CBSE Class 10 Science 2022 · Paper 31/1/1 · Question 13

(a) Producers — green plants (and other organisms, such as blue-green algae, that make food by photosynthesis). They are called producers because they make their own food: using the energy of sunlight, in the presence of chlorophyll, they produce organic substances such as sugar and starch from carbon dioxide and water, and every other organism of the food chain depends on this food, directly or indirectly. (b) Harmful chemicals such as pesticides are not degradable. They enter the food chain and accumulate progressively at each trophic level (biological magnification). Human beings occupy the top level of the food chains they belong to, so the maximum concentration of these chemicals accumulates in their bodies. (c) The nutrients in dead plants, dead animals and wastes would not be returned to the soil, because nothing would break them down into simple substances; the soil would not be replenished. (Also accepted: dead remains and wastes would pile up.)