Two molecules that can cross a lipid bilayer without from membrane proteins are o2 and co2, what property allows this to occur

O2 and CO2 are both nonpolar molecules that can easily pass through the hydrophobic interior of a membrane! Hope it helps

both the molecules are too small and have no charge therefore they can move across a membrane via gradient pressure from higher concentration to lower via simple diffusion. they don't need any atp or energy.

the answer is b.) hydrogen bonds between bases.