EVERYDAY SCIENCE

Detailed explanation-1: -Because the cell membrane is semipermeable, only small, uncharged substances like carbon dioxide and oxygen can easily diffuse across it.

Detailed explanation-2: -Small uncharged molecules can diffuse freely through a phospholipid bilayer. However, the bilayer is impermeable to larger polar molecules (such as glucose and amino acids) and to ions.

Detailed explanation-3: -Gases like carbon dioxide and oxygen can move across the cell membrane via diffusion. Diffusion is the movement of gas molecules from a region of higher concentration, to a region of lower concentration through a semi-permeable membrane.

Detailed explanation-4: -Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly. Small polar molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly.