What is true about non-polar molecules?

• A. They don't have positive or negative ends
• B. They have charged ends
• C. They require protein channels to cross membranes
• D. They are always large

Answer: (A)

Non-polar molecules lack distinct charged regions because their electrons are distributed evenly, giving them no positive or negative ends. This lack of polarity means they don’t interact strongly with water and are hydrophobic, so they dissolve in and pass through the lipid bilayer of membranes by diffusion. That’s why they can cross membranes without protein channels. The idea that non-polar molecules have charged ends or must use channels is not true, and being non-polar does not imply they are always large—many are actually small, like oxygen or carbon dioxide.