_____ immunity defends against antigens and pathogens in body fluids.

How many different amino acids compose all human polypeptides (proteins)?

This tissue group is able to control other tissues.

The process where DNA makes RNA is called _____?

Which of the following provides the best example of a negative feedback control mechanism?

Protection and support is the function of the ____ of the eye.

This cell delivers oxygen to the tissues

Which of the following is NOT a characteristic of connective tissue?

extension

The sum of all the chemical reactions that occur in a cell is