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ScienceCh 13 Hamara Environment

Our Environment (Hamara Environment): Class 10 Science Chapter 13 Hinglish mein

Science · Hinglish notes, simulations aur practice · Official NCERT chapter PDF ↗

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  • 75 min
  • 21 practice questions
  • 21 MCQs

Is chapter mein aap kya seekhenge

  • Ecosystem ke biotic aur abiotic components pehchaano, aur natural ecosystems ko human-made ecosystems se alag karo
  • Organisms ko producers, consumers (herbivores, carnivores, omnivores, parasites) ya decomposers mein classify karo, aur samjhao ki decomposers kyun zaroori hain
  • Food chains aur food webs banao aur har organism ka trophic level batao
  • 10 per cent law se har trophic level par energy nikaalo, aur samjhao ki energy flow one-way kyun hai aur food chains chhoti kyun hoti hain
  • Biological magnification samjhao aur pesticides ka intake kam karne ke tareeke suggest karo
  • Samjhao ki ozone kaise banti hai, ozone layer kyun zaroori hai, CFCs use kaise nuksaan pahunchate hain aur Montreal Protocol ne kya haasil kiya hai
  • Waste ko biodegradable aur non-biodegradable mein sort karo, aur use manage karne ke tareeke suggest karo, jismein segregation at source bhi shaamil hai

NCERT Science Class 10, Chapter 13, pp. 208–217 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Har saal 5 June ko, World Environment Day par, newspapers tree-planting drives aur beach clean-ups ki photos se bhar jaate hain. Lekin environment aakhir hai kya? Kisi bhi living thing ke liye yeh uske aas-paas ki har cheez hai: doosre plants, animals aur microbes, aur hawa, paani, soil, light aur temperature, jo sab ek doosre par asar daalte hain.

Is chapter mein tum dekhoge ki nature ke living aur non-living parts kaise ek saath fit hote hain, aur food aur energy ek organism se agle tak kaise pahunchte hain. Tum do human-made problems bhi padhoge jo is balance ko bigaadti hain: patli hoti ozone layer aur badhte kachre ke dher.

13.1 Eco-system — Iske Components kya hain?

July mein kisi paddy field ki oonchi bund par chalo. Rice ke plants takhne tak ke paani mein khade hain, snails unke stems se chipke hain, bund par ek frog baitha hai aur ek egret uthle paani mein dabe paon shikaar dhoondh raha hai. Keechad mein chhupe bacteria aur fungi dead leaves ko break down kar rahe hain. Sunlight, baarish, garam hawa aur soil in sabke liye conditions tay karte hain. Field ko sookhne do, to usmein lagbhag har organism par asar padta hai.

Living things kabhi akele nahi rehte: woh ek doosre par aur apne aas-paas ki non-living cheezon par asar daalte hain. Ek jagah ke saare organisms aur unka yeh mahaul, jab ek unit ki tarah kaam karte hain, to milkar ek ecosystem (पारितंत्र) banate hain. Iska living part biotic component hai: plants, animals aur microorganisms. Iska non-living part abiotic component hai: soil aur uske minerals, paani, sunlight, hawa, aur woh jagah kitni garam ya thandi hai (Fig. 13.1).

Definition
Ecosystem

Kisi area ke saare living organisms (biotic components) aur unka physical mahaul (abiotic components), jo ek unit ki tarah ek doosre par asar daalte hain.

ExampleEk pond, ek forest, ek paddy field.

4/4Keechad mein bacteria aur fungi dead remains ko break down karte hain. Yeh sab milkar biotic parts hain.

Fig. 13.1Paddy field ek ecosystem hai: living things aur unka non-living mahaul ek doosre par asar daalte hain.

Paani se bhare paddy field ka side view. Step 1 mein sirf non-living parts hain: Sun aur uski light, chalti hawa, baarish ka badal, paani ki ek layer aur uske neeche soil. Step 2 mein producers aate hain: grain wale rice plants ke jhunde aur paani mein algae ke dhaage. Step 3 mein consumers aate hain: paani mein khada ek egret, keechad ke kinare par ek frog aur rice ke stem par ek snail. Step 4 mein decomposers aate hain: keechad mein padi ek dead leaf par chhote bacteria aur ek chhota fungus.

