Distinguish between grazing and detritus food chains. How do food chains form a food web, and what is a trophic level?

1. 1 · Define in one line. A food chain is a sequence of organisms in which each feeds on the one before it, passing on energy.
2. 2 · Explain the GFC. Starts with green plants: grass → goat → man; the main energy path in aquatic ecosystems.
3. 3 · Explain the DFC. Starts with detritus; decomposers (saprotrophs) such as fungi and bacteria; the main energy path on land.
4. 4 · Explain the food web. Chains link up, since DFC organisms are prey for GFC animals, and omnivores like crows feed at many levels.
5. 5 · Sketch a small food web. [Sketch: grass → grasshopper → frog → snake; grass → rabbit → fox; dead leaves → earthworm → crow, linked to the chain]
6. 6 · Define trophic level. Producers first, herbivores second, carnivores third; a sparrow can be at the second and third.
7. 7 · Link to real life. Humans eat at several trophic levels: rice and dal (primary), fish (secondary or higher).
8. 8 · Close in one line. So food webs, not single chains, carry energy through real ecosystems.

Scoring tip: Give one example chain for each type, with arrows pointing from the food to the eater.