 14. b 15. d Modified
True/False 16. F; smaller 17. T 18. F; two directions
Completion 19. protein coat 20. nucleotide 21.
double helix 22. Hydrogen bonds 23. enzymes 24.
telomeres Short Answer 25. The hydrogen bonds
between the base pairs must be broken, and the
molecule must unwind. 26. The molecule is DNA
polymerase, an enzyme that joins individual
nucleotides to make a strand of DNA. 27. In
prokaryotes, DNA replication starts in one place, and
in eukaryotes DNA replication starts in many places.
Using Science Skills 28. The experiments were done
by Hershey and Chase, and they confirmed that DNA
was the genetic material found in genes. 29. The
DNA was labeled with 32P, and the protein was
labeled with 35S. The two labels can be distinguished
in the lab. 30. They would have found that the
bacteria contained 35S.
Chapter 13 —Test A
Multiple Choice 1. c 2. a 3. a 4. d 5. a 6. b 7. d 8. a 9.
b 10. c 11. b 12. c 13. c 14. b 15. d Completion 16.
promoter 17. frameshift mutations 18. inversion 19.
mutagen 20. Hox genes Short Answer 21. RNA
polymerase might be unable to bind to the promoter,
and, as a result, the gene would not be transcribed. 22.
GGU, GGC, GGA, and GGG specify glycine. 23. The
lactose binds to the lac repressors, causing the
repressors to release the operator. 24. A molecule of
miRNA is a small loop of RNA that combines with
proteins to create a silencing complex that binds
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Answer Key—Tests • Chapter 14
to and destroys mRNA that matches the miRNA’s
sequence. 25. Messenger RNA provides the code for
the translation, ribosomal RNA reads the code, and a
tRNA molecule brings the next amino acid specified
by the code. Using Science Skills 26. Structure D
is made from structure A, which is one of the strands
of DNA. 27. Structure F is a codon that specifies the
amino acid alanine. 28. Structure E is the start codon,
which specifies the amino acid methionine. 29. The
base sequence of the codon (structure F) would
change from GCU to GUG. 30. The deletion of
structure C would shift the reading frame of the
codons during translation. As a result, the sequence of
the amino acids that follows after structure C might
change. Essay 31. Messenger RNA carries copies of
instructions for assembling proteins from DNA to the
ribosomes. Ribosomal RNA is a component of the
ribosomes. Transfer RNA carries amino acids to the
ribosomes for assembly into proteins. 32. After a
molecule of mRNA is transcribed in the nucleus it
moves to the cytoplasm. A ribosome then positions
itself at the start codon on the mRNA molecule. As
each successive codon passes the ribosome, a
molecule of tRNA brings an amino acid to the
ribosome. Only a tRNA molecule with an anticodon
that is complementary to the codon on the mRNA can
attach an amino acid to the growing polypeptide
chain. The ribosome attaches each new amino
acid to the chain, and the bond holding the tRNA to
the amino acid is broken. The ribosome moves to the
next codon, and the process repeats until the entire
mRNA molecule is translated. 33. Point mutations
include substitutions, insertions, and deletions of
single nucleotides in DNA. Insertions and deletions
have a greater effect on proteins than do substitutions,
because insertions and deletions can affect every
amino acid that is specified by the nucleotides that
follow the point of mutation. In contrast, a
substitution affects a single amino acid. A change
in more than one amino acid is more likely to alter the
ability of the protein to function normally than is a
change in a single amino acid. 34. The lac repressor
might be unable to bind with the operator. As a result,
RNA polymerase would not be prevented from
beginning the process of transcription, and the lac
genes would be turned on permanently. Another
effect of the mutation might be that the lac repressor
would be unable to bind with lactose. As a result, the
repressor would permanently bind with the operator,
RNA polymerase would be prevented from binding to
the promoter, and the lac genes would be turned off
permanently. 35. Every cell that has a nucleus in a
multicellular organism has all the genes to build that
organism. But not every cell needs every gene, so it is
important that the unneeded genes are switched off .
For example, nerve tissue needs to be flexible, not
stiff and rigid. So, the genes that code for the proteins
that create the rigidity of bones would be
inappropriate in nerves. Genes that create bone
structure need to be turned off in nerve cells.
Chapter 13 —Test B
Multiple Choice 1. b 2. c 3. c 4. c 5. b 6. c 7. a 8. c
9. a 10. b 11. a 12. a 13. c 14. a 15. a Completion
16. ribose 17. RNA polymerase 18. amino acids 19.
stop codon 20. lactose 21. anticodons Short Answer
22. Molecule B is tRNA, which carries amino acids to
the ribosomes. 23. A ribose molecule, a phosphate
group, and a nitrogenous base are the three main parts
of an RNA nucleotide. 24. The DNA molecule must
be separated into two strands. 25. Information is
transferred from DNA to RNA to protein. 26. The
Hox genes descended from the genes of common
ancestors. Using Science Skills 27. A
chromosomal mutation results from processes A, B,
C, and D. 28. Process D involves two chromosomes.
29. A segment of a chromosome becomes oriented in
the reverse direction during process C. 30. Process D
is a translocation.
Chapter 14 —Test A
Multiple Choice 1. c 2. d 3. b 4. c 5. b 6. c 7. b 8. c
9. b 10. b 11. a 12. d 13. d 14. a 15. b Completion
16. mother 17. pedigree 18. Turner’s syndrome 19.
Genetic Information Nondiscrimination Act Short
Answer 20. Males have just one X-chromosome. 21.
The probability that their son will be colorblind is
50%. 22. The DNA sequence of the allele that causes
cystic fibrosis has a deletion of three bases. 23. The
frequency of the sickle cell allele would probably
decrease because the allele would no longer be
beneficial in heterozygous individuals. 24. If human
cells have a Y chromosome, the person is a male
regardless of how many X chromosomes are in the
cells. 25. The sex chromosomes are homologous
because one is inherited from one parent, and the
other is inherited from the other parent.
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Answer Key—Tests • Chapter 15
Using Science Skills 26. The chromosomes in
each group are called homologous chromosomes. 27.
The chromosomes in each pair are similar in shape
and size. They also contain the same genes, though
not necessarily the same alleles of those genes. 28.
The chromosomes in groups 1 through 22 are
autosomes. 29. This person will be male, due to the
presence of a Y chromosome. This person has
Klinefelter’s syndrome and is likely to be infertile.
30. The karyotype shows a chromosomal
abnormality. Position 23 has three chromosomes
instead of the usual two. This abnormality was caused
by nondisjunction of sex chromosomes during
meiosis while a sperm or egg cell was developing in a
parent. Essay 31. The figure could not show the
transmission of colorblindness. If it did, female
number 5 would have to be either colorblind or a
carrier of the allele for colorblindness. According to
the pedigree in the figure, the mother (1) would have
one recessive allele for colorblindness and one
normal allele. The father (2), having just one X
chromosome, would have one recessive allele for
colorblindness and no normal alleles. So, the mother
would be a carrier, and the father would be
colorblind. All of the females born from these parents
would inherit the father’s abnormal allele on one of
their X chromosomes. So, all the females in this
pedigree would either be colorblind (if they also
got an abnormal allele from their mother), or
carriers of the trait (if they inherited their mother’s X
chromosome with the normal allele). Since female
number 5 is neither colorblind nor a carrier, this
cannot be a pedigree for a sexlinked, recessive trait,
such as colorblindness. 32. Because the allele for
colorblindness is recessive and X-linked, the girl must
have inherited the alleles for colorblindness on the X
chromosomes from both her mother and father. Since
the father has a single X chromosome, it must carry
the allele for colorblindness, and he must be
colorblind. 33. Both Turner’s syndrome and
Klinefelter’s syndrome result from nondisjunction
of the sex chromosomes. A female with Turner’s
syndrome inherits only one X chromosome. A male
with Klinefelter’s syndrome has at least one extra X
chromosome. 34. Sequencing DNA requires
restriction enzymes and DNA polymerase. Restriction
enzymes cut up the huge DNA molecule into smaller,
more manageable fragments. DNA polymerase
replicates those pieces using normal bases and some
bases that are tagged with dye. Each base can be
tagged with a different color dye. The dye-tagged
bases stop replication, and after running the bases on
a gel, scientists can determine the sequence of the
DNA by reading the order of the colored bands on the
gel. 35. The larger chromosome might be larger
because it has longer stretches of repetitive DNA than
does the smaller chromosome. Because repetitive
DNA does not code for proteins, it does not contain
genes. Thus, in this case, the larger chromosome does
not have more genes than the smaller chromosome.
Chapter 14 —Test B
Multiple Choice 1. c 2. a 3. a 4. d 5. b 6. c 7. d 8. b
9. d 10. b 11. c 12. c 13. c Modified True/False 14.
T 15. T 16. F; recessive 17. F; father’s gamete
Completion 18. 50% or ½ 19. karyotype 20. IB 21.
two 22. Turner’s syndrome Short Answer 23. A
sperm that has 23 chromosomes fertilizes an egg
that has 23 chromosomes resulting in a 23 pairs of
chromosomes (46 total) in the autosomal cells of the
individual. 24. Males have just one X chromosome.
25. The probability that their son will be colorblind is
50%. 26. The DNA sequence of the allele that causes
cystic fibrosis has a deletion of three bases. 27. If
human cells have a Y chromosome, the person is a
male regardless of how many X chromosomes are in
the cells. 28. Restriction enzymes cut large DNA
molecules into smaller, more manageable pieces.
Using Science Skills 29. The individual is
heterozygous (Ff), since her daughter has attached
earlobes. The daughter inherited one allele for
attached earlobes from individual 2 and another from
individual 1 30. None of those children have attached
earlobes.
Chapter 15 —Test A
Multiple Choice 1. a 2. a 3. b 4. b 5. b 6. b 7. d 8. a
9. a 10. c 11. c 12. c 13. b 14. c 15. c Completion
16. Inbreeding 17. hybridization 18. polyploid 19.
Restriction enzymes 20. transgenic genetically
engineered Short Answer 21. The polymerase
chain reaction enables scientists to make many
copies of a gene. 22. Dolly and the sheep from which
she was cloned have identical genes. 23. Farmers can
spray their crops with herbicides that will kill the
weeds and leave the crop plants unharmed. 24. A
DNA probe is short piece of DNA designed to detect
a certain gene. A probe can be made to be
complementary to part of the sequence of a diseasecausing allele,
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Answer Key—Tests • Chapter 15
and it will only bind to that specific allele. This
enables scientists to see who has the allele and who
does not. 25. Viruses are used in gene therapy
because they can transfer genes into human cells.
Using Science Skills 26. The bands consist of
DNA fragments. 27. The bands in group D moved
faster because they consist of smaller DNA
fragments. 28. The restriction enzyme is cutting the
DNA into fragments. 29. The bands consist of DNA,
which is negatively charged. 30. No, none of the
DNA samples were from the same person because
they produced different patterns of bands on the gel.
Essay 31. Extract DNA from the cells of people who
can make the digestion enzyme. Cut the DNA with
restriction enzyme, then use gel electrophoresis and a
DNA probe to locate the gene. Use the polymerase
chain reaction to copy the gene. Choose a plasmid
that has an antibiotic-resistance genetic marker, and
cut the plasmid with the same restriction enzyme used
to cut out the human gene. Insert the copies of the
human gene into the plasmids. Allow bacterial cells
to take in the plasmids. Select for transformed
bacteria by growing them in a culture containing the
antibiotic. These bacteria will make the digestion
enzyme. 32. Sample answer: Genetic engineering can
help improve human health in many ways. • First,
scientists can use genetic engineering to make more
nutritional crops, such as golden rice. When people
have better nutrition, they are less likely to get certain
diseases. • Second, scientists can use transgenic
animals in medical research. Animals with modified
genomes are used as models in medical experiments.
• Third, scientists can treat diseases using genetic
engineering. Some diseases can be treated with drugs
made through genetic engineering, and some diseases
can be treated directly through gene therapy. 33.
Poachers kill elephants for their tusks, but officials
can use genetic information to identify the herds from
which the poached elephants came from, and better
police those areas. 34. Sample answer: Animal
breeders might first produce an animal with particular
desirable traits through hybridization or by inducing
mutations. Then, instead of using inbreeding to
maintain the animal’s desirable traits, they might
produce clones of that animal. The clones would be
genetically identical to the original animal and thus
would have all of its desirable traits. 35. Sample
answer: One potentially controversial issue is
whether or not parents should be able to “design”
their children. For example, should parents be able to
decide which genetic traits they would like their
children to have? All citizens have a duty to ensure
that the tools of science are used properly, and should
work toward developing a consensus on how genetic
engineering should be applied in the context of
society.
Chapter 15 —Test B
Multiple Choice 1. a 2. b 3. c 4. c 5. d 6. d 7. c 8. b
9. a 10. d 11. b 12. b 13. a 14. b 15. c Completion
16. polyploid 17. antibiotics 18. forensics 19.
beneficial; helpful; needed; good Short Answer 20.
Structures C and D are the sticky ends of a DNA
fragment, which allow the fragment to be inserted
into a piece of DNA that has complementary sticky
ends. 21. A plasmid is a circular DNA molecule that
is naturally found in bacteria. Scientists use them to
transform bacteria and plants. 22. The polymerase
chain reaction enables scientists to make many copies
of a gene. 23. Farmers can spray their crops with
herbicides that will kill the weeds and leave the crop
plants unharmed. 24. Viruses are used in gene therapy
because they can transfer genes into human cells. 25.
These sections of DNA vary widely from person to
person. Using Science Skills 26. Sheep A 27. The
nucleus was removed from the egg cell to make sure
that all of the DNA in the clone was from a single
sheep. 28. The lamb is a clone. 29. Sheep B 30. Sheep
A and the lamb are genetically identical.
Unit 4 —Test A
Multiple Choice 1. c 2. b 3. d 4. c 5. d 6. b 7. b 8. a
9. c 10. b 11. a 12. d 13. c 14. d 15. d Completion
16. independent assortment 17. transcription 18.
hybridization 19. restriction enzymes 20. nucleotide
Short Answer 21. Oswald Avery and his group
concluded that DNA was the transforming factor. 22.
A transgenic organism contains genes from another
species. 23. Mitosis produces two genetically
identical diploid cells. Meiosis produces four
genetically different haploid cells. 24. DNA
polymerase joins together individual nucleotides to
produce a DNA molecule and it proofreads each new
DNA strand. 25. During cell transformation, a cell
takes in DNA from outside the cell. This external
DNA becomes part of the cell’s DNA. Using
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Answer Key—Tests • Chapter 16
Science Skills 26. Gel electrophoresis is illustrated
in the figure. 27. The DNA must be extracted from
the cell before step A can occur. 28. The longer
fragments are located at point C because longer
fragments move more slowly through the gel. 29.
DNA is negatively charged because it moves toward
the positive end of the gel. 30. The DNA is being cut
into fragments at point A in the diagram when it is
mixed with restriction enzymes. Essay 31. To
produce the recessive phenotype, both parents must
be heterozygous for the dominant phenotype. Punnett
squares should illustrate a two-factor cross in which
both parents are heterozygous for seed color and seed
shape. 32. DNA is a double helix in which two
strands are wound around each other. Each strand is a
chain of nucleotides. Each nucleotide is made up of a
deoxyribose sugar, a phosphate backbone, and a
nitrogenous base. The four nitrogenous bases are
adenine, guanine, thymine, and cytosine. The two
strands are held together by hydrogen bonds between
adenine and thymine and between guanine and
cytosine. Th e sugar and phosphate groups form the
backbone of the DNA strand. 33. All three types of
RNA molecules are single-stranded molecules, have a
ribose sugar, and have uracil instead of thymine.
However, each type has a different shape and
function. Messenger RNA carries copies of the
genetic instructions for making proteins. Ribosomal
RNA combines with proteins to form ribosomes.
Proteins are assembled on the ribosomes. During
translation, transfer RNA carries the amino acid to the
ribosome that is specified by messenger RNA. 34.
Prokaryotes are unicellular organisms. Their DNA
molecule only needs to control the needs for one cell.
Multicellular organisms have the same DNA in every
cell nucleus. However, the cells are specialized for
different functions. Genes that code for liver
enzymes, for example, are not expressed in nerve
cells. Therefore, only a small fraction of the available
genes need to be expressed in the appropriate cells of
different tissues throughout the body. The complexity
of gene regulation in eukaryotes makes this
specificity possible. 35. A genetic disorder caused by
a nonfunctioning or abnormally functioning allele
gives scientists clues to the function of the normal
protein produced by the normal allele.
messenger RNA 19. inbreeding 20. independent
assortment 21. nucleotide Short Answer 22. There
is a 25 percent chance that a white guinea pig will be
produced. 23. A transgenic organism contains genes
from another species. 24. Males have only one X
chromosome. 25. DNA polymerase joins together
individual nucleotides to produce a DNA molecule
and it proofreads each new DNA strand. 26.
