Question

Endocytosis and exocytosis are forms of active transport. What is active transport?
1. Movement of molecules down a concentration gradient from high to low, using no energy.
2. Movement of molecules up a concentration gradient from low to high, using no energy.
3. Movement of molecules up a concentration gradient from low to high, using energy.
4. Movement of molecules down a concentration gradient from high to low, using energy.

Answer 1

Active transport is defined as:

**3. Movement of molecules up a concentration gradient from low to high, using energy.**

This process requires energy, typically in the form of ATP, as it involves moving substances against their concentration gradient.