1. which type of macromolecule stores energy and provides thermal insulation for the body? * a. lipid b. protein c. nucleic acid b. carbohydrate 2. which structural feature of the cell membrane allows molecules such as oxygen and carbon dioxide to diffuse into and out of the cell? * a. the cell membrane contains proteins molecules. b. the cell membrane contains cholesterol molecules. c. the cell membrane is made up of two layers of phospholipids. d. the cell membrane is anchored to the cytoplasm by the cytoskeleton.