Food Chains and Webs

• how energy flows from the sun through producers, consumers, and decomposers.
• why a food chain is a straight line but real ecosystems form interconnected food webs.
• the 10% law — why energy pyramids get smaller at every trophic level, and a worked example you can copy into your notebook.

1. Trophic levels — Producers (green plants, algae — make their own food) → Primary consumers (herbivores) → Secondary consumers (carnivores/omnivores that eat herbivores) → Tertiary consumers (top carnivores).
2. Direction of arrows — An arrow in a food chain points from the organism being eaten to the organism eating it — it shows the direction of energy flow, not "who is stronger".
3. 10% law (Lindeman) — Only about 10% of the energy at one trophic level is transferred to the next; the rest is lost as heat, movement, and unused parts. This is why energy pyramids are always upright and food chains rarely have more than 4-5 links.
4. Food web — A food web is many overlapping food chains in the same ecosystem — most organisms eat more than one kind of food and are eaten by more than one predator.
5. Decomposers — Bacteria and fungi break down dead organisms and waste chemically, returning nutrients to the soil so producers can reuse them — without them nutrients would stay locked in dead bodies.

A grassland food chain: Grass → Grasshopper → Frog → Snake → Eagle.

Step 1 — Grass (producer) traps 100,000 J of sunlight energy as food.
Step 2 — Grasshopper (primary consumer) gets only ~10% = 10,000 J.
Step 3 — Frog (secondary consumer) gets only ~10% of that = 1,000 J.
Step 4 — Snake (tertiary consumer) gets ~10% of that = 100 J.
Step 5 — Eagle (apex predator) gets ~10% of that = 10 J — a tiny fraction of the original sunlight.

• Thinking the arrow points from predator to prey (it actually points from prey/food to the eater, showing energy flow).
• Confusing a food chain (one straight line) with a food web (many connected chains).
• Forgetting decomposers — they are not 'consumers' in the numbered sense but are essential to recycle nutrients.
• Assuming energy transfer is 100% efficient — most energy is lost as heat and movement at every step.

• List the trophic levels in: Algae → Small fish → Big fish → Shark.
• If a producer traps 50,000 J, roughly how much energy reaches the secondary consumer?
• Explain in 2 lines why removing one species can disturb an entire food web.

Open the Practice tab for graded questions on Food Chains and Webs.

• Use the platform-native live simulation or PhET-style tool for this topic (number line, Venn, physics playground, molecule builder, sensor dashboard, etc.).
• Mirror / body / home activity: physically do the concept (count objects, measure, role-play) and photograph or describe for portfolio.
• Voice or text reflection with AI Mentor: explain the concept to a younger student or family member.

• "Explain this concept to a Class 6 student using one real example from an Indian home, school, market, or festival."
• "What is one common mistake students make here, and how would you catch yourself making it?"
• Stretch: "How does this connect to coding, robotics, money, health, environment, or a future career?"

• Complete the core practice + one extension activity (photo, table, short reflection, or mini-project) for base XP + topic badge.
• 5-7 day streak or family discussion note = multiplier + visible artifact in parent/principal dashboard.
• Best real-world application stories (anonymised) featured on class or national leaderboard.

• One hands-on project or measurement using the Drishti kit or household items that makes the concept physical.
• Direct link to at least one Future Skill track (Money Management, Green Tech, Cyber Defenders, Micro-Entrepreneurship, AI Mastery, Sustainable Living, Personality Development).
• Coding extension where relevant (simple script, simulation, or data logging).

This material emphasises experiential "learning by doing", competency (apply/create/analyse), vocational exposure, critical thinking, and multidisciplinary connections. Designed to feed live worlds, AI Mentor (with memory), gamification, robotics, parent analytics, and future skills — not just exam prep.

Portfolio Evidence Idea: Your photo/table/reflection/project + one sentence on "How this helps me in real life or a possible future path."

Open the Practice tab for aligned questions (easy/medium/hard + case-based) with full AI scaffolding.

See curriculum for cross-links and the full future-skills/robotics chapters.