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Section 1: Studying Viruses and Prokaryotes
Study Guide A
KEY CONCEPT
Infections can be caused in several ways.
VOCABULARY
virus
viroid
pathogen
prion
MAIN IDEA: Viruses, bacteria, viroids, and prions can all cause infection.
1. In the top left side of the Y shape below, fill in the blanks in the characteristics
of bacteria.
2. In the top right side of the Y shape below, fill in the blanks in the
characteristics of viruses.
3. At the bottom of the Y shape below, fill in the blanks in the characteristics that
both bacteria and viruses share.
Bacteria
Viruses
Made only of a strand
of ______ or ______
surrounded by a
_________ coat.
Can cause
____________.
One-celled
_________________.
Can cause
_______________.
Both
Can cause ________________ in the body.
Are considered ________________.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
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Viruses and Prokaryotes
Section 1: Studying Viruses and Prokaryotes
Study Guide A continued
Choose the best answer to the question.
4. Why is it hard to say whether viruses are alive or not?
a. Viruses are very tiny and impossible to see without a microscope.
b. Viruses cannot reproduce if they are alone — they need living cells to help
them.
c. Viruses can cause infection in the body and are considered pathogens.
d. Viruses do not contain any genetic material such as DNA or RNA.
5. In the chart below, fill in the blanks in the description of each type of
infectious particle.
Infectious Particle
Description
Virus
Made only of a __________ strand of DNA or ____
surrounded by a _________ coat.
Need living cells in order to _______________ and to
make __________.
Much smaller than most __________.
Not classified by Linneaus.
Viroid
Has less in common with _____________ things than
viruses do.
Cause disease in ___________.
Made of single _________ of ____.
Unlike viruses, do not have a ___________ coat.
Prion
Made only of __________ that can cause other
____________ to fold incorrectly.
Contain no ___________ material.
Cause brain diseases such as _______________________.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
1
Viruses and Prokaryotes
Section 1: Studying Viruses and Prokaryotes
Study Guide A continued
Vocabulary Check
Write a word from the box in the space provided. Each word will be used more
than once.
virus
pathogen
viroid
prion
______________________
6. Does not have genes
______________________
7. Includes infectious bacteria
______________________
8. Made of only RNA
______________________
9. Any living thing or particle that can cause
infectious disease
______________________ 10. Made only of protein
______________________ 11. Infects plants
______________________ 12. Made of genetic material surrounded by a
protein coat
______________________ 13. Can contain RNA or DNA but is not living
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
2
Viruses and Prokaryotes
Section 1: Studying Viruses and Prokaryotes
Section 2: Viral Structure and Reproduction
Study Guide A
KEY CONCEPT
Viruses exist in a variety of shapes and sizes.
VOCABULARY
capsid
lytic infection
bacteriophage
lysogenic infection
prophage
MAIN IDEA: Viruses differ in shape and in ways of entering host cells.
1. Sketch the three common shapes of viruses, using Figure 2.2 as a reference.
Enveloped
Helical
Polyhedral
Choose the best answer to the question.
2. What is the protein shell around each viral particle called?
a. virion
b. capsid
c. lipid envelope
d. host cell
3. What must viruses do before they can reproduce?
a. infect a host cell
b. undergo cell division
c. prey on bacteria
d. develop a lipid envelope
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
3
Viruses and Prokaryotes
Section 2: Viral Structure and Reproduction
Study Guide A continued
4. A virus cannot infect a host cell unless
a. its surface proteins give the virus a helical shape.
b. its surface proteins are surrounded by a lipid envelope.
c. its surface proteins fit receptor molecules on the host cell’s surface.
d. its surface proteins have spikes that can be used to attach to a host cell.
5. How do the structures of bacteriophages help them infect host cells?
a. They have spikes to help them attach to the host cells.
b. They are the same shape as the host cells.
c. They do not have cell walls, unlike the host cells.
d. They are protected from the host cells by a lipid envelope.
