Class 8 Science · Chapter 12
Short answer:
Chapter 12 'How Nature Works in Harmony' — Class 8 Science ki nayi Curiosity textbook (2026-27 rationalised syllabus) ka ecology-focused chapter hai jo food chains, food webs, trophic levels, 10% energy law, aur decomposers ke role ko cover karta hai. Isse samajhna zaroori hai ki nature ka balance kaise interdependence par tika hua hai.
Chapter 12 'How Nature Works in Harmony' NCERT Class 8 Science ki nayi Curiosity textbook ka ek core ecology chapter hai jo dikhata hai ki nature mein har cheez — chhote se chhota microorganism se lekar bade se bada predator tak — ek doosre se interconnected hai. Jaise NCERT Class 8 Science Curiosity chapter 1 solutions mein humne matter ka particulate nature dekha, waise hi is chapter mein hum dekhenge ki living organisms energy aur nutrients ke liye kaise ek doosre par depend karte hain through food chains aur food webs. Ye chapter direct tarike se our home earth a unique life sustaining planet class 8 chapter se connected hai, kyunki dono batate hain ki Earth par life kaise sustain hoti hai balance aur harmony ke through.
Is chapter mein food chains, food webs, trophic levels, energy flow ka 10% law, aur decomposers ka crucial role cover hota hai. Ye samajhna important hai ki agar ecosystem ka koi ek part disturb ho jaaye — chahe woh deforestation ho ya ek species ka extinction — toh poora chain affected hota hai. Ye concepts sirf exam ke liye nahi, balki real-life environmental awareness ke liye bhi zaroori hain, jo class 8 science exploring forces notes jaise physical science chapters se thoda different perspective deta hai — yahan focus biology aur ecology par hai.
Chapter 12 Summary — 5 Minute Revision
Chapter 12 'How Nature Works in Harmony' humein sikhata hai ki nature ek interconnected system hai jahan har organism — chahe woh producer ho, consumer ho, ya decomposer — ek doosre par depend karta hai. Food chains (linear energy flow) aur food webs (interconnected network) ye dikhate hain ki energy kaise ek organism se doosre mein transfer hoti hai, aur 10% law ke according har trophic level par sirf 10% energy hi agle level ko milti hai, jisse pyramid shape banti hai.
Decomposers jaise bacteria aur fungi dead organic matter ko todke nutrients wapas soil mein daalte hain, jisse nutrient cycle complete hota hai. Ye chapter ye bhi dikhata hai ki agar ecosystem ka koi ek part disturb ho — jaise ek species ka extinction ya habitat destruction — toh poora balance bigad sakta hai. Yahi wajah hai ki biodiversity conservation itna important hai. Ye concepts invisible living world beyond our naked eye class 8 microorganisms chapter se bhi connect hote hain, jahan microorganisms (jo decomposers ka bhi hissa hain) ka detailed study hota hai, aur our home earth a unique life sustaining planet class 8 chapter se bhi jud'ta hai jo Earth ke life-sustaining conditions explain karta hai.
Overall, ye chapter environmental awareness aur ecological balance ki understanding build karta hai jo real-world conservation aur sustainability ke liye foundation hai.
In-Text Questions — Solutions
Ek food chain likhiye jisme 4 trophic levels ho aur har level ka naam bataiye.
Food chain: Ghaas → Tiddi (Grasshopper) → Mendak (Frog) → Saanp (Snake)
Trophic levels: Ghaas ek producer hai jo photosynthesis se apna food khud banata hai. Tiddi ek primary consumer hai jo ghaas kha kar energy leta hai. Mendak ek secondary consumer hai jo tiddi ko khaata hai. Saanp ek tertiary consumer hai jo mendak ko khaata hai. Har level par energy 90% kam hoti jaati hai, jaisa 10% law kehta hai.
Agar ek ecosystem se saare decomposers hata diye jaayein, toh kya hoga?
Agar decomposers (bacteria, fungi) hata diye jaayein, toh dead plants aur animals decompose nahi honge aur unke bodies accumulate hote jaayenge. Isse nutrients (jaise nitrogen, phosphorus) soil mein wapas nahi jaayenge, jisse soil ki fertility kam ho jaayegi aur naye plants properly grow nahi kar payenge. Waste material bhi build up ho jaayega jisse pollution aur diseases badh sakti hain. Isliye decomposers ecosystem ke nutrient cycle ke liye essential hain — inke bina poora system collapse ho sakta hai.
