Unit A: The Science of Biology
What is Science?
1. What does science study?
Science is the study of the natural world, the search for patterns and connections between events.
2. What does it mean to describe a scientist as skeptical? Why is skepticism considered a valuable
quality in a scientist?
Skeptics question both existing ideas and new hypotheses. Skepticism is valuable because scientific
understanding is always changing.
3. What is the main difference between qualitative and quantitative observations?
Qualitative observations involve characteristics that cannot be measured or counted.
4. What is a scientific hypothesis? In what two ways can a hypothesis be tested?
A hypothesis is a proposed scientific explanation for a set of observations. One can be tested by
performing a controlled experiment or by gathering more data.
5. Is a scientific hypothesis accepted if there is no way to demonstrate that the hypothesis is
wrong? Explain your answer.
No. Scientific hypotheses must be proposed in a way that enables them to be tested.
6. Suppose a community proposes a law to require the wearing of seatbelts in all moving vehicles.
How could scientific research have an impact on the decision?
Answers will vary. A typical response might suggest that research could determine whether seatbelts
would reduce accident fatalities.
Making a Table
List the five main senses – vision, hearing, smell, taste and touch – and give an example of an observation
that you have made using each sense. Then, add at least one inference that could be made based on each
observation.
How Scientists Work?
1. Why is Redi’s experiment on spontaneous generation considered a controlled experiment?
Redi controlled all variables but one – whether or not there was gauze over each jar.
2. How does a scientific theory compare with a scientific hypothesis?
A hypothesis is a proposed scientific explanation for a set of observations, whereas a theory is a welltested explanation that unifies a broad range of observations.
3. How do scientists today usually communicate their results and conclusions?
They often publish a report of their work in a scientific journal.
4. How did the design of Pasteur’s flask help him successfully refute the hypothesis of
spontaneous generation?
The curved neck of Pasteur’s flask prevented microorganisms from the air from getting into the
broth, keeping the broth free of microorganisms. He showed that all living things come from other
living things.
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5. Evaluate the impact of Pasteur’s research on both scientific thought and society. What was the
effect of Pasteur’s investigations on scientists’ ideas and people’s lives?
Pasteur’s work represented a major shift in the way scientists viewed living things. He showed that
infectious diseases were the result of microorganisms entering bodies, and therefore this discovery set
the stage for medical advances that have protected people from diseases.
Critique a Hypothesis
Write a paragraph in which you analyze the spontaneous generation hypothesis. Hint: In preparation, ask
yourself questions such as these: What observations did the hypothesis account for? Why did it seem
logical at that time? What evidence was overlooked or ignored?
Studying Life
1. Describe five characteristics of living things.
Students should describe any five of these eight characteristics:
- living things are made up of units called cells
- living things reproduce
- living things are based on a universal genetic code
- living things grow and develop
- living things obtain and use materials and energy
- living things respond to their environment
- living things maintain a stable internal environment
- taken as a group, living things change over time
2. What topics might biologists study at the community level of organization?
Students should describe topics about populations that live in an area, such as interactions among
different populations and changes in size or habits.
3. Compare sexual reproduction and asexual reproduction.
In sexual reproduction, cells from two different parents unite to produce the first cell of a new
organism. In asexual reproduction, the new organism has a single parent.
4. What biological process includes chemical reactions that break down materials?
Metabolism
5. What is homeostasis? Give an example of how it is maintained.
Homeostasis is the process by which organisms keep internal conditions fairly constant. Examples
will vary, though most students will describe an internal feedback mechanism, such as temperature
regulation.
6. Suppose you feel hungry, so you reach for a peach you see in a fruit bowl. Explain how both
external and internal stimuli are involved in your action.
External stimuli might include the sight and smell of the peach. Internal stimuli might include feeling
hungry or the thought that this food would be good to eat.
Science as a Way of Knowing
List some observations that could be made to determine whether an object that is not moving is living or
nonliving. Refer to Section 1-1 to help yourself recall what an observation is.
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Tools and Procedures
1. Why do scientists use a common system of measurement?
They need to replicate one another’s experiments, which often involve measurements.
2. What is the difference in the way light microscopes and electron microscopes produce images?
Light microscopes produce images by focusing visible light rays, whereas electron microscopes
produce images by focusing beams of electrons.
3. What types of objects can be studied with a light microscope? What types can be studied with
an electron microscope?
Light microscopes and electron microscopes can be used to study dead and preserved specimens.
Only light microscopes can be used to study living organisms or cells.
4. Describe the technique and purpose of cell fractionation.
In cell fractionation, cells are broken into pieces, added to a liquid, and placed in a tube. The tube is
spun in a centrifuge, where the cell parts are separated into layers according to density. This
technique is done to study specific parts of a cell.
5. It has been said that many great discoveries lie in wait for the tools needed to make them.
What does this statement mean to you? If possible, include an example in your answer.
Sample answer: More advanced tools might reveal parts of living things never observed before.
Students may list discoveries that required the development of microscopes.
Safety Poster
After reading the safety guidelines in Appendix 8, prepare a poster on lab safety to display in your school in
which you describe at least five safety rules. You might organize your poster or brochure in two columns
labeled Dangerous Way and Safe Way, and contrast unsafe behaviors with their safe alternatives.
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Unit B: Taxonomy
Finding Order in Diversity
1. How are living things organized for study?
Biologists use a classification system to name organisms with a universally accepted name. They
also group organisms in a logical manner. Organisms placed into a particular group are more similar
to one another than they are to organisms in other groups.
2. Describe the system for naming species that Linnaeus developed.
Each species is assigned a two-part scientific name.
3. What are the seven taxonomic categories of Linnaeus’s classification system? Rank these taxa
in hierarchical order, beginning with the largest level and ending with the smallest.
Kingdom, phylum, class, order, family, genus, species
4. Why do scientists avoid using common names when discussing organisms?
Because common names vary among languages and even among regions within a single country.
5. What is binomial nomenclature?
A two-word naming system.
6. Look at Figure 18-5. Are foxes more closely related to sea stars or to snakes: Explain.
They are more closely related to snakes, because they are in the same phylum.
Explanatory Paragraph
Think of a classification system that you use in everyday life, and then write a paragraph explaining how the
classification system organizes objects or other things. Hint: Before you write, make a diagram that shows
the organization of the classification system.
Modern Evolutionary Classification
1. How is information about evolutionary, or phylogenetic, relationships useful in classification?
Organisms are placed in various taxonomic groups based on evolutionary descent.
2. How are genes used to help scientists classify organisms?
Scientists compare the DNA of different organisms to establish similarities between them and
reconstruct possible evolutionary relationships.
3. What is the principle behind cladistic analysis?
Cladistic analysis traces the process of evolution in a group of organisms by focusing on unique
features that appear in some organisms but not in others.
4. What gene indicates that yeasts and humans share a common ancestor?
A gene that codes for the protein myosin.
5. Describe the relationship between evolutionary time and the similarity of genes in two species.
The longer it has been since two species descended from a common ancestor, the more different their
genes are likely to be.
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6. Would a barnacle’s DNA be more similar to the DNA of a crab or that of a limpet? Explain.
It would be more similar to the DNA of a crab, because barnacles and crabs have a closer
evolutionary relationship.
Constructing a Chart
Draw a cladogram of a manufactured item, such as an automobile or a household item, that has changed over
the years. Label derived characters that appeared as new models arose. For example, automobiles came to
have electronic fuel injection and antilock brakes.
