Answer:
The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful.
Information
The immune system protects the body from possibly harmful substances by recognizing and responding to antigens. Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens.
Your body's cells have proteins that are antigens. These include a group of antigens called HLA antigens. Your immune system learns to see these antigens as normal and usually does not react against them.
two balls until they are out
Oxygen in the air can cause sliced fruit to brown, a process called enzymic browning (an oxidation reaction). Phenols and the enzyme phenolase are found in the cells of the apple, and when these are exposed to oxygen in the air, for example through slicing, the oxygen causes a reaction.
Burns are classified into four(4) classification, first degree, second degree, third degree and the fourth degree. First degree burns affects only the outer layer of our skin, the second degree affects our epidermis, the third degree destroys the dermis and epidermis and lastly the fourth degree damages the bones, muscles and tendons in our body.