Advanced Placement (AP) Biology Practice Exam

What is the process of dehydration synthesis primarily used for?

1. To cleave polymers into monomers.

2. To extract energy from organic compounds.

3. To join monomers by removing water.

4. To break down carbohydrates into simple sugars.

The correct answer is: To join monomers by removing water.

The process of dehydration synthesis is primarily utilized to join monomers by removing water, which creates polymers. During this process, when two monomer molecules are brought together, a hydroxyl group (-OH) from one monomer and a hydrogen atom (H) from another combine to release a molecule of water (H2O). This reaction forms a covalent bond between the monomers, resulting in the creation of a larger biomolecule, such as carbohydrates, proteins, or nucleic acids. This mechanism is essential in biological systems as it facilitates the building of complex macromolecules necessary for various cellular functions. In contrast, cleavage of polymers into monomers entails hydrolysis rather than dehydration synthesis, and extracting energy from organic compounds involves metabolic processes like cellular respiration, which is unrelated to the dehydration process. Breaking down carbohydrates into simple sugars specifically refers to hydrolysis as well, highlighting the distinct roles of these biochemical processes.