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PART IV DIVERSITY
OF
LIFE
17
THE FIRST FORMS
OF
LIFE
CHAPTER REVIEW
This chapter provides basic information about microbes
and the various ways they acquire nutrients and reproduce.
Such knowledge enables us not only to fight the diseases
microbes sometimes cause, but also to take advantage of
the many benefits they provide.
Viruses are noncellular particles that take over the
machinery of the host cell when they reproduce. Therefore, they are obligate parasites. Bacteriophages, plant
viruses, and animal viruses have been well studied.
Bacteria and archaea are termed prokaryotes because they lack a nucleus and other cellular organelles of
eukaryotes. Being heterotrophic, bacteria contribute to
ecological cycling and produce various foods and prod-
ucts for humans. They also cause numerous diseases. The
archaea are known for living in harsh environments that
lack oxygen, or are too hot, or too acidic for most organisms.
The protists are eukaryotes that tend to be unicellular. Some are multicellular. The algae, being photosynthetic, are important producers in aquatic environments;
the protozoans are heterotrophic and also serve as a food
source in such environments. Some protozoans cause diseases such as dysentery, sleeping sickness, and malaria.
Slime molds and water molds, despite their name, are
also protists because their characteristics differ in significant
ways from fungi.
CHAPTER KEY TERMS
After studying the key terms of this chapter, match the following phrases with the alphabetized list of terms.
algae
prion
amoeboid
protist
bacteriophage
protozoan
binary fission
retrovirus
ciliate
saprotroph
endospore
sporozoan
lysogenic cycle
symbiotic
lytic cycle
viroid
peptidoglycan
virus
phagocytosis
zooflagellate
plasmid
a. heterotrophic unicellular protist that is usually motile _______________________
b. spore formed within a cell _______________________
c. type of protist that carries on photosynthesis _______________________
d. infectious strand of RNA devoid of a capsid _______________________
e. nonphotosynthetic protist that moves by flagella _______________________
f. unique molecule found in bacterial cell walls _______________________
g. bacteriophage life cycle in which the virus incorporates its DNA into that of a bacterium _______________________
h. bacteriophage life cycle in which the virus immediately takes over the operation of the bacterium, destroying
it _______________________
i. RNA virus containing the enzyme reverse transcriptase; carries out RNA/DNA transcription _______________________
j. virus that infects bacteria _______________________
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k. spore-forming protist that has no means of locomotion; parasitic _______________________
l. complex unicellular protist that moves by means of cilia and digests food in food vacuoles _______________________
m. self-duplicating ring of accessory DNA in the cytoplasm of bacteria _______________________
n. cell that moves and engulfs debris with pseudopods _______________________
o. bacterial reproduction _______________________
p. noncellular obligate parasite of living cells _______________________
q. process by which amoeboid-type cells engulf large substances _______________________
r. infectious particle, consisting of protein only and no nucleic acid _______________________
s. two different species living together in an unique way _______________________
t. unicellular eukaryotes with a nucleus and wide range of organelles _______________________
u. organism that secretes digestive enzymes and absorbs the resulting nutrients across the plasma membrane
_______________________
S T U DY E X E R C I S E S
Study the text section by section as you answer the questions that follow.
17.1 THE VIRUSES (PP. 266–269)
• All viruses have an outer capsid composed of protein and an inner core of nucleic acid. Some animal viruses
have an outer membranous envelope.
• In human cells, viruses reproduce in much the same way as they do in bacteria.
• Emerging viral disease, including those caused by retroviruses, are of special concern today.
1. Label the following diagram of a virus:
b.
a.
c.
d.
