a. Explain why the isomers d-pentose and l-pentose have such varied permeabilities although nearly the same structure.
b. Explain what relationship is shown with urea, thiourea and dimethyl urea.
c. Explain why glycerol has a low permeability but can be the backbone of the membrane triglycerides.

I think
a) Due to same molecular weight and different atom spacial arragement d-pentose and l-pentose have such varied permeabilities. Is this right?

b) In above chart the urea, thiourea, and dimethyl urea are in sigmiodal fashion and has same basic chemical structure. urea is most soluable in water and thiourea is not really soluable in water, and dimethyl urea is a big compound and they are polar molecule. thiourea is slightly polar?

c) glycerol has low permeability b/c it as three hydrophilic group that makes it water soulable and glycerol is backbone because it is central for all fatty acid know as triglycerides?

I’m sorry if my asnwer don’t make sense, I’m really having trouble with this class.