AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Bacteria and fungi break down organic matter like food using specific enzymes. However, enzymes are highly specific in their action — a particular enzyme can break down only a particular substance.
Plastics are human-made (synthetic) materials whose chemical structure is not found in nature. Therefore, bacteria and fungi do not possess the specific enzymes needed to break down plastics. As a result, plastics are non-biodegradable and persist in the environment for a very long time. They can only be broken down by physical processes like heat and pressure, not by biological processes.
Source: Our Environment, Chapter 13, Section 13.2.2 — Managing the Garbage we Produce
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The key concept here is enzyme specificity. The textbook explicitly states: "Enzymes are specific in their action; specific enzymes are needed for the break-down of a particular substance." Since plastics are synthetic, no natural biological enzyme exists to decompose them. Examiners expect students to clearly link enzyme specificity → absence of suitable enzymes → plastics being non-biodegradable. Avoid vague answers like "bacteria can't eat plastic" — use correct terminology: enzymes, specific, non-biodegradable.