Ecosystems har size ke hote hain. Forest, grassland, pond, lake ya samundar ka ek hissa apne aap chalta hai: yeh natural ecosystems hain. Crop field, park, school garden ya aquarium ko log banate aur sambhalte hain: yeh human-made (artificial) ecosystems hain. Paddy field human-made hai, kyunki farmers crop chunte hain, field mein paani bharte hain aur weeds ukhaadte hain.

Compare

Ecosystem ke do types

Natural

  • forest, grassland, pond, lake, desert, samundar
  • insaanon ki madad ke bina apne aap chalta rehta hai
  • aam taur par ismein kai tarah ke organisms hote hain

Human-made

  • khet, park, garden, aquarium
  • ise lagane, paani dene, khilane ya saaf karne ke liye logon ki zaroorat hoti hai
  • aam taur par ismein kuch chune hue types hote hain

Producers, consumers aur decomposers

Pichhli classes mein tumne organisms ko is hisaab se sort kiya tha ki woh apna food kaise paate hain. Green plants, algae aur kuch bacteria chlorophyll se trap ki gayi sunlight ki energy se carbon dioxide aur paani ko sugars mein badalte hain, jinhe woh starch ke roop mein store kar sakte hain. Baaki har organism inke banaye food par jeeta hai, isliye yeh producers (उत्पादक) hain.

Baaki saare organisms consumers (उपभोक्ता) hain. Woh food bana nahi sakte, isliye bana-banaya lete hain: bakri seedhe ghaas se, aur leopard bakri ko khaakar second-hand. Diet ke hisaab se inke chaar groups hain. Herbivores plants khaate hain (bakri, grasshopper) aur carnivores doosre animals khaate hain (kingfisher, leopard). Omnivores dono khaate hain, jaise kauwa, bhaalu ya zyadatar log. Parasites kisi doosre living thing par ya uske andar rehte hain aur usi se food lete hain, jaise tapeworm ya bina pattiyon wali peeli amarbel (Cuscuta) jo jhaadiyon par lipat jaati hai.

Table 13.2Kaun food kaise paata hai
GroupFood kaise paata haiExamples
Producersphotosynthesis se khud banakarghaas, rice, algae
Herbivoresplants khaakargaay, grasshopper, water flea
Carnivoresdoosre animals khaakarfrog, kingfisher, tiger
Omnivoresplants aur animals dono khaakarkauwa, bhaalu, insaan
Parasiteskisi living host se food lekartapeworm, lice (joon), amarbel
Decomposersdead matter ko break down karkebacteria, mushrooms, moulds

Giri hui leaf ya mare hue beetle ka kya hota hai? Decomposers (अपघटक), mainly bacteria aur fungi, dead remains aur wastes par enzymes daalte hain, unhe bahar se digest karte hain aur bane products ko absorb karte hain. Bade organic molecules aakhir mein chhote inorganic molecules ban jaate hain: carbon dioxide, paani aur mineral salts. Yeh soil aur paani mein ris jaate hain, aur roots inhe phir se le leti hain (Fig. 13.2).

Definition
Decomposer

Ek microorganism, mainly bacterium ya fungus, jo dead matter aur wastes ko khaata hai. Aisa karte hue woh unmein band minerals ko waapas soil aur paani mein chhod deta hai.

ExampleSadti hui lakdi par phailne wala safed fungus.

4/4Roots minerals absorb karti hain, aur wahi materials nayi leaves banate hain.

Fig. 13.2Decomposers dead matter ke minerals ko soil mein waapas laate hain, taaki plants unhe phir se use kar sakein.

Left mein ek chhota tree khada hai jiski roots soil mein hain, aur uske right mein zameen par ek dead leaf padi hai. Step 1 mein dead leaf par label hai. Step 2 mein leaf par mushrooms aur bacteria dikhte hain, aur leaf sikud gayi hai. Step 3 mein leaf gayab hai aur soil mein blue mineral dots phaile hain, saath mein ek arrow leaf wali jagah se roots ki taraf jaata hai. Step 4 mein roots se trunk ke upar jaata ek arrow aata hai, jis par likha hai ki roots ne le liya.

Decomposers ke bina dead bodies, giri hui leaves aur gobar ke dher lag jaate, aur unmein band minerals kabhi soil mein waapas nahi aate. Plants ko dheere-dheere nutrients ki kami ho jaati, aur plants par depend karne wale har animal ko bhi. Producers ecosystem mein energy laate hain; decomposers uske materials ko ghumaate rehte hain.

