Passive Transport of Small Molecules through Cell Membrane
Passive transport is a process by which molecules move across a cell membrane without the input of energy. This process is driven by the concentration gradient of the molecules, with them moving from an area of high concentration to an area of low concentration. Small molecules, such as oxygen, carbon dioxide, and water, can pass easily through the cell membrane via passive transport.

True or False?
It is true that smaller molecules can pass easily through the cell membrane without the requirement of energy. This is because the cell membrane is selectively permeable, allowing small, non-polar molecules to pass through its lipid bilayer without the assistance of transport proteins.

Explanation
- **Size of Molecules**: Small molecules are able to pass through the cell membrane easily due to their size. Larger molecules may require the assistance of transport proteins to facilitate their passage.
- **Lipid Bilayer**: The lipid bilayer of the cell membrane is made up of phospholipids, which form a hydrophobic barrier. Small, non-polar molecules can dissolve in the lipid bilayer and pass through it easily.
- **Concentration Gradient**: Passive transport relies on the concentration gradient of molecules. Small molecules moving from an area of high concentration to an area of low concentration can pass through the cell membrane without the input of energy.
- **Examples**: Small molecules like oxygen and carbon dioxide can diffuse across the cell membrane through passive transport. Water molecules can also pass through specialized channels called aquaporins.
In conclusion, small molecules can pass through the cell membrane easily without the requirement of energy through passive transport. This process is essential for the normal functioning of cells and helps maintain the internal environment of the cell.