Increasing the genetic variation of a population gives
breeders a larger selection of traits from which to
choose, increasing the chance that a desired trait is
available in the population. Using Science Skills
27. A bacterial cell is being transformed. 28. The
plasmid and human gene are cut with the same
restriction enzyme, so their cut ends are
complementary to each other and will easily join
together. 29. The recombinant DNA molecule in the
diagram is made up of the bacterial plasmid and the
human gene for growth hormone. 30. Researchers can
identify transformed cells because the plasmid also
carries a genetic marker. The genetic marker is a gene
that gives the bacterial cell resistance to a certain
antibiotic. With the addition of the antibiotic to the
growth medium, only those bacteria that have the
genetic marker—and the human gene—will grow.
Chapter 16 —Test B
Multiple Choice 1. c 2. a 3. b 4. d 5. b 6. b 7. c 8. b
9. c 10. c 11. b 12. b 13. a 14. a 15. c Modified
True/False 16. F; differ; are different; have natural
variations 17. T 18. T Completion 19. acquired 20.
radio-activity; radioactive dating 21. Homologous 22.
natural selection; adaptation Short Answer 23.
Darwin collected many examples of similar, but not
identical, modern organisms as well as fossils that
were previously unknown. These specimens helped
him form his theory of evolution by natural selection.
24. In artificial selection, humans do the
“selecting”—that is, they choose which traits they
want to appear in future generations. In natural
selection, the environment does the “selecting.” 25. It
suggests that there is no disadvantage to fitness
associated with the vestigial structures. If there were a
disadvantage, then the structures would be selected
against and you’d expect them to no longer be
present. 26. The similarity of Hox genes in many
types of organisms is evidence that the organisms all
evolved from a common
Unit 4 —Test B Multiple Choice 1. a 2. b 3. d
4. a 5. d 6. a 7. a 8. c 9. c 10. b 11. a 12. d 13 c 14. b
15. c 16. a Completion 17. DNA fingerprinting 18.
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Answer Key—Tests • Chapter 17
survive because it had so little variation. 35. In their
mature forms, homologous structures, such as bird
wings and mammal forelimbs, appear somewhat
different, but they develop from the same kinds of
embryonic tissues. From this evidence, scientists infer
that the particular species evolved from a common
ancestor population that moved into different
environments, where the populations were changed
through natural selection.
ancestor. Using Science Skills 27. Darwin
proposed that over time, natural selection made a
population more fit for its environment. Sharks and
dolphins both live in the ocean, where natural
selection favors organisms that move efficiently
through water. 28. Sharks show fitness because they
are able to survive and reproduce successfully in their
ocean environment. Students should give two of the
following examples: (1) Sharks have an overall body
shape that enables them to move rapidly through
water. (2) Sharks have a large tail and fins that
provide balance and enable them to steer. (3) Sharks
have teeth that make them successful predators. 29.
Student answer may include that the dolphin’s landdwelling ancestors were probably made up of
populations with different body shapes and limbs.
Those land-dwellers began to spend more time in the
ocean, perhaps because food was easier to find. In
each generation, those with bodies that moved
efficiently in water survived longer and produced
more off spring than others. Eventually, the whole
population came to resemble today’s dolphins. 30. It
is not likely. Possible arguments: (1) Darwin
emphasized that evolution usually requires millions,
not thousands, of years. (2) The bodies of dolphins
are well adapted to life in water, with little observable
variation; it’s unlikely that the population’s relevant
characteristics could change in just thousands of
years. 31. Student answer could include that although
their skeletons are made of different materials, there
are likely to be homologous structures in the skull,
backbone, and limbs. There may also be homologous
structures among internal organs such as heart, brain,
and digestive system. Essay 32. On the Beagle,
Darwin saw three species of large, flightless birds
living in similar habitats on different continents.
Rheas lived only in South America, ostriches only in
Africa, and emus only in Australia. 33. Malthus
thought that humans would run out of living space
and food because the number of births exceeded the
number of deaths. Darwin applied this idea to all
species, realizing that populations produce huge
numbers of off spring, yet only a small percent-age
survives. Darwin then sought to determine which
factors affect an organism and what effect those
events would have over time. 34. The population’s
survival would depend on how well adapted its
members were to the new environment. If they were
not well adapted, the population would probably not
Chapter 16 —Test B
Multiple Choice 1. c 2. a 3. b 4. b 5. b 6. b 7. b
8. b 9. a 10. b 11. b 12. a 13. a 14. d 15. b Modified
True/False 16. T 17. T 18. F; homologous 19. F;
physical characteristics; phenotype Completion 20.
Lyell; James Lyell 21. evolution 22. radio-activity;
radioactive dating 23. natural selection; adaptation
Short Answer 24. In artificial selection, humans do
the “selecting”—that is, they choose which traits they
want to appear in future generations. In natural
selection, the environment does the “selecting.” 25.
All living and extinct species are descended from a
common ancestor. Using Science Skills 26.
Scientists probably used the fossil bones of ancient
horses from several sites and compared them with the
bodies of modern horses. 27. Body size increased in
mass and volume. (The horse became taller and
heavier.) 28. The head becomes larger. 29. The
number of toes decreased from three to one.
Chapter 17 —Test A
Multiple Choice 1. c 2. c 3. a 4. a 5. d 6. b 7. d
8. c 9. c 10. d 11. c 12. b 13. c 14. b 15. c
Completion 16. gene pool 17. lateral gene transfer.
18. directional 19. compete 20. molecular clock
Short Answer 21. Yes, the term population is
defined in terms of a species. A population is a group
of individuals of the same species that interbreed. 22.
No. An allele for a trait that has no effect on fitness
will not be affected by natural selection because it
does not affect the survival and reproduction of
individuals in a population. 23. Generally, the smaller
a population is, the easier it is for allele frequencies to
change. Genetic drift occurs when the allele
frequencies in small populations change by chance.
24. Gene duplication can affect evolution because the
duplicate might acquire a mutation. If that mutation is
positive, it will be will be selected for by natural
selection to become more
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Answer Key—Tests • Chapter 17
frequent in the population. 25. A small change in
what a Hox gene does can cause a large change in an
organism. If a Hox gene turns off a gene for wings in
an insect larva, the adult insect will probably not have
wings. Using Science Skills 26. Figure 17–3
shows the times of mating activity for seven species
of frogs. Four of the species mate in the spring. The
other three species mate in the summer. 27. Frog
mating nearly stops in early to mid-May. 28. The
graph shows that bullfrogs typically mate after the
other frog species shown, an example of temporal
isolation. Bullfrogs might also use different courtship
rituals, such as different mating calls, which would be
an example of behavioral isolation. 29. The two
species must be behavior-ally isolated because they
are not isolated either temporally or geographically.
30. Since temperatures in the south are typically
warmer than in the north, frog mating seasons might
also occur earlier. In that case, the curves likely
would shift to the left . Essay 31. The frequencies
of phenotypes for a single-gene trait are best
expressed as a bar graph because variations in the
gene lead to only a few distinct phenotypes. The
frequencies of phenotypes for a polygenic trait,
however, are usually best expressed as a bell-shaped
curve because one polygenic trait can have many
possible phenotypes. 32. The founder effect is a
situation in which frequencies of alleles change as a
result of the migration of a small subgroup of a
population. This subgroup may carry alleles in
different frequencies than does the larger population
from which it came. The founder effect arises from
genetic drift —a change in the frequencies of alleles
due to chance rather than to natural selection. 33. In a
gene pool of a population, the allele frequencies will
change (1) when non-random mating occurs, since
sexual selection can change gene frequency, (2) when
there is immigration or emigration to add or remove
genes, and (3) when natural selection favors a
particular phenotype. 34. The directional selection
likely would not have been as pronounced as it was
because it was driven by availability of vegetation of
different types. Evolution probably would not have
progressed as quickly as it did because selection
pressures would have been lower under those
circumstances. 35. Student’s answer could include
reasoning that during meiosis, a chromosome may
acquire a duplicate gene. If a mutation occurs in the
duplicate gene, that mutation might cause a change in
the function of the duplicate gene. If the gene affects
the phenotype of the organism, natural selection could
act on the population.
Chapter 17 —Test B
Multiple Choice 1. d 2. b 3. d 4. c 5. b 6. b 7. b 8. b
9. c 10. b 11. b 12. a 13. b 14. c 15. b Completion
16. genetic equilibrium 17. speciation; species
formation 18. directional 19. common ancestor Short
Answer 20. The allele frequency of an allele is the
number of times the allele occurs in the gene pool
divided by (or compared with) the total number of
alleles for the same gene. 21. Generally, the smaller a
population is, the easier it is for allele frequencies to
change. Genetic drift occurs when the allele
frequencies in small populations change by chance.
22. The five conditions are non-random mating, small
population size, immigration or emigration,
mutations, and natural selection. 23. A large river
would likely keep populations of small rodents apart,
but it would not necessarily isolate birds and other
populations that can fl y. 24. Gene duplication can
affect evolution because the duplicate might acquire a
mutation. If that mutation is positive, it will be will be
selected for by natural selection to become more
frequent in the population. 25. Hox genes can turn
other genes on or off during embryological
development. A change in the activity of one Hox
gene can affect how an entire segment of an organism
is patterned. For example, whether the segment has
legs or wings, and how big or small those legs or
wings will be. Using Science Skills 26. The
average beak size of the birds represented in Graph A
has increased through directional selection. There are
now no birds with the smallest beaks, and some birds
with very large beaks have evolved. 27. Stabilizing
selection has occurred. There are more birds with a
body mass of average size and no birds with
extremely large or small body mass. 28. Disruptive
selection has occurred. There are more birds with
smaller or larger beak sizes and few or no birds
having the average beak size. 29. Graph C in Figure
17–5 shows a population with two very different beak
sizes, which indicates that the birds could be eating
different foods. 30. Student answers might include
that a change in the birds’ environment, such as the
introduction of a larger kind of food, could have
caused the directional selection in favor of larger
beaks.
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Answer Key—Tests • Chapter 19
Chapter 18 —Test A
kingdoms: Plantae, Animalia, Protista, Fungi,
Eubacteria, and Archaebacteria). 34. As biologists
learned more about the natural world, they realized
that Linnaeus’s two king-doms, Animalia and
Plantae, did not adequately represent the full diversity
of life. As a result, the original two kingdoms have
today become six kingdoms, with two of those groups
used just for classifying bacteria—unknown in
Linnaeus’s time! 35. The three-domain system was
based on genomic analysis, which suggests the evolution of organisms follows three main lines. The sixkingdom system, on the other hand, includes at least
one kingdom (Protista) that is based on general
similarities rather than evolutionary relationships.
Multiple Choice 1. b 2. c 3. a 4. a 5. b 6. d 7. c 8. b 9.
b 10. c 11. b 12. b 13. c 14. b 15. c Modified
True/False 16. F; genus 17. T Completion 18.
phylum 19. traditional classification; Linnaean
classification 20. Eukarya 21. Bacteria Short Answer
22. segmentation and a molted external skeleton 23.
Diagram B indicates that the traditional taxonomic
grouping shown in diagram A classified less closely
related groups together based on overall similarities
and differences. 24. DNA analysis can supply further
evidence of relatedness. In general, the more derived
genetic characters two organisms share, the more
closely related they are. 25. Both fungi and plants are
eukaryotes, meaning that their cells have nuclei. Most
fungi and plants are multicellular. All fungi are
heterotrophs; all plants are autotrophs. Fungi have
cell walls made of chitin; plants have cell walls made
of cellulose. Using Science Skills 26. The humpback
whale and the spider monkey are most closely related
because they belong to the same class. 27. the class
28. two; Plantae and Animalia 29. No, because this
species belongs to the kingdom Protista. 30. The
whale and the shark look most alike, yet they belong
to different classes. The monkey and the whale are
more closely related than any other pair here, yet they
differ greatly in size and shape. Essay 31. Common
use of the microscope by biologists likely would have
increased the number of species that were identified,
and it would have forced biologists to establish new
classification criteria and categories because it would
have revealed the widespread existence of
microscopic organ-isms. 32. Cladistic analysis
considers derived characters, which are traits passed
to the descen-dants of a common ancestor. If a
specific derived character is present in one species but
absent in another species, biologists infer that the
species possessing the character evolved second. 33.
At first, there were just two groups of organisms—
plants and animals (two kingdoms: Plantae,
Animalia). Then, when microorganisms were
identified, they got their own kingdom—Protista
(three kingdoms: Plantae, Animalia, and Pro-tista).
Later, the fungi were separated from plants and
placed into their own kingdom and prokary-otes were
separated from single-celled eukaryotes and placed in
their own kingdom, called Monera (five kingdoms:
Plantae, Animalia, Protista, Fungi, and Monera).
Today, the monerans have been divided into two
kingdoms, Eubacteria and Archaebacteria (six
Chapter 18 —Test B
Multiple Choice 1. a 2. d 3. a 4. b 5. d 6. a 7. a 8. c 9.
c 10. c 11. b 12. c 13. c 14. d Modified True/False
15. T 16. F; families 17. T Completion 18. Panthera
19. binomial 20. species 21. Eukarya Short Answer
22. segmentation and a molted external skeleton 23.
DNA analysis can supply further evidence of
relatedness. In general, the more derived genetic
characters two organisms share, the more closely
related they are. 24. Both fungi and plants are
eukaryotes, meaning that their cells have nuclei. Most
fungi and plants are multicellular. All fungi are
heterotrophs; all plants are autotrophs. Fungi have
cell walls made of chitin; plants have cell walls made
of cellulose. 25. the presence of a nucleus in its cell(s)
Using Science Skills 26. the kingdom 27. Yes; from
the genus through the kingdom, each general category
contains the categories shown beneath it. 28. No; the
genus Ursus contains the species Ursus arctos and
possibly other species, but it does not contain any of
the categories above it. 29. The species has the least
diversity. From genus upward, each category has
more diversity than the one before it. The kingdom
shows the greatest diversity. 30. Ursidae is a family,
and Carnivora is an order. Therefore, in general,
members of Ursidae would be more similar to one
another, since organisms that belong to the same
family are more similar than organisms of the same
order.
Chapter 19 —Test A
Multiple Choice 1. a 2. c 3. b 4. a 5. d 6. b 7. d 8. b 9.
a 10. d 11. b 12. c 13. b
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Answer Key—Tests • Chapter 19
14. c 15. c Completion 16. mass extinction 17.
nitrogen 18. Chloroplasts Short Answer 19. The
formation of a fossil depends on a precise
combination of conditions; therefore, many ancient
organisms died without leaving a trace. 20. Fossil A
is older than fossil B. A fossil with a smaller
proportion of carbon-14 than another fossil has been
in existence longer. 21. The divisions of geologic
time are based on evidence from rock layers that
reveal major changes in fossil animals and plants.
These divisions vary in length. 22. Microorganisms
are composed of the very molecules Miller and Urey
were trying to produce, so their presence or their
waste products might have falsely indicated that
organic molecules were produced from the simpler
molecules. 23. Scientists could see that the
membranes of mitochondria and chloroplasts
resembled the plasma membranes of free-living
prokaryotes. 24. As photosynthetic organisms
increased in number, the massive amounts of oxygen
these organisms generated caused the dissolved iron
in ocean water to settle out. They also pulled large
quantities of carbon dioxide out of the atmosphere
and replaced it with oxygen. This reduction in carbon
dioxide caused Earth to cool. 25. This is asexual
reproduction because there is a single parent. Using
cuttings from a single plant would reduce the genetic
diversity of the population. Using Science Skills 26.
The Sirenians are the most closely related of the
groups in this evolutionary tree. 27. The Artiodactyls
have existed the longest, because their branch in the
evolutionary tree is the longest branch. 28. The
different groups are most likely the result of adaptive
radiation, because they share a recent common
ancestor. 29. The evolutionary tree most likely will
look different thousands of years from now, because
the modern mammals in each of these groups are still
evolving. New groups may evolve through adaptive
radiation, causing the appearance of new branches in
the tree. One or more groups may become extinct due
to natural selection or a catastrophic event that causes
a mass extinction. This would cause some branches to
stop growing over time. 30. Some of the differences
between the groups might be due to land-forming
events or continental drift, but environmental changes
were probably the most responsible for the great
diversity shown in the evolutionary tree. The groups
represented live in very different environments. For
example, artiodactyls live in desert biomes, while
perissodactyls and proboscideans are found mostly in
grassland and some forest biomes. Cetaceans and
sirenians are marine aquatic species. As
environmental changes occurred, adaptations led to
new branches of the evolutionary tree forming. Essay
31. Sample answer: The fish died and was buried in
sediment at the bottom of a body of water. Over time,
the weight of upper layers of sediment compressed
the lower layers, containing the fish, into new rocks.