Quick check
4 mein se 1
Inmein se kaun pond ecosystem ka abiotic component hai?
Answer dekho

Answer (B) Dissolved oxygen

Dissolved oxygen paani ka ek physical factor hai. Algae, bacteria aur frogs sab living hain, isliye biotic hain, bhale hi bacteria itne chhote hain ki dikhte nahi.

13.1.1 Food Chains aur Webs

Paddy field mein kaun kise khaata hai, iski list banao, to ek sequence dikhne lagta hai. Rice plants ko rats khaate hain, rats ko cobras, aur cobras ko crested serpent eagle. Aisa sequence, jismein har organism ko agla organism khaata hai, ek food chain (आहार श्रृंखला) hai. Har food chain ek producer se shuru hoti hai. India ke alag-alag hisson se kuch aur:

  • Pond: algae → water fleas → small fish → kingfisher
  • Kitchen garden: cabbage → caterpillar → bulbul → shikra (ek chhota baaz)
  • Samundar: tairti hui tiny algae → krill → blue whale, ek chhoti chain jo ab tak ke sabse bade animal par khatam hoti hai

5/5Khaane ka har step ek trophic level hai, jiski numbering producers se hoti hai.

Fig. 13.3Ek pond food chain. Har arrow ka matlab hai is eaten by (khaaya jaata hai).NCERT Fig. 13.1, 13.2 · p. 210

Left se right bani ek food chain. Step 1 mein Sun algae ke ek jhunde par chamakta hai, jis par producer likha hai. Step 2 mein ek arrow water flea tak jaata hai, jis par herbivore likha hai. Step 3 mein ek arrow small fish tak jaata hai, jis par carnivore likha hai. Step 4 mein ek arrow kingfisher tak jaata hai, jis par top carnivore likha hai. Step 5 mein chaaron organisms ke neeche level I se level IV tak ki bands aati hain aur ek lamba arrow jis par likha hai food aur energy is taraf.

Chain ke steps ko neeche se number karo, to har number ek trophic level (पोषी स्तर) hai. Level I hamesha producers (autotrophs) ka hota hai, kyunki chain ki saari food energy unhi ke through andar aati hai. Plant-eaters agle level II par aate hain; yeh primary consumers hain. Jo animal plant-eater ko khaata hai woh secondary consumer (level III) hai, aur jo secondary consumers ko khaata hai woh tertiary consumer (level IV) hai. Table 13.4 do chains ko is tarah sort karta hai.

Definition
Trophic level

Food chain mein khaane ka har step. Producers level I par, herbivores level II par, aur carnivores level III aur usse upar hote hain.

Table 13.4Do chains mein trophic levels
LevelRolePondField
Iproduceralgaerice plants
IIprimary consumer (herbivore)water fleasrats
IIIsecondary consumersmall fishcobras
IVtertiary consumerkingfisherserpent eagle

Energy kaise flow hoti hai

Food fuel hai. Chapati mein stored energy se tum chalte ho, sochte ho aur garam rehte ho. To jab ek organism doosre ko khaata hai, energy chain mein aage badhti hai. Sab sunlight se shuru hota hai: producers light energy ko food mein stored chemical energy mein badalte hain. Unse yeh herbivores aur carnivores tak jaati hai, aur jab bhi koi marta hai, decomposers tak.

Har transfer mein energy barbaad hoti hai. Tum padh chuke ho ki jab bhi energy ek form se doosre form mein badalti hai, uska kuch hissa heat ban jaata hai jo phir use nahi ho sakti. Asli ecosystems ke measurements dikhate hain ki yeh losses kitne bade hain:

  • Leaf par girne wali saari sunlight mein se sirf lagbhag 1 % food mein store hoti hai. Baaki reflect ho jaati hai, aar-paar nikal jaati hai ya bas leaf ko garam karti hai.
  • Ghaas charti bakri ke baare mein socho. Ghaas ki energy ka kuch hissa bina digest hue uske gobar mein nikal jaata hai. Bakri jo absorb karti hai uska zyadatar hissa use garam rakhne, chalne aur saans lene mein jal jaata hai aur heat bankar nikal jaata hai. Sirf lagbhag 10 % nayi bakri ki body banti hai, yaani woh hissa jo leopard kha sakta hai.
  • Har agle step par yahi hota hai, isliye ek level ki energy ka lagbhag dasvaan hissa agle level tak pahunchta hai. Yeh rule of thumb 10 per cent law hai.
Law10 per cent law

Average mein, ek trophic level ki energy ka sirf lagbhag 10 % agle level tak jaata hai. Baaki 90 % life processes mein use hota hai ya heat bankar kho jaata hai.