Exercise Questions — Solutions (Q1–Q5)
1. Nature mein har jeev doosre jeev se kaise judaa hota hai? Ek udaharan ke saath samjhaiye.
Nature mein har jeev energy aur matter ke liye doosre jeevon par depend karta hai — ye interdependence food chains aur food webs ke through hota hai. Udaharan: ghaas → hiran → sher. Ghaas (producer) sunlight se apna food banati hai photosynthesis se. Hiran (primary consumer/herbivore) ghaas khaakar energy leta hai. Sher (secondary consumer/carnivore) hiran ko khaakar energy leta hai. Agar hiran khatam ho jaayein, toh sher ke paas food nahi bachega aur ghaas uncontrolled badh jaayegi — is tarah ek species ka change poore ecosystem ko affect karta hai.
2. Decomposers ka role kya hota hai ecosystem mein? Do examples dijiye.
Decomposers (jaise bacteria aur fungi) mare hue plants aur animals ko simple substances mein todte hain (decompose karte hain) aur unhe wapas soil mein nutrients ke roop mein release karte hain. Isse nutrient cycle complete hota hai aur soil fertile banti hai naye plants ke liye. Do examples: (i) Mushroom (fungus) jo gire hue patton ko decompose karta hai, (ii) Soil bacteria jo dead animal bodies ko break karke nitrogen wapas mitti mein daalte hain.
3. Food chain aur food web mein kya antar hai?
Food chain ek sidhi line hoti hai jisme energy ek organism se doosre organism mein ek hi direction mein transfer hoti hai (jaise: ghaas → tiddi → mendak → saanp). Food web multiple food chains ka interconnected network hota hai jisme ek organism kai chains ka part hota hai (jaise mendak, tiddi aur doosre insects dono kha sakta hai, aur saanp ke alawa bagula bhi mendak kha sakta hai). Food web nature ki actual complexity ko zyada accurately dikhata hai kyunki real ecosystems mein organisms ke multiple food sources hote hain.
4. 10% law kya hai? Isse energy pyramid par kaise diagram banaate hain?
10% law ke according, ek trophic level se agle trophic level mein sirf 10% energy transfer hoti hai — baaki 90% energy respiration, movement, aur heat ke roop mein loss ho jaati hai. Isliye energy pyramid hamesha ek pyramid shape mein banta hai jisme producers (base) sabse zyada energy rakhte hain, aur har agle level (primary consumer, secondary consumer, tertiary consumer) mein energy ghatati jaati hai. Yahi wajah hai ki food chain mein usually 4-5 se zyada trophic levels nahi hote — kyunki uske aage energy itni kam bach jaati hai ki agla level survive nahi kar sakta.
5. Ek balanced ecosystem banaye rakhne ke liye biodiversity kyun zaroori hai?
Biodiversity ecosystem ko stable aur resilient banati hai. Jab ecosystem mein bahut saari species hoti hain, toh agar ek species affected ho (disease, climate change, etc.), toh doosri species us gap ko fill kar sakti hain aur food web collapse nahi hota. Kam biodiversity wale ecosystems fragile hote hain — ek species ke khatam hone se pura chain disturb ho sakta hai. Biodiversity pollination, soil fertility, climate regulation aur natural pest control jaise essential services bhi provide karti hai jo humans aur dusre organisms dono ke liye zaroori hain.
Important Equations — Ek Nazar Me
| Concept | Rule/Formula | Example |
|---|---|---|
| 10% Law (Energy Transfer) | Energy transferred to next trophic level = 10% of energy received | Agar ghaas ke paas 1000 J energy hai, toh hiran ko sirf 100 J milegi, aur sher ko sirf 10 J |
| Food Chain Direction | Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer | Ghaas → Tiddi → Mendak → Saanp → Baaz |
| Trophic Level Count | Energy pyramid mein usually 4-5 levels se zyada nahi hote | 5th level tak energy itni kam ho jaati hai ki survival mushkil ho jaata hai |
| Ecosystem Balance | Producers > Primary Consumers > Secondary Consumers > Tertiary Consumers (biomass/number wise) | Ek jungle mein ghaas ki matra hamesha herbivores se zyada hoti hai |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Food chain mein arrows ki direction galat banana — arrow hamesha energy flow ki direction mein hona chahiye, yani jo khaya ja raha hai uski taraf se jo khaa raha hai uski taraf (Ghaas → Tiddi, na ki Tiddi → Ghaas).
- 10% law ko confuse karna ki 10% energy transfer hoti hai ya 90% — yaad rakhein ki sirf 10% energy hi agle trophic level ko milti hai, baaki 90% heat/respiration mein loss hoti hai.
- Decomposers ko consumers ke saath confuse karna — decomposers dead organic matter ko todte hain, woh living organisms ko directly nahi khaate jaise consumers karte hain.
