Define a food chain, and write out the grassland food chain used in Activity 12.6 and Fig. 12.9.
Hint. The book gives one example directly from the six named grassland organisms.
✦ 'A food chain is a simple sequence showing 'who eats whom' in an ecosystem.' Fig. 12.9's grassland example: Grass → Grasshopper → Frog → Snake → Eagle.
In Activity 12.7's millet-mouse-eagle pyramid, why does the number of organisms at each level decrease as you move from the base to the top?
Hint. The activity has you arrange counted numbers from highest at the base to lowest at the top — what real-world pattern does that arrangement reveal?
✦ Counting the actual number of millets, mice and eagles in the crop field and arranging them from highest number at the base to lowest at the top produces a pyramid shape, showing that producers (millets) are the most numerous, their consumers (mice) fewer, and the top predator (eagle) fewest of all — a general pattern of decreasing numbers at each successive feeding level, which is exactly what gives the food-chain pyramid its shape.
Name the chapter's four trophic levels, from first to last, with one example organism at each.
Hint. The chapter names exactly four levels — not five, and without 'primary/secondary/tertiary consumer' labels.
✦ Trophic level 1 — producers (like green plants); level 2 — herbivores (like hares and deer); level 3 — small carnivores (like frogs); level 4 — large carnivores (like tigers or vultures).
What does 'trophic level' mean, and where does the word come from?
Hint. The chapter gives the Greek root right alongside the definition.
✦ A trophic level (troph = food) is the specific position an organism occupies in a food chain, based on its feeding relationship to the organisms below and above it in the chain.
Define a food web, and explain why it is a more realistic picture of an ecosystem than a single food chain.
Hint. A food chain shows one line of who-eats-whom; real ecosystems rarely have such a clean, single line.
✦ 'Each of the organisms may be eaten by two or more types of organisms. Thus, in an ecosystem, the food chains are interlinked with each other to form a network, called a food web.' A single food chain only shows one linear sequence, but in reality, most organisms are eaten by more than one predator and eat more than one kind of food, so many food chains interlinking into a web gives a far more accurate picture of how feeding relationships actually work in a whole ecosystem.
In Activity 12.8's food web (Fig. 12.11) — grasses, grasshopper, bird, frog, snake, hawk, fox, hare, mouse, owl — why might a single organism like the snake be connected to several other organisms by arrows, rather than just one?
Hint. In a food web, unlike a food chain, one organism sits at the crossing point of multiple separate feeding relationships.
✦ In a food web, an organism like the snake can both eat more than one type of prey (such as frogs and mice) and be eaten by more than one type of predator (such as a hawk), so several arrows connect to it at once — showing multiple, simultaneous feeding relationships rather than the single incoming and single outgoing arrow a food chain would show for the same organism.
Between a producer, a herbivore, a small carnivore, and a large carnivore, which trophic level would typically have the SMALLEST population in a stable ecosystem, and why?
Hint. The pyramid shape from Activity 12.7 answers this directly.
✦ Large carnivores, the fourth and topmost trophic level, would typically have the smallest population — this is exactly why Activity 12.7's arrangement of counted organisms, from highest number at the base to lowest at the top, forms a pyramid shape rather than a rectangle or an inverted pyramid.
Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 12 (hecu112.pdf), Reprint 2026-27, pages 190-209. Questions are referenced from the NCERT textbook for identification.
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