Example 13.1

Grassland chain mein energy ka safar

Ek dhoop wale din meadow ki ghaas par 500 000 kJ (5 lakh kJ) sunlight girti hai. Chain grass → grasshopper → frog → snake ko follow karo. Har level par kitni energy store hoti hai, aur sunlight ka kitna fraction snakes tak pahunchta hai?

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Example 13.2

Heron se ulta hisaab lagao

Chain algae → water fleas → small fish → heron mein ek heron small fish khaakar din mein 120 kJ energy paata hai. 10 per cent law use karke batao ki har neeche wale level mein kitni energy honi chahiye, aur algae par kitni sunlight girni chahiye?

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Example 13.1 ko phir se dekho: ghaas ki stored 5000 kJ mein se snakes ko sirf 5 kJ milte hain. Paanchve level ko aadha kilojoule milta, jo predators ki population ko zinda rakhne ke liye bahut kam hai. Isliye zyadatar food chains teen ya chaar steps ke baad ruk jaati hain, aur tigers aur eagles jaise top carnivores kam hote hain aur unhe bahut bade territories chahiye hote hain.

Yahi losses numbers ko bhi samjhaate hain. Ek meadow mein laakhon grass plants hote hain, unse kam grasshoppers, aur bhi kam frogs aur bas gine-chune snakes. Zyadatar ecosystems mein producers sabse zyada hote hain, aur trophic levels mein upar jaate hue individuals ki sankhya ghatti jaati hai.

InteractiveFood-chain energy explorer

Ek food-chain explorer jismein chunne ke liye teen chains hain: field (rice plants, rats, cobras, serpent eagles), pond (algae, water fleas, small fish, big fish, herons) aur garden (cabbage plants, caterpillars, bulbuls, shikras). Ek slider tay karta hai ki din mein plants par kitni sunlight girti hai, 1 se 20 lakh kJ tak. Producers uska 1 % store karte hain. Pass energy up one level ko har baar dabane par agla level judta hai jismein neeche wale level ki 10 % energy hoti hai, aur neeche wala bar do hisson mein bant jaata hai: aage diya gaya dasvaan hissa aur use hua ya heat bankar khoya nau-dasvaan hissa. Saare bars ka scale ek hi hai, isliye upar wale bars itne patle ho jaate hain ki dikhte nahi, aur unhe ek arrow se mark kiya jaata hai. Ek status line har transfer samjhaati hai aur chain ke top par batati hai ki sunlight ka kitna fraction wahan tak pahuncha.

Fig. 13.4Ek chain aur sunlight ki amount chuno, phir energy ko ek-ek level upar bhejo aur bars ko chhota hote dekho.

In losses ko saath rakho to Fig. 13.5 wali energy-flow picture banti hai. Isse do khaas baatein pata chalti hain. Energy sirf ek direction mein jaati hai, jaise seedhiyon se neeche behta paani. Bakri jo khaati hai woh kabhi ghaas mein waapas nahi jaata, aur ghaas jo trap karti hai woh Sun ko waapas nahi jaata. Aur yeh amount har step par ghatti jaati hai, kyunki har level jo paata hai uska zyadatar hissa kharch karke heat ke roop mein kho deta hai. Materials alag hain: decomposers carbon, nitrogen aur minerals ko soil mein waapas dete hain, isliye materials cycles mein ghoomte hain jabki energy bas ek baar guzarti hai.

5/5Koi energy neeche wale level ki taraf waapas nahi jaati: flow unidirectional hai.

Fig. 13.5Energy ek taraf behti hai aur har level par ghatti hai.NCERT Fig. 13.4 · p. 211

Left se right ek flow diagram, scale ke hisaab se nahi. Step 1 mein Sun aur light ki ek moti band producers ke bade green block mein jaati hai, jis par about 1 % likha hai. Step 2 mein herbivores, carnivores aur top carnivores ke chhote se chhote blocks aate hain, jo patle hote arrows se jude hain, har ek par 10 % likha hai. Step 3 mein har block se upar uthte lehardaar red arrows aate hain, jin par heat likha hai. Step 4 mein har level se neeche ek lambe decomposers bar tak dashed arrows aate hain. Step 5 mein herbivores se waapas producers tak ek dashed arrow aata hai, jo kata hua hai aur jis par waapas nahi likha hai.

