Which major group of macromolecules are the lastest source of energy? A. lipids B. proteins C. nucleic acids D. carbohydrates

## Step 1<br />The question asks us to identify which major group of macromolecules is the lastest source of energy. The options provided are lipids, proteins, nucleic acids, and carbohydrates.<br /><br />## Step 2<br />Lipids, such as fats and oils, are the most energy-dense macromolecules. They provide more than twice the energy per gram compared to carbohydrates and proteins. Lipids are primarily used for long-term energy storage in the body.<br /><br />## Step 3<br />Proteins, while they can be used for energy, are primarily used for building and repairing tissues. They are not the primary source of energy.<br /><br />## Step 4<br />Nucleic acids, such as DNA and RNA, are not used for energy. They are used for storing and transmitting genetic information.<br /><br />## Step 5<br />Carbohydrates are the body's primary source of energy, but they are not the lastest source of energy. They are used for immediate energy needs, not long-term storage.