Minerals replaced parts of the fish’s body, producing
a fossil. The once-deep sedimentary layer containing
the fossil was uplifted by geological forces and then
eroded, exposing the fossil. 32. The survival of a
clade is determined by its rates of speciation and
extinction. Speciation that results in a wide genetic
diversity among the different species of the clade
enhances the clade’s ability to survive major changes
in the environment rather than become extinct. As
long as the rate of speciation is at least equal to the
rate of extinction, the clade will survive, even if some
of the smaller clades within that clade become
extinct. However, if the rate of speciation is less than
the rate of extinction, then the clade will suffer
extinctions faster than species can evolve to keep the
clade going. This leads to the extinction of the clade.
For example, all of the dinosaur species except those
that evolved into modern bird are extinct in the clade
Dinosauria, but there are many different species in the
larger clade Reptilia. Dinosauria is a member of the
Reptilia clade. 33. The Galápagos finches followed a
model known as punctuated equilibrium. In
gradualism, species evolve slowly and steadily over a
long period of time. In contrast, punctuated
equilibrium has long periods of equilibrium broken
up (“punctuated”) by periods of structural change.
During periods of equilibrium, no structural change
occurs. These periods of structural change occur
relatively fast in the geologic time scale, and usually
follow some event that upsets their equilibrium. An
event often is a mass extinctions or something that
causes the isolation of a small group from the main
population. Some biologists think that most new
species develop during these periods of change. 34.
Chlamydomonas will evolve more quickly during
unfavorable conditions. When an organism
reproduces asexually, its offspring are genetically
identical to the parent. This means that there is little
genetic variation within the species. The variation that
does occur is primar532
Answer Key—Tests • Chapter 19
ily caused by mutations in the DNA. In sexual
reproduction, off spring are produced by two parents.
Since both parents contribute DNA to the off spring
and their genes mix and remix during fertilization, the
off spring cannot be identical to the parent. Mixing
and remixing of genes also occurs during meiosis.
The constant mixing of genes causes a great genetic
diversity within the species. The greater the genetic
diversity, the more adaptable a species is to changing
environmental conditions and the more rapidly the
species will evolve. 35. A large asteroid probably
struck Earth during the Cretaceous. An impact of this
size would have thrown large amounts of dust and
water into the atmosphere, changing the global
climate and causing the mass extinction of many
organisms including the dinosaurs.
change in the relative frequency of alleles in a
population. 22. The evolution of photosynthetic
bacteria, which produced oxygen as an end product of
photosynthesis, led to the accumulation of oxygen in
Earth’s atmosphere. 23. Coevolution is the process by
which two species evolve in response to changes in
each other over time. 24. Reproductive isolation has
occurred when the members of two populations
cannot interbreed and produce fertile off spring. 25.
DNA analysis has revealed that American vultures
are more closely related to storks than to African
vultures. Using Science Skills 26. As beak size
increases, bird survival also increases. 27. Through
time, the curve would shift toward the larger-beak
end. 28. Directional selection appears to be occurring
in the bird population. 29. No birds survive with
beaks 8 mm or less in size. 30. If birds with smaller
beaks had greater survival, the curve would slope
down, rather than up, as beak size increased. Essay
31. Directional selection, in which individuals at one
end of the distribution have highest fitness, leads to
the curve’s shifting toward the high-fitness end.
Stabilizing selection, in which individuals near the
center of the distribution have highest fitness, leads to
the curve’s narrowing around the center. Disruptive
selection, in which individuals at both ends of the
curve have higher fitness than individuals near the
middle, leads to the curve’s developing two peaks at
either end and a low spot in the middle. 32. Hutton’s
and Lyell’s ideas about geological change and the
ancient age of Earth helped Darwin realize that life
could change and that there had been enough time for
changes in life forms to occur. 33. Most fossils form
in sedimentary rock. As layers of sediment build up
over time, dead organisms may sink to the bottom and
become buried. The weight of layers of sediment,
along with chemical activity, turns the dead
organisms into rock. Most organisms are not
preserved as fossils because the formation of fossils
depends on a precise combination of conditions. 34.
The domain Bacteria corresponds to the kingdom
Eubacteria. The domain Archaea corresponds to the
kingdom Archaebacteria. The domain Eukarya
includes the kingdoms “Protista,” Fungi, Plantae, and
Animalia. 35. Darwin presented evidence for
evolution from the fossil record, the geographical
distribution of living species, homologous structures
of
Chapter 19 —Test B
Multiple Choice 1. c 2. d 3. a 4. c 5. b 6. c 7. b 8. c
9. d 10. c 11. b 12. b 13. c 14. c 15. c Modified
True/False 16. T 17. T Completion 18. extinct 19.
plate tectonics; continental drift 20. mass extinction
21. convergent evolution 22. amino acids Short
Answer 23. The formation of a fossil depends on a
precise combination of conditions; therefore, many
ancient organisms died without leaving a trace. 24.
Relative dating allows paleontologists to estimate a
rock layer’s or fossil’s age compared with that of
other rock layers or fossils. 25. Background
extinction is the extinction of a single species as the
result of the normal process of natural selection. It
takes place over a long period of time. Mass
extinction is the rapid extinction of many species over
a short period of time as the result of a catastrophic
environmental event. Using Science Skills 26. 12
periods are shown in Figure 19–4. The Cambrian
Period is the earliest one. 27. The disappearance of
many species is called a mass extinction. The mass
extinction at the end of the Paleozoic Era occurred at
the end of the Permian Period. 28. 65.5 million years
ago 29. The Silurian Period lasted for 29 million
years. 30. Marsupials evolved during the Cretaceous
Period.
Unit 5—Test A
Multiple Choice 1. c 2. d 3. a 4. c 5. a 6. d 7. b 8. b
9. c 10. a 11. b 12. c 13. d 14. a 15. c Completion
16. gene pool 17. punctuated equilibrium 18. Thomas
Malthus 19. allele frequency 20. molecular clock
Short Answer 21. In genetic terms, evolution is any
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Answer Key—Tests • Chapter 20
living organisms, and similarities in early
development, or embryology.
existing disease that suddenly becomes harder to
control. The disease is probably an existing disease
that is caused by bacteria that have become
antibioticresistant. Emerging diseases are a risk
because humans have little resistance to them. Using
Science Skills 26. Sample answer: The student has
controlled all the variables except the solution that
each disk is soaked in. She is probably trying to test
the effectiveness of different disinfectants against E.
coli bacteria. 27. The disk soaked in distilled water is
the control. 28. Sample answer: The student can
measure the width of the area around each disk where
bacteria have not grown to determine the
effectiveness of the solution in which each disk was
soaked. 29. Disinfectant 1 shows the largest area
where bacterial growth has been inhibited; thus, it is
the most effective disinfectant tested against E. coli.
30. Sample answer: Disinfectants act in different
ways to combat bacterial growth. Some disinfectants
are more effective than other disinfectants at
controlling a particular bacterial species. Also,
bacteria may develop a resistance to some
disinfectants. Essay 31. Cells are living. Unlike
cells, viruses are nonliving particles of nucleic acid,
protein, and sometimes lipids. Viruses cannot
reproduce without infecting a host cell. In viruses,
DNA or RNA is surrounded by a protein coat called a
capsid. Some viruses have a protein-studded
membrane envelope. Similarly, cells are surrounded
by a cell membrane, which is studded with proteins
and surface carbohydrates. Some cells, such as plant
cells, have a cell wall. Like cells, viruses have nucleic
acids (DNA or RNA) that contain genes and they
evolve over time. Unlike cells, viruses do not grow
and develop, they cannot reproduce independently,
they do not obtain and use energy, and they do not
respond to the environment. 32. Photoautotrophs
carry out photosynthesis in a manner similar to that of
plants. Chemoautotrophs obtain energy directly from
chemical reactions involving compounds such as
ammonia and hydrogen sulfide. Heterotrophs obtain
energy by taking in organic molecules from the
environment or other organisms. Photoheterotrophs
take in organic molecules, but they can also get
energy from photosynthesis.Humans obtain energy
most like prokaryotes that are heterotrophs. 33. Many
prokaryotes are decomposers, breaking down organic
materials and recycling nutrients. Some prokaryotes
are
Unit 5—Test B
Multiple Choice 1. b 2. a 3. a 4. d 5. a 6. c 7. d 8. c
9. b 10. c 11. a 12. b 13 c 14. d 15. b Completion
16. gene pool 17. homologous 18. punctuated
equilibrium 19. allele frequency 20. eukaryotic cells
Short Answer 21. The evolution of photosynthetic
bacteria, which produced oxygen as an end product of
photosynthesis, led to the accumulation of oxygen in
Earth’s atmosphere. 22. Coevolution is the process by
which two species evolve in response to changes in
each other over time. 23. Cladograms, unlike systems
of classification based on visible similarities, are
based on derived characters, which show evolutionary
relationships. 24. Reproductive isolation has occurred
when the members of two populations cannot
interbreed and produce fertile off spring. 25. The
distribution of phenotypes for a polygenic trait often
fits a bell-shaped curve. Using Science Skills 26.
Red lizards died out, brown lizards became less
common, and black lizards became more common.
27. Natural selection could cause the lizard
population to change in this way if red lizards had
lowest fitness, brown lizards intermediate fitness, and
black lizards highest fitness. 28. Assuming that lizard
color is a single-gene trait, the change in color could
not be an example of directional selection, because
this type of selection acts on polygenic traits. 29. This
type of random genetic change is called the founder
effect. It is a type of genetic drift .30. Green lizards
would become more common and both brown lizards
and black lizards would become less common.
Chapter 20 —Test A
Multiple Choice 1. c 2. a 3. c 4. b 5. b 6. a 7. c 8. d
9. b 10. b 11. c 12. d 13. c 14. d 15. b Modified
True/False 16. T 17. T 18. T 19. F; A vaccine
Completion 20. prions 21. nitrogen fixation 22.
prophage Short Answer 23. A prophage is DNA of
a bacteriophage that becomes part of a bacterial host
cell’s DNA. It may stay part of the host’s DNA for
many generations. 24. Viral diseases are prevented by
vaccines and good personal hygiene. Viral diseases
cannot be treated with antibiotics, but some antiviral
drugs have been developed that attack specific viral
enzymes. 25. The patients are likely infected by an
emerging disease, which is a new disease or an
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Answer Key—Tests • Chapter 21
Chapter 21 —Test A
producers that form the base of food chains. Finally,
many prokaryotes are nitrogen fixers that convert
nitrogen gas to a form that can be used by plants.
Without decomposers, the nutrients in dead
organisms and wastes would not be recycled. Without
these nutrients, other organ-isms could not survive.
The loss of prokaryote producers would cause the
collapse of many food chains, resulting in the loss of
many organisms. Without nitrogen fixers, plants and
the organisms that eat them would not be able to get
enough nitrogen to build the proteins and other
nitrogen-containing molecules needed for survival.
34. Varicella-zoster is probably a lysogenic virus.
Once a person overcomes the chickenpox, some of
the viruses continue to replicate lysogenically in the
person’s cells. Shingles then appears when the virus
changes from the lysogenic cycle to the lytic cycle.
35. At one time, prokaryotes were placed in a single
kingdom. However, due to their differences, they are
now classified in two domains. Bacteria make up the
larger of the two domains of prokaryotes. Archaea
make up the other domain. Although both bacteria
and archaea are small, have cell walls, and lack
nuclei, they differ in the chemical composition of
their cell walls and membranes. Archaea also contain
key gene sequences that are more like those of
eukaryotes than those of bacteria. Scientists reason
from this that archaea may be the ancestors of
eukaryotes.
Multiple Choice 1. b 2. b 3. c 4. a 5. a 6. c 7. d 8. a
9. c 10. c 11. a 12. b 13. c 14. d 15. b Modified
True/False 16. F; single-celled; unicellular 17. F;
cilia Completion 18. cytoplasm, pseudopod 19.
photosynthesis 20. food vacuoles, lysosomes 21.
enzymes Short Answer 22. The ancestors of
protists were among the last to split from the
ancestors of plants, animals, and fungi. 23. Amoebas
surround a cell or food particle and take it inside
themselves to form a food vacuole, where the food is
stored for a short time before it is digested. 24.
Malaria is caused by Plasmodium and is spread by
Anopheles mosquitoes. African sleeping sickness is
caused by Trypanosoma and is spread by the tsetse fl
y. 25. Lichens are tolerant of harsh conditions. They
have layers of hyphae that function to protect the
organism and anchor it to almost any surface. They
also contain algae or cyanobacteria that are able to
produce food for the lichen through photosynthesis.
Using Science Skills 26. They are opposite mating
types: plus (+) and minus (–). 27. II 28. The
zygospore (structure B) is a diploid (2N) structure
that was formed by the fusion of haploid gametes of
different mating types. A fertilized animal egg is also
a diploid structure formed by the fusion of haploid
gametes. 29. Structure B, which is the zygospore,
would become dormant until environmental
conditions improved. 30. I Essay 31. The scientists
are probably correct. Organ-isms within a single
kingdom are supposed to be more like each other than
like organisms in other kingdoms. However, many
protists are more like organisms that are part of the
animal, plant, and fungus kingdoms than they are like
other protists. This means the organisms don’t really
fit in one kingdom. Classifying protists in multiple
kingdoms may overcome this problem. 32. Paramecia
exchange genetic material during the process of
conjugation. During conjugation, two paramecia
attach to each other. Meiosis of their diploid
micronuclei produces four haploid micronuclei. Three
of these disintegrate, and the remaining micronucleus
divides by mitosis. The two cells exchange one of the
pair of micronuclei. In each cell, the micronuclei fuse,
forming a diploid micronucleus, and the
macronucleus disintegrates. A new macronucleus
forms from the micronuclei. 33. Autotrophic protists
form the base of many food chains, so a decrease in
population means that less food will be available
Chapter 20 —Test B
Multiple Choice 1. b 2. c 3. d 4. c 5. d 6. b 7. d 8. c
9. b 10. d 11. c Modified True/False 12. T 13. F;
prokaryotes 14. T 15. T 16. T Completion 17. A,
cell wall 18. nitrogen fixation 19. nucleic acids,
proteins 20. tail sheath 21. head 22. germ theory of
disease Short Answer 23. A: cell wall; B: cell
membrane; C: ribosome; D: pili; E: DNA; F:
flagellum 24. A prophage is DNA of a bacterio-phage
that becomes part of a bacterial host cell’s DNA. It
may stay part of the host’s DNA for many
generations. 25. Misfolded proteins called prions
cause chain reactions in brain cells. Normal proteins
misfold, forming prion proteins. The prion proteins
build up in cells, eventually damaging the cells and
causing them to stop functioning. Using Science
Skills 26. The figure shows the cycles for lytic
infection and lysogenic infection. 27. The host cell is
destroyed during the lytic cycle. 28. C 29. E 30. G
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Answer Key—Tests • Chapter 22
for consumers. Populations of organisms that rely on
autotrophic protists directly and indirectly will likely
decrease. In coral reefs, the loss of red algae will
affect the food chain and reduce the production of
calcium carbonate, which stabilizes growing coral
reefs. Kelps provide shelter for many marine
organisms. Without kelp, many of these species will
be vulnerable to predators. 34. Ecosystems would be
littered with the bodies of dead animals and plants.
Materials would remain tied up in dead bodies and
would not reenter the ecosystem to be used by other
living things. Eventually, raw materials for new living
things might be depleted to the extent that no more
new living things could be produced, and life on
Earth would end. 35. During their life cycle, the
nuclei of most fungi are haploid. Asexual
reproduction involves only haploid structures. Diploid
nuclei form only during sexual reproduction. Shortly
after the nuclei fuse, however, meiosis occurs and
produces haploid nuclei that dominate the remainder
of the life cycle.
angiosperms, were the last group of plants to evolve.
23. Like roots, rhizoids anchor plants in the ground
and absorb water and minerals from the soil. Unlike
roots, rhizoids do not have vascular tissue. 24. Xylem
transports water while phloem transports solutions of
nutrients and carbohydrates. 25. A pollen grain is a
tiny structure produced by seed plants that contains
the male gametophyte. 26. Lilies and corn should be
categorized together because their features described
are of monocots. The features described of roses are
of dicots. Using Science Skills 27. Structures B,
D, E, F, G, H, I, J, K, L, and N are haploid. 28.
