1. Mike injured his knee while playing. Examination revealed that the injured area was red, swollen, and warmer than the surrounding area. What does this condition indicate?

an inflammation

a tumor–like growth

a hemorrhage

2. When a virus invades the body, some B cells recognize it as nonself and produce plasma cells that release a substance to kill the virus. What is this substance called?

antigen

antibody

pathogen

3. Which of the following forms blood clots?

fibrin

macrophages

thrombin


4. An antigen has invaded a mammal's body. Specific immune cells engulf and ingest it. Some of the digested pieces are displayed on the cells' bodies. What happens next?

B cells are activated and release antibodies.

T cells are activated and produce clones.

B cells withdraw the immune response as the antigen is killed.