Answer:
The movement of molecules across a membrane without the input of energy is known as passive transport. When energy (ATP) is needed, the movement is known as active transport. Active transport moves molecules against their concentration gradient, from an area of low concentration to an area of high concentration.
Explanation:
hope this helps :D
Lead I believe would be the heaviest because gold is relatively light
(x-3)² = (x-3)(x-3)
= x² - 3x - 3x + 9
= x² - 6x + 9
The cell is the basic unit of living things ,or the cell structure explains the properties