The correct option is **B. Natural biopolymers are synthesized through biological processes, whereas synthetic polymers are created through chemical processes in a laboratory.** ### Detailed Explanation: 1. **Understanding Biopolymers and Synthetic Polymers:** - **Natural Biopolymers:** These are large molecules made up of repeating units (monomers) that are produced by living organisms. Common examples include proteins, nucleic acids (like DNA and RNA), and polysaccharides (like cellulose and starch). These biopolymers are formed through biological processes such as photosynthesis, cellular respiration, and protein synthesis. - **Synthetic Polymers:** These are man-made polymers created through chemical reactions in a laboratory or industrial setting. Examples include plastics like polyethylene, polystyrene, and nylon. They are typically produced through processes such as polymerization, where small monomer units are chemically bonded to form long chains. 2. **Why Option B is Correct:** - The key distinction highlighted in option B is the origin of the polymers. Natural biopolymers arise from biological processes, meaning they are produced by living organisms using enzymes and metabolic pathways. In contrast, synthetic polymers are engineered through chemical reactions that can be controlled and manipulated in a lab setting, allowing for a wide variety of materials with specific properties. 3. **Why the Other Options are Incorrect:** - **Option A:** "Natural biopolymers are always biodegradable, while synthetic polymers are never biodegradable." - This statement is misleading. While many natural biopolymers are biodegradable due to their biological origin, not all synthetic polymers are non-biodegradable. Some synthetic polymers, like polylactic acid (PLA), are designed to be biodegradable. Therefore, this option overgeneralizes the biodegradability of both types of polymers. - **Option C:** "Natural biopolymers have a fixed molecular weight, while synthetic polymers can have variable molecular weights." - This statement is also incorrect. Natural biopolymers can have a range of molecular weights depending on their source and the conditions under which they are synthesized. For example, proteins can vary significantly in size. Synthetic polymers can also be designed to have specific molecular weights, but they can also exhibit a distribution of molecular weights depending on the polymerization process used. Thus, both types can have variable molecular weights. - **Option D:** "Natural biopolymers are only found in plants, while synthetic polymers are only produced from petroleum-based sources." - This statement is inaccurate. Natural biopolymers are found in all living organisms, including animals, fungi, and microorganisms, not just plants. Additionally, while many synthetic polymers are derived from petroleum, there are also bio-based synthetic polymers that can be made from renewable resources, such as corn or sugarcane. Therefore, this option is overly restrictive and does not accurately represent the diversity of sources for both types of polymers. ### Summary: - **Natural biopolymers** are produced by living organisms through biological processes. - **Synthetic polymers** are created through chemical processes in laboratories or industrial settings. - The biodegradability of polymers varies and cannot be generalized as stated in the options. - Both natural and synthetic polymers can have variable molecular weights depending on their synthesis. ### Revision Summary: - Natural biopolymers are synthesized biologically; synthetic polymers are chemically created. - Biodegradability is not absolute; some synthetic polymers can be biodegradable. - Both types of polymers can exhibit variable molecular weights. - Natural biopolymers are found in all life forms, not just plants.