1. What is the percentage of natural killer cells?
5 to 15 percent
4 to 15 percent
50 percent

2. Why are natural killer cells called natural killers?
They do need to recognize a specific antigen.
They do not need to recognize a specific gene.
They do not need to recognize a specific antigen.

3. In several immunodeficiency diseases, including AIDS, natural killer cell function is ___ , thus allowing the viruses to ___ inside of human cells.
normal / multiply
abnormal / multiply
normal / divide

4. How do natural killer cells kill?
on contact
with products
with no contact

5. How do killer cells kill?
They release toxins and create holes.
They take the toxins from the infected cell
They absorb the infected cell.

6. It creates events that destroy ___ and cleaves DNA into many pieces in a program cell death.
the cancer cell membrane
more membrane
any membrane

7. How many cells can Natural killer cells kill?
many others

8. How much time does it take to kill them?

9. Naural killer cells contribute to ___
destruction regulation
immune regulation
circulating regulation

10. ...which affects our overall health. Finally we come back ___ of our knowledge about other natural killer cells.
at the beginning
to the end
to the beginning

11. Then it on the surrounding sheep red blood cells cytotoxin is ___ .
completely destroyed
partially destroyed
not completely destroyed

12. The natural killer cell is one of the ___ in the fight against viral and ___ .
key soldiers / cancer growth
most important element / immune system
key soldiers / aids growth