Asli feeding relationships shayad hi kabhi ek seedhi line hote hain. Grasshoppers ko frogs bhi khaate hain aur mynas bhi; snakes frogs ke saath rats bhi khaate hain; eagle snakes, rats, hares aur birds ko pakadta hai. In saari chains ko jodo to ek doosre ko kaatta hua network banta hai, ek food web (आहार जाल) (Fig. 13.6). Ek organism alag-alag levels par bhi ho sakta hai: rat khaane wala snake secondary consumer hai, lekin frog khaane wala snake tertiary consumer hai.

3/4Saare links milkar ek food web banate hain.

Fig. 13.6Food web: kai food chains aapas mein judi hui.NCERT Fig. 13.3 · p. 211

Organisms rows mein labelled ovals ki tarah bane hain: sabse neeche grass aur wheat; unke upar grasshopper, rat aur hare; unke upar myna, frog aur snake; aur sabse upar eagle, aur arrows food se khaane wale ki taraf point karte hain. Step 1 mein ek chain solid blue mein highlight hoti hai: grass, grasshopper, frog, snake, eagle. Step 2 mein doosri chain dashed orange mein aati hai: wheat, rat, snake, eagle. Step 3 mein saare links poori strength se dikhte hain, isliye chains ek doosre ko kaat kar web ban jaati hain. Step 4 mein rat kata hua hai aur uske links fade ho jaate hain, jabki snake aur eagle tak abhi bhi doosre arrows pahunchte hain.

Webs ecosystem ko zyada stable banate hain. Agar kisi khet ke rats bimaari se khatam ho jaayein, to snakes aur eagles frogs, birds aur hares khaane lagte hain. Jo animal sirf ek food par depend karta hai, uske paas aisa koi back-up nahi hota.

Quick check
4 mein se 1
Ek pond ke producers mein 8000 kJ energy hai. Secondary consumers tak kitni energy pahunchti hai?
kJ
Answer dekho

Answer 80 kJ

Producers 8000 kJ → primary consumers 800 kJ → secondary consumers 80 kJ. 800 kJ answer karna ek level pehle ruk jaana hai.

Food chain mein harmful chemicals

Food chains energy ke saath zeher bhi le ja sakti hain. Farmers insects, fungi aur weeds ko maarne ke liye pesticides spray karte hain, lekin spray ka bada hissa kisi pest ko chhoota bhi nahi. Woh zameen par tapak jaata hai ya hawa mein ud jaata hai, aur agli baarish use soil, naaliyon aur gaon ke ponds mein baha le jaati hai. Roots use soil ke paani ke saath sokh leti hain, aur algae aur water plants use seedhe pond se absorb karte hain. Ek baar producer ke andar pahunch gaya, to woh upar ke har organism ke menu par hai.

Aise kai chemicals, jaise insecticide DDT, mushkil se tootte hain aur paani ke bajaye fat mein ghulte hain. Animal na unhe digest kar sakta hai na excrete, isliye woh uske body fat mein reh jaate hain. Ek small fish apni zindagi mein hazaaron plankton khaati hai aur un sabka chemical apne andar rakh leti hai; ek heron aisi saikdon fish khaata hai. Isliye chain mein har step upar concentration badhta jaata hai (Fig. 13.7). Is build-up ko biological magnification (जैव आवर्धन) kehte hain. Hum insaan kai chains ke top se khaate hain (fish, meat, milk), isliye hamari body mein sabse zyada doses mein se kuch pahunch sakte hain.

Definition
Biological magnification

Food chain ke har agle trophic level par kisi non-degradable chemical, jaise pesticide, ke concentration ka badhna.

ExampleLake ke paani ka DDT fish khaane wale birds mein kahin zyada concentrated ho jaata hai.

5/5Sabse upar fish khaane wale heron mein concentration sabse zyada hota hai.

Fig. 13.7Har oonche trophic level par pesticide zyada concentrated hota jaata hai.

