What is a measurement of the earths history divided into time periods

Explain how sequences of amino acids in proteins can be used to reveal relationships among organisms.

Vaccines are weakened forms of disease causing microorganisms, which are given to patients to prevent disease. after the vaccine is administered, the immune system responds by creating a(n) to recognize the a.) antibody, antibiotic b.) antigen, antibody c.)antibiotic, antibody d.)antibody, antigen

The function of the excretory system is to control homeostasis and