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Viral Reproduction ( PP . 266–267)
2. Label the following diagram, which describes how viruses such as bacteriophages replicate, using the
alphabetized list of terms:
attachment
lytic cycle
biosynthesis
maturation
integration
penetration
lysogenic cycle
release
h.
bacterial
cell wall
capsid
nucleic acid
bacterial
chromosome
c.
g.
a.
d.
f.
prophage
b.
e.
prophage
Cloning of viral DNA
i. Which cycle produces viruses? ____________________
j. In which cycle is the virus dormant? ____________________
k. Which cycle kills, or lyses, the host? ____________________
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3. Place the correct number from the following diagram next to its description:
a.
reverse transcription
b.
integration
c.
biosynthesis
d.
attachment
1
2
e.
fusion and entry
envelope
HIV
f.
maturation
g.
release
spike
h.
replication
i.
uncoating
9
receptor
3
viral RNA
8
4
reverse transcriptase
cDNA
5
7
doublestranded DNA
viral RNA
6
viral RNA
host
DNA
Nucleus
4. The life cycle shown in question 3 is that of a(n)
b. ____________________
produced by:
provirus
DNA
a. ____________________.
In this life cycle,
integrates into the host genome until transcription occurs. Then new viruses are
c. ____________________, d. ___________________,
viruses leave the cell, they are surrounded by a(n)
17.2 VIROIDS
ribosome
AND
and
e. ____________________.
When the
f. ____________________.
PRIONS (P. 270)
• Viroids that attack crops and prions that attack animals are less complex than viruses.
5. Indicate whether these statements are true (T) or false (F):
a.
The disease called kuru, a fatal neurodegenerative disorder, is caused by a viroid.
b.
Viroids are RNA not covered by a capsid.
c.
Prions are neither viruses nor bacteria; they are protein particles.
d.
A prion can interact with normal proteins changing their shape.
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17.3 THE PROKARYOTES (PP. 270–275)
• Prokaryotes—the bacteria and archaea—lack a nucleus and most of the other cytoplasmic organelles found in
eukaryotic cells.
• Prokaryotes reproduce asexually by binary fission.
6. The two types of prokaryotes are
a. ____________________
and b. ____________________.
Bacteria (pp. 270–275)
• Most bacteria are free-living heterotrophs that play important roles in the environment, food science, and
biotechnology. Some bacteria are disease-causing parasites.
7. Label the three shapes of bacteria in the following diagram:
a.
c.
b.
8. Describe the events of bacterial reproduction shown in the following diagram:
a.
b.
c.
chromosome
9. Match the descriptions to these terms, which pertain to the reproduction or survival of bacteria:
1. binary fission
2. conjugation
3. transformation
4. transduction
5. endospores
a.
Bacteria picks up free pieces of DNA.
b.
a means of survival
c.
asexual division
d.
Donor cell passes DNA to recipient cell.
e.
Bacteriophages carry bacterial DNA from one cell to the next.
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10. Match the descriptions to these organisms:
1. photoautotrophs
2. chemoautotrophs
3. chemoheterotrophs
a.
decomposers
b.
photosynthesizers
c.
cyanobacteria
d.
acquire electrons from inorganic molecules
e.
oxidize sulfur
f.
produce food without the need for solar energy
g.
help keep ecological cycles going by passing nutrients to producers
h.
consume organic food
i.
saprotrophs
11. a. Certain bacteria live in root nodules. Why is this relationship mutualistic? _____________________________
How does the plant benefit? ___________________________________________________________________________
How does the bacteria benefit? _________________________________________________________________________
b. Certain bacteria live in our intestines. Why is this relationship mutualistic? ____________________________
How do we benefit? _________________________________________________________________________________
How does the bacteria benefit? _________________________________________________________________________
c. Certain bacteria cause disease. Why is this a parasitic relationship? ___________________________________
How does the bacteria benefit? _________________________________________________________________________
How is the host harmed? _____________________________________________________________________________
12. Place a (B) next to the items that pertain to the ability of bacteria to cause disease; place an (A) next to those
items that pertain to antibiotic therapy:
a.
production of a toxin
b.
interference with cell wall biosynthesis
c.
invade organs or cells
d.
ability to adhere to surfaces
e.
interference with protein biosynthesis
Archaea ( P. 275)
• Biochemical characteristics distinguish archaea from bacteria and eukaryotes.
• The archaea are quite specialized and are well known for living in extreme habitats.