Kingdoms & Domains
1. What are the six kingdoms of life as they are now identified?
The six kingdoms are Archaebacteria, Eubacteria, Protista, Plantae, Fungi and Animalia.
2. What are the three domains of life?
The three domains are Archaea, Bacteria and Eukarya.
3. Why was the kingdom Monera divided into two separate kingdoms?
Monera was divided into two kingdoms because scientists have come to recognize profound
differences among two broad groups of Monera.
4. Why might kingdom Protista be thought of as the “odds and ends” kingdom?
Members of the kingdom Protista display the greatest variety, sharing characteristics with plants,
fungi, or animals; protists cannot be classified in any other group.
5. How are members of the kingdom Fungi different from members of the kingdom Plantae?
How are members of the two kingdoms similar?
Fungi are heterotrophic; Plantae are autotrophic. Both are nonmotile.
6. Which kingdoms include only prokaryotes? Which kingdoms include only heterotrophs?
Eubacteria and Archaebacteria include only prokaryotes. Fungi and Animalia contain only
heterotrophs.
Unity and Diversity
Review what you learned in Chapter 7 about how the cells of various organisms differ. Then, write a riddle
(What kingdom am I?) describing the characteristics of members of a particular kingdom. Exchange your
riddle with a classmate, and see if you can guess the kingdom being described.
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Unit C – Ecology
What is Ecology
1. List the six different levels of organization that ecologists study, in order from smallest to
largest.
Individual, population, community, ecosystem, biome, biosphere
2. Describe the three basic methods of ecological research.
Observing involves using the senses to gather information. Experimenting involves testing
hypotheses in a laboratory or natural ecosystem. Modeling involves making representations of
ecological phenomena.
3. Identify two ways in which you interact every day with each of the three parts of the biosphere
– land, water and air.
Student answers should give examples of interactions with land, water and air.
4. Suppose you wanted to know if the water in a certain stream is safe to drink. Which ecological
method(s) would you choose and why?
Most students will choose experimenting, which would involve testing a hypothesis about whether
the water is safe to drink. Some students might choose modeling, which would involve using a
model to investigate whether pollutants or organisms could enter the water.
5. Give an example of an ecological phenomenon that could be studied by modeling. Explain why
modeling would be useful.
Answers may vary. A typical response might suggest using a mathematical model to study the
effects of global warming on an ecosystem.
Creating a Table
Refer to Figure 3-2, which shows the various levels of organization that ecologists study. In a table, provide
examples of the ecological levels where you live – individuals, populations, communities and ecosystems –
that could be studied by ecologists. Hint: You may wish to use library resources or the internet.
Energy Flow
1. What are the two main forms of energy that power living systems?
Solar energy is harnessed by autotrophs that conduct photosynthesis. Chemical energy – the energy
within the chemical bonds of inorganic molecules – is harnessed by autotrophs that conduct
chemosynthesis.
2. Briefly describe the flow of energy among organisms in an ecosystem.
Students should describe a one-way flow of energy from autotrophs (producers) to consumers – first
herbivores, and then carnivores and/or omnivores.
3. What proportion of energy is transferred from one trophic level to the next in an ecosystem?
In general, about 10 percent
4. Explain the relationships in this food chain: omnivore, herbivore and autotroph.
The autotroph is the producer, and it is eaten by the herbivore. The herbivore is then eaten by the
omnivore.
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5. Draw an energy pyramid for a five-step food chain. If 100 percent of the energy is available at
the first trophic level, what percentage of the total energy is available at the highest trophic
level?
Students’ pyramids should show 100 percent of the energy available at the first (producer) level, 10
percent at the second level, 1 percent at the third level, 0.1 percent at the fourth level, and 0.01
percent at the fifth level.
Interdependence in Nature
Refer to Figure 3-8, which shows a food web in a salt marsh. Choose one of the food chains within this web.
Then, write a paragraph describing the feeding relationships among the organisms in the food chain. Hint:
Use the terms producers, consumers and decomposers in your description.
What Shapes an Ecosystem
1. What is the difference between a biotic factor and an abiotic factor?
A biotic factor is a living organism. An abiotic factor is nonliving.
2. Name three types of community interactions that can affect an ecosystem.
Competition, predation and symbiosis
3. What is the difference between primary succession and secondary succession?
Primary succession occurs on surfaces where no soil exists. Secondary succession occurs when a
disturbance of some kind changes an existing community without removing the soil.
4. How is an organism’s niche determined?
An organism’s niche is determined by the physical and biological conditions in its environment and
how it uses those conditions.
5. How are the three types of symbiotic relationships different? Similar?
In mutualism, both species benefit. In commensalism, only one species benefits; the other is neither
helped nor harmed. In parasitism, one species benefits; the other is harmed. In all three, two species
live closely together.
6. Summarize the role of organisms, including micro-organisms, in maintaining the equilibrium
of a marine ecosystem while a dead whale decays on the ocean floor.
Students should describe how scavengers and decomposers eat the decaying meat, how the
decomposition of the whale’s body forms an oasis for sediment dwellers, and how bacteria
decompose the oils inside the whale’s bones.
Creative Writing
Use the information from this section to write a short story about an ecosystem that is disturbed and
undergoes succession. Hint: Include a flowchart with your story to show the main stages of change.
How Populations Grow
1. List three characteristics that are used to describe a population.
Geographic distribution, density, growth rate
2. What factors can change a population’s size?
Births, deaths, immigration, emigration
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3. What is the difference between exponential growth and logistic growth?
Exponential growth occurs when the population grows at a constant rate. Exponential growth occurs
only under ideal conditions (ample space and food; protection from predators and disease). Logistic
growth occurs when a population’s growth rate slows or stops following a period of exponential
growth.
4. What is meant by population density?
The number of individuals per unit area
5. Define carrying capacity.
The largest number of individuals that a given environment can support.
6. What factors might cause the carrying capacity of a population to change?
Accept all reasonable answers. Sample answer: A natural disaster such as a forest fire, flood, or
hurricane might reduce the amount of resources available to a population.
Using Graphic Organizers
Draw a concept map that shows how populations grow. Include the following terms: exponential growth,
logistic growth, birthrate, death rate, immigration, emigration. Add any other terms that you think are useful
to complete the map.
Limits to Growth
1. List three density-dependent factors and three density-independent factors that can limit the
growth of a population.
Density-dependent: competition, predation, parasitism and disease; density-independent: unusual
weather, natural disasters, seasonal cycles, human activities
2. What is the relationship between competition and population size?
When populations become larger and more crowded, organisms must compete with one another for
food, water, space, sunlight and other essential resources.
3. If an entire lynx population disappears, what is likely to happen to the hare population on
which it preys?
The hare population would probably undergo explosive growth.
4. Identify how a limited resource can affect the size of a population. Give an example that
illustrates this situation.
Accept all reasonable responses. Students might mention any of the density-independent factors as
limiting a resource. A limited resource limits the size of a population.
5. Give an example of a density-independent limiting factor that has affected a human population.
Describe how this factor changed the human population.
Accept all reasonable responses. Sample answer: A prolonged drought, with its associated crop loss,
could cause deaths, financial hardship and emigration to other countries.
Interdependence in Nature
Study the factors that limit population growth as shown in Figure 5-5. Classify each factor as either biotic or
abiotic. Refer to the information on biotic and abiotic factors in section 4-2.
