Download ch. 18 (practice exam)

H03 CH. 18 EXAM: BACTERIA AND VIRUSES
True/False
Indicate whether the sentence or statement is true or false.
____
1. Although viruses do not consist of cells, biologists consider them to be living because they are capable of
reproduction.
____
2. A virus can only reproduce by controlling a cell.
____
3. Smallpox is caused by bacteria.
____
4. Some viruses have a membranous envelope surrounding their protein coat and the envelope helps the
viruses gain entry into host cells.
____
5. Viruses consist of RNA or DNA surrounded by a coat of protein.
____
6. The lytic cycle is a cycle of viral infection, replication, and cell destruction.
____
7. During the lysogenic cycle, the viral genome replicates and the host cell is destroyed.
____
8. HIV initially infects cells of the nervous system.
____
9. An HIV-infected individual can feel healthy and still spread the virus to others.
____ 10. Bacteria lack nuclei and therefore, also lack genetic material.
____ 11. Bacterial cells have membrane-bound organelles and chromosomes.
____ 12. Bacterial cells are usually much larger than eukaryotic cells.
____ 13. Although there are some bacteria that are heterotrophic, the vast majority are autotrophic.
____ 14. Photosynthetic bacteria are present in leguminous plants and convert atmospheric nitrogen into a form
that is usable by the plants.
____ 15. Escherichia coli is a eukaryotic cell with a rigid cell wall made of peptidoglycan.
____ 16. Tuberculosis is a disease of the respiratory tract caused by a virus.
____ 17. Certain antibiotics have become ineffective against certain strains of bacteria. These bacteria have
developed a resistance, which may be passed on from one generation of bacteria to the next.
____ 18. Genetically engineered bacteria are used to produce drugs and other chemicals that benefit humans.
Completion
Complete each sentence or statement.
19. ____________________ are segments of nucleic acids contained in a protein coat.
20. A disease of tobacco plants in which growth is stunted and leaves are blotchy is caused by the
____________________ ____________________ virus.
21. ____________________ are bacterial viruses with a polyhedral head attached to a helical tail.
22. The protein coat of a virus is called a(n) ____________________.
23. All viruses reproduce by taking over the reproductive machinery of a(n) ____________________.
24. Microscopic, nucleic acid–containing particles that invade cells of organisms in order to reproduce, and
often destroy the cells in the process, are called ____________________.
25. An enzyme called ____________________ ____________________ manufactures DNA that is
complementary to a virus’s RNA.
26. The virus that causes AIDS is called ____________________ ____________________
____________________.
27. The cell walls of eubacteria are composed of ____________________, a network of polysaccharide
molecules that are linked together with chains of amino acids.
28. Structurally, bacteria have one of two types of ____________________ ____________________ that can
be distinguished by the Gram stain.
29. The procedure used to distinguish between two types of bacterial cell wall structures is called
____________________ ____________________.
30. Protective coverings that some bacteria may form under harsh conditions are ____________________.
31. Spiral bacteria are called ____________________.
32. Round bacteria are called ____________________.
33. Rod-shaped bacteria are called ____________________.
34. Bacteria that obtain their energy by removing electrons from inorganic molecules, rather than obtaining
energy from the sun, are called ____________________ bacteria.
35. Plants that possess nitrogen-fixing bacteria in swellings on their roots are called ____________________.
36. A species of bacteria that lives in the intestines of many mammals is ____________________
____________________.
37. The process in which ammonia is oxidized into nitrate, a form of nitrogen commonly used by plants, is
called ____________________.
38. ____________________ is a disease of the respiratory tract caused by the bacterium Mycobacterium
tuberculosis.
39. A(n) ____________________ is a substance that can be obtained from bacteria or fungi and can be used
as a drug to fight pathogenic bacteria.
40. Mining companies use ____________________ bacteria to harvest copper or uranium.
Essay
41. A new disease has suddenly appeared and scientists are trying to determine whether the disease agent is a
virus or a bacterium. They collect the following information:
1. The disease can be transmitted through the air.
2. The disease agent is too small to be seen under a light microscope.
3. There are no known antibiotics that are effective against the disease.
4. The genetic material of the disease agent is DNA.
5. The disease agent cannot be cultured using any known culture medium.
Is the disease agent most likely a bacterium or a virus? Explain your answer in the space below.
42. Viruses are not considered to be living organisms, but they are still studied as part of biology. Explain.
43. Explain why viruses are not considered to be living.
44. It has been observed that antibiotics are generally effective against bacterial infections but cannot be used
to treat viral infections. Why is this the case?
H03 CH. 18 EXAM: BACTERIA AND VIRUSES
Answer Section
TRUE/FALSE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
F
T
F
T
T
T
F
F
T
F
F
F
F
F
F
F
T
T
COMPLETION
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
Viruses
tobacco mosaic
Bacteriophages
capsid
cell
viruses
reverse transcriptase
human immunodeficiency virus or HIV
peptidoglycan
cell walls
Gram staining
endospores
spirilli
cocci
bacilli
chemoautotrophic
legumes
Escherichia coli
nitrification
Tuberculosis
39. antibiotic
40. chemoautotrophic
ESSAY
41. The disease agent is most likely a virus. Like bacteria, many viruses can be transmitted through the air.
Almost all viruses are too small to be seen under a light microscope, although many bacteria are also too
small to be seen under a light microscope. Antibiotics are ineffective against viruses, while there are
antibiotics that are effective against most bacteria. The genetic material of viruses may be DNA or RNA
and the genetic material of bacteria is always DNA. Viruses cannot be cultured on artificial media, while
most bacteria can be cultured. Facts 2, 3, and 5 provide the most significant information indicating that
the disease agent is a virus.
42. Viruses are active inside living cells, making them an important part of the study of biology. Although
viruses contain genetic material and can evolve as this material changes over time, they are not
considered living because they are not cellular, cannot make their own protein, and cannot use energy in
metabolic processes.
43. Viruses are segments of nucleic acids contained in a protein coat. Because viruses do not grow, do not
maintain homeostasis, and do not metabolize, biologists do not consider viruses to be living.
44. Antibiotics work by interfering with cell wall formation or cellular processes such as protein synthesis.
Some antibiotics can cause disruption of the cell membrane. All of these actions can negatively affect the
survival of bacteria. However, since viruses do not undergo cellular processes, they are not influenced by
the actions of antibiotics. Thus, antibiotic treatment is ineffective against viral infections.