AEMCA Practice Exam

What is facilitated diffusion?

1. A process where ions and chemicals are transported into the cell by protein transporters

2. A method for cells to move plants gracefully

3. A type of cellular respiration method

4. A process that requires ATP energy for substance movement

The correct answer is: A process where ions and chemicals are transported into the cell by protein transporters

Facilitated diffusion is indeed a process where ions and chemicals are transported into the cell by protein transporters. This mechanism involves the movement of substances across a cell membrane along their concentration gradient, meaning that molecules move from areas of higher concentration to areas of lower concentration without the expenditure of cellular energy (ATP). In facilitated diffusion, specific proteins embedded within the cell membrane, often referred to as channel proteins or carrier proteins, function as gateways for certain molecules that cannot easily pass through the lipid bilayer due to their size, charge, or polarity. These proteins interact with the substances and help transport them into or out of the cell efficiently. This process is essential for maintaining cellular homeostasis, allowing cells to regulate the intake of vital nutrients and the removal of waste products, while preserving the integrity of the cell's internal environment. Given these characteristics, the other options do not accurately describe facilitated diffusion: the transportation of chemicals via protein transporters directly correlates with the fundamental definition of the process.