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Human Population Growth
1. Describe the general trend of human population growth that has occurred over time.
For tens of thousands of years, the human population grew very slowly. Then, about 500 years ago,
the population started to grow exponentially and increased dramatically.
2. What factors explain why populations in different countries grow at different rates?
Birthrates, death rates and the age structure of a population
3. What is demography?
The scientific study of human populations
4. Describe the demographic transition and explain how it might affect a country’s population
growth rate.
When the demographic transition begins, the birthrate and the death rate are high. Then, the death
rate drops while the birthrate remains, high. Finally, the birthrate also drops. After the demographic
transition, a population’s growth rate would be very low, and growth could even stop.
5. Why do you think age-structure diagrams can help predict future population trends?
Age-structure diagrams include data on younger individuals in age groups that will contribute to
population growth as members of those groups mature.
Explanatory Writing
Write a paragraph on the trends in the growth of world population from 1950 to 2050. Be sure to distinguish
between population growth and population growth rate. Hint: Refer to Figure 5-14 to help with your
explanation.
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Unit D: Microbiology
Bacteria
1. Describe the characteristics of the two kingdoms of prokaryotes.
Archaebacteria lack peptidoglycan, and their membrane lipids are quite different. Also, the DNA of
key archaebacterial genes are like those of eukaryotes.
2. What factors can be used to identify prokaryotes?
They are identified by their shapes, the chemical natures of their cell walls, the ways they move, and
the ways they obtain energy.
3. Give one example of how bacteria maintain equilibrium in the environment.
Bacteria are vital to maintaining the living world. Some are producers, others are decomposers, and
others have human uses.
4. Identify the parts of a prokaryote.
Cell wall, cell membrane, cytoplasm, DNA, ribosomes, pili and flagella.
5. What are some ways that prokaryotes obtain energy?
Some consume organic molecules made by other organisms, whereas others make their own food
from inorganic molecules.
6. Why might an infection by Gram-negative bacteria be more difficult to treat than a Grampositive bacterial infection?
Gram-positive bacteria have only one cell membrane, whereas gram-negative bacteria have a second,
outer, layer of lipid and carbohydrates. Therefore, gram-negative bacteria might be more difficult to
kill.
Making a Venn Diagram
Create a Venn diagram that illustrates the similarities and differences between eubacteria and archaebacteria.
Hint: Before you start, you may want to list the similarities and differences.
Viruses
1. What are the parts of a virus?
A typical virus is composed of a core of either DNA or RNA surrounded by a protein coat, which is
called a capsid.
2. Describe the two ways that viruses cause infection.
In a lytic infection, a virus enters a cell, makes copies of itself, and causes the cell to burst. In a
lysogenic infection, a virus embeds its DNA into the DNA of the host cell and replicates.
3. What is the difference between a bacteriophage and a prophage?
A bacteriophage is a virus that infects bacteria. A prophage is the lysogenic viral DNA that is
embedded in the host’s DNA.
4. What is a retrovirus?
A retrovirus is a virus that contains RNA.
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5. Do you think viruses should be considered a form of life? Describe the reasons for your
opinion.
Most students will assert that viruses should not be considered a form of life because they do not
exhibit all the characteristics of life.
Structure and Function
Viruses and cells are similar yet different. Compare the structure of a virus to the structure of a eukaryotic
cell. Organize your information in a table. You may wish to refer to Chapter 7, which discusses the
structures of cells in detail.
Diseases Caused by Bacteria
1. What are the two ways that bacteria cause disease?
Some damage cells and tissues directly by breaking down the host’s cells for food. Others release
toxins that interfere with the host’s normal activity.
2. Describe the three methods of preventing bacterial growth in food.
Students should describe sterilization, disinfectants and food storage and processing.
3. Describe how viruses cause disease.
Viruses cause disease by disrupting the body’s normal equilibrium.
4. What are viroids?
Single-stranded RNA molecules that have no surrounding capsids.
5. You think you might have a bacterial infection. Would you ask for a vaccination against the
bacteria? Why or why not?
It would probably not be a good idea because vaccinations prevent infection rather than attacking and
destroying bacteria.
6. How might epidemiologists collaborate with scientists who study viruses as they investigate
viral diseases?
Epidemiologists are primarily concerned with tracking and preventing the spread of diseases. They
might collaborate with virologists to find out the characteristics of specific viruses, including how
they spread and how they infect a host.
Creative Writing
In War of the Worlds Earth is invaded by aliens. No weapons can kill the invaders. Earth is saved when the
invaders die from diseases they contract. Write a summary of a story about people from Earth voyaging to
another planet. Include information on how the people from Earth might protect themselves from possible
new diseases.
The Kingdom Protista
1. What is a protist?
A protist is a eukaryote that is not a member of the kingdoms Plantae, Animalia, or Fungi.
2. Describe Margulis’s theory about the evolution of protists.
The first eukaryotic cells may have evolved from a symbiosis of several prokaryotes with larger cells.
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3. Are most protists unicellular or multicellular?
Most are unicellular.
4. What are the three methods that protists use to obtain food?
Animal-like protists ingest or absorb food; plantlike protists produce food by photosynthesis; and
funguslike protists obtain their food by external digestion either as decomposers or as parasites.
5. Identify the characteristics of organisms belonging to the kingdom Protista.
Protists are eukaryotic organisms and most are unicellular.
6. In what way is the kingdom Protista similar to a group of people who do not belong to a
political party.
Like people who do not belong to a political party, protists are defined less by what they are and
more by what they are not.
Creative Writing
Write and illustrate a brief newspaper story explaining the hypothesis that eukaryotic cells evolved from a
symbiosis of several prokaryotes with larger cells. Hint: Begin with a draft and then revise that draft,
looking at organization and word choice.
Animal-like Protists
1. What are the four major phyla of animal-like protists? How do members of each of these
groups move?
Zooflagellates swim with flagella; sarcodines move by extensions of their cytoplasm; ciliates move
by means of cilia; and sporozoans do not move at all.
2. What animal-like protists cause disease?
Plasmodium causes malaria; Trypanosoma causes African sleeping sickness; Entamoeba causes
amebic dysentery; and Giardia can cause diarrhea and digestive problems.
3. How does a macronucleus differ in function from a micronucleus?
A macronucleus contains multiple copies of most of the genes that the cell needs; a micronucleus
contains a copy of all the genes.
4. Describe the role of animal-like protists in the environment.
Some live symbiotically. Others recycle nutrients by breaking down dead matter. Many live in seas
and lakes, where they are eaten.
5. Compare animal-like protists that have flagella to those that have cilia.
Zooflagellates have flagella; some live within other organisms. Ciliates have cilia; most are free
living.
6. Summarize how Plasmodium can cause a major disruption in the equilibrium of a human
population.
Students should describe the effects of the disease malaria, caused by Plasmodium.
Information and Heredity
Compare asexual and sexual processes in paramecia. Include the terms mitosis and meiosis in your answer.
You may wish to refer back to Chapters 10 and 11 to review mitosis and meiosis.
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Plant-like Protists – Unicellular
1. What do chlorophyll and accessory pigments do in algae.
They allow algae to harvest and use the energy from sunlight.
