Lipids and Organelles Watch

I'm not sure to what depth you require for these answers, but here's just a basic look.

1) You take the weight of the lipids in the plasma membrane, then you take the weight of all of the components in the plasma membrane (I imagine this would be done by centrifugation, then once you've measured the weight of the membrane, add some lipases and wash out to calculate how much lipids you have).

2) You'll have to think of the function of cholesterol, and how this aids in the function of RBCs in comparison to the function of cells lining the ileum.

3) You'll have to think specifically to which organelle is responsible for the secretion of cellular contents.