Questions:

1. Which of the following is not an A-B exotoxin?
1. Streptolysin O
2. Staphylococcus aureus enterotoxin
3. Cholera toxin
4. Diphtheria toxin
5. Tetanus toxin
2. All of the following are true of A-B exotoxins except:  
1. The B portion of the toxin binds to surface receptors on host cells.
2. They consist of two polypeptide components.
3. They are only produced by gram-negative bacteria.
4. The A portion of the toxin is the active component.
5. Many exotoxins are A-B toxins.
3. Which of the following bacterial toxins binds to nerve cells, preventing chemical communication between nerve and muscle cells? 
1. Diphtheria toxin
2. Erythrogenic toxin
3. Staphylococcal enterotoxin
4. E. coli endotoxin
5. Botulinum toxin
4. Which is true of endotoxins?
1. They increase blood pressure.
2. They are produced by gram-positive bacteria.
3. They are disease-specific.
4. They are released upon cell lysis.
5. They are proteins.
5. In a bacterial exotoxin:
1. The A subunit allows the toxin to bind to the surface of specific host cells.
2. The A subunit is part of the outer bacterial membrane, released when the bacterialcell dies.
3. The A subunit is able to interfere with a specific host cell activity, once it has beentaken into the host cell.
4. We expect the A subunit for all exotoxins to operate in the same manner.
6. What effect does botulin toxin have on the body?
1. It causes excitation of neurons.
2. It stimulates the removal of fluid from the tissues.
3. It stimulates increased intestinal motility.
4. It paralyzes the muscles of the respiratory tract.
5. It prevents gastrointestinal motility.