Structure A is a sporophyte. It is diploid. It produces
spores and is dependent on the gametophyte for water
and nutrients. Structure B is a gametophyte. It is
haploid. It carries out most of the plant’s
photosynthesis and has rhizoids. Both represent
different stages in the life cycle of a moss. 29.
Structure M is formed by fertilization; it is called a
zygote. 30. Spores, which are labeled D, are formed
by meiosis. 31. Structure H is an archegonium, which
produces eggs. Structure I is an antheridium, which
produces sperm. Essay 32. Over time, the carbon
dioxide concentration would decrease and the oxygen
content would increase. This happens because the
plant takes in carbon dioxide for photosynthesis and
releases oxygen, which is a byproduct of
photosynthesis. Over time, the plant will use most or
all of the carbon dioxide. Without carbon dioxide, the
plant cannot continue photosynthesis. Eventually, it
will die. 33. Land plants and multicellular green algae
are both part of the plant kingdom. They both have
cellulose-based cell walls and identical
photosynthetic pigments. They also have similar
reproductive cycles. These similarities suggest that
plants evolved from an organism much like the
multicellular green algae living today. 34. Both
angiosperms and gymnosperms are vascular plants
that produce seeds. The gametophytes of angiosperms
and gymnosperms grow and mature within the
sporophyte. In gymnosperms, the gametophytes are in
cones. In angiosperms, the gametophytes are in
flowers. In both gymnosperms and angiosperms, the
male gametophyte is a pollen grain. In gymnosperms,
the pollen grain is transferred to the female
gametophyte by wind. In angiosperms, the pollen
grain is transferred to the female gametophyte by
wind or animals. In gymnosperms, the
Chapter 21 —Test B
Multiple Choice 1. b 2. b 3. a 4. a 5. c 6. a 7. d 8. b
9. a 10. b 11. b 12. a 13. d 14. a 15. a Modified
True/False 16. F; cilia 17. F; plants 18. T 19. F;
eukaryotes Completion 20. alternation of
generations 21. malaria Short Answer 22. The
ancestors of protists were among the last to split from
the ancestors of plants, animals, and fungi. 23.
Students should list any two of the following:
phytoplankton, red and brown algae, euglenas,
dinoflagellates. 24. Individual threads of fungi are
hyphae; together they form a mycelium. 25. Instead
of male and female, the mating types of fungi are
called + (plus) and – (minus). 26. fruiting body.
Using Science Skills 27. One fruiting body is
shown. 28. Both are composed of hyphae. 29. No; a
mycelium could be completely buried. As a result, it
may not be visible. 30. The mycelium would be
embedded in the tree’s bark.
Chapter 22—Test A
Multiple Choice 1. c 2. b 3. a 4. d 5. c 6. b 7. c 8. c
9. b 10. a 11. d 12. c 13. a 14. c 15. b 16. a Modified
True/False 17. T 18. T Completion 19. alternation
of generations 20. Green algae 21. seed coat Short
Answer 22. Green algae are most closely related to
the ancestor of all plants. Flowering plants, or
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Answer Key—Tests • Chapter 23
25. Guttation does not occur in the leaves of trees
because root pressure alone cannot force water high
enough to reach the leaves. Using Science Skills 26.
Label G indicates the vascular cambium and label H
indicates the cork cambium. Together, these two
meristems allow for the secondary growth of the
stem. 27. Label A indicates cortex and label F
indicates pith; both are parenchyma, a type of ground
tissue. Ground tissue can be parenchyma,
collenchyma, or sclerenchyma. 28. Labels H and G
indicate meristems. Growth in these two areas makes
the stem wider. 29. Label C points to secondary
phloem and label B points to primary phloem. Label
C points to the secondary growth tissues. 30. Labels
A, B, E, and F indicate structures that were formed by
primary growth. Label A indicates the cortex, B
indicates the primary phloem, E indicates the primary
xylem, and F indicates the pith. Essay 31. From the
soil, roots absorb water, which is used for photosynthesis in the leaves, and nutrients, which the leaves
need for growth. The stem transports the water and
nutrients from the roots to the leaves. The stem also
holds the leaves up to the sun, allowing them to
absorb sunlight for photosyn-thesis. 32. The cell
membranes of root hairs and other cells in the root
epidermis contain active transport proteins. These
proteins use ATP to pump mineral ions from the soil
into the plant. The high concentration of mineral ions
in the plant cells causes water molecules to move into
the plant by osmosis. 33. The height of a tree
increases only at the tip of the trunk (stem), where the
apical meristem is located. There is no increase in
length along the rest of the trunk. Thus, the nail
remains at that same height for the lifetime of the
tree. 34. Mesophyll cells contain chloroplasts and
carry out nearly all of the photosynthetic activity of
the plant. The meso-phyll is composed of the palisade
mesophyll, which consists of closely packed cells that
absorb much of the light that enters the leaf. The
spongy mesophyll consists of loosely packed cells
separated by spaces. The spaces in this layer connect
with stomata, which allow gases to pass in and out of
the leaf. 35. Some roots store sugars or starches.
During periods of decreased photosynthesis,
carbohydrates stored in the roots move up from the
roots through the phloem to the leaves. The plant can
then use these carbohy-drates for life functions. In
this case, the source
seeds that result from pollination are formed on the
surfaces of cone scales. In angiosperms, the seeds are
formed in flowers. In angiosperms, a protective tissue
called an ovary covers a seed. The ovary develops
into a fruit. 35. Some animals, such as bees, are
attracted to flowers. They transfer male gametophytes
(pollen grains) to the structures that house female
gameto-phytes. Animals also help to disperse seeds
by picking up seeds on their fur or feathers or by
eating fruits and the seeds inside them and then
passing the seeds out of their bodies, usually some
distance from the parent plant.
Chapter 22 —Test B
Multiple Choice 1. a 2. b 3. b 4. c 5. d 6. b 7. b 8. b
9. c 10. c 11. a 12. c 13. a 14. b Modified True/False
15. T 16. F; green algae 17. F; angiosperms 18. T
Completion 19. flowering plants 20. vascular tissue
21. alternation of generations Short Answer 22.
Plants take in energy from sunlight, carbon dioxide
from the atmosphere, and water and nutrients from
soil. They release oxygen into the atmosphere. 23.
Xylem trans-ports water while phloem transports
solutions of nutrients and carbohydrates. 24. A pollen
grain is a tiny structure produced by seed plants that
contains the male gametophyte. 25. Pollen grains are
moved by wind from male cones to female cones. 26.
A fruit is an angiosperm structure that forms from an
ovary and contains one or more seeds. Using Science
Skills 27. A corn seed has one seed leaf. 28. The
maple leaf is a dicot because it has branching veins.
29. The vascular bundles are scattered throughout the
stem. 30. The iris is a monocot because it has six fl
oral parts, which is a multiple of three.
Chapter 23 —Test A
Multiple Choice 1. c 2. b 3. b 4. a 5. c 6. d 7. b 8. a 9.
a 10. d 11. c 12. d 13. a 14. d 15. d Modified
True/False 16. T 17. F; dermal 18. T Completion 19.
Mer-istems 20. endodermis, Casparian strip 21.
companion cells Short Answer 22. Through the
xylem, water moves only upward into the plant.
Through the phloem, carbohydrates and other
materials can move both upward and downward. 23.
The plant forms wood, which results from secondary
growth. Monocots rarely go through secondary
growth, so the scientist likely discovered a dicot. 24.
On a hot sunny day, stomata will most likely be
closed because the plant will need to conserve water.
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Answer Key—Tests • Chapter 24
cells are in the roots, and the sink cells are in the
leaves.
when they have a long period of uninterrupted
darkness. They are short-day plants. 30. He or she
grow should grow the plants inside and control
photoperiod, exposing the plants to more light during
wintertime and less light during summer-time. Essay
31. Vegetative reproduction produces plants more
quickly than fertilization, seed production, and
germination do. Vegetative reproduction also ensures
that new plants are genetically identical to the parent
plant, so the plants will have the desired traits. This
might not be the case if parent plants were pollinated.
32. After fertilization, nutrients flow into the flower
tissue and support the development of the growing
embryo within the seed. As the seed matures, the
ovary wall thickens to form the fruit that surrounds
the seeds. 33. If a gardener snips off the tip of a
growing plant, the apical meristem will be removed.
Auxin from the apical meristem will stop inhibiting
the auxin production in the lateral meristems. The
buds will begin to develop new branches, and the
plant will take on a new shape that is rounder and
fuller. The gardener has interrupted apical dominance.
34. A large, tasty fruit is likely to be eaten by an
animal, and the seeds of the plant will be dispersed
away from the parent plant in the animal’s feces.
Because seeds are dispersed away from the parent
plant, the new plant will be less likely to face
competition from its parent. Thus, it is more likely
that the plant will survive and pass on its genetic
material to its off spring. 35. The seeds of some pine
species are enclosed in sealed cones, which open only
after being exposed to the heat of a forest fire. When
the cones open, the seeds come out of dormancy and
germinate. This process allows the pines to recover
quickly after a fire.
Chapter 23 —Test B
Multiple Choice 1. c 2. d 3. b 4. c 5. d 6. a 7. b 8. d
9. d 10. a 11. a 12. a 13. d 14. c 15. b Modified
True/False 16. F; dermal 17. F; Casparian strip;
endodermis Completion 18. Meristems 19. root
hairs 20. buds 21. primary growth 22. Guard cells
Short Answer 23. Roots absorb water and dissolved
nutrients from the soil. 24. On a hot sunny day,
stomata will most likely be closed because the plant
will need to conserve water. 25. Water rises from the
roots to the top of a tree by root pressure, capillary
action, and transpirational pull. 26. Meristems
develop into dermal, vascular, and ground tissues.
Using Science Skills 27. Structure F is a leaf vein;
its tissues, xylem and phloem, lack chlorophyll. 28.
The stomata, one of which is indicated by letter E, are
open. 29. The spaces connect with the stomata,
allowing gases to be exchanged between the
mesophyll cells and the atmosphere. 30. Structure F is
a leaf vein, which includes xylem and phloem.
Chapter 24 —Test A
Multiple Choice 1. a 2. a 3. b 4. a 5. c 6. d 7. b 8. c
9. a 10. c 11. a 12. a 13. d 14. a 15. b Modified
True/False 16. F; petal 17. T 18. T 19. F; Cytokinins
20. F; endosperm Completion 21. anther 22. ethylene
Short Answer 23. Angiosperms undergo double
fertilization, which produces a diploid zygote and a
triploid cell that eventually produces endosperm. 24.
Seeds that are contained in dry, lightweight seeds
likely are dispersed by wind or water, whereas seeds
encased in a sweet, fleshy fruit likely are dispersed by
animals. 25. Through selective breeding, humans
developed modern corn from a wild grass called
teosinte. Teosinte has tiny kernels. Over thousands of
years, humans selected certain traits, producing the
much larger kernels of modern corn. Using Science
Skills 26. Chrysanthemum. A chrysanthemum
blooms and produces seeds in the fall. Cytokinin is
produced in developing seeds. 27. Phytochrome
regulates the response to photoperiod. It causes the
iris to bloom on long days, which take place in the
summer. 28. The chrysanthemum will bloom, but the
bearded iris will not. The chrysanthemum is a shortday plant, and the bearded iris is a long-day plant.
29.Chrysanthe-mums are adapted to blooming only
Chapter 24 —Test B
Multiple Choice 1. a 2. b 3. a 4. a 5. d 6. c 7. c 8. c
9. b 10. c 11. c 12. d 13. d 14. a 15. a Modified
True/False 16. T 17. T 18. F; auxin Completion
19. stolons; stems 20. fruit 21. ethylene 22.
phytochrome 23. corn Short Answer 24.
temperature and moisture 25. A plant hormone is a
chemical signal that affects a plant’s growth, activity,
and development and that coordinates its responses to
the environment. Using Science Skills 26. J, the
petal 27. Labels F, G, and H point to male parts.
Labels A, B, C, D, and E point to
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Answer Key—Tests • Chapter 24
female parts. 28. F, the anther 29. D, the stigma 30.
the style
the plant roots absorb water and minerals from the
soil, which are essential for the growth of many
plants. 34. Both bryophytes and ferns reproduce by
spores. Both also require water for fertilization.
Gymnosperms and angiosperms both reproduce with
seeds. The reproductive structures in gymnosperms
are cones. The reproductive structures in angiosperms
are flowers. 35. Angiosperms have adaptations to
entice mobile animals to spread their pollen and seed
away from the parent plant. Flowers have colorful
petals and nutrients to attract pollinators. The animal
pollinators are attracted to the source of nectar and
pollen provided by the flower. While feeding from
one flower to the next, the animals also pollinate the
flowers. Many angiosperm seeds are surrounded by
protective fleshy fruits that are eaten by many
different animals. The seeds travel unharmed through
the animal’s digestive system and are deposited in
feces far from the parent plant. Other seeds cling to
animal fur when animals brush past the plant. Later,
the seed drops off the fur in a new location.
Unit 6—Test A
Multiple Choice 1. b 2. c 3. b 4. c 5. c 6. a 7. d 8.
c 9. b 10. b 11. c 12. c 13. a 14. c 15. d Completion
16. cocci 17. retroviruses 18. pseudopods 19. hyphae
20. gametophyte; sporophyte Short Answer 21.
Archaea lack the peptidoglycan of bacteria and also
have different membrane lipids. The DNA sequences
of key archaea genes are more like those of
eukaryotes than those of bacteria. 22. Like land
plants, green algae have cellulose in their cell walls,
contain chlorophyll a and b, and store food in the
form of starch. 23. Monocots have seeds with one
cotyledon, parallel leaf veins, floral parts in multiples
of three, vascular bundles scattered throughout stems,
and fibrous roots. Dicots have two cotyledons,
branched leaf veins, floral parts in multiples of four or
five, vascular bundles arranged in a ring, and
taproots. 24. Meristem tissue is the only plant tissue
that produces new cells by mitosis. It is responsible
for plant growth. 25. Adaptations that allow seed
plants to reproduce without water include flowers or
cones, the transfer of sperm by pollination, and the
protection of embryos in seeds. Using Science
Skills 26. Leaves absorb light and carry out
photosynthesis. 27. No, because the stomata are open.
28. The structure labeled F transports water and the
products of photosynthesis. 29. As cold weather
approaches, chlorophyll production stops. When light
destroys the remaining green pigment, the leaves
change color. Photosynthesis stops. Enzymes extract
nutrients from the broken-down chlorophyll, which
are then stored in other parts of the plant. 30. If the
leaf were from a salt-tolerant plant, it would have
specialized cells that pump salt out of the plant and
onto the leaf surface, where it is washed off by the
rain. Essay 31. In a lytic infection, a bacteriophage
injects DNA into a bacterium and then takes over the
bacterium’s metabolism, causing synthesis of new
bacteriophage proteins and nucleic acids, which
assemble into viral particles. The bacteriophage then
lyses the bacterium’s cell wall, releasing the
bacteriophage particles. 32. Malaria is caused by the
sporeforming protist, Plasmodium. This protist is
spread through bites of the female Anopheles
mosquito. 33. Mycorrhizae are mutualistic
relationships of plant roots and fungi. The fungi help
Unit 6—Test B
Multiple Choice 1. d 2. c 3. d 4. c 5. c 6. a 7. b 8.
c 9. a 10. c 11. d 12. c 13. a 14. c 15. b Completion
16. vaccine 17. phytoplankton 18. antibiotics 19.
vascular tissue 20. dicot Short Answer 21.
Antibiotics are compounds that block the growth and
reproduction of bacteria. Viruses are not bacteria, and
viruses have few of the characteristics of living
things. 22. They recycle nutrients by breaking down
the bodies and wastes of other organisms. 23.
Meristem tissue is the only plant tissue that produces
new cells by mitosis. It is responsible for plant
growth. 24. Adaptations that allow seed plants to
reproduce without water include flowers or cones, the
transfer of sperm by pollination, and the protection of
embryos in seeds. 25. Stomata on the undersides of
leaves open and close in response to changes in water
pressure within the guard cells that surround the
opening. When the guard cells are swollen with
water, the stomata are open. When the guard cells
lose water, the stomata close, limiting further water
loss from the leaf. Using Science Skills 26.
unicellular 27. Structure B represents a cell
membrane. 28. The DNA is found free within the
cytoplasm and not within a nucleus. 29. The
flagellum is a structure used in movement. 30. The
organism
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Answer Key—Tests • Chapter 25
is a prokaryote, or a bacterium. Its characteristics
include a cell wall, a cell membrane, DNA but no
nucleus, and fl agella used in movement.
into contact with new parts of the environment first.
