Answer: Variables
Explanation: Variables are used during an experiment and must be controlled so that researchers can draw a logical conclusion. The independent variable is the one that is changing and the dependent variable is the one being measured.
Explanation:
Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart.
Second one: Water expands when it freezes
When a scientist finds in the field, the scientist first compare to other known organisms to organisms that are physically similar to the organism. This is verified through encyclopedia and database of organisms. Then the scientist then compares genetically one organism to another organism.