2. What are the four phyla of unicellular plantlike protests?
Euglenophyta, Pyrrophyta, Chrysophyta, Bacillariophyta
3. How do most unicellular algae get food? How does this differ from the way most animal-like
protists get food?
Most unicellular algae use the energy of sunlight to product food. Animal-like protists get food by
absorbing, capturing or trapping it.
4. What is the role of unicellular algae in the environment?
They are at the base of aquatic food chains, and they make up a considerable part of the
phytoplankton. Unicellular algae also form symbiotic relationships with other organisms.
5. Identify two ways to reduce the problem of algal blooms in fresh water.
Sample answer: Eliminate sewage discharge and reduce the amount of plant fertilizers.
6. Summarize the role of a red tide in disrupting an ecosystem.
The dinoflagellates that cause a red tide produce a potentially dangerous toxin. Filter-feeding
shellfish become filled with the toxin, and fish that eat those shellfish can become seriously ill.
Write a News Broadcast
Use the library or the Internet to investigate the number of algal blooms off the California coast in the last
five years. Be sure to note the causes, the types of protists identified, and the effects on wildlife and people.
Present your findings to the class as an unbiased investigative report.
Plantlike Protists – Coloured Algae
1. Describe the main features of the major phyla of multicellular algae.
Students should describe the main features of algae in the phyla Rhodophyta, Phaeophyta and
Chlorophyta.
2. What is alternation of generations?
A process in which algae switch back and forth beween haploid and diploid during their life cycles.
3. How are multicellular algae important at a global level?
Multicellular algae provide food and generate oxygen and are an important part of the food chain
along coastal waters and in the Sargasso Sea.
4. Why can red algae live in deeper water than green algae?
Red algae contain the reddish accessory pigments known as phycobilins, which are especially good at
absorbing blue light, which penetrates deeper, enabling red algae to live deeper in the ocean than
other algae.
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5. Choose a green alga and illustrate its life cycle. Identify which parts are haploid and which are
diploid. Show where meiosis and mitosis occur. Illustrate which part of the life cycle involves
sexual reproduction and which involves asexual reproduction.
Students may choose any of the examples of green algae discussed in the section. A typical response
will illustrate either Chlamydomonas or Ulva and use Figure 20-17 or 20-18 for reference.
Organizing Information
Make a poster illustrating three types of multicellular algae. Your poster should have detailed drawings or
photographs of each group. Each illustration should show the correct classification and list two written
characteristics of each group.
Funguslike Protists
1. How are funguslike protists and fungi similar? How are they different?
Like fungi, funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic
matter. Unlike most true fungi, funguslike protists have centrioles and lack and chitin cell walls of
true fungi.
2. Compare acellular slime molds, cellular slime molds, and water molds.
The individual cells of cellular slime molds remain distinct throughout the life cycle. Acellular slime
molds pass through a stage in which their cells fuse to form large cells with many nuclei. Water
molds have a diploid life cycle. The only haploid stage is the gamete.
3. What is the role of slime molds in the environment?
They recycle organic material.
4. How can water molds affect other living things?
Water molds can cause plant diseases, such as potato blight.
5. How is the sluglike mass of cellular slime molds similar to the plasmodium of acellular slime
molds? How do they differ?
Both the cellular slime mold mass and the plasmodium function like a single organism, and both
produce a fruiting body. They differ in that the cells of a plasmodium fuse, while cells in a slime
mold mass preserve their separate cellular identities.
Constructing a Flowchart
Draw two flowcharts – one showing the steps from unicellular existence through multicellular existence and
reproduction in cellular slime molds and one showing those steps in acellular slime molds.
The Kingdom Fungi
1. Identify the characteristics all fungi have in common.
Fungi are eukaryotic heterotrophs that have cell walls. Fungi do not ingest food; they digest food
outside their cells and absorb it.
2. Describe the structure of the body of a typical fungus.
The bodies of multicellular fungi are composed of many hyphae tangled together into a thick mass
called a mycelium. The visible portion of the mycelium is the reproductive structure, or fruiting body.
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3. Briefly describe asexual and sexual reproduction in fungi.
Asexual reproduction takes place when cells or hyphae break off from a fungus and begin to grow on
their own. Some fungi also produce asexual spores. Sexual reproduction in fungi usually involves
two different mating types, which mate to form zygote nuclei.
4. By what means are fungal spores spread to new locations?
Some spores are scattered by the wind and some, by animals.
5. Tissue from several mushrooms gathered near the base of a tree were tested and found to be
genetically identical. How might you explain this?
The genetically identical mushrooms were part of the same mycelium, which means they were part of
the same organism.
Writing a Proposal
A house may become uninhabitable because of the presence of mold spores. Research how to detect and
identify mold allergens in the home. Assume you are a contractor. Write a proposal for how you will assess
this problem in preparation for a cleanup. Hint: Write a draft of your proposal.
Classification of Fungi
1. List the four phyla of fungi, and identify the main characteristics of the members of each
phylum.
Zygomycota have life cycles that include a zygospore. Ascomycota have asci that contain spores.
Basidiomycota have a reproductive structure that resembles a club. Deuteromycota do not have an
observed sexual phase.
2. How do conidia form? What is their function?
In asexual reproduction of some ascomycetes, tiny spores called conidia are formed at the tip of
specialized hyphae.
3. Which fungal phylum contains the largest number of species?
Phylum Ascomycota
4. Compare the structure and function of an ascus and a basidium.
The ascus, a sac that contains spores, forms within the fruiting body of an ascomycete. Within the
ascus, two nuclei fuse to form a diploid zygote. The spore-bearing structure of a basidiomycete,
called the basidium, is found on the gills of mushrooms. A basidiospore germinates to produce a
haploid primary mycelium.
5. Compare asexual and sexual reproduction in bread mold. At what stage does meiosis occur?
Students should describe both sexual and asexual reproduction, as discussed on page 530 and in
Figure 21-5. Meiosis occurs when conditions become favorable and the zygospore germinates.
Exploring Your Community
Visit a local supermarket to find out how fungi are used in the cuisines of different cultures. Select a
particular fungus, research recipes in which it is used, and try one of the recipes. You may also want to find
the scientific name of the fungus you have selected.
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Ecology of Fungi
1. What is the major role of fungi in an ecosystem?
To recycle nutrient material by breaking down organic matter.
2. Explain the roles of fungi in causing disease in humans and in other living things.
Parasitic fungi cause serious plant and animal diseases, including those in humans.
3. Describe two mutualistic relationships that fungi form with other organisms.
A lichen is a symbiotic association between a fungus and an alga or a cyanobacterium. Mycorrhizae
are mutualistic relationships between plant roots and fungi.
4. Describe the life cycle of wheat rust.
Spores produced by the rust in barberry plants are carried by wind into wheat fields where they infect
wheat plants and produce a second type of spore that infects other wheat plants. Another type of
spore survives through the winter and produces yet another spore that infects barberry plants.
5. What might happen to a garden if it were sprayed with a long-acting fungicide?
The garden plants would not flourish, because the mycorrhizae between plants and fungi benefit both
plants and fungi.
6. Summarize the role of fungi in disrupting the equilibrium in an ecosystem. Give one specific
example.
Answers will vary. Most students will focus on plant or animal diseases caused by fungi.
Structure and Function
Both bacteria and fungi are decomposers. What characteristics do these two groups share that allow them to
function in this ecological role? Use the information in Chapter 19 to help answer this question.