This trait enables them to respond to the environment
more quickly and in more sophisticated ways than
simpler animals can. 33. The outermost germ layer of
the embryo is the ectoderm. The ectoderm develops
into the structures that lie mostly along the outer
edges of the body. These structures include the
outermost layer of skin, nerves, and the sense organs.
The mesoderm is the middle layer of the embryo.
This layer develops into the structures in what can be
considered the middle layer of the adult vertebrate—
muscles, the circulatory system, the reproductive
system, and the excretory system. The endoderm
develops into the digestive and respiratory systems.
These systems are located in the innermost part of the
adult vertebrate. 34. Many different phyla share the
same pattern of embryological development, but very
different body plans as adults. If scientists only
considered embryological development patterns when
classifying animals, many unrelated animals would be
grouped together within phyla. For example,
echinoderms and chordates both develop as
deuterostomes as embryos. However, echinoderms
are invertebrates that develop radial symmetry as
adults, while most chordates are vertebrates with
bilateral symmetry as adults. Echinoderms also lack
segmentation and cephalization, which chordates
have both. 35. Development of a more complex body
system is not necessarily an improvement. As long as
a simple system allows an animal to survive and
reproduce successfully within an environment, it will
remain within the phylum. For example, vertebrates
have brains of different sizes and levels of
complexity. Mammals have more complex brains
than amphibians, fishes, reptiles, and birds, but
mammals do not necessarily survive and reproduce
better as a result of this difference. The simpler brains
of the other animals allow them to survive and
reproduce successfully as well. Animal groups with
body systems that do not promote survival and
successful reproduction become extinct.
Chapter 25 —Test A
Multiple Choice 1. c 2. d 3. a 4. d 5. b 6. d 7. d 8. b
9. b 10. b 11. b 12. a 13. c 14. b 15. c Modified
True/False 16. T 17. T Completion 18. multicellular
19. Invertebrates 20. cladogram Short Answer 21.
Animal cells do not have cell walls as plant cells do,
and all animals are heterotrophs, obtaining energy by
feeding on organic compounds from other organisms.
22. They are multicellular, heterotrophic, and
eukaryotic, and their cells lack cell walls. 23. Yes, she
can classify it as a chordate because it has a backbone. This means that the animal is a vertebrate. All
vertebrates are chordates. 24. A body system most
likely will remain in a phylum if animals with that
system are able to survive and reproduce with that
body system. 25. Humans are bilaterally symmetrical,
are segmented, and show cephalization, and they have
an internal skeleton, jointed legs, and front limbs that
have evolved into arms. Using Science Skills 26.
endoderm 27. Structure C 28. Structure A shows that
the zygote has developed into a hollow ball of cells
called a blastula. Structure B shows that cells in the
blastula have diff eventuated into three types of cells:
endoderm, mesoderm, and ectoderm. The opening
and pocket formed by the endoderm is called the
blastopore. Structure D shows the embryo after the
second opening has developed, while the mesoderm
has completely lined the interior of the endoderm and
ectoderm layers. This series of steps illustrates the
development of a deuterostome. 29. the digestive tract
30. Structure E Essay 31. When your body
temperature goes up, feedback inhibition causes your
body to sweat. Sweat cools your skin as it evaporates.
If your body gets too cold, feedback inhibition tells
your body to stop sweating and start shivering to
generate more heat. 32. In animals with bilateral
symmetry, only a single imaginary plane can divide
the body into two equal halves. Bilateral symmetry
allows for segmentation, in which segments can have
external body parts on each side of the body, such as
appendages. Animals with bilateral symmetry usually
exhibit cephalization, or the concentration of sense
organs and nerve cells at the anterior end of the body.
Animals with cephalization usually move with the
anterior end of the body forward, so this end comes
Chapter 25 —Test B
Multiple Choice 1. d 2. c 3. d 4. d 5. b 6. c 7. b 8. b
9. c 10. d 11. d 12. a 13. d 14. b 15. c Modified
True/False 16. T 17. T Completion 18. multicellular
19. circulatory 20. blastopore 21. vertebrates 22.
Invertebrates Short Answer 23. Animal
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Answer Key—Tests • Chapter 26
cells do not have cell walls as plant cells do, and all
animals are heterotrophs, obtaining energy by feeding
on organic compounds from other organisms. 24. A
vertebrate is a chordate that has a backbone. Most
chordates are vertebrates, but there are a few aquatic
animals that never develop a backbone with
vertebrae. 25. The anterior end of the body usually
comes into contact with a new environment first in an
animal with bilateral symmetry. A concentration of
sense organs and nerve cells at the anterior end
enables the animal to respond effectively. 26.
Materials can move efficiently through their bodies
by diffusion. Using Science Skills 27. Cnidarians
28. Echinoderms are more closely related to
chordates than to arthropods because echinoderms
and chordates are both deuterostomes. Arthropods are
protostomes. 29. All phyla that have specialized cells,
tissues, and organs also have three germ layers. An
animal must need to have all three germ layers in
order to form organs. 30. The teacher needs to
determine what type of body cavity the worm has,
because each phylum of worm has a different type of
body cavity.
mammals, most of the brain would have consisted of
cerebrum. A large cerebrum is another feature of
primates. 27. Homo neanderthalensis was probably
capable of more complex behaviors than Homo
erectus, which was probably capable of more
complex behaviors than Australopithecus africanus.
In mammals, most of the brain is taken up by the
cerebrum, which is the center of complex behaviors.
A larger cerebrum allows for more complex
behaviors. 28. Australopithecus africanus appeared
first, then Homo erectus, then Homo
neanderthalensis. 29. Homo erectus and Homo
neanderthalensis are more closely related to Homo
sapiens than is Australopithecus africanus, because
both H. erectus and H. neanderthalensis are in the
same genus as H. sapiens. Some students might note
that if the multiregional model is correct, H. erectus is
more closely related to H. sapiens than is H.
neanderthalensis, because that model proposes that
H. sapiens descended directly from H. erectus. If the
out-of-Africa model is correct, it would be impossible
to say whether H. erectus or H. neanderthalensis is
more closely related to H. sapiens. 30.
Paleontologists most likely look at jaw shape and
size, the length and slope of the face, the teeth, and
facial features such as the size and placement of the
eye sockets and nose area, because each of these
skulls have distinct differences in these features.
Essay 31. Many of these animals must have
absorbed nutrients from the surrounding water.
Others may have had algae living within their bodies.
Some of the food produced by the algae through
photosynthesis may have been used as nutrients by
the animals. 32. Answers should include references to
the following facts: Since trochophores are a larval
stage, they would need to mature before they could be
classified as either an annelid or mollusk. If the
animal was an annelid, it would be a worm with a
segmented body. The segments would look like a
series of rings. If the animal was a mollusk, it would
have a soft body with either an internal or external
shell and a complex organ system. 33. The node for
shelled eggs should appear above “Reptilian
ancestor,” because both modern reptiles and modern
birds produce shelled eggs. This means that the
shelled egg adaptation occurred before the first major
branch in the cladogram. Since feather development
most likely occurred between the appearance of
Saurischia and Archaeopteryx, this node should go on
the main branch between these two
Chapter 26 —Test A
Multiple Choice 1. b 2. d 3. c 4. c 5. b 6. b 7. c 8. c
9. d 10. d 11. c 12. a 13. b 14. d 15. a Completion
16. Flatworms; Platyhelminthes 17. cerebrum;
cerebral cortex 18. Old World 19. New World
monkeys 20. erectus Short Answer 21. Some
animals of the Cambrian Period had shells, skeletons,
and other hard body parts, which are well preserved
in fossils. 22. Students should identify one of the
following: Cnidarians have stinging tentacles around
their mouths, but echinoderms do not. Not all
cnidarians have skeletons, but all echinoderms do.
Echinoderms have 5-part radial symmetry, but
cnidarians are not limited to five parts. Echinoderms
are deuterostomes, but cnidarians are neither
deuterostomes nor protostomes. 23. notochord and
paired muscle blocks 24. Salamanders have moist
skin with mucous glands. Dry scaly skin is a
characteristic of reptiles. A lizard is a reptile. 25.
Fossilized footprints of Australopithecus indicate that
it walked bipedally, and fossilized skulls of
Australopithecus show that it had a small brain
compared to later species. Using Science Skills 26.
The skulls show that all three species had eyes that
faced forward. The skulls also indicate that all three
species had relatively large brains. Because they were
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Answer Key—Tests • Chapter 27
groups because both Archaeopteryx and modern birds
share this characteristic. Since birds are the only
reptiles that can maintain their internal body
temperature, the node for endothermy should go on
the cladogram branch that leads directly to modern
birds. 34. Binocular vision occurs when the field of
view of one eye overlaps with the field of view of the
other eye. For binocular vision to provide adequate
depth perception, both eyes must face forward so that
the fields of view can overlap. An unusually narrow
face might have the effect of keeping the eyes from
facing completely forward, so that the fields of view
do not overlap at all, and this would limit the
monkey’s depth perception. 35. Answers should
include two of the following features described for
each skeleton: In a bipedal primate, the skull sits atop
an S-shaped spine, and the spinal cord exits at the
bottom of the skull. The arms are shorter than the
legs, so the hands do not touch the ground during
walking. The pelvis is bowl shaped, and the thigh
bones are angled inward, directly below the body. In
a primate that is not bipedal, the skull sits atop a Cshaped spine, and the spinal cord exits near the back
of the skull. The arms are longer than the legs, so the
hands touch the ground during walking. The pelvis is
long and narrow, and the thigh bones are angled away
from the pelvis.
appear to have appendages and it is not clear which
end, if either, is the anterior end. 28. A. It appears to
have a skeleton, a complex body plan, and specialized
appendages, which are features that first appeared
during the Cambrian Period. 29. Arthropods, because
they have an exoskeleton and specialized, jointed
appendages, like invertebrate A. 30. B. It appears to
be flat, plate-shaped, soft -bodied, and bilaterally
symmetrical, like many other animals from that
period.
Chapter 27 —Test A
Multiple Choice 1. c 2. d 3. a 4. d 5. d 6. a 7. b 8.
c 9. b 10. b 11. c 12. d 13. a 14. b 15. d Completion
16. gastrovascular cavity 17. enzymes 18. lower 19.
lungs 20. amphibian Short Answer 21. Mechanical
digestion physically breaks down food into smaller
particles by crushing or breaking it. Chemical
digestion uses enzymes to release nutrients from the
food particles. 22. Oxygen would stop diffusing into
the blood. 23. The earthworm’s skin will dry out if it
remains exposed to air. If its skin dries out, oxygen
and carbon dioxide will not be able to diffuse across
it. The earthworm will die from lack of oxygen. 24.
The partition keeps oxygen-rich blood from remixing
with oxygen-poor blood before it is pumped out to the
body. It transforms one pump into two parallel
pumps. 25. The excretory systems of animals that
excrete uric acid all empty into the gut, while the
systems of animals that secrete urine have a separate
opening or openings to the outside of the animal’s
body. Using Science Skills 26. kidney 27. The
fish in the top row has a greater salt concentration
than the water that it is in, because its body has a
higher concentration of salt than fresh water does. 28.
The fish drink less water and gain water through
osmosis as in B and C. 29. Because the fish’s body
has a lower concentration of salt than the surrounding
water, it absorbs salt and loses water by osmosis. 30.
The fish stops drinking water and excretes excess
water in very dilute urine. Essay 31. Cows benefit
from the microorganisms breaking down cellulose
into nutrients the cows can use for growth and energy.
The microorganisms benefit from having food
supplied to them by the cows and also by having a
place to live. The relationship is mutualism. 32. The
fish was pumping water over its gills so that oxygen
could diffuse from the water into the blood across the
mem-
Chapter 26 —Test B
Multiple Choice 1. c 2. b 3. d 4. b 5. d 6. c 7. b 8.
b 9. d 10. c 11. c 12. a 13. c 14. b 15. d Modified
True/False 16. F; binocular 17. T Completion 18.
deuterostomes 19. neanderthalensis 20. tools Short
Answer 21. notochord and paired muscle blocks 22.
All of the dinosaurs died in a mass extinction at the
end of the Cretaceous Period. 23. continental drift 24.
Anthropoids are the humanlike primates. This group
includes monkeys, great apes, and humans. The
hominoid group is a subgroup of anthropoids that
consists of gibbons, orangutans, gorillas,
chimpanzees, and humans. 25. Fossilized footprints
of Australopithecus indicate that it walked bipedally,
and fossilized skulls of Australopithecus show that it
had a small brain compared to later species. Using
Science Skills 26. bilateral symmetry 27. The two
animals both have bilateral symmetry, and both
appear to have segmentation. However, the animal
labeled A has definite appendages and clear anterior
and posterior ends. The animal labeled B does not
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Answer Key—Tests • Chapter 28
branes of the gill filaments and so carbon dioxide
could diffuse from the blood into the water. If the fish
stopped pumping water over its gills, it would get less
oxygen than it needed, and might suffocate. Also,
since the gills have excretory functions, the fish might
be unable to maintain its proper water balance. 33.
The amphibian lung is the simplest lung, because it is
a simple sac with ridges that increase the surface area
of the respiratory membranes. The reptile lung is
more complicated, and is divided into chambers to
increase the surface area. The most complicated lung
is the mammalian lung, which is large and has many
branches in the airways. The lung is full of air sacs
called alveoli, giving it the greatest surface area of the
three types of lung. This is necessary because the
mammal has the greatest metabolic rate of the three
animals and needs much more oxygen to maintain
that rate. 34. Water is needed to excrete nitrogenous
wastes, but animals need to keep the amount of the
water in their bodies at the correct level. This means
that animals need to eliminate excess water but avoid
eliminating too much water while still getting rid of
the nitrogenous wastes. Urea is more soluble in water
than uric acid, so animals that convert ammonia to
uric acid excrete less water than animals that convert
ammonia to urea 35. Urine contains urea, which
requires water for excretion. In a desert environment,
an animal that excretes urine instead of uric acid has
to work harder to maintain water balance. Desert
animals can overcome this disadvantage by excreting
highly concentrated urine and absorbing as much
water as possible from their feces.
secrete urine have aseparate opening or openings to
the outside of the animal’s body. Using Science
Skills 27. Both systems are closed circulatory
systems, because the blood is traveling through closed
loops of blood vessels. There are no sinuses or open
blood vessels present. 28. Vertebrates with gills; the
art shows gill capillaries and one heart in a singleloop circulatory system 29. You would find this
system in a terrestrial vertebrate, because
invertebrates do not use lungs for respiration. 30.
Oxygen-poor blood goes to the lungs (lung
capillaries) to pick up oxygen and get rid of carbon
dioxide.
Chapter 28 —Test A
Multiple Choice 1. c 2. d 3. a 4. d 5. d 6. c 7. b 8. a
9. d 10. a 11. c 12. d 13. c 14. b 15. c Modified
True/False 16. T 17. T 18. T 19. F; ovoviviparous
Completion 20. stimulus 21. nerve net 22. bone
23. pairs groups 24. homeostasis Short Answer 25.
If the immune system cannot tell the difference, it
might attack the body’s own cells. Using Science
Skills 26. reptiles, birds, and a few mammals 27.
Chorion 28. The embryo develops in a fluid-filled sac
called the amnion. 29. The shell of an amniotic egg is
selectively permeable to oxygen and carbon
dioxide, but unlike a respiratory membrane it is not
moist—in fact, the shell is waterproof. 30. The
amniotic egg is attached to the embryo through a
circulatory system, and it provides the embryo with a
way to obtain nutrients, exchange gases, and remove
wastes. It also gives the embryo a favorable
environment in which to grow. Essay 31. The more
cephalized an animal is, the more complex its nervous
system is, and a complex nervous system is capable
of processing more sensory stimuli. In highly
cephalized animals, sensory neurons are organized
into organs such as eyes, ears, and noses. These
animals have evolved complex nervous systems
capable of processing all the information detected by
these varied sense organs and necessary to develop
responses to widely varied stimuli. 32. The three
types of skeletons are hydrostatic skeletons,
exoskeletons, and endoskeletons. All three skeletons
provide structural support for animals. However, only
the hydrostatic skeleton can cause drastic changes in
the shape of the animal’s body. It is
Chapter 27 —Test B
Multiple Choice 1. d 2. d 3. d 4. b 5. b 6. d 7. a 8. c
9. b 10. d 11. c 12. b 13. a 14. b 15. b Completion
16. parasites 17. enzymes 18. Gills 19. book lung 20.
osmosis Short Answer 21. A parasite has a harmful
effect on its host because it feeds on the host’s blood
and tissues. In some cases the parasite can cause
disease in the host. 22. digestive tract 23. Oxygen
would stop diffusing into the blood. 24. The
earthworm’s skin will dry out if it remains exposed to
air. If its skin dries out, oxygen and carbon dioxide
will not be able to diffuse across it. The earthworm
will die from lack of oxygen. 25. The grasshopper has
an open circulatory system, because the blood vessels
have open ends. They are not closed loops. 26. The
excretory systems of animals that excrete uric acid all
empty into the gut, while the systems of animals that
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Answer Key—Tests • Chapter 29
Chapter 28 —Test B
also the only skeleton that relies on fluid to control
movement and provide support, and does not need
joints to provide flexibility. Both exoskeletons and
endoskeletons are rigid, jointed skeletons.
