Metabolism:This refers to all chemical reactions involved in maintaining life within an organism, much like all steps involved in making a cake - from mixing ingredients to baking it.
Enzymes:These are proteins that act as catalysts within living cells, speeding up chemical reactions just like yeast speeds up bread dough rising.
Lipids:These are organic compounds such as fats and oils which provide energy storage for organisms - think about butter providing richness and flavor in baked goods.