This is a measure of the quantity of matter.

Mass

Explanation:

Mass is one of the most fundamental and important physical quantities, because it is a quantification of the amount of matter.

Mass is also often described as a measure of the inertia of an object, which is the resistance of an object to be moved.

Many laws and equations of nature make use of the concept of mass and the official unit of mass in the international system is the kilogram (Kg).

cell differentiation  is how generic embryonic  cells  become specialized  cells. this occurs  through a process called gene expression. gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a  cell  functions.

explanation:

the independent variable, or the one that is intentionally manipulated is the speed.