Where does the energy required for anabolic reactions come from? Unused energy from metabolism Heat Catabolic reactions

## Step 1<br />Anabolic reactions, also known as anabolism, are a set of metabolic pathways that construct molecules from smaller units. These reactions require energy to form new chemical bonds.<br /><br />## Step 2<br />The energy required for anabolic reactions comes from catabolic reactions, also known as catabolism. Catabolic reactions break down larger molecules into smaller ones, releasing energy in the process.<br /><br />## Step 3<br />This energy is then used to drive anabolic reactions. Therefore, the correct answer is "Catabolic reactions".