Left se right upar chadhti chaar levels ki seedhi, jismein red dots pesticide dikhate hain. Step 1 mein spray kiya hua crop field hai aur ek runoff arrow lake ke paani mein jaata hai, jismein sirf teen bikhre dots hain. Step 2 mein paani mein teen plankton aate hain, har ek mein ek dot. Step 3 mein ek step upar small fish aati hai, jismein paanch dots hain. Step 4 mein aur upar big fish aati hai jismein das dots hain. Step 5 mein sabse upar heron aata hai jismein pandrah dots hain, aur label upar sabse zyada.

Isiliye food-testing laboratories ko cereals, sabziyon, fruits, milk aur fish mein aksar pesticides ke traces milte hain. Nal ke neeche dhone se tomato ke chhilke par baitha residue to hat jaata hai, lekin woh chemical nahi jo plant pehle hi apne tissues mein kheench chuka hai.

Quick check
3 mein se 1
Ek lake aise pesticide se polluted hai jo tootta nahi. Iska concentration kahan sabse zyada hoga?
Answer dekho

Answer (C) Fish khaane wale birds mein

Chemical har level par concentrate hota hai, isliye top consumers, yaani fish khaane wale birds, mein sabse zyada hota hai. Paani mein khud sabse kam concentration hota hai.
Practice · 2 questions

Practice 13.1 (NCERT ke in-text questions, p. 212): answers ke saath

  1. Short answerEasyNCERT in-text Questions p. 212, Q1

    Gaon ke ek pond mein tumhe algae, mosquito larvae, small fish aur ek kingfisher dikhte hain. Trophic level kya hai? Chaaron ko ek food chain mein lagao aur har ek ka trophic level batao.

    Solution dikhao

    AnswerAlgae (I, producer) → mosquito larvae (II, primary consumer) → small fish (III, secondary consumer) → kingfisher (IV, tertiary consumer).

    Trophic level food chain mein khaane ka ek step hai, jise producers se gina jaata hai. Chain hai algae → mosquito larvae → small fish → kingfisher.

    • Algae: level I, producer.
    • Mosquito larvae: level II, primary consumer (herbivore).
    • Small fish: level III, secondary consumer.
    • Kingfisher: level IV, tertiary consumer.
  2. Short answerEasyNCERT in-text Questions p. 212, Q2

    Ek farmer pichhle season ki crop ke thhoonth (stubble) ko jalaane ke bajaye khet mein sadne ke liye chhod deta hai. Decomposers stubble ke saath kya karte hain, aur isse agli crop ko kaise madad milti hai?

    Solution dikhao

    AnswerWoh ise minerals samet simple inorganic substances mein tod dete hain, jo agli crop ke liye soil mein waapas jaate hain.

    Soil ke bacteria aur fungi stubble par enzymes chhodte hain. Woh uske bade organic molecules ko digest karke carbon dioxide, paani aur mineral salts tak tod dete hain. Minerals soil mein waapas jaate hain, jahan agli crop ki roots unhe absorb karti hain. Is tarah decomposers nutrients ko recycle karte hain aur dead matter ko saaf bhi karte hain; iske bajaye stubble jalaane se uska bahut sara organic matter barbaad hota hai aur hawa polluted hoti hai.

13.2 Hamari Activities Environment par kaise asar daalti hain?

Koi aur species apne aas-paas ko utna nahi badalti jitna hum badalte hain. Hum forests kaatte hain, nadiyon par dam banate hain, fuels jalaate hain aur zameen ko kachre ke neeche daba dete hain, aur yeh badlaav laut kar hum par hi asar daalte hain. Yahan do aisi problems ko dhyaan se dekhenge: ozone layer ka patla hona aur woh kachra jo hum phenkte hain. (Air, water aur soil pollution Class 9 mein padha tha.)

13.2.1 Ozone Layer aur yeh kaise Deplete ho rahi hai

Tumse lagbhag 15–35 km upar, stratosphere mein, ek gas ki patli si layer hai jo tumhe zinda rakhti hai: ozone layer (ओज़ोन परत). Yeh Sun ki zyadatar ultraviolet (UV) radiation ko zameen tak pahunchne se pehle hi absorb kar leti hai. Yeh gas ozone hai, oxygen ka ek form jiske molecule mein teen atoms hote hain, OX3, jabki jo oxygen hum saans mein lete hain usmein do hote hain, OX2. Neeche sadak ke level par yahi gas ek pollutant hai: yeh shehar ke smog mein banti hai aur lungs ko nuksaan pahunchati hai.

