How does a small, nonpolar gas like oxygen get across a membrane? A) Active transport from a low to high concentration B) Diffusion from a high to low concentration C) Osmosis from a high to low concentration D) Membrane transport (facilitated diffusion) from a high to low concentration
Answer (1)
To understand how a small, nonpolar gas like oxygen gets across a cell membrane, we must consider the properties of the molecule and the membrane.
Nature of Oxygen and Cell Membranes:
Oxygen (O₂) is a small, nonpolar molecule.
Cell membranes are primarily composed of a phospholipid bilayer which is also nonpolar. This allows nonpolar molecules to pass through easily while polar or charged molecules require assistance.
Diffusion Process:
Oxygen crosses the membrane through a process known as diffusion .
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached.
Why Diffusion is Suitable for Oxygen:
Because oxygen is nonpolar and small, it can move freely across the lipid bilayer without the need for energy or transport proteins.
Therefore, the correct answer is B) Diffusion from a high to low concentration , as it describes this natural, energy-free movement of oxygen across the cell membrane.