13. Archaea are able to live in extreme environments. Name the type of archaea that live in the following habitats:
a. swamps and marshes; produce methane _______________________
b. salty environments (Great Salt Lake in Utah) _______________________
c. hot and acidic environments (hot sulfur springs of Yellowstone National Park) _______________________
14. Place the appropriate letter next to each statement:
A—Archaea
B—Bacteria
E—Eukarya
a.
Which two are more likely to be parasites?
b.
Which two do not have a nucleus?
c.
Which two are more closely related to each other?
d.
Methanogens belong to which group?
e.
Which two more likely contain photosynthesizers?
f.
Which has peptidoglycan in their cell walls?
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17.4 THE PROTISTS (PP. 276–279)
• Endosymbiosis may have played a role in the origin of the eukaryotic cell.
• The protists are largely unicellular, but are quite varied in structure and life cycle.
• This text groups the protists according to their modes of nutrition.
15. Consider the adjacent diagram of the endosymbiotic
hypothesis, then answer the questions:
Common ancestor
cytoplasm
a. Based on the diagram, explain how the
eukaryotic cell acquires mitochondria.
DNA
plasma
membrane
Bacteria
b. Based on the diagram, explain how the
eukaryotic plant cell acquired chloroplasts.
Archaea
nucleus
nuclear
envelope
endoplasmic
reticulum
c. Which type of eukaryotic cell has both
Cell has nucleus
and endoplasmic reticulum.
mitochondria and chloroplasts?
aerobic
bacterium
photosynthetic
cyanobacterium
mitochondrion
aerobic
bacterium
Eukaryotic cell
has mitochondria
(animal cell).
mitochondrion
chloroplast
Eukaryotic cell
has mitochondria,
chloroplasts,
(plant cell).
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16. Label the following diagram of Chlamydomonas using the alphabetized list of terms:
cell wall
chloroplast
a.
contractile vacuole
b.
endoplasmic reticulum
f.
flagellum
g.
Golgi apparatus
h.
mitochondrion
i.
nucleus
plasma membrane
pyrenoid
starch
thylakoid
c.
vacuole
d.
j.
k.
l.
m.
e.
17. Match the organisms to the phrases (some questions will have more than one answer):
1. algae
2. protozoans
3. slime molds
4. water molds
a.
eukaryotes
b.
usually live in aquatic environments
c.
heterotrophic
d.
sometimes parasitic
e.
often ingest their food
f.
photosynthetic
g.
classified by color
h.
classified by type of locomotion
i.
decomposer
18. Match the organism to the description:
1. ciliates
2. amoeboids
3. zooflagellates
4. sporozoans
a.
move by flagella
b.
move by cilia
c.
produce spores
d.
cause disease
e.
move by cytoplasmic extensions
f.
not motile
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19. Label the following diagram of Paramecium, using the following alphabetized list of terms:
anal pore
cilia
contractile vacuole (used
twice)
food vacuole
gullet
macronucleus
micronucleus
oral groove
pellicle
20. Match the photos to the organism:
1. multicellular alga
2. unicellular alga
3. colonial alga
4. zooflagellate
5. amoeboid
a.
b.
d.
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c.
e.
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K E Y WO R D C RO S S WO R D
Review key terms by completing this crossword puzzle, using the following alphabetized list of terms:
1
2
3
4
5
6
7
9
8
algae
Archaea
bacteria
ciliate
protozoan
pseudopod
radiolarian
retrovirus
sporozoan
trypanosome
zooflagellate
10
11
Across
1 member of a genus of parasitic zooflagellates that
cause severe disease in human beings and domestic animals
4 RNA virus containing the enzyme reverse transcriptase that carries RNA/DNA transcription; for
example, the AIDS virus
7 animal-like, heterotrophic, unicellular organism
9 aquatic, plantlike organism carrying out photosynthesis and belonging to the kingdom Protista
10 unicellular organism that lacks a nucleus and cytoplasmic organelles other than ribosomes; reproduces by binary fission and occurs in one of three
shapes
11 complex unicellular protist that moves by means
of cilia and digests food in food vacuoles
Down
2 cytoplasmic extension of amoeboid protists; used
for locomotion and engulfing food
3 spore-forming protist that has no means of locomotion and is typically a parasite
5 protozoan; marine amoeba having a calcium carbonate skeleton
6 protozoan that moves by means of flagella
8 one of three domains of life, often found living in
extreme habitats; prokaryotic cells that have unique
genetic, biochemical, and physiological characteristics
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CHAPTER TEST
OBJECTIVE QUESTIONS
Do not refer to the text when taking this test.