Exoskeletons are external and must be shed by the
animal for it to be able to grow, while an
endoskeleton is internal and can grow with the
animal. Exoskeletons are made of a protein called
chitin or of calcium carbonate, but endoskeletons are
made of calcified plates, cartilage, or a combination
of bones and cartilage. Unlike hydrostatic skeletons,
which use contractile cells to control movement,
exoskeletons and endoskeletons use muscles that are
usually arranged in opposing pairs or groups. Both
endoskeletons and exoskeletons have joints and move
when pairs or groups of muscles pull across the joints
in different directions. 33. A hermaphrodite is an
animal that is either both male and female at the same
time, or changes from one sex to another during its
lifetime. If a species is the first type of
hermaphrodite, individuals would never face a
shortage of either males or females—any other
member of the species is always a potential mate.
This availability is especially important if the
individuals in the species live alone instead of in
groups or colonies. If a species tends to live in groups
or colonies, then either type of hermaphrodite would
increase the chances of there always being an
adequate number of mates available within the group.
34. Metamorphosis in both groups of animals results
in change between the larval form of the animal and
the adult form, and is regulated by hormones. In
arthropods, metamorphosis can be complete or
incomplete. In complete metamorphosis, the adult
arthropod looks completely different from the larval
stage. In incomplete metamorphosis, the young are
called nymphs and look more like the adults. By
contrast, metamorphosis in amphibians would be
considered only complete metamorphosis, because
the larvae not only look different from the adults but
are aquatic, while the adults are terrestrial. 35. The
lizard is an ectotherm, and the dog is an endotherm.
The lizard had to move out of the sun in order to
reduce its body temperature by letting the excess heat
escape into its environment. The dog was able to stay
in place and reduce its body temperature by panting,
because the dog’s body has the ability to reduce its
body temperature by combining panting with
controlling its own heat production.
Multiple Choice 1. d 2. c 3. b 4. c 5. a 6. d 7. c 8. b
9. d 10. d 11. d 12. c 13. a 14. b 15. b Modified
True/False 16. T 17. F; incomplete Completion
18. molt 19. external 20. homeostasis 21. endotherm
Short Answer 22. It moves from sensory neurons in
your finger to one or more interneurons to motor
neurons in your finger muscle. 23. cerebellum 24. A
hydrostatic skeleton relies on muscles and water
instead of a hard substance such as chitin, bone, or
cartilage. 25. The joint limb would be unable to
move. 26. The figure shows incomplete
metamorphosis. 27. The student should hypothesize
that the fly is an ectotherm, because if it were an
endotherm it would probably have been active before
the sun warmed up the window. Using Science
Skills 28. sexual reproduction 29. The female and
male medusas are diploid (2N), and the sperm and
egg each are haploid (N). 30. External fertilization;
this part of a jellyfish’s reproductive cycle is most
likely to occur when the release of eggs and sperm
can be synchronized, such as during a particular tide,
moon phase, or season.
Chapter 29 —Test A
Multiple Choice 1. c 2. d 3. a 4. b 5. c 6. b 7. c 8. a
9. a 10. b 11. b 12. a 13. c 14. d 15. a Modified
True/False 16. F; classical conditioning 17. T 18. F;
a circadian rhythm Completion 19. innate; inborn
20. insight learning; trial-and-error learning 21.
social; kin selection 22. pheromone Short Answer
23. Behaviors evolve through natural selection if they
are coded for by an animal’s genes and they promote
survival and reproduction. The behaviors can then be
passed on to off spring. 24. Classical conditioning is a
type of learning that occurs when an animal makes a
mental connection between the stimulus and some
kind of reward or punishment. 25. When food or
other resources are scarce, dormancy and migration
allow animals to survive by becoming inactive or by
moving to another place where resources are more
plentiful. Using Science Skills 26. Bats in
experiment A, which could not see, were still able to
avoid the wires as oft en as bats in the control group,
which could see. This means that vision is not
important when bats are trying to avoid obstacles. 27.
Hearing is very important for obstacle avoidance in
bats. Bats that had both ears covered and therefore
could not hear were
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Answer Key—Tests • Chapter 29
only half as successful at avoiding the wires as bats in
the control group, which could hear. 28. Bats that had
one ear covered and therefore could hear with only
one ear were about as unsuccessful at avoiding the
wires as bats that had both ears covered and therefore
could not hear at all. This means that bats must be
able to hear with two ears in order to avoid obstacles.
29. The data shows that bats need to be able to
produce sound as well as to hear to avoid obstacles.
Bats that had their mouth covered could not produce
the high-pitched sounds that would reflect off of the
surface of obstacles, so they were as unsuccessful at
avoiding the wires as the bats that had both ears
covered and therefore could not hear. 30. Using
hearing rather than vision to avoid obstacles is
adaptive for bats because bats are active at night,
when darkness makes vision less useful. The ability
to locate obstacles using sound lets bats avoid
obstacles they cannot see with their eyes. Essay 31.
Many of its predators have probably learned that
snakes are dangerous. The caterpillar’s enlarged,
snakelike front end will discourage many possible
predators from attacking and killing the caterpillar.
Therefore, the ability to resemble a snake helps
enable the caterpillar to survive. 32. In classical
conditioning, an animal learns to make a mental
connection between a stimulus and some kind of
reward or punishment. The stimulus is one that the
animal did not previously associate with the reward or
punishment. In operant conditioning, an animal learns
through trial and error to produce a certain behavior
to receive a reward or avoid punishment. 33. Sample
answer: I most likely wake up at 6:30 a.m. on the
weekends because of my circadian rhythm. A
circadian rhythm is a daily cycle of behavior. Since I
am used to waking up at the same time most
mornings, my circadian rhythm causes me to wake up
at that time even when the alarm clock does not wake
me up. 34. Competition that involves physical attacks
can injure the winner as well as the loser of the
competition. An animal that is injured may be more
vulnerable to predators or may have difficulty feeding
itself. It therefore will be less likely to survive and
reproduce. Rituals and displays can signal to both
competitors that one is stronger and the other is
weaker before either is seriously injured. Both
competitors then have a greater chance of surviving
after the competition. 35. Communication can occur
whenever one individual passes information to
another. This information can be as simple as a flash
of light, a sound, or a chemical released into the
environment. Animals use these signals to
communicate such things as warnings, readiness to
mate, and the boundaries of a territory.
Chapter 29 —Test B
Multiple Choice 1. a 2. c 3. c 4. a 5. d 6. a 7. b 8. c
9. c 10. d 11. a 12. d 13. c 14. d 15. a Modified
True/False 16. F; innate; inborn; instinctive 17. T
18. F; classical conditioning 19. T 20. F; migration
Completion 21. stimulus 22. social; kin selection
Short Answer 23. Because innate behaviors can be
performed without previous experience, a mammal
can suckle immediately after it is born, which is
important to its survival. 24. Because of habituation,
an animal can decrease or stop its response to a
repetitive stimulus that is nonthreatening or
unrewarding, which allows the animal to spend its
time and energy more efficiently. 25. No, it does not
make up a society because the geese probably are not
closely related and do not cooperate with each other.
Using Science Skills 26. The behavior is innate.
27. The female begins the courtship. 28. The nest is
likely built by the male because the male guides the
female to the nest. 29. The male swims zigzag to the
female, swims toward the nest, points to the nest,
trembles, and nudges the female. 30. The female
gives a head-up display, swims head-up toward the
male, enters the nest, lays eggs in the nest, and leaves
the nest.
Unit 7—Test A
Multiple Choice 1. c 2. b 3. b 4. c 5. b 6. b 7. c 8. c
9. a 10. b 11. a 12. a 13. c 14. a 15. c Completion
16. flatworm 17. radial 18. invertebrate 19.
amphibian 20. response; stimulus Short Answer 21.
polyp and medusa 22. An open circulatory system is
one in which blood is pumped through vessels into
sinuses. 23. Internal fertilization takes place inside
the animal’s body. External fertilization takes place
outside the body. 24. Echinoderms have a closer
evolutionary relationship to chordates than to
mollusks. Both echinoderms and chordates are
deuterstomes, whereas mollusks are protostomes. 25.
Both tunicates and lancelets have a hollow nerve
cord, a notochord, pharyngeal pouches, and a tail at
some stage of their life cycle. Using Science Skills
26. The process is complete metamorphosis.
Butterflies and beetles (lady
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Answer Key—Tests • Chapter 30
bugs) undergo this process. 27. Drawing 1 represents
the insect’s eggs, which are formed through internal
fertilization during sexual reproduction. 28. Drawing
2 represents a larva, which looks and acts nothing like
the parents. 29. Drawing 3 represents a pupa. During
the pupal stage, the body is completely remodeled
inside and out. 30. The other form, called incomplete
metamorphosis, is much less dramatic. The immature
form, called a nymph, looks very much like an adult,
and there is a gradual change from nymph to adult.
Essay 31. In a developing embryo, the blastopore
leads into a central tube that runs the length of the
embryo. The tube becomes the digestive tract and is
formed in one of two ways. A protostome is an
animal whose mouth is formed from the blastopore. A
deuterostome is an animal whose anus is formed from
the blastopore. 32. A hydrostatic skeleton consists of
muscles surrounding a fluid-filled body cavity that
supports the muscles. When the muscles contract,
they push against the body cavity, causing the body to
change shape. An exoskeleton is a tough external
covering. An endoskeleton is an internal skeleton. 33.
Terrestrial invertebrates must conserve water while
removing nitrogenous wastes from the body. To do
this, many animals convert ammonia into a compound
called urea, which is less toxic than ammonia. Urea is
eliminated from the body in urine, which is highly
concentrated. Some insects and arachnids have Malpighian tubules, saclike organs that convert ammonia
into uric acid. The uric acid and digestive wastes
combine to form a thick paste that leaves the body
through the rectum. This paste contains little water.
34. Like in the evolution of other chordate groups, a
series of complex adaptive radiations produced a
large number of species. These adaptive radiations
included the ability to walk upright on two feet, grasp
objects and use tools with opposable thumbs, and the
development of a much larger cerebrum than other
chordates. 35. The behavior of an animal determines
whether it will get food and other resources, find a
mate, and get protection from predators. If an animal
has an adaptive behavior that makes it better suited to
get any of the things it needs, it will have a better
chance of surviving and passing its genes to off
spring.
16. larva 17. invertebrate 18. molting 19.
cephalization 20. opposable thumb Short Answer
21. Internal fertilization takes place inside the
animal’s body. External fertilization takes place
outside the body. 22. Both tunicates and lancelets
have a hollow nerve cord, a notochord, pharyngeal
pouches, and a tail at some stage of their life cycle.
23. Primates have binocular vision, a well-developed
cerebrum, relatively long fingers and toes, and arms
that can rotate around their shoulder joints. 24. The
embryos of both birds and reptiles develop within
amniotic eggs. Both excrete nitrogenous wastes as
uric acid and have a cloaca. Both have similar bones
that support the front and hind limbs. 25. Members of
a society are oft en closely related, and therefore,
share a large proportion of each other’s genes.
Helping a relative survive increases the chance that
the genes an individual shares with the relative will
be passed along to off spring. 26. A coelom is a fluidfilled body cavity that is lined with tissue derived
from the mesoderm. Invertebrates that have a true
coelom include annelids, mollusks, arthropods, and
echinoderms. Using Science Skills 27. Diagram
III 28. The circulatory system in diagram III supports
gills. The circulatory systems in diagrams I and II
support lungs. 29. The vessels labeled A and B have
oxygen-poor blood. The vessels labeled C and D have
oxygen-rich blood. 30. The circulatory system in
diagram I is most efficient at delivering oxygen
because oxygen-rich blood is always completely
separated from oxygen-poor blood.
Chapter 30 —Test A
Multiple Choice 1. b 2. b 3. c 4. d 5. c 6. d 7. a 8. b
9. b 10. a 11. b 12. a 13. a 14. c 15. c Modified
True/False 16. F; opposes or blocks 17. T 18. T 19.
F; esophagus 20. F; more Completion 21. minerals
22. sodium bicarbonate 23. bacteria Short Answer
24. Fiber is a complex carbohydrate called cellulose.
It is important because it helps muscles move food
and wastes through your digestive system. 25. If the
liver is damaged it may not be able to produce bile, a
fluid loaded with lipids and salts. Bile breaks up the
globs of fat, making it easier for the enzyme lipase to
digest them in the small intestine. Without bile, the
body has difficulty in breaking down fat. Using
Science Skills 26. The function of the small
intestine is to absorb nutrients from
Unit 7—Test B
Multiple Choice 1. b 2. d 3. a 4. c 5. a 6. c 7. d 8. d
9. b 10. c 11. b 12. c 13. b 14. c 15. d Completion
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Answer Key—Tests • Chapter 31
Bowman’s capsule and it would appear in the waste
products. This would cause blood to appear in the
urine. 35. Teeth cut and grind the apple into smaller
pieces. Salivary glands secrete saliva, which moistens
the apple pieces and makes them easier to swallow.
Saliva also contains an enzyme that breaks down
chemical bonds in the apple pieces. The tongue and
muscles in the throat force the chewed food down the
throat into the esophagus. Muscles move the food
through the esophagus into the stomach, where the
food is churned and mixed with acids to further break
down the food molecules. The food mixture, called
chyme, moves into the small intestine. Here, the
nutrient molecules are absorbed into cells lining the
small intestine. Undigestible substances move into the
large intestine, or colon. Water is removed from this
material, and the remaining waste is eliminated from
the body through the rectum.
food through its walls. 27. Villi 28. Microvilli 29.
They increase the surface area of the small intestine
walls, allowing it to absorb more nutrients. 30.
Epithelial tissue would be found inside the lining of
the small intestine because one of the functions of
epithelial tissue is absorption and excretion of
materials. Essay 31. Answer should include six of the
following systems. The nervous system coordinates
the body’s response to changes in its internal and
external environment. The integumentary system
serves as a barrier against infection and injury, helps
to regulate body temperature, and provides protection
against ultraviolet radiation from the sun. The skeletal
system supports the body, protects internal organs,
allows movement, stores mineral reserves, and
provides a site for blood cell formation. The muscular
system works with the skeletal system to provide
voluntary movement and helps to circulate blood and
move food through the digestive system. The
circulatory system brings oxygen, nutrients, and
hormones to cells; fights infection; removes cell
wastes; and helps regulate body temperature. The
respiratory system provides oxygen needed for
cellular respiration and removes excess carbon
dioxide from the body. The digestive system converts
foods into simpler molecules that can be used by the
cells of the body. The excretory system eliminates
waste products from the body. The endocrine system
controls growth, development, and metabolism. The
reproductive system produces reproductive cells and,
in the female, nurtures and protects the developing
embryo. The lymphatic system helps protect the body
from disease, collects fluid lost from blood vessels,
and returns the fluid to the circulatory system. 32.
Answers should show an understanding that a
balanced diet should include a combination of
carbohydrates, proteins, fats, vitamins, and minerals.
