Previous Year Question

A Food Chain represents the sequence through which food and energy are transferred among organisms in an ecosystem. Each organism occupies a particular Trophic Level. Green plants and algae prepare their own food through Photosynthesis and are therefore called Producers. Organisms that directly consume plants are known as Primary Consumers, while those that feed on Primary Consumers are called Secondary Consumers.

Humans are Omnivores because they can obtain food from both plant and animal sources. When humans consume wheat, rice, fruits, vegetables, or other plant products, they function as Primary Consumers. For example, in the food chain Wheat → Human, wheat acts as the Producer and the human acts as the Primary Consumer. In this situation, humans occupy the Second Trophic Level.

When humans consume the meat of herbivorous animals, they function as Secondary Consumers. For example, in the food chain Grass → Goat → Human, grass is the Producer, the goat is the Primary Consumer, and the human is the Secondary Consumer. In this situation, humans occupy the Third Trophic Level. If humans consume fish that feed on other consumers, they may also function as Tertiary Consumers, depending on the food chain.

A Trophic Level is not a permanent classification of an organism; it represents its feeding position within a food chain. The same species may occupy different trophic levels in different food chains. In natural ecosystems, numerous food chains are interconnected to form a Food Web. At each trophic level, a substantial portion of energy is used in biological processes and dissipated as heat. According to the general Ten Percent Law of ecology, approximately 10% of energy is transferred to the next trophic level on average.