1. Which is NOT generally true of viruses?
a. have a nucleic acid core
b. have a capsid
c. have a specific host range
d. reproduce independently
2. Which viral life cycle does NOT immediately
rupture the bacterial cell?
a. lysogenic
b. lytic
3. Which is true concerning animal viruses?
a. lack an envelope when they leave the host cell
b. attack the host cell by exocytosis
c. have an outer coat of nucleic acid
d. Some have RNA genomes.
4. In the lytic cycle, the term maturation refers to
the
a. translation of RNA.
b. integration of cDNA.
c. assembly of parts into new viruses.
d. All of these are correct.
5. Which shape is NOT a bacterial shape?
a. bacillus
b. coccus
c. flagellar
d. spirillum
6. Which of the following is NOT a form of genetic
recombination in bacteria?
a. binary fission
b. conjugation
c. transduction
d. transformation
7. The function of the bacterial endospore is to
a. increase the rate of anaerobic respiration.
b. promote asexual reproduction.
c. protect against attack from immune systems.
d. withstand harsh environmental conditions.
8. A bacterium produces vitamins for a host while
gaining a habitat. This relationship is
a. commensalism.
b. mutualism.
c. parasitism.
d. predation.
9. Which of these is an incorrect association?
a. viroids—naked RNA
b. prions—cause diseases in prokaryotes only
c. prions—rogue proteins
d. viroids—cause plant diseases only
150
10. Chemoautotrophic bacteria
a. give off oxygen just like plants do.
b. are exemplified by the nitrifying bacteria that
oxidize ammonia (NH 3 ) to nitrites (NO 2 − ).
c. are decomposers like all bacteria.
d. Both b and c are correct.
11. Which of these is (are) a true statement(s)?
a. Archaea are in a separate kingdom.
b. Archaea are in their own domain.
c. Archaea cause many human diseases.
d. Archaea are found in extreme habitats like
swamps, salty lakes, hot, acidic aquatic
habitats.
e. Both b and d are correct.
12. How are archaea different from bacteria?
a. Archaea have a nucleus and bacteria do not.
b. Archaea live in extreme habitats and bacteria
do not.
c. Archaea have nucleotide sequences not found
in bacteria.
d. Archaea have a cell wall and bacteria do not.
e. Both b and c are correct.
13. Classification of algae according to color
a. can no longer be justified.
b. is based on the type of pigments they contain.
c. suggests that they do not have chlorophyll.
d. means that some algae are colorless.
14. Protozoans are not animals because they are
a. pigmented.
b. motile.
c. unicellular.
d. All of these are correct.
15. Amoeboids
a. have pseudopods.
b. never have a shell.
c. always live in fresh water.
d. All of these are correct.
16. Ciliates
a. have a macronucleus and a micronucleus.
b. do not move.
c. are parasitic.
d. are usually saprotrophic.
17. Which one of these is NOT an alga?
a. Chlamydomonas
b. Volvox
c. Paramecium
d. All of these are algae.
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19. Slime molds
a. are exactly like fungi.
b. have a body composed of hyphae.
c. produce spores.
d. All of these are correct.
18. In the life cycle of Plasmodium vivax, the cause
of one type of malaria,
a. sexual reproduction occurs in a mosquito.
b. red blood cells burst, causing chills and fever.
c. spores and gametes both form.
d. All of these are correct.
CRITICAL THINKING QUESTIONS
The introduction to this chapter is about microbes.