33. Skin: excretes excess water, salts and a small
amount of urea as sweat; Lungs: excrete carbon
dioxide and small amounts of vapor, which are waste
products of cellular respiration; Liver: converts
potentially dangerous nitrogen wastes into less toxic
urea; Kidneys: remove excess water, urea, and
metabolic wastes from the blood; Ureter: transports
urine from the kidneys to the urinary bladder;
Bladder: stores urine until it is released from the
body; Urethra: tube through which urine is released
from the body 34. The glomerulus is a dense network
of capillaries found in the nephrons of kidneys. If
their walls were damaged blood would enter
Chapter 30 —Test B
Multiple Choice 1. d 2. b 3. c 4. c 5. b 6. a 7. c 8. d
9. c 10. b 11. b 12. d 13. c 14. c 15. c Modified
True/False 16. F; opposes or blocks 17. T 18. F;
more Completion 19. nutrition 20. chyme 21. urine
22. Ureters Short Answer 23. A tissue is a group of
similar cells that perform a single function. An organ
is a group of tissues that work together to perform a
complex function. 24. Calories measure the energy in
food. Active people need more energy than do people
who get little exercise. 25. Structure A is unsaturated
fat and Structure B is saturated fat. Saturated fat is
solid at room temperature and is associated with heart
problems. An example is butter. Unsaturated fat is
liquid at room temperature and is not associated with
heart problems. An example is olive oil. 26. These
vitamins dissolve in water and cannot be stored in the
body the way fat-soluble vitamins can. Using
Science Skills 27. hydrochloric acid; protein; fat
28. the percent of bicarbonate and digestive enzymes
in pancreatic juice 29. fat; 80% 30. hydrochloric acid;
80%
Chapter 31 —Test A
Multiple Choice 1. b 2. c 3. c 4. c 5. a 6. a 7. a 8. c
9. d 10. a 11. a 12. c 13. b 14. d 15. d Modified
True/False 16. F; slower 17. T 18. F; rods
Completion 19. ganglia 20. reflex arc 21. taste buds
Short
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Answer Key—Tests • Chapter 32
Answer 22. The brain stem controls or is involved in
some of the body’s most important functions,
including breathing, heart rate, and blood pressure
regulation. These involuntary processes are essential
to life, so the disruption of any of these processes can
cause death. 23. A drug user’s brain reacts to
excessive dopamine by reducing the number of
receptors for the neurotransmitter. Because there are
fewer receptors, larger amounts of the drug are
required to produce the same high. 24. The chemical
substances that make jalapeno peppers taste “hot”
actually bind to thermoreceptors in the mouth. 25.
Vibrations from the oval window cause waves in the
fluid-filled cochlea. The waves cause the movement
of hair cells that line the cochlea. These hair cells
send nerve impulses to the brain. Using Science
Skills 26. spinal cord 27. structure A, the cerebrum
28. structure D, hypothalamus 29. Structure A, the
cerebrum, provides a command such as to move a
particular muscle, to structure B, the cerebellum,
which in turn coordinates and balances the actions of
the muscle. 30. Structure F is the brain stem and it
regulates the flow of information between the brain
and the body. Essay 31. The first category is the
nervous system. Central nervous system (consists of
brain and spinal cord, processes information and
creates a response that is delivered to the appropriate
part of the body by the peripheral nervous system)
and peripheral nervous system (consists of nerves and
supporting cells, collects information about the
body’s environment) branch off nervous system.
Sensory division (transmits impulses from sense
organs to central nervous system) and motor division
(transmits impulses from the central nervous system
to muscles or glands) then branch off peripheral
nervous system. The motor division is then divided
into somatic nervous system (regulates body activities
that are under conscious control) and autonomic
system (regulates body activities that are involuntary).
32. Frontal lobe: located at the front of the skull,
responsible for evaluating consequences, making
judgments, and forming plans; Parietal lobe: located
behind the frontal lobe towards the back of the skull,
responsible for reading and speech; Temporal lobe:
located beneath the frontal lobe and parietal lobe,
responsible for hearing and smelling; Occipital lobe:
located at the back base of the skull, responsible for
vision. 33. Student responses may include reasons
such as a desire for immediate pleasure or a desire to
suppress physical or emotional pain. Excess
dopamine levels in the brain caused by drugs reduce
the number of receptors for neurotransmitters. As a
result, normal activities no longer produce the
sensations of pleasure that they once did. If you start,
and then stop, taking the drugs, you may feel
depressed and sick without them. This causes addicts
to take more and more drugs, developing a deeper
habit that is harder to break. 34. 1) Sensory receptors
react to the sensation of the tack and send an impulse
to sensory neurons. 2) Sensory neurons relay the
information to the spinal cord. 3) An interneuron in
the spinal cord processes the information and forms a
response. 4) A motor neuron carries impulses to its
effector, a muscle that it stimulates. 5) The muscle
contracts and the leg moves. 35. Fingertips most
likely have a greater concentration of sensory
receptors than the palms of a hand because fingertips
are more sensitive to touch.
Chapter 31 —Test B
Multiple Choice 1. c 2. d 3. a 4. c 5. b 6. a 7. a 8. d 9.
b 10. c 11. c 12. d 13. a 14. b 15. a Modified
True/False 16. T 17. F; autonomic Completion 18.
peripheral 19. nodes 20. brain stem 21. hypothalamus
Short Answer 22. Impulses travel faster down axons
that have myelin sheaths than they travel down axons
without them. 23. An impulse will not be able to pass
from one cell to another. 24. Smells from food
activate the chemoreceptors. Going on amusement
rides activates mechanoreceptors. Photoreceptors are
stimulated by the sunshine or flashing lights. 25.
Impulses are always transmitted in one direction
across the synapse because axons, not dendrites,
release neurotransmitters. Using Science Skills 26.
vesicles 27. An impulse reaches the end of the axon
of one neuron. 28. The impulse will travel from the
axon to the dendrite of the adjacent neuron. 29. The
neurotransmitters may be broken down by enzymes,
or taken up and recycled by the axon terminal. 30.
muscle cells and glands
Chapter 32 —Test A
Multiple Choice 1. a 2. c 3. c 4. d 5. c 6. c 7. a 8. d 9.
a 10. c 11. a 12. a 13. c 14. d 15. d Modified
True/False 16. F; osteoblasts 17. T Completion 18.
immovable 19. melanin 20. histamine Short Answer
21. In osteoporosis, osteoclasts break
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Answer Key—Tests • Chapter 32
down bone faster than osteoblasts rebuild it. This
leads to a decrease in bone density and therefore
makes bones weaker. 22. Skeletal muscle movements
are controlled voluntarily while cardiac muscle
movements are controlled involuntarily. Having a
heart made of skeletal muscles would be a
disadvantage because the person would have to
consciously control the beating of his or her heart. 23.
A muscle is made up of many muscle fibers. The
strength of a muscle contraction varies depending
upon the total number of individual muscle fibers that
contract. 24. The skin produces vitamin D, which is
needed for absorption of calcium and phosphorus
from the small intestine into the blood. 25. The
epidermis is made up of layers of epithelial cells and
contains pigment-producing melanocytes. The dermis
contains nerve endings, blood vessels, smooth
muscle, sweat glands, sebaceous glands, and hair
follicles. Using Science Skills 26. A 27. B, dermis
28. This sebaceous gland produces oil, called sebum,
that can clog hair follicles. Bacteria, trapped in the
clog, can lead to infection and inflammation. 29.
Structure D is a sweat gland. Sweat glands produce
perspiration, or sweat. When sweat evaporates, it
takes heat away from the body. 30. The figure shows
that there are no blood vessels in the outer layer of the
skin, so a slight scratch will probably not be deep
enough to break blood vessels. Essay 31. Compact
bone is found beneath the periosteum. It is a dense
bone, although not solid. Running through compact
bone is a network of tubes called Haversian canals
that contain blood vessels and nerves. Spongy bone is
less dense than compact bone and is found in long
bones and in the middle of short, flat bones. It is
strong and organized in a latticework structure, which
adds strength to the bone without adding mass. 32.
Possible answers include: Pivot joints in the elbow
and ball-and-socket joints in the shoulder allow you
to brush your teeth or comb your hair. Hinge joints in
the knees allow you to stand up after getting out of
bed and walk. Saddle joints in the hand allow you to
hold clothes, shoes, toothbrushes, or combs. Pivot
joints in the neck allow you to look both ways as you
cross the street to get to the bus stop. 33. When the
biceps muscle contracts, it flexes the elbow joint.
When the triceps muscle contracts, it extends the
elbow joint. A controlled movement, such as playing
the violin, requires coordinated contraction and
relaxation of both muscles. The brain must learn how
to work opposing muscle groups to just the right
degree, or contract in balance, to get the joint to move
precisely. 34. The skin helps to control body
temperature through its blood vessels and its sweat
glands. When the body needs to conserve heat, the
blood vessels in the dermis narrow, limiting heat loss.
When the body needs to increase heat loss, the blood
vessels widen. The sweat glands produce a secretion
known as sweat, or perspiration. These secretions are
stimulated by nerve impulses when the temperature of
the body rises above normal. As sweat evaporates
from the skin, it takes heat away from the body. 35.
Hair is produced at the base of hair follicles from
columns of cells that die when they are filled with
keratin. Hair follicles, made of clusters of such cells,
are anchored in the dermis. Cells multiply rapidly in
the base of the follicle, causing the hair to grow
longer.
Chapter 32 —Test B
Multiple Choice 1. a 2. b 3. d 4. b 5. b 6. d 7. a 8. d
9. c 10. b 11. a 12. c 13. c 14. a 15. c Modified
True/False 16. T 17. F; shortens 18. T 19. F;
ultraviolet Completion 20. sliding-filament model 21.
melanin Short Answer 22. In osteoporosis,
osteoclasts break down bone faster than osteoblasts
rebuild it. This leads to a decrease in bone density and
therefore makes bones weaker. 23. Skeletal muscle
movements are controlled voluntarily while cardiac
muscle movements are controlled involuntarily.
Having a heart made of skeletal muscles would be a
disadvantage because the person would have to
consciously control the beating of his or her heart. 24.
The skin produces vitamin D, which is needed for
absorption of calcium and phosphorus from the small
intestine into the blood. 25. The epidermis is made up
of layers of epithelial cells and contains pigmentproducing melanocytes. The dermis contains nerve
endings, blood vessels, smooth muscle, sweat glands,
sebaceous glands, and hair follicles. 26. Answers
should show an understanding that acne develops
when sebum and dead skin cells form plugs in hair
follicles, which leads to infection and inflammation.
Answers could also address the fact that high
hormone levels during puberty lead to increased
sebum production or that acne can be caused by
bacteria. Using Science Skills 27. Structure B is
spongy bone and Structure D is compact bone.
Compact bone is found beneath the periosteum. It is a
dense
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Answer Key—Tests • Chapter 33
bone, although not solid. Running through compact
bone is a network of blood vessels and nerves.
Spongy bone is less dense than compact bone and is
found in long bones and in the middle of short, flat
bones. It is strong and organized in a latticework
structure, which adds strength to the bone without
adding mass. 28. C, yellow bone marrow 29. The
Haversian canal contains blood vessels and nerves.
30. The periosteum contains blood vessels that
provide oxygen and nutrients to the bone.
within the lungs. Essay 31. A city’s transportation
system is a network of streets, highways, and subway
or train lines that deliver food and goods to the city
and remove wastes from it. The human body’s major
transportation system is a closed circulatory system
made up of a heart, blood vessels, and blood. Like
people in a city, the body’s cells need food and goods
that are produced elsewhere. They also need to get rid
of their garbage and other wastes. Some cells, such as
blood cells, also need a way to move around the body
similar to people moving around a city. 32.
Thromboplastin is a protein involved in the bloodclotting process. When a blood vessel is injured by a
cut or scrape, platelets clump at the site and release
the clotting factor thromboplastin. Thromboplastin
then triggers a series of reactions. First,
thromboplastin converts the protein prothrombin into
the enzyme thrombin. Thrombin then converts the
soluble plasma protein fibrinogen into insoluble,
sticky fibrin filaments, which form a clot. The clot
seals the damaged area and prevents further blood
loss. Without thromboplastin, the clotting process
would not take place normally. 33. Atherosclerosis is
a condition in which fatty deposits called plaques
build up in the artery walls and eventually cause the
arteries to stiffen. Over time, the plaques can bulge
into the center of the vessel restricting blood flow.
This can lead to hypertension, or high blood pressure,
because the heart will need to pump harder to get
blood through those stiff, narrow blood vessels. On
the other hand, hypertension can cause atherosclerosis
because the pressure on the blood vessel walls may
cause small tears to form. Plaque may build up in the
tears. 34. Within the heart, the sinoatrial node
(pacemaker), atrioventricular node, and conducting
fibers are all involved in the regulation of heartbeat. If
any one of these structures is functioning improperly,
heart rate will be affected. The autonomic nervous
system also influences heart rate, so it may send
signals that increase heart rate. 35. As a person
continues to hold his or her breath, the amount of
carbon dioxide in the blood increases. As the carbon
dioxide level rises, nerve impulses from the breathing
center cause the diaphragm to contract, bringing air
into the lungs. The higher the carbon dioxide level,
the stronger the impulses are. If the carbon dioxide
level reaches a critical point, the impulses become so
powerful that the medulla oblongata sends impulses
to the
Chapter 33 —Test A
Multiple Choice 1. a 2. c 3. a 4. b 5. c 6. d 7. b 8.
b 9. c 10. b 11. b 12. d 13. c 14. a 15. d Modified
True/False 16. F; thrombin 17. T 18. T
Completion 19. oxygen 20. blood pressure 21.
statins Short Answer 22. The heart is involved in
both circuits of circulation. In pulmonary circulation,
the right side of the heart pumps oxygen-poor blood
to the lungs, where it is oxygenated and returned to
the heart. In systemic circulation, the left side of the
heart pumps oxygen-rich blood to the rest of the
body. The cells absorb oxygen and load the blood
with carbon dioxide, which is returned to the right
side of the heart. 23. LDL is the cholesterol carrier
that is most likely to cause trouble in the circulatory
system because it becomes part of plaque. HDL is the
cholesterol carrier that generally carries excess
cholesterol from tissues and arteries to the liver for
removal from the body. 24. The combination of hair
and mucus in the nose filters out solid particles. The
moisture in the nose helps to moisten the air. This
moist air helps to prevent the lungs and other parts of
the respiratory system from drying out. When air
enters the respiratory system through the mouth,
much less filtering occurs. 25. Hemoglobin actively
binds to dissolved oxygen, removing it from plasma
and enabling diffusion of oxygen from the alveoli to
continue. Normally the process would stop when
oxygen concentrations in the blood and alveoli are the
same. Using Science Skills 26. D, bronchi; Each
bronchus leads to a lung. 27. C, the diaphragm 28.
trachea; It is called a windpipe because air travels
through it. 29. Structure A are the alveoli. They are
covered by capillaries because the capillaries are the
sites at which carbon dioxide and oxygen diffuse in
and out of the blood. 30. The air passes from the
outside into the body through the nose or mouth,
passes through the pharynx, the larynx, the trachea,
and then enters the bronchi, bronchioles, and alveoli
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Answer Key—Tests • Chapter 34
Completion 19. lipids 20. kidney Short Answer
21. The cell would not be able to respond to the
hormone.22. Answer should show that sperm are
produced in the seminiferous tubules. From there,
they travel through the epididymis, vas deferens, and
urethra (in the penis). 23. The follicle may not have
developed, because estrogen levels increase when it
develops normally. The result of low estrogen levels
may be that the lining of the uterus doesn’t thicken
and the hypothalamus and the pituitary do not
decrease the amount of FSH and LH they secrete.
24. Once a sperm nucleus has entered the egg, the cell
membrane of the egg cell changes, preventing other
sperm from entering the cell. 25. Sample answer: If
the placenta completely covers the cervix, it is
blocking the way the baby would exit the uterus.
Using Science Skills 26. Sample answer: It shows
the feedback mechanism that controls the thyroid
gland. 27. High thyroxine levels inhibit the
hypothalamus and the anterior pituitary. Less TRH
and TSH are released. 28. thyroxine 29. Sample
answer: Hyperthyroidism is a condition that occurs
when the thyroid gland produces too much thyroxine.
The process in Figure 34–4 could be altered to show
this by having the hypothalamus fail to respond to
high thyroxine levels and continue to produce TRH.
Hyperthyroidism is characterized by nervousness,
elevated body temperature, increased heart and
metabolic rates, increased blood pressure, and weight
loss. 30. Sample answer: The hypothalamus is
sensitive both to temperature and to the level of
thyroxine in the blood. When body temperature
decreases, such as on a cold day, the hypothalamus
will produce more TRH even if the level of
thyroxine doesn’t stimulate it to do so. TRH will
stimulate the anterior pituitary to produce more
TSH, and more thyroxine will be released into
the blood, speeding up metabolism and increasing
body temperature. Essay 31. Endocrine glands
usually release their secretions directly
into the blood, which transports the secretions
throughout the body. Exocrine glands however,
release their secretions outside the blood. They
release their secretions through tubelike structures
either out of the body or directly into the digestive
system. 32. Since the pituitary would not increase its
production of LH, the person would not go through
puberty. If a person does not go through puberty, he
or she could not
conscious part of the brain and the person is forced to
breathe.