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Unit E: Plant Biology
Introduction to Plants
1. Identify the characteristics of the plant kingdom.
Multicellular eukaryotes; cell walls made of cellulose; develop from multicellular embryos; the green
pigments, chlorophyll a and b, carry out photosynthesis.
2. To live successfully on land, what substances must plants obtain from their environment?
Sunlight, water and minerals, and oxygen and carbon dioxide.
3. From which group of protists did the first plants evolve? How are plants similar to these
protists?
Multicellular green algae; similar in size, color, appearance, reproductive cycles, cell walls and
photosynthetic pigments.
4. Compare the gametophyte and sporophyte stages of the plant life cycle. Which is haploid?
Which is diploid?
Gametophyte: haploid, produces eggs and sperm by mitosis, formed from spores; Sporophyte:
diploid, produces spores by meiosis, formed during fertilization with fusion of egg and sperm
5. Compare the roles of mitosis and meiosis in a plant life cycle. Which of these processes is
related to sexual reproduction? To asexual reproduction?
Mitosis: sexual reproduction; occurs in the haploid gametophytes to produce the haploid gametes.
Meiosis: asexual reproduction; produces haploid spores in the sporophyte, which grow into the
gametophyte.
Structure and Function
How do the cells of plants differ from those of animals? How are they different from those of fungi? You
may whish to use labeled diagrams or a compare-and-contrast table to present your results. Refer to
Chapters 7 and 21 for help in answering these questions.
Bryophytes
1. How is water essential in the life cycle of a bryophyte?
Bryophytes produce sperm that must swim through water to reach the eggs of others.
2. List the three groups of bryophytes. In what type of habitat do they live?
Mosses, liverworts and hornworts; in moist, shaded areas.
3. What is the relationship between the gametophyte and the sporophyte in mosses and other
bryophytes?
The gametophyte is the dominant, recognizable stage and is the form that carries out most of the
plant’s photosynthesis. The sporophyte depends on the gametophyte for water and nutrients.
4. What is an archegonium? An antheridium? How are these structures important in the life
cycle of a moss?
An archegonium is the reproductive structure that produces egg cells; an antheridium is the
reproductive structure that produces sperm. These gametes fuse to form a diploid zygote, the
beginning of the sporophyte stage.
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5. What characteristic of bryophytes is responsible for their small size? Explain.
Bryophytes are limited in size because they lack vascular tissue and therefore can draw only a few
centimeters of water up from the ground by osmosis.
Descriptive Writing
You are writing a pocket field guide about plants and are working on the bryophytes chapter. Develop
several paragraphs to help your readers distinguish among the mosses, hornworts and liverworts. Hint: Do
additional library or internet research to find examples of bryophytes in your locality.
Seedless Vascular Plants
1. What are the two types of vascular tissue? Describe the function of each.
Xylem carries water from the roots to the rest of the plant. Phloem transports solutions of nutrients
and the products of photosynthesis.
2. What are the three phyla of seedless vascular plants? Give an example of each.
Lycophyta: club mosses; Arthrophtya: horsetails; and Pterophyta: ferns
3. What is the dominant stage of the fern life cycle? What is the relationship of the fern
gametophyte and sporophyte?
The diploid sporophyte; the gametophyte grows independently of the sporophyte. The young
sporophyte grows from the gametophyte.
4. The size of plants increased dramatically with the evolution of vascular tissue. How might
these two events be related?
Plants without vascular tissue can draw up water by osmosis only a few centimeters above the
ground. Vascular tissue moves fluids efficiently throughout a plant, even against gravity. The rigidity
of vascular tissue also helps support a tall plant.
5. Explain why xylem and phloem together can be considered to be a transport system.
Xylem moves water from roots to leaves and phloem moves nutrients from leaves to roots. Together
they move materials throughout a plant, forming a transport system.
Making a Visual Essay
Find out more about club mosses, horsetails and ferns. Research information such as description, method of
development, ecology and scientific name. Use this information along with photographs or drawings of
these plants to create a two-page photo essay about seedless vascular plants.
Seed Plants
1. Identify the main characteristics of seed plants.
The ability to reproduce without water, the formation of cones or flowers, the transfer of sperm by
pollination and the protection of embryos in seeds.
2. What are the different groups of gymnosperms?
Gnetophytes, cycads, ginkgoes and conifers.
3. What major change in Earth’s climate favored the evolution of seed plants?
Earth’s climate became much drier.
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4. Pollination is a process that occurs only in seed plants. What process in seedless plants is
analogous to pollination?
In seedless plants, the swimming of the male gametes to the female gametes is analogous to
pollination in seed plants.
Comparing and Contrasting
Compare reproduction in non-seed plants and seed plants. Then, explain how the evolution of the seed was
critical to the success of gymnosperms and angiosperms.
Angiosperms
1. What reproductive structures are unique to angiosperms? Briefly describe the function of
each.
Flowers and fruits; flowers attract pollinators; fruits protect the seed and aid in its dispersal.
2. What are monocots and dicots?
Monocots have one seed leaf or cotyledon, in the plant embryo; dicots have two.
3. How do annuals, biennials and perennials differ?
Annuals complete a life cycle within one growing season. Biennials complete their life cycle in two
years. Perennials live for more than two years, usually many years.
4. Compare the growth forms of plants with woody stems and those with herbaceous stems.
Plants with woody stems are trees, shrubs or vines. Plants with herbaceous stems include flowers
such as zinnias and petunias.
5. Which are more likely to be dispersed by animals – the seeds of an angiosperm or the spores of
a fern? Explain your reasoning.
The seeds of angiosperms, because the seeds are enclosed in fruit, which animals eat.
Creating a Display
Prepare a display comparing two specific plants, one monocot and one dicot. On this display, show
photographs or drawings of the plants and write a brief summary of the basic differences between these two
types of angiosperms.
Specialized Tissues in Plants
1. What are the three main organs of seed plants? Describe the structure of each.
Roots: tissue to transport and anchor; stems: tissue for transport and to support leaves and branches;
leaves: flat surfaces for light absorption
2. List the three tissue systems of plants. Describe how each tissue is distributed in stems, tissues
and leaves.
Dermal tissue: outermost layer of cells; vascular tissue: cells that transport water and nutrients
throughout the plant; ground tissue: all other cells making up the plant
3. What two cell types make up xylem? Phloem?
Tracheids and vessel elements; sieve tube elements and companion cells.
4. What is the function of meristematic tissue in a plant?
Produces new cells by mitosis
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5. In a stem that needs to support heavy leaves, what type of ground tissue might you expect to
find?
Sclerenchyma cells; they have thicker and harder cell walls that make ground tissue stronger.
6. Choose a group of cells making up vascular tissue in the root, the stem and the leaf. Compare
these cells, showing how they are alike and different.
The structure of cells making up vascular tissue in roots, stems and leaves is similar. However, the
arrangement of the cells differs in each. Figure 23-1 shows this arrangement.
Comparing and Contrasting
You probably have some knowledge of the human circulatory system. Based on this knowledge, write a
paragraph comparing and contrasting the vascular system of a plant to the human circulatory system. Hint:
Show how the systems are alike and different.
Roots
1. Compare a taproot and a fibrous root.
Taproots: central primary root, grow deep; fibrous roots: shallow, many thin roots.
2. How are tissues distributed in a plant root?
Roots have an outside layer of epidermal cells and a central cylinder of vascular tissue; between these
lies ground tissue.
