Answers to Virus and Bacteria Workbook pages

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Answers to Virus and Bacteria Workbook pages

• Chapter 19

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19-1 Prokaryotes

• They are single-celled organisms that lack a
  nucleus.
• True
• Eubacteria and Archaebacteria
• Eubacteria
• They live almost everywhere. Some live in the
  soil, whereas others infect large organisms.

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19-1

• 6. The cell wall protects it.
• 7. B
• 8. It is a carbohydrate in the cell walls of
  eubacteria.
• 9. Membrane
• 10. a,c,d
• 11. They are more like those of eukaryotes than
  those of eubacteria.

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19-1

• 12. Scientists reason that archaebacteria may be
  the ancestors of eukaryotes.
• 13. They are prokaryotes that produce methane
  gas. They live in oxygen-free environments, such
  as thick mud and the digestive tracts of animals.
• 14. Cell wall, cell membrane
• Flagellum, DNA

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19-1

• 15. Their shapes, the chemical natures of their
  cell walls, the way they move, the ways they
  obtain energy.
• 16. a. bacilli
• b. cocci
• c. spirilla
• 17. Gram staining
• 18. Gram-positive bacteria appear purple, and
  gram-negative bacteria appear pink.

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19-1

• 19. They are whip-like structures used for
  movement.
• 20. True
• 21. Photoautotroph
• Organism that obtains energy directly from
  inorganic molecules.
• Heterotroph
• Organism that captures sunlight for energy
  also needs organic molecules for nutrition

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19-1

• 22. Cyanobacteria
• 23. They obtain energy from hydrogen sulfide gas
  that flows from the vents.
• 24. Obligate aerobes
• Organisms that must live in the absence of
  oxygen
• Organisms that can survive with or without
  oxygen

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19-1

• 25. It is caused when the obligate anaerobe
  Clostridium botulinum grows in canned food that
  has not been properly sterilized.
• 26. Fermentation
• 27. It is a type of asexual reproduction in which
  a prokaryote grows to nearly double its size,
  replicates its DNA, and divides in half,
  producing two identical daughter cells.

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19-1

• 28. A hollow bridge forms between 2 cells, and
  genes move from one cell to the other.
• 29. False
• 30. It is a type of spore that is formed when a
  bacterium produces a thick internal wall that
  encloses its DNA and a portion of its cytoplasm.

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19-2

• Armies of bacteria attack and digest the dead
  tissue. The bacteria break down dead matter into
  simpler substances, which are released into the
  soil and taken up by the roots of plants.
• Plants would drain the soil of minerals and die,
  and animals that depend on plants for food would
  starve.

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19-2

• 3. They need nitrogen to make amino acids, which
  are the building blocks of proteins.
• 4. Plants use the nitrogen to build amino acids.
• 5. They have symbiotic relationships.
• 6. They are disease-causing agents.
• 7. Some damage the tissues of the infected
  organisms directly by breaking them down for
  food.
• Others release toxins that harm the body.

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19-2

• 8. They break down lung tissue.
• 9. They are caused by bacterial toxins.
• 10. They are compounds that block the growth and
  reproduction of bacteria.
• 11. There is an increased understanding of how to
  prevent and cure bacterial infection.
• 12. Foods include cheese, yogurt, buttermilk,
  sour cream, pickles, and vinegar.

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19-2

• 13. One type of bacterium can digest petroleum.
• 14. Those bacteria may be a rich source of
  heat-stable enzymes, which can be used in
  medicine, food production, and industrial
  chemistry.
• 15. It is a way of destroying bacteria by
  subjecting them either to heat heat or to
  chemical action.

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19-2

• 16. Disinfectant
• 17. The bacteria in the food will take much
  longer to multiply.
• 18. This method involves heating food to a high
  temperature and then immediately placing it into
  sterile glass jars or metal cans and sealing the
  container.
• 19. They include salt, vinegar, and sugar.

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19-3 Viruses (Worksheet done 2-25 for sub)

• They are particles of nucleic acid, protein, and
  in some case lipids that can reproduce only by
  infecting living cells.
• They enter living cells and, once inside, they
  use the machinery of the infected cell to produce
  more viruses.
• True
• A typical virus is composed of a core of either
  DNA or RNA surrounded by a protein coat.

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19-3

• 5. A
• 6. The capsid proteins bind to the surface of a
  cell and trick the cell into allowing it
  inside.
• 7. Once inside, the viral genes take over. The
  cell transcribes the viral genes, putting the
  genetic program of the virus into effect.
  Sometimes the program may cause the cell to make
  copies of the virus, but often it destroys the
  host cell.

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19-3

• 8. Viruses must bind precisely to proteins on the
  cell surface and then use a hosts genetic
  system.
• 9. They are viruses that infect bacteria.
• 10. The host cell is lysed and destroyed.
• 11. B, C, D
• 12. Cell wall, DNA, genes, burst, particles
• 13. It is the viral DNA that is embedded in the
  hosts DNA.

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19-3

• 14. Viruses cause polio, measles, AIDS, mumps,
  influenza, yellow fever, rabies, and the common
  cold.
• 15. It is a preparation of weakened or killed
  virus or viral proteins.
• 16. It stimulates the immune system, sometimes
  producing permanent immunity to the disease.
• 17. Oncogenic viruses

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19-3

• 18. They are viruses that contain RNA as their
  generic information.
• 19. They produce a DNA copy of their RNA. This
  DNA is inserted into the DNA of the host cell.
• 20. Prion
• 21. D