- Food chain aur food web ko same samajhna — food chain ek single linear path hai jabki food web multiple interconnected food chains ka network hai.
- Producer ko hamesha 'plant' hi samajhna — algae aur kuch bacteria bhi producers ho sakte hain jo photosynthesis karte hain, sirf land plants nahi.
- Trophic level ki numbering mein confusion — primary consumer hamesha herbivore hota hai (plant khaane wala), secondary consumer carnivore/omnivore hota hai jo primary consumer ko khaata hai — is sequence ko galat likhna common mistake hai.
Board-Style Important Questions
- CBSE board pattern ke similar questions is chapter se food chain construction aur trophic level identification par based ho sakte hain (exact previous year paper reference available nahi hai kyunki ye naya rationalised chapter hai 2026-27 session ke Curiosity textbook mein).
- Energy flow aur 10% law explain karne wale short answer type questions is category ke chapters mein common rahe hain.
- Food web diagram banake usse related questions (kaun kis par depend karta hai) practice ke liye important hain.
- Decomposers ka role aur nutrient cycling explain karne wale questions expected hain, jaisa purane 'Conservation of Plants and Animals' chapter mein tha jo ab is naye chapter mein partially merge ho gaya hai.
- Note: Kyunki ye chapter bilkul naya hai (rationalised 2026-27 syllabus), specific exam-year attributed PYQs available nahi hain — practice ke liye NCERT exemplar aur textbook ke end ke exercises use karein.
Aksar Poochhe Jaane Wale Sawaal
Class 8 Science Chapter 12 'How Nature Works in Harmony' mein kya padhaya jaata hai?
Ye chapter NCERT Class 8 Science ki nayi Curiosity textbook (2026-27 session) ka hissa hai. Isme food chains, food webs, trophic levels, energy flow (10% law), decomposers ka role, aur ecosystem mein balance kaise maintain hota hai — ye sab cover hota hai. Ye chapter dikhata hai ki nature ke saare organisms — plants, animals, microorganisms — ek doosre se kaise interconnected hain.
NCERT Class 8 Science Curiosity book pdf 2026-27 kahan se download karein?
Official NCERT Curiosity Class 8 Science textbook PDF ncert.nic.in ki official website se free download ho sakti hai — NCERT publications section mein jaakar 'Curiosity' textbook select karein. Ye rationalised syllabus ke hisaab se 2026-27 session ke liye updated hai, jisme total 13 chapters hain.
Class 8 Science mein kitne chapters hain naye rationalised syllabus ke according?
Naya Curiosity textbook (2026-27 session) 13 chapters ka hai. Purane chapters jaise Crop Production, Cell Structure, Friction, Sound, Pollution — inhe rationalise karke naye chapters mein merge kar diya gaya hai, jaise 'Exploring Forces', 'Invisible Living World Beyond Our Naked Eye', 'Our Home Earth', etc.
How Nature Works in Harmony chapter ka Health the Ultimate Treasure chapter se kya connection hai?
Dono chapters ek doosre ko complement karte hain — 'Health the Ultimate Treasure' individual aur community health par focus karta hai jabki 'How Nature Works in Harmony' bataata hai ki ek healthy environment (clean air, balanced ecosystem, biodiversity) directly human health ko support karta hai. Polluted ya imbalanced ecosystem se diseases badhti hain, jo dono chapters ke concepts ko jodta hai.
Food chain aur trophic levels exam mein kaise likhein for full marks?
CBSE marking scheme ke hisaab se: sabse pehle definition likhein, phir ek clear diagram/example do arrows ke saath (jaise Grass → Grasshopper → Frog → Snake), fir explain karein ki har trophic level (producer, primary consumer, secondary consumer, tertiary consumer) kya role play karta hai. 10% law mention karna important hai jab energy flow ka question ho — isse extra marks milte hain.
Is chapter ke important diagrams kaunse hain jo exam mein aa sakte hain?
Sabse important diagrams hain: (i) Food chain diagram with arrows showing energy direction, (ii) Food web diagram dikhata hua multiple interconnected chains, (iii) Energy pyramid (trophic level pyramid) jisme har level par energy 10% reduce hoti hai, (iv) Nutrient cycle diagram dikhata hua decomposers ka role. Diagram labeling aur arrows ki direction exam mein carefully check ki jaati hai.
Class 8 Science — Saare Chapters
NCERT Kaksha ek swatantra shaikshik platform hai aur NCERT ya CBSE se aadhikarik roop se sambaddh (officially affiliated) nahi hai. Kisi galti ki jaankari dene ke liye contact kijiye.