Advanced Placement (AP) Biology Practice Exam

What is dehydration synthesis?

1. The breakdown of larger molecules

2. A process that releases energy

3. A method that requires water to form bonds

4. Using energy to form bonds and molecules

The correct answer is: Using energy to form bonds and molecules

Dehydration synthesis is a biochemical process that involves the formation of bonds between molecules through the removal of water. During this process, two smaller molecules, such as monosaccharides or amino acids, combine to form a larger molecule—such as a disaccharide or a polypeptide—while simultaneously releasing a water molecule. This is an important mechanism in the synthesis of macromolecules in biological systems. The key aspect of this process is that it requires energy to form the new bonds between the molecules, which is why it is associated with the use of energy. While breaking down larger molecules, the reverse process called hydrolysis occurs, where water is added to break bonds and release energy. Therefore, the correct choice highlights the essential relationship between energy utilization and the formation of new bonds, which is a fundamental concept in understanding how larger biological macromolecules are synthesized in living organisms.