Florida Biology EOC Practice Test

Which of the following processes does NOT require energy and moves with the concentration gradient?

1. Active transport

2. Osmosis

3. Passive transport

4. Vesicle transport

The correct answer is: Passive transport

The correct answer is passive transport. This process does not require energy because it relies on the natural movement of molecules from an area of higher concentration to an area of lower concentration, following the concentration gradient. In passive transport, substances such as small, nonpolar molecules and certain ions move through cell membranes without the input of energy, allowing cells to maintain homeostasis efficiently. In contrast, active transport requires energy because it moves substances against their concentration gradient, from an area of lower concentration to one of higher concentration. This process is essential for maintaining the proper balance of ions and molecules within the cell. Osmosis, which specifically refers to the movement of water across a semi-permeable membrane, is a form of passive transport but is specifically focused on water. Vesicle transport involves the energy-dependent movement of large molecules or particles into or out of the cell through vesicles, further underscoring the need for energy in that process.