OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

How can polymer molecules be reverted back to sugars?

1. By bonding with water

2. By breaking chemical bonds between monomers

3. By heating them

4. By introducing more carbon

The correct answer is: By breaking chemical bonds between monomers

Polymer molecules can be reverted back to sugars through the process of breaking chemical bonds between monomers. Polymers are composed of long chains made up of repeating units called monomers, which, in the case of sugars, are typically monosaccharides. When polymers, such as starch or glycogen, are digested or hydrolyzed, enzymes or water can facilitate the breaking of the glycosidic bonds that link these monomers together. This process effectively cleaves the polymer into its constituent sugar units, allowing them to enter metabolic pathways or be utilized by the body in various ways. The other options do not adequately describe how polymers can revert to sugars. Bonding with water is part of the hydrolysis reaction but does not fully address the mechanism of bond breaking itself. Heating may change the structure of polymers but does not specifically revert them to sugars without breaking the chemical bonds. Introducing more carbon changes the chemical structure but does not help revert polymers to their monomeric forms. Thus, breaking the chemical bonds between monomers is the accurate representation of how the process occurs.