CBSE Class 10 Science 2022 · Paper 31/3/1 · Question 1(b)

Reason: Pesticides and other chemicals used on crops are not degradable. They are absorbed by plants from the soil and water and get accumulated progressively at each trophic level, so their concentration rises up the food chain. Human beings are usually at the top trophic level of the food chains they belong to, so the maximum concentration of these chemicals accumulates in human bodies. Washing: The plants take up these chemicals along with water and nutrients, so the chemicals are inside the tissues of the fruits and vegetables, not just on their surface. Ordinary washing removes only surface residue, so it cannot remove the chemical inside the food.