MAIN IDEA: Viruses cause two types of infections.
6. In the top left side of the Y shape below, fill in the blanks in the characteristics
of a lytic infection.
7. In the top right side of the Y shape below, fill in the blanks in the
characteristics of a lysogenic infection.
8. At the bottom of the Y shape below, fill in the blanks in the characteristics that
both types of infections have in common.
Lytic infection
Lysogenic infection
Viral __________
combines with host’s
__________, producing
new __________ called a
__________.
Host cell __________
and passes on the new
_________.
Takes control of host
cell’s __________.
Produces new
__________.
Dissolves cell
__________so that new
__________ are released.
Both
Begin infection process by _______________ host
cells.
Reproduce with the help of host _____________.
Infect cells using genetic material.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
4
Viruses and Prokaryotes
Section 2: Viral Structure and Reproduction
Study Guide A continued
Vocabulary Check
Write each word from the box next to its definition below.
capsid
bacteriophage
lytic infection
lysogenic infection
______________________
prophage
9. Virus that infects bacteria
______________________ 10. Viral DNA plus host cell DNA
______________________ 11. Protein shell of a virus
______________________ 12. Infection where virus combines its DNA with
host cell’s DNA
______________________ 13. Infection where host cell bursts, releasing viral
offspring
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
5
Viruses and Prokaryotes
Section 2: Viral Structure and Reproduction
Section 3: Viral Diseases
Study Guide A
KEY CONCEPT
Some viral diseases can be prevented with vaccines.
VOCABULARY
epidemic
vaccine
retrovirus
MAIN IDEA: Viruses cause many infectious diseases.
Choose the best answer to the question.
1. What is the body’s first defense against infection?
a. white blood cells
b. the skin
c. cell membranes
d. lipid envelopes
2. What is one way in which viruses commonly enter the body?
a. through unbroken skin
b. through mucous membranes in the nose or mouth
c. through the fingernails
d. through the skeletal system
3. How do some viruses trick cells into letting them in?
a. by using their surface proteins as “keys” to the cell’s receptors
b. by trying to look as much like normal body cells as possible
c. by producing spikes that they can use to penetrate the body cells
d. by changing their DNA or RNA to match that of the body
4. Why is it not easy to find a cure for the common cold?
a. because cold viruses cannot be weakened for use in a vaccine
b. because cold viruses enter the body through the nose and mouth
c. because cold viruses contain DNA and RNA that scientists have never seen
before
d. because cold viruses often mutate as they move from one person to another
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
6
Viruses and Prokaryotes
Section 3: Viral Diseases
Study Guide A continued
5. Why must a new flu vaccine be made every year?
a. Scientists keep trying, but they cannot get the vaccine just right.
b. New mutations of the flu appear every year that are different from the
previous year’s flu.
c. If people did not get vaccinated against the flu every year, they would be
sure to get sick.
d. Every year people are vaccinated with all the previous vaccines and a new
one, just in case.
6. Why might a person who has AIDS have a hard time fighting off normally
harmless microorganisms?
a. One of the symptoms of the HIV virus is that it makes you feel tired all
the time.
b. The HIV virus attacks white blood cells from the body’s immune system.
c. HIV can remain dormant, so its victims don’t realize that they need to take
care of themselves.
d. HIV is constantly mutating, and the body is so weak from fighting it that it
cannot fight other pathogens.
MAIN IDEA: Vaccines are made from weakened pathogens.
Circle the word or phrase that best completes the sentence.
7. A vaccine is a weakened / strengthened version of the same pathogen that
causes the disease that the vaccine is intended to prevent.
8. Vaccines work by provoking the body’s immune system into a mild / strong
response, so that it will recognize the pathogen again in the future if it should
encounter it.
9. Vaccines cause the body’s immune system to react when it meets the surface
proteins / cell membrane of a bacteria or virus.