20. What unifies all the microbes? ______________________________________________________________________________
21. Why do algae rarely cause disease? _________________________________________________________________________
22. Why do viruses always cause disease? ______________________________________________________________________
23. In this context, what does the word “germ” mean? ___________________________________________________________
24. One way to stop an infection is to know how a disease is transmitted. For example, how is AIDS transmitted?
_______________________ What is the best way to prevent getting AIDS?
Test Results: ______ number correct ÷ 24 = ______ × 100 = ______ %
EXPLORING
THE
INTERNET
ARIS, the Essentials of Biology website: http://www.mhhe.com/maderessentials
ARIS, the website for Essentials of Biology, offers access to a wide variety of tools to help students learn biological
concepts and to reinforce their knowledge. Online study aids such as practice quizzes, interactive activities, animations, labeling exercises, flashcards, and much more are organized according to the major sections of each chapter.
There is even an online tutorial service!
ANSWER KEY
CHAPTER KEY TERMS
a. protozoan b. endospore c. algae d. viroid e. zooflagellate f. peptidoglycan g. lysogenic cycle h. lytic cycle
i. retrovirus j. bacteriophage k. sporozoan l. ciliate
m. plasmid n. amoeboid o. binary fission p. virus
q. phagocytosis r. prion s. symbiotic t. protist u. saprotroph
STUDY EXERCISES
1. a. capsid b. protein subunit c. DNA d. spike
2. a. lytic cycle b. lysogenic cycle c. attachment d. penetration e. integration f. biosynthesis g. maturation
h. release. See Figure 17.3, page 267, in text. i. lytic
j. lysogenic k. lytic 3. a. 4 b. 6 c. 7 d. 1 e. 2 f. 8
g. 9 h. 5 i. 3 4. a. retrovirus b. cDNA c. biosynthesis d. maturation e. release f. envelope 5. a. F
b. T c. T d. T 6. a. bacteria b. archaea 7. a. spirillum b. coccus c. bacillus 8. a. Replication of DNA has
occurred. b. Cell has elongated and DNA molecules have
moved apart. New plasma membrane and cell wall is form-
ing. c. Two new cells are present. 9. a. 3 b. 5
c. 1 d. 2 e. 4 10. a. 3 b. 1 c. 1 d. 2 e. 2 f. 2 g. 3
h. 3 i. 3 11. a. Both species benefit; Receives nitrogen
compounds from bacteria; Receives organic nutrients, such
as glucose, from the plant. b. Both species benefit; Receive vitamins produced by the bacteria; The intestine provides them with nutrients. c. One species benefits and one
is harmed; They acquire nutrients from the host; The host
becomes ill. 12. a. B b. A c. B d. B e. A
13. a. methanogens b. halophiles c. thermoacidophiles
14. a. B, E b. B, A c. A, E d. A e. B, E f. B 15. a. The
cell engulfs aerobic bacterium. b. The cell engulfed photosynthetic bacterium. c. plant cell 16. a. flagellum
b. contractile vacuole c. Golgi apparatus d. cell wall e. plasma
membrane f. chloroplast g. thylakoid h. vacuole i. endoplasmic reticulum j. nucleus k. pyrenoid l. mitochondrion
m. starch 17. a. 1, 2, 3, 4 b. 1, 2, 4 c. 2, 3, 4 d. 2, 4
e. 2, 3 f. 1 g. 1 h. 2 i. 4 18. a. 3 b. 1 c. 4 d. 1, 2, 3, 4
e. 2 f. 4 19. a. cilia b. contractile vacuole c. food vacuole d. macronucleus e. anal pore f. contractile vacuole
g. gullet h. micronucleus i. oral groove j. pellicle
20. a. 2 b. 1 c. 5 d. 4 e. 3
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KEYWORD CROSSWORD
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CHAPTER TEST
1. d 2. a 3. d 4. c 5. c 6. a 7. d 8. b
9. b 10. b 11. e 12. c 13. b 14. c 15. a 16. a
17. c 18. d 19. d 20. small size 21. They make
their own food. 22. They reproduce inside cells.
23. A microbe that causes a disease. 24. Through sexual contact; Avoid sexual contact except with people you
know for sure are free of the disease.