UV radiation mein itni energy hoti hai ki woh DNA ko nuksaan pahuncha sake. Insaanon mein isse sunburn, skin cancer aur cataract (aankh ke lens ka dhundhla hona) hota hai, aur body ki defences kamzor hoti hain. Yeh crop plants ki growth bhi rokti hai aur ocean food chains ke base par tairti algae ko nuksaan pahunchati hai. Isliye ozone layer ka nuksaan sirf hum par nahi, poore ecosystems par asar daalta hai.

Mazedaar baat yeh hai ki yeh shield usi radiation se banti hai jise yeh rokti hai. Jab high-energy UV kisi oxygen molecule se takraati hai, to uske do atoms ke beech ka bond tod sakti hai (13.1). Akela oxygen atom itna reactive hota hai ki zyada der akela nahi reh sakta: woh kisi poore oxygen molecule se jud jaata hai, aur teen atoms wala jo banta hai woh ozone hai (13.2).

UV oxygen ko todti hai
OX2→UVO+O
(13.1)
Ozone banti hai
O+OX2→OX3
(13.2)

5/5CFCs ka chlorine ozone ko khatam karta hai, layer patli hoti hai aur zyada UV zameen tak pahunchti hai.

Fig. 13.8Ozone aasmaan mein bahut upar banti hai aur UV ko rokti hai; zameen se gaye CFCs use patla karte hain.

Aasmaan ka side view: top left mein Sun, ek dashed band jis par ozone layer, 15 to 35 km up likha hai, aur zameen par ek refrigerator aur ek spray can. Step 1 mein Sun se aate zigzag UV arrows ozone band par ruk jaate hain. Step 2 mein ek panel hai jismein UV do atoms wale oxygen molecule ko do alag atoms mein tod deti hai. Step 3 mein ek free atom ek oxygen molecule se judkar teen atoms wala ozone molecule banata hai. Step 4 mein fridge aur spray can se CFC molecules band ki taraf upar jaate hain. Step 5 mein band ka ek hissa fade ho jaata hai aur us par patli likha hai, aur zyada UV arrows zameen tak pahunchte hain.

1980s ke beech tak zameen aur satellites par lage instruments ozone mein tez giraavat record kar rahe the. Sabse bura haal Antarctica ke upar tha, jahan har September aur October mein ek seasonal ozone hole khulta hai. Main culprits synthetic chlorofluorocarbons (CFCs) the. Kabhi inka bahut use hota tha: refrigerators aur air conditioners mein coolants ki tarah, spray cans mein aur foam banane mein. Fire extinguishers mein use hone wale, halons naam ke inse jude bromine compounds ne bhi aisa hi nuksaan kiya. CFCs itne unreactive hote hain ki dashakon tak tike rehte hain aur dheere-dheere stratosphere tak upar chale jaate hain. Wahan UV inhe tod deti hai aur chlorine atoms free ho jaate hain, jo ozone ko khatam karte hain.

Jab scientists ne yeh link saabit kar diya, to deshon ne milkar kadam uthaya. 1987 mein unhone United Nations Environment Programme (UNEP) ki pehal par Montreal Protocol sign kiya. Pehle isne CFC production ko 1986 ke levels par rok diya. Baad ke revisions ne CFCs aur zyadatar doosre ozone khatam karne wale chemicals ko poori tarah phase out kar diya, isliye har jagah fridges, air conditioners aur sprays ozone-safe gases par shift ho gaye. India ne 1 August 2008 ko CFCs ka production aur use band kar diya, developing countries ki deadline se pehle.

Yeh kaam kar raha hai. 2022 ka UN scientific assessment, jo January 2023 mein publish hua, ummeed karta hai ki duniya ke zyadatar hisson ke upar ozone layer lagbhag 2040 tak apne 1980 ke level par laut aayegi. Arctic ke upar yeh lagbhag 2045 tak aur Antarctica ke upar lagbhag 2066 tak recover honi chahiye. NASA aur NOAA ne 2025 ke Antarctic ozone hole ko 1992 ke baad paanchva sabse chhota bataya. Ek twist bhi hai: kuch replacement gases, yaani HFCs, ozone ko nuksaan nahi pahunchati lekin heat ko bahut zyada trap karti hain, isliye 2016 ka Kigali Amendment ab inhe bhi phase down kar raha hai. India ne ise 2021 mein ratify kiya.