3. Describe the two main functions of roots.
Anchor a plant in the ground and absorb water and dissolved nutrients from the soil.
4. How is osmosis involved in the absorption of water and nutrients?
Active transport through the root epidermis results in a high concentration of mineral ions in the root
cells that causes water molecules to move into the root by osmosis.
5. Analyze how a root is part of a plant’s transport system. Which parts of a root may be thought
of as a subsystem?
A root is the starting point for the movement of water through the vascular system. Subsystems:
epidermis, cortex, endodermis, vascular cylinder
6. Why is it important that the root endodermis permit only a one-way passage of materials?
The one-way passage of materials creates the root pressure that moves water up into the stem and
leaves.
Making a Diagram
Make two diagrams, one showing a root’s structure and growth, the other showing how roots absorb water
and nutrients. Label the diagrams and write brief descriptions of the processes shown in each.
Stems
1. How do the functions of a stem relate to the roots and leaves of a plant?
Stems transport substances between roots and leaves.
2. Describe how the arrangement of vascular bundles differs between monocot and dicot stems.
Monocots: scattered throughout stem; dicots: arranged in a cylinder
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3. Define primary and secondary growth. Which involves divisions of the apical meristem?
Primary growth occurs only at the ends of plants. Secondary growth is a pattern in which stems
increase in width. Primary growth involves the apical meristem.
4. How do heartwood and sapwood differ?
Heartwood contains old, nonfunctioning xylem. Sapwood contains active xylem.
5. Analyze how a stem is part of a plant’s transport system. Which parts of a stem may be thought
of as a subsystem?
The stem conducts water and nutrients; xylem and phloem form a subsystem.
6. Evaluate the significance of the structural adaptations of the white potato. How does a tuber
enable the plant to survive unfavorable conditions?
The plant uses the food stored in the tuber for survival until favorable conditions return and the plant
can make food again.
Descriptive Writing
Pretend that you are small enough to enter a plant through its root system. Describe what you would see as
you traveled into a plant and through one of its stems. Include illustrations to enhance your description.
Hint: Review the illustrations in this chapter for ideas.
Reproduction with Cones & Flowers
1. What are the reproductive structures of gymnosperms?
The reproductive structures of gymnosperms are pollen cones, pollen grains, seed cones, ovules and
pollen tubes.
2. Describe the flower and how it is involved in reproduction.
Flowers are reproductive organs that are composed of four kinds of specialized leaves: sepals, petals,
stamens and carpels. The stamens produce male gametophytes, and the carpels produce female
gametophytes.
3. Are angiosperms typically wind pollinated or animal pollinated? How does this process occur?
Angiosperms are typically pollinated by animals. Insects, birds and bats carry pollen from one flower
to another as they gather nectar.
4. What is endosperm? Where does it form in a flowering plant?
A food-rich tissue that nourishes a seedling as it grows; inside the embryo sac.
5. Many flowers have bright patterns of coloration that directly surround the reproductive
structures. How might this type of coloration by advantageous to the plant?
Bright patterns of coloration might attract insects and other animals to the reproductive structures of
the flower and increase the chances of pollination.
Information and Heredity
Review the life cycle of the green alga Chlamydomonas on Section 20-4. Make a compare-and-contrast
table comparing alternation of generations in seed plants and Chlamydomonas. Include which stage (haploid
or diploid) of each organism’s life cycle is dominant and when meiois occurs.
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Seed Development & Germination
1. Describe what happens as fertilized angiosperm seeds mature.
Nutrients flow into the flower tissue and support the development of the embryo within the seed.
Parts of the ovule toughen to form a seed coat, and the ovary wall thickens and joins with other
flower parts to form a fruit that encloses and protects the seed.
2. Compare the typical structure of seeds that are dispersed by animals to those dispersed by
wind and water.
Seeds dispersed by animals typically have a tough coat and are contained in fleshy fruits. Seeds
dispersed by wind and water typically are lightweight and may be encased in wing-like structures.
3. Why is it adaptive for some seeds to remain dormant before they germinate?
It allows for long-distance dispersal and for germination under ideal conditions.
4. The seeds of a bishop pine germinate only after they have undergone a forest fire. Evaluate the
significance of this structural adaptation.
It enables the species to recover after a fire and ensures that seedlings grow in a favorable
environment.
5. Describe which adaptations of a seed would enable it to germinate in a vacant lot where a
building once stood.
Dispersal by wind and possibly animals.
Writing a Book
Imagine that you are writing a children’s book on seeds and that you are working on the chapter on dispersal.
Write from one to three paragraphs on seed dispersal by wind. Hint: Try to include details that you would
have found appealing when you were about 8 years old.
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Unit F: Evolution
The Puzzle of Life’s Diversity
1. What did Darwin’s travels reveal to him about the number and variety of living species?
Darwin’s travels showed him that the diversity of living species was far greater than he had
previously known.
2. How did tortoises and birds differ among the islands of the Galapagos?
Each Galapagos island had its own type of tortoises and birds that were clearly different from the
tortoises and birds on other islands.
3. What is evolution? Why is evolution referred to as a theory?
Evolution, or change over time, is the process by which modern organisms have descended from
ancient ones. Evolution is referred to as a theory because it is a well-supported explanation of
phenomena that have occurred in the natural world.
4. What is a fossil?
A fossil is the preserved remains of an ancient organism.
5. Darwin found fossils of many organisms that were different from any living species. How
would this finding have affected his understanding of life’s diversity?
It would have greatly increased his estimates of biological diversity.
Interdependence in Nature
In Chapter 5, you learned that both biotic and abiotic factors affect ecosystems. Distinguish between these
two factors, give some examples of each, and explain how they might have affected the tortoises that Darwin
observed on the Galapagos Islands.
Ideas That Shaped Darwin’s Thinking
1. What two ideas from geology were important to Darwin’s thinking?
Earth is very old, and the same processes that shaped Earth millions of years ago continue in the
present.
2. According to Lamarck, how did organisms acquire traits?
Lamarck thought that organisms acquired traits by using their bodies in new ways.
3. According to Malthus, what factors limited population growth?
War, famine and disease
4. How did Lyell’s Principles of Geology influence Darwin?
It suggested Earth was very old and continued to change, allowing time for living things to change
and for evolution to occur.
5. Imagine that you are Thomas Malthus. Write an article describing your ideas. Explain the
impact of a growing population on society and the environment.
Students’ articles will vary. However, students should include that if human population growth
continues to grow unchecked, eventually resources will become scarce.
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Science as a Way of Knowing
Describe the idea and observations proposed by Lamarck regarding his theory of evolution. Include in your
description what Lamarck observed and the conclusions he made based on his observations. In addition,
include the scientific evidence that eventually proved Lamarck’s theory incorrect.
Darwin Presents His Case
1. How is artificial selection dependent on variation in nature?
Nature provides the variation, and humans select the variations that are useful.
2. The theory of evolution by natural selection explains, in scientific terms, how living things
evolve over time. What is being selected in this process.
The traits that help an organism survive in a particular environment.
3. What types of evidence did Darwin use to support his theory of change over time?
The fossil record, geographic distribution of species, homologous structures and similarities in
embryology.
4. Use scientific evidence to evaluate Darwin’s theory of evolution by natural selection.
Scientific advances in many fields of biology, along with geology and physics, have confirmed most
of Darwin’s hypotheses. Specific examples of evidence supporting Darwin’s theory include
similarities in embryology and homologous structures.