Chapter 33 —Test B
Multiple Choice 1. a 2. b 3. b 4. b 5. a 6. a 7. c 8. d
9. b 10. c 11. a 12. c 13. d 14. c 15. c Completion
16. hemoglobin 17. water 18. atherosclerosis 19.
larynx 20. alveoli 21. nervous Short Answer 22.
White blood cells are the “army” of the circulatory
system because they guard against infection, fight
parasites, and attack bacteria. 23. LDL is the
cholesterol carrier that is most likely to cause trouble
in the circulatory system because it becomes part of
plaque. HDL is the cholesterol carrier that generally
carries excess cholesterol from tissues and arteries to
the liver for removal from the body. 24. Hemoglobin
actively binds to dissolved oxygen, removing it from
plasma and enabling diffusion of oxygen from the
alveoli to continue. Normally the process would stop
when oxygen concentrations in the blood and alveoli
are the same. 25. Smoking can cause bronchitis,
emphysema, and lung cancer. In bronchitis, the
bronchi become swollen and clogged with mucus.
Emphysema is a lack of elasticity in the tissues of the
lungs, and lung cancer is a deadly disease that can
spread to other parts of the body. Using Science
Skills 26. Oxygen-poor blood enters the right atrium
(J) of the heart. It then travels into the right ventricle
(G). From the right ventricle, the blood is pumped
into the lungs where it is oxygenated. After it leaves
the lungs, the blood enters the left atrium (C) of the
heart and moves into the left ventricle (F). Th e left
ventricle then pumps oxygenated blood to the rest of
the body. 27. The heart is made of cardiac muscle.
The left ventricle (F) is more muscular than the right
ventricle (G) because the right ventricle only pumps
blood to the lungs, while the left ventricle pumps
blood throughout the entire body. 28. These are
valves that prevent backward blood flow. 29.
Structure L is the superior vena cava and it brings
oxygen-poor blood from the upper body to the heart.
Structure I is the inferior vena cava and it brings
oxygen-poor blood from the lower body to the heart.
30. The heart would not be able to pump oxygen-rich
blood to the rest of the body.
Chapter 34—Test A
Multiple Choice 1. a 2. d 3. a 4. c 5. a 6. a 7. d 8. d 9.
b 10. c 11. b 12. c 13. b 14. b 15. c Modified
True/False 16. F; prostaglandins 17. T 18. F; fi rst
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Answer Key—Tests • Chapter 35
reproduce. Males would not produce sperm and
females would not produce or release mature eggs.
33. Sample answer: Sperm are stored in the scrotum
of the male body, which is lower in temperature than
the rest of the male body or the inside of the female
body. The higher temperature could limit the lifespan
of sperm inside the female body. The effect on
fertilization is that an egg would need to be in
Fallopian tube at about the same time as the sperm
arrive. 34. During months 4–6, the fetus becomes
more complex and specialized. The heart becomes
large enough to be heard with a stethoscope. Bone
continues to replace the cartilage forming the early
skeleton. A layer of soft hair grows over the skin of
the fetus. As the fetus increases in size, the mother’s
abdomen swells to accommodate it. The mother
begins to feel it moving. During months 7–9, the
organ systems of the fetus mature and the fetus grows
in size and mass. The lungs and other organs undergo
a series of changes that prepare them for life outside
the uterus. The fetus is now able to regulate its body
temperature. In addition, the central nervous system
and lungs complete their development. 35. The
hypothalamus contains cells that are sensitive to the
concentration of water in the blood. When my body
loses water as sweat, the concentration of dissolved
materials in the blood rises. The hypothalamus
responds by first signaling the posterior pituitary
gland to release a hormone called ADH (antidiuretic
hormone). ADH molecules are carried by the blood to
the kidneys, where the removal of water from the
blood is quickly slowed down. The hypothalamus
also causes a thirst sensation. When I drink water, the
water is absorbed into the blood. To avoid the water
diluting the blood, the hypothalamus causes the
pituitary to release less ADH. They kidneys respond
by removing water from the blood.
nucleus of a cell and change the pattern of gene
expression in a target cell. Nonsteroid hormones bind
to receptors on cell membranes and cause the release
of secondary messengers that affect cell activities. 25.
Sample answer: Bacterial STD: caused by bacteria,
treated by antibiotics, include chlamydia, gonorrhea,
and syphilis; Overlap: spread by sexual contact; Viral
STD: caused by viruses, vaccine has been developed
for one, includes HPV and AIDS 26. Oxytocin affects
a group of large involuntary muscles in the uterine
wall. As these muscles are stimulated, they begin a
series of rhythmic contractions collectively known as
labor. Using Science Skills 27. Diagram I is the
female reproductive system. Diagram II is the male
reproductive system. 28. The ovary—structure A—
releases eggs. 29. Fertilization usually occurs in a
Fallopian tube. Structure F indicates a Fallopian tube.
30. Sperm are formed in the testis, structure K.
Chapter 35 —Test A
Multiple Choice 1. c 2. b 3. c 4. b 5. a 6. b 7. c 8. a
9. c 10. c 11. b 12. c 13. b 14. c 15. d Modified
True/False 16. F; antigens 17. T 18. F; humoral
Completion 19. pathogens 20. helper 21. resistance
Short Answer 22. Interferons, which interrupt viral
replication, are produced by virus-infected cells and
help slow down viral infections; thus, they are not
effective at stopping nonviral pathogens. 23. A
primary response occurs when the body is first
exposed to a pathogen. A secondary response occurs
when the body is exposed to the same pathogen for a
second time. Memory B cells and T cells that
survived after the first infection react quickly when
the same pathogen enters the body again. 24.
Antibiotics are compounds that kill bacteria, not
viruses. If people take them unnecessarily, strains of
bacteria develop that are resistant to antibiotics and
other medications. 25. Lupus is classified as an
autoimmune disease because antibodies attack organs
and tissues causing areas of chronic inflammation
throughout the body. Using Science Skills 26. The
dotted line shows the T cell concentration in patients
starting at 800 days after infection with HIV. The
solid line shows the T cell concentration in patients
starting at 1200 days after infection with HIV. 27.
Graph A shows the T cell concentration in HIVinfected patients who are not receiving treatment.
Graph B shows the T cell
Chapter 34—Test B
Multiple Choice 1. d 2. b 3. b 4. c 5. b 6. b 7. a 8. b
9. d 10. b 11. a 12. d 13. c 14. c 15. b Modified
True/False 16. T 17. F; implantation 18. F; prolactin
Completion 19. adrenal glands 20. kidney 21.
follicle 22. human papillomavirus (HPV) Short
Answer 23. A target cell is a cell that has receptors
for a particular hormone. If a cell does not have
receptors for a particular hormone, the hormone has
no effect on it. Since only certain cells have receptors
for specific hormones, all cells are not target cells for
all hormones. 24. Steroid hormones can enter the
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Answer Key—Tests • Chapter 35
concentration in HIV-infected patients who are
receiving treatment. Both graphs compare the T cell
concentration in patients over 500 days at different
stages of infection. 28. The T cell concentration
decreases between days 800 and 1200 during an HIV
infection. Students should compare the dotted line
and the solid line on each graph at 0 days to answer
this question. 29. The T cell concentration of an HIVinfected person at 1000 days after infection could fall
anywhere between 800 and 950 cells per mm3 30.
Sample answer: The best time to begin treatment is at
800 days, rather than at 1200 days, after infection
because less strong drugs are needed. The patients
who are not treated until 1200 days after infection
must take the maximum strength of the drugs for
about 100 days before T cell concentration is at the
same level as the patients whose treatment begins at
800 days. Also, the strength of the drugs is reduced
much more quickly for patients who begin treatment
at 800 days than for patients whose treatment begins
at 1200 days. Essay 31. Sample answer: The germ
theory of disease is the idea that infectious diseases
are changes to body physiology that disrupt normal
body functions by microorganisms. It is incorrect to
use the word “germ” because it has no scientific
meaning. A better name for the theory might be the
microorganism theory of disease. 32. Natural
selection favors viruses that have adaptations that
help them spread from host to host because if a virus
infects only one host, it will die when the host’s
immune system kills it or when the host dies.
Answers should include four of the following ways
viruses and other pathogens can be spread: through
coughing, sneezing, physical contact, sexual activity,
and contaminated water and food; and by vectors. 33.
The two main factors are public health measures and
the development of medication. Public health
measures help prevent disease by monitoring and
regulating food and water supplies. They also
promote childhood vaccination and behaviors that
avoid infection. Medications such as antibiotics and
antiviral drugs work to slow down and kill bacteria
and viruses that cause infections. 34. Sample answer:
Asthma is caused, in part, by the immune system’s
overreaction to a particular antigen; however,
scientists do not fully understand why some
individuals become oversensitive to certain materials.
With repeated exposure to certain pollutants, a person
could become oversensitive to those pollutants,
causing him or her to become asthmatic or making
the asthma worse. This hypothesis could be tested by
monitoring asthma cases and air pollutants in
different areas over time. Comparing the number of
cases, as well as the number and severity of asthma
attacks, could show a correlation between air
pollution and asthma, if one exists. 35. At first, the
antibodies and T cells attack HIV and reduce the
number of viruses in the blood. However, the viruses
continue to invade and replicate within T cells, where
they are protected from the antibodies. As the viruses
destroy T cells, they enter the blood, increasing their
number in the blood and decreasing the number of T
cells in the blood.
Chapter 35 —Test B
Multiple Choice 1. c 2. a 3. b 4. c 5. b 6. a 7. c 8. d 9.
b 10. c 11. d 12. b 13. c 14. a 15. a Completion 16.
vectors 17. histamines 18. antigens 19. helper 20.
autoimmune Short Answer 21. Pathogens that infect
the digestive tract are spread through water
contaminated with feces from infected people or other
animals. This is more common in areas where water
is not sanitized. 22. Interferons, which interrupt viral
replication, are produced by virus-infected cells and
help slow down viral infections; thus, they are not
effective at stopping nonviral pathogens. 23. A
primary response occurs when the body is first
exposed to a pathogen. A secondary response occurs
when the body is exposed to the same pathogen for a
second time. Memory B cells and T cells that
survived after the first infection react quickly when
the same pathogen enters the body again. 24.
Antibiotics are compounds that kill bacteria, not
viruses. If people take them unnecessarily, strains of
bacteria develop that are resistant to antibiotics and
other medications. 25. Humoral immunity depends on
the action of antibodies that are found embedded in B
cells. When an antigen binds to antibodies, helper T
cells activate B cells to grow and divide rapidly.
Without helper T cells, B cells would not be
stimulated to grow and divide. Using Science Skills
26. It represents an antigen (or pathogen) and an
antibody. 27. Humoral immunity, which is carried out
by antibodies, is represented in Figure 35–3. 28. The
part labeled B represents antigen-binding sites. 29.
The shapes of the antigen-binding sites enable an
antibody to recognize a specific antigen with a
complementary shape. 30. When antibodies
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Answer Key—Tests • Chapter 35
bind to free-floating antigens or antigens on the
surface of pathogens, they signal other types of cells
and proteins to respond by attacking and destroying
the pathogens.
bloodstream. Hormonal communication is relatively
slow but can reach cells everywhere in the body. The
nervous system communicates with nerve impulses,
which travel through a system of interconnected
neurons. Nervous communication is very rapid but
limited to parts of the body that are interconnected by
nerves. 32. The levels of organization are cells,
tissues, organs, and organ systems. Possible examples
include: red blood cell (cell); blood (tissue); heart
(organ); and cardiovascular system (organ system).
33. The skeleton of an embryo is composed almost
entirely of cartilage. Beginning around seven months
before birth, ossification begins to take place. Bone
tissue forms as osteoblasts secrete mineral deposits
that replace the cartilage in developing bones. The
growth of cartilage at the ends, or growth plates, of
long bones causes the bones to lengthen. Gradually
this new growth of cartilage is also replaced by bone
tissue, and the bones become larger and stronger. By
adulthood, the cartilage in the growth plates is
replaced by bone and the bones become completely
ossified. 34. The thyroid gland controls metabolism.
Its hormone, thyroxine, stimulates cells to increase
their metabolic activity. When the hypothalamus
senses that the level of thyroxine in the blood is low,
it secretes thyroid-releasing hormone (TRH). TRH
stimulates the pituitary to produce thyroid-stimulating
hormone (TSH), which stimulates the thyroid to
produce thyroxine. The opposite events occur if the
level of thyroxine in the blood is high. 35. The body’s
nonspecific defenses are the skin, inflammatory
response, fever, and interferons. The skin is a
physical barrier that few pathogens can penetrate.
Sweat and skin oils also kill many bacteria. The
inflammatory response occurs in reaction to tissue
damage. It brings many white blood cells to the site to
fight infection. Fever raises the body temperature,
which slows the growth of many pathogens.
Interferons are proteins produced by cells infected
with virus. Interferons help block viral replication.
Unit 8—Test A
Multiple Choice 1. a 2. b 3. d 4. c 5. a 6. c 7. c 8. b
9. c 10. b 11. b 12. c 13. a 14. c 15. c Completion
16. compact 17. bronchus 18. B cells 19. bile 20.
reflex Short Answer 21. The dermis contains
collagen fibers, blood vessels, nerve endings, glands,
sensory receptors, smooth muscles, and hair follicles.
22. When platelets come into contact with the edges
of a broken blood vessel, they become sticky and
cluster together around the wound. The platelets then
release proteins called clotting factors, which start a
series of chemical reactions that lead to the formation
of a clot. 23. Ligaments hold bones together in joints.
Tendons attach skeletal muscles to bones and make
them work like levers around the joints. 24. The teeth
contribute to mechanical digestion by tearing and
grinding food into smaller pieces. The enzyme
amylase in saliva begins the chemical digestion of
starch. 25. Answers should contain three of the
following methods: Infectious diseases can be spread
by physical contact, including coughing and sneezing;
by exchange of bodily fluids; by contaminated food
or water; and by infected animals. Science Skills
26. Diagram I shows the action of a steroid hormone.
Diagram II shows the action of a nonsteroid hormone.
27. In Diagram I, structure A is the receptor. It is
found only in target cells. It binds to the hormone to
form structure B, a hormone-receptor complex, which
enters the nucleus of the cell and binds to DNA. 28.
The hormone in diagram I directly affects gene
expression by turning on or off whole sets of genes.
29. In Diagram II, structure A is the receptor. It is
found only on the cell membranes of target cells. The
receptor binds to the hormone and activates an
enzyme on the inner surface of the cell membrane.
This enzyme activates structure B, a secondary
messenger, which carries the message of the hormone
inside the cell. 30. The steroid hormone in Diagram I
is made of lipids, so it can cross cell membranes. The
nonsteroid hormone in Diagram II is made of
proteins, so it cannot cross cell membranes. Essay
31. The endocrine system communicates with
hormones, which travel throughout the body via the
Unit 8—Test B
Multiple Choice 1. c 2. c 3. d 4. a 5. b 6. c 7. b 8. a
9. c 10. b 11. c 12. a 13. c 14. c 15. c Completion
16. threshold 17. reflex 18. capillaries 19. bile 20.
autoimmune Short Answer 21. The pancreas
produces enzymes that break down carbohydrates,
proteins, lipids, and nucleic acids in the small
intestine. The pancreas also produces
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Answer Key—Tests • Chapter 35
diseases such as heart attack and stroke. Science
Skills 26. A cell-mediated immune response is
shown in the diagram. 27. Structure A is a helper T
cell. In Step 1, the T cell binds to the macrophage and
becomes activated. 28. Structure B is a helper T cell.
It activates cytotoxic T cells and B cells, and
produces memory T cells. 29. Structure C is a
cytotoxic T cell. In Step 3, the cytotoxic T cell binds
to the infected cell, disrupting its cell membrane and
destroying it. 30. Cell-mediated immunity, shown in
the diagram, involves cytotoxic T cells attacking cells
infected with pathogens. Humoral immunity, in
contrast, involves B cells producing antibodies that
disable pathogens in the blood. Both processes are
similar in their being specific defenses in the immune
response.
sodium bicarbonate, a base that neutralizes stomach
acid so that these enzymes can be effective. 22. When
platelets come into contact with the edges of a broken
blood vessel, they become sticky and cluster together
around the wound. The platelets then release proteins
called clotting factors, which start a series of
chemical reactions that lead to the formation of a clot.
23. Nutrients are absorbed across the inside surface of
the small intestine. Villi are tiny projections on the
surface of the small intestine that greatly increase the
intestine’s surface area and ability to absorb nutrients.
24. Ligaments hold bones together in joints. Tendons
attach skeletal muscles to bones and make them work
like levers around the joints. 25. Atherosclerosis is a
buildup of fat deposits on the inner walls of arteries.
It increases the risk of cardiovascular
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