The correct option is 2 and 3 only.
Explanation
Decomposition is a chemical process where complex organic substances are broken down into simpler matter. This process is mediated by enzymes produced by decomposers (bacteria and fungi). A fundamental property of enzymes is their specificity, often described by the "lock and key" model, meaning a specific enzyme is required to catalyze the breakdown of a specific molecular structure.
Statement-wise Analysis
- Statement 1 is Incorrect. Enzymes in living systems do not act non-specifically on all substrates. They are highly specific biological catalysts. Each enzyme is designed to bind to a specific substrate (molecule) to facilitate a reaction. For example, the enzyme cellulase breaks down cellulose, but it cannot break down plastics.
- Statement 2 is Correct. The persistence of certain materials (such as plastics or DDT) in the environment is due to the lack of specific enzymes in decomposers capable of breaking their molecular bonds. Since these synthetic materials have structures different from natural organic matter, natural enzymes cannot degrade them, rendering them non-biodegradable.
- Statement 3 is Correct. Enzyme specificity ensures that a reaction occurs only when the enzyme encounters a compatible substrate. This biological rule dictates which materials can be decomposed (biodegradable) and which remain in the environment (non-biodegradable).
Key Takeaway: Biodegradability is determined by the presence of specific enzymes in nature that can break the chemical bonds of a substance. Materials for which no such enzymes exist persist as non-biodegradable pollutants.