Newspaper Article
Write a newspaper article about the meeting in which Darwin’s and Wallace’s hypotheses of evolution were
first presented. Explain the theory of evolution by natural selection for an audience who knows nothing
about the subject.
The Fossil Record
1. What can be learned from the fossil record?
The fossil record provides evidence about the history of life on Earth and how different groups of
organisms changed over time.
2. Which type of dating provides an absolute age for a given fossil? Describe how this is done.
Radioactive dating provides an absolute age for a given fossil. Scientists calculate the age of a
sample based on the amount of remaining radioactive isotopes it contains.
3. How are eras and periods related?
Periods are subdivisions of the eras of the geologic time scale.
4. How do fossils form?
Most fossils form when dead organisms are covered with layers of sediment.
5. What geologic era is known as the Age of Mammals? When did this era begin?
The Cenozoic Era; 65 million years ago
6. Many more fossils have been found since Darwin’s day, allowing several gaps in the fossil
record to be filled. How might this information make relative dating more accurate?
More fossils might make relative dating more accurate because the method depends on
comparison of fossils.
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Constructing a Timeline
Create a timeline that shows the four main divisions in the geologic time scale and the key events that
occurred during those divisions. Then, as you read Section 17-3, add more events to your timeline.
Earth’s Early History
1. What substances probably made up Earth’s early atmosphere?
Hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide and water.
2. What molecules were the end products in Miller and Urey’s experiments?
Amino acids, which are the building blocks of proteins.
3. How did the addition of oxygen to Earth’s atmosphere affect life of that time?
Oxygen drove some life-forms to extinction; others became restricted to oxygen-free habitats; still
others evolved ways of using oxygen for respiration.
4. According to the endosymbiotic theory, how might chloroplasts and mitochondria have
originated?
Ancient aerobic and photosynthetic bacteria may have been engulfed by primitive eukaryotes and
evolved into mitochondria and chloroplasts.
5. You just read that life arose from nonlife billions of years ago. Could life arise from nonlife
today? Explain.
Probably not. The same conditions no longer exist on Earth. The oxygen in the atmosphere would
likely react with and destroy any new kinds of organic molecules or they would be consumed by
bacteria and molds.
Cellular Basis of Life
The endosymbiotic theory accounts for the evolution of mitochondria and chloroplasts in eukaryotic cells.
Review the description of eukaryotic cells in Chapter 7, and then describe the structure and function of
mitochondria and chloroplasts.
Evolution of Multicellular Life
1. Where did life exist during the early Paleozoic Era?
Early life existed in the sea
2. What evolutionary milestone involving animals occurred during the Devonian Period?
During the Devonian Period, animals began to invade the land.
3. What are two key events from the Mesozoic Era?
Events include the first appearance of dinosaurs and the appearance of seed plants, including conebearing and flowering types.
4. If you were a paleontologist investigating fossils from the Cenozoic Era, what fossils might you
find?
You might find fossils of flowering plants, insects, birds and mammals, including humans.
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Creative Writing
Choose one of the periods described in this section. Then, write a story about life during that time. Include
information about the life-forms, weather and other characteristics.
Patterns of Evolution
1. What is macroevolution? Describe two patterns of macroevolution?
Macroevolution is large-scale evolutionary change over long time periods. Students should describe
any two patterns.
2. What role have mass extinctions played in the history of life?
Mass extinctions periodically wiped out huge numbers of species and made way for the rapid
evolution of new species.
3. What is convergent evolution? Describe an example.
The process by which unrelated organisms, such as dolphins and sharks, come to resemble one
another.
4. How might hox genes contribute to variation?
Hox genes regulate timing of genetic control in the embryo. Even small changes in timing can cause
variation in traits.
5. Compare and contrast the hypotheses of gradualism and punctuated equilibrium.
Gradualism: evolutionary change is slow and steady. Punctuated equilibrium: evolutionary change
occurs in spurts of rapid change after long periods of little change.
Making a Table
Create a table that lists each of the six patterns of macroevolution, explains each pattern, and gives one
example for each. Add a title to your table.
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Unit G: Animal Biology
Introduction to the Animal Kingdom
1. What are the characteristics of members of the animal kingdom?
An animal is a multicellular, eukaryotic heterotroph whose cells lack cell walls.
2. Describe the seven essential functions performed by all animals.
Students should describe feeding, respiration, circulation, excretion, response, movement and
reproduction.
3. In what ways are complex animals different from simple animals?
Complex animals tend to have high levels of cell specialization and internal organization, bilateral
symmetry, cephalization and a body cavity.
4. How is the embryology of echinoderms similar to that of vertebrates? What might this
similarity indicate about their evolutionary relationship?
Echinoderms and all vertebrates are deuterostomes. This similarity may indicate that vertebrates
have a close evolutionary relationship to echinoderms.
5. How are body symmetry and cephalization related?
Animals with bilateral symmetry usually exhibit cephalization.
6. How is hunger an internal feedback mechanism for maintaining homeostasis?
An animal becomes hungry when it needs energy to maintain homeostasis. Hunger subsides when
enough food has been taken in to maintain homeostasis.
Constructing a Chart
Make a two-column chart of the different functions that enable animals to survive and respond to the
environment. In the first column, list each function. In the second column, include a drawing, photograph or
magazine clipping that illustrates an example of that function.
Phylum Porifera (Sponges)
1. What features do sponges share with all other animals?
Sponges are heterotrophic, have no cell walls and contain specialized cells.
2. How do sponges use water to carry out essential functions?
The movement of water through the sponge carries needed materials, such as food and oxygen, and
carries wastes away. Water also carries sperm to eggs.
3. Describe the different types of sponge skeletons.
The skeleton of many sponges is made of spiny spicules. Softer sponges have a skeleton made of
flexible spongin.
4. Why would sponges be unable to live on land?
Sponges depend on the movement of water for most functions, including feeding, respiration,
circulation, excretion, and reproduction.
Interdependence in Nature
In Chapter 4, you learned about mutualism, commensalisms and other symbiotic relationships. Compare and
contrast mutualism and commensalisms, and explain how each is important in the life of a sponge.
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Phylum Cnidaria
1. Describe three characteristics that all cnidarians share.
All Cnidarians are soft-bodied, are carnivorous, and have stinging tentacles arranged in circles around
the mouth.
2. How do two body plans of cnidarians differ?
A polyp has a cylindrical body with armlike tentacles; the mouth points upward. A medusa has a
bell-shaped body with the mouth pointing downward.
3. Describe the three groups of cnidarians and give an example from each.
Hydrozoans, such as hydras, spend most of their lives as polyps. Scyphozoans, such as jellyfishes,
live their lives primarily as medusas. Anthozoans, such as corals, have only the polyp stage in their
life cycle.
4. Describe how the digestion and absorption of food take place in cnidarians.
Extracellular digestion takes place in the gastrovascular cavity. Digestion is completed
intracellularly.
5. How has human activity affected coral reefs?
Many coral reefs are suffering due to human activity.
6. A medusa typically has more specialized organs for movement and response than a polyp does.
Why might this be the case? Hint: How does the lifestyle of a medusa differ from that of most
polyps?
A polyp is sessile and, thus, does not move around. A medusa is motile and, thus, needs a more
complex nervous system.
