The three main nutrients used for energy are carbohydrates, protein, and fats, with carbohydrates being the most important source. Your body can also use protein and fats for energy when carbs have been depleted. When you eat, your body breaks down nutrients into smaller components and absorbs them to use as fuel.
It prevents harmful substances from entering a cell. I uses carrier proteins to do so.
C) saturated fats have only single bonds on all the carbon atoms
hope this helps :)
