MPPSC 2023 Prelims Paper-I · Question 7 of 100

Correct — C, Insecticides. Insecticides are synthetic chemical pesticides (classic examples include organochlorines such as DDT), and many of them resist breakdown by natural microbial action — they persist in soil and water for long periods and can even bioaccumulate up the food chain. That makes them the odd one out among the four options, which are otherwise all organic materials that microorganisms readily decompose.

• (a)Paper — Paper is made largely of cellulose, a natural organic compound that fungi and bacteria break down readily — a standard biodegradable pollutant.
• (b)Food and Plant waste — Kitchen and plant waste is organic matter that decomposes quickly through microbial and fungal action — the classic biodegradable, compostable pollutant.
• (d)Wood and cellulose — Wood and cellulose are natural plant materials that decomposers (fungi, bacteria) can break down, even if more slowly than softer organic waste — still biodegradable.

Pollutants are classed as biodegradable (broken down by natural biological processes — bacteria, fungi — into simpler, usually harmless substances) or non-biodegradable (resistant to such breakdown, so they persist and accumulate in the environment). Paper, food/plant waste, and wood/cellulose are all organic materials that decomposers can break down. Synthetic chemical pesticides such as insecticides, by contrast, are engineered to be chemically stable and often resist microbial degradation, making them the standard example of a non-biodegradable pollutant in this classification.

The trap is grouping every 'natural-sounding' or plant-derived item together and forgetting that a chemical pesticide, even though it is sprayed on plants, is itself a synthetic, persistent compound rather than an organic waste product.

• Biodegradable pollutants (paper, food/plant waste, wood/cellulose) are broken down by microorganisms into simpler substances
• Non-biodegradable pollutants resist microbial breakdown and persist/accumulate in the environment
• Insecticides are the classic example of a non-biodegradable pollutant in this four-option classification
• Persistent pesticides can also bioaccumulate up the food chain, compounding their environmental impact

• Assuming every plant-related item (including pesticides sprayed on plants) is automatically biodegradable
• Not distinguishing a synthetic chemical pollutant from an organic waste material

MPPSC/UPSC frequently ask 'which of the following is/is not biodegradable' by mixing organic waste items with a synthetic chemical (pesticide/insecticide/plastic) as the odd one out.

No directly related past PYQ was found.

• practice — not a real PYQ

  Dichloro-diphenyl-trichloroethane (DDT), once widely used as an insecticide, is best described as a:

  • (a)Non-pollutant
  • (b)Non-biodegradable pollutant
  • (c)Biodegradable pollutant
  • (d)Radioactive pollutant

  Answer(b) Non-biodegradable pollutant — DDT resists microbial breakdown and persists in the environment.

• practice — not a real PYQ

  Which of the following pairs of pollutants is correctly classified as biodegradable?

  • (a)Plastic and DDT
  • (b)Food waste and paper
  • (c)Insecticides and heavy metals
  • (d)Radioactive waste and plastic

  Answer(b) Food waste and paper — both are organic materials broken down readily by microorganisms.