Descriptive Writing
Write a paragraph describing the body of a hydra. Assume that your readers know nothing about hydras.
Hint: First, list all the details you want to include in your paragraph. Then, decide how you want to organize
those details – for example, from the outside of the hydra to the inside.
Phylum Platyhelminthes
1. What is a flatworm?
A flatworm is a soft, flattened worm with tissues, organ systems, three germ layers, bilateral
symmetry and cephalization.
2. List the three groups of flatworms and give an example of each.
Turbellaria: planarian; Trematoda: fluke; Cestoda: tapeworm
3. How do the feeding methods of parasitic and free-living flatworms relate to their specific
environments?
Many parasitic flatworms obtain nutrients from their host’s body. Free-living flatworms capture and
digest food.
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4. Describe the life cycle of the blood fluke, Schistosoma mansoni.
S. mansoni matures and reproduces sexually in the blood vessels of human intestines. Embryos are
released with feces and hatch into swimming larvae that infect a snail, where they reproduce
asexually. Larvae released from the snail into water can infect humans.
5. How do a turbellarian’s nervous system and digestive system work together to provide the food
that the worm’s body needs?
The nervous system allows the worm to gather information about its environment, including the
location of food. The digestive system digests and absorbs the food.
Compare-Contrast Paragraph
Write a paragraph comparing free-living and parasitic flatworms. Be sure to explain how these worms are
alike as well as how they are different. Hint: Before you write, construct a Venn diagram to organize your
ideas.
Phylum Nematoda
1. What is a roundworm?
A roundworm is an unsegmented worm that has a pseudocoelom and a digestive system with two
openings – a mouth and an anus.
2. What are the parasitic roundworms?
Parasitic roundworms include trichinosis-causing worms, filarial worms, ascarid worms and
hookworms.
3. Describe how humans become infected with the parasitic roundworm Ascaris lumbricoides.
A human becomes infected by ingesting food or water containing Ascaris eggs.
4. How do hookworms enter the human body?
Hookworms enter the human body by burrowing into the skin of a foot.
5. What have scientists already learned about Caenorhabditis elegans? What do they hope to
learn in the future?
Students should mention basic features of the species as well as its DNA sequence. In the future,
scientists hope to learn how that sequence controls differentiation.
6. What steps might individual people and governments take to reduce the spread of
elephantiasis?
Individuals could wear protective clothing and use insect repellant. Governments could implement
strategies to reduce the numbers of biting insects.
Creating a Poster
Choose a type of roundworm that can cause disease in humans. Design an educational poster that promotes
prevention of the disease. Be sure to include information about how the roundworm infects humans.
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Phylum Annelida
1. What features distinguish annelids from roundworms?
Unlike roundworms, annelids have segmented bodies and a true coelom that is lined with mesoderm.
2. List the defining characteristics for each class of annelid.
Oligochaetes typically have fewer setae than polychaetes and live in soil or fresh water. Leeches are
typically external parasites that suck the blood and body fluids of their host. Polychaetes are marine
annelids that have paired, paddlelike appendages tipped with setae.
3. Describe the feeding strategies of earthworms and leeches.
Earthworms use their pharynxes to suck soil and detritus into their esophagus. Leeches suck the
blood and body fluids of their host.
4. An earthworm has more light-sensitive cells in its anterior and posterior segments than in other
parts of its body. Explain how this is advantageous for the worm.
Having more light-sensitive cells in the front and back ends is advantageous, because the animal
moves forward and may be attacked by a predator from the rear.
Interdependence in Nature
Review what you learned about food chains in Chapter 3. Then, draw a possible food chain involving an
annelid. The food chain should include at least three levels.
Phylum Mollusca
1. What is a mollusk?
A mollusk is a soft-bodied animal that usually has an internal or external shell.
2. List and describe the four parts of the mollusk body plan.
Foot, mantle, shell, visceral mass. Descriptions should agree with information on page 702.
3. Describe the main characteristics of the three major classes of mollusks.
Gastropods – shell-less or one shell, ventral foot; bivalves – two shells; cephalopods – head attached
to foot.
4. Why are land snails restricted to moist environments?
Land snails respire using a mantle cavity lined with blood vessels. This lining must be kept moist.
5. Describe how a cephalopod responds to external stimuli and explain how a cephalopod’s
nervous system is more complex than that of other mollusks.
Cephalopods exhibit complex behavior and can locate a variety of prey. Students should describe
cephalopods’ complex sense organs.
6. Compare open and closed circulatory systems. Why are open circulatory systems found mostly
in small animals that move slowly?
In an open circulatory system, blood leaves the vessels and moves through sinuses. In a closed
circulatory system, blood is contained within vessels. A closed circulatory system supports greater
oxygen needs because blood moves quickly.
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Interdependence in Nature
Recall from Chapter 4 the definition of symbiosis. The mutualism that exists between bivalves and bacteria
near deep-sea vents is one type of symbiosis. Describe an example of another type of symbiosis that you
have read about in this chapter. How is it different from mutualism?
Phylum Arthropoda
1. What are the main features of arthropods?
Arthropods have a segmented body, a tough exoskeleton and jointed appendages.
2. What is the evolutionary trend for segmentation in arthropods?
The evolution of arthropods has led to fewer body segments in some groups.
3. How is the process of molting related to growth in arthropods?
During molting, an arthropod sheds its entire exoskeleton and manufactures a larger one to take its
place. This process creates room for growth.
4. What body system controls molting?
The endocrine system.
5. How are both the circulatory and excretory systems involved in removing nitrogenous wastes
from an arthropod’s body?
In most terrestrial arthropods, wastes from cells move through the circulatory system to the
Malpighian tubules, which extract wastes from blood.
6. How are the muscle cells of arthropods and other animals different from other body cells?
How does this difference enable movement?
Muscle cells can contract when stimulated by nerves. Muscles generate force by contracting and then
pulling on the exoskeleton.
Cellular Basis of Life
Use what you learned about cellular respiration in Chapter 9 to explain why every cell in an arthropod’s
body needs oxygen. Then, describe how the respiratory system delivers the needed oxygen.
Phylum Echinodermata
1. What is an echinoderm?
An echinoderm has a spiny skin, an internal skeleton, and a water vascular system with tube feet.
Most have five-part radial symmetry.
2. What is the water vascular system? How is it important to echinoderms?
The water vascular system is a system of internal tubes. The system carries out respiration,
circulation and movement.
3. List the major classes of echinoderms and describe their characteristics.
Students should list the classes and characteristics described on pages 737-738.
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4. What are tube feet? What functions do they perform, and how do they perform them?
Tube feet are structures attached to the radial canal of echinoderms. Each has a sucker on the end,
and muscles pull the center of the sucker upward, creating suction. Tube feet allow echinoderms to
walk and to pull open shelled prey.
5. Echinoderms are deuterostomes. What does this indicate about their relationship to other
animals?
Echinoderms are more closely related to chordates than to other invertebrates, most of which are
protostomes.
6. Why is tearing a sea star apart and throwing it back into the water an ineffective way of trying
to reduce sea star populations?
If a sea star is pulled into pieces, each piece will usually grow into a new animal.
Structure and Function
In Chapter 26, you learned about the different kinds of body symmetry exhibited by animals. What kind of
body symmetry do adult sea stars have? How is this kind of symmetry similar to that of a cnidarian? How is
it different?
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