10. Vaccines are usually one way / the only way that scientists can fight against the
spread of a viral infection.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
7
Viruses and Prokaryotes
Section 3: Viral Diseases
Study Guide A continued
Vocabulary Check
Write each word from the box next to its definition.
epidemic
vaccine
retrovirus
______________________ 11. Contains RNA and uses a special enzyme to make
a DNA copy
______________________ 12. Rapid outbreak of an infection that affects many
people
______________________ 13. Stimulates the body’s own immune response
against invading microbes
Identify the Infection
Match each infection with its characteristics. Refer to Figure 3.4 as you work.
14. Disease caused by the bite of an
infected animal
a. chicken pox
15. Disease caused by the bite of an
infected insect
b. rabies
16. Disease caused by contact with a
particular rash
c. West Nile
17. Disease that causes swelling in glands
under a person’s jaw
d. mumps
18. Disease that causes yellow skin, fatigue,
and abdominal pain
e. hepatitis A
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
8
Viruses and Prokaryotes
Section 3: Viral Diseases
Section 4: Bacteria and Archaea
Study Guide A
KEY CONCEPT
Bacteria and archaea are both single-celled prokaryotes.
VOCABULARY
obligate anaerobe
plasmid
obligate aerobe
flagellum
facultative aerobe
conjugation
endospore
MAIN IDEA: Prokaryotes are widespread on Earth.
Choose the best answer for the question.
1. Bacteria and archaea together make up the most widespread group of
organisms on Earth, the
a. eukaryotes.
b. prokaryotes.
c. viruses.
d. pathogens.
2. Some prokaryotes are poisoned if they come into contact with oxygen. Where
might you find one?
a. in a desert
b. in the digestive tract of a cow
c. on a polar ice cap
d. in a body of water
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
9
Viruses and Prokaryotes
Section 4: Bacteria and Archaea
Study Guide A continued
MAIN IDEA: Bacteria and archaea are structurally similar but have different
molecular characteristics.
3. In the top left of the Y shape, fill in the blanks in the characteristics
of bacteria.
4. In the top right of the Y shape, fill in the blanks in the characteristics
of archaea.
5. At the bottom of the Y shape, fill in the blanks in the characteristics bacteria
and archaea have in common
Archaea
Bacteria
Found in _________
environments.
Common, widespread
Cell walls contain a
polymer called
_______________.
Cell walls and
membranes contain
_________ that are
not found in any other
organism on Earth.
Both
Small, single-_________ organisms
Have cell _____ and plasma ____________
Most have the ability to __________ on their own.
MAIN IDEA: Bacteria have various strategies for survival.
Choose whether the statement is true or false.
6. true / false Since prokaryotes reproduce asexually, they do not exchange any
genetic material with other organisms.
7. true / false Binary fission, which means “division in half,” is a method
scientists use when they are studying prokaryotes.
8. true / false During the process of conjugation, prokaryotes build bridges
between organisms in order to exchange genetic material with each other.
9. true / false Some bacteria can survive even harsh conditions by producing an
endospore.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
10
Viruses and Prokaryotes
Section 4: Bacteria and Archaea
Study Guide A continued
10. true / false Endospores can last for hundreds of years and have even been
found inside Egyptian mummies.
11. true / false To form an endospore, the bacterium undergoes binary fission.
Vocabulary Check
Draw lines to match each word or phrase with its definition.
12. Can survive whether oxygen is
present or not
a. endospore
13. Long whiplike structure used
for movement
b. conjugation
14. Needs oxygen to survive
c. flagellum
15. Specialized prokaryotic cell that
can withstand harsh conditions
d. plasmid
16. Prokaryotic method of
gene exchange
e. facultative aerobe
17. Cannot live in the presence
of oxygen
f. obligate aerobe
18. Separate circular piece of a
prokaryote’s genetic material
g. obligate anaerobe
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
11
Viruses and Prokaryotes
Section 4: Bacteria and Archaea
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
12
Viruses and Prokaryotes
Section 6: Bacterial Diseases and Antibiotics