What structural difference explains why lipids
provide more energy to a cell than an equal mass of
proteins or carbohydrates?

the answer is golgi apparatus

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;

here is the answer

water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. weathering is the breaking down or dissolving of rocks and minerals on earths surface. once a rock has been broken down, a process called erosion transports the bits of rock and minerals away.