Timeline

Ozone layer ko bachana

  1. 1974

    CFCs par shak

    Mario Molina aur Sherwood Rowland ne dikhaya ki CFCs atmosphere mein bahut upar chlorine release karke ozone ko khatam kar sakte hain.

  2. 1985

    Ozone hole report hua

    British Antarctic Survey ke scientists ne Antarctica ke upar spring ke mausam mein ozone mein gehri giraavat report ki.

  3. 1987

    Montreal Protocol sign hua

    16 September ko sign hua; yeh date ab World Ozone Day hai.

  4. 1995

    Nobel Prize

    Paul Crutzen, Mario Molina aur Sherwood Rowland ko unki ozone research ke liye chemistry ka prize mila.

  5. 2008

    India mein CFCs khatam

    1 August 2008 ko production aur use band hua.

  6. 2009

    Har desh saath aaya

    Yeh protocol pehli UN treaty bani jise har desh ne ratify kiya.

  7. 2016

    Kigali Amendment

    Desh HFCs ko phase down karne par raazi hue, jo ozone-safe gases hain lekin climate ko garam karti hain.

  8. 2025

    Ek chhota hole

    NASA aur NOAA ne us saal ke Antarctic ozone hole ko 1992 ke baad paanchva sabse chhota bataya.

Quick check
4 mein se 1
Atmosphere mein bahut upar ozone layer hamare liye zaroori hai kyunki yeh:
Answer dekho

Answer (D) Sun ki zyadatar harmful UV radiation absorb karti hai

Ozone UV absorb karti hai, jisse skin cancer aur cataract hota hai. Hum saans mein normal oxygen, OX2, lete hain, ozone nahi.

13.2.2 Hamare Banaye Garbage ko Manage karna

Kal ke dustbin mein tumhare ghar se jo kuch gaya, uske baare mein socho: sabziyon ke chhilke, milk ka packet, biscuit ka wrapper, shayad ek tooti pen. Bin khaali hone ke baad hum mein se zyadatar log uske baare mein phir kabhi nahi sochte. Woh aakhir jaata kahan hai, aur kya woh kabhi gayab hota hai? Do mahine ka ek experiment doosre sawaal ka jawab deta hai.

Kuch cheezein gayab kyun ho jaati hain jabki kuch tiki rehti hain? Decomposers dead matter ko enzymes se todte hain, aur jaisa tumne Life Processes mein dekha, enzymes specific hote hain: har enzyme sirf kuch khaas substances par kaam karta hai. Tumhare gut mein roti ke starch ke liye enzymes hain, lekin uske chokar (bran) ke cellulose ke liye koi nahi, isliye chokar bina digest hue nikal jaata hai. Laakhon saalon mein bacteria aur fungi mein natural materials jaise cellulose (paper, cotton aur lakdi mein), proteins aur fats ke liye enzymes evolve hue hain.

Plastics, synthetic fibres aur aluminium jaise metals naye, insaan ke banaye materials hain, aur lagbhag kisi microbe ke paas aise enzymes nahi hain jo inpar kaam kar sakein. Sunlight aur mausam ki maar plastics ko dheere-dheere bhurbhura bana dete hain, isliye woh tukdon mein toot jaate hain. Lekin yeh tukde phir bhi plastic hi hain, aur soil ya paani mein dashakon ya sadiyon tak bane rehte hain.

Definition
Biodegradable

Jise bacteria, fungi aur doosre living things simple substances mein tod sakte hain.

ExampleSabziyon ke chhilke, paper, cotton, gobar.

Definition
Non-biodegradable

Jise living things nahi tod paate, isliye yeh saalon ya sadiyon tak bana rehta hai.

ExamplePolythene, plastic bottles, glass, aluminium foil.

Khet mein padi glass ki bottle zyada nuksaan nahi karti: woh inert hai, bas bahut lambe samay tak tikti hai. Bahut si doosri non-biodegradable cheezein harmful hain. Jo gaay khaane ke tukdon ke saath polythene bags nigal leti hai, woh pet block hone se mar sakti hai, aur purani batteries se rise metals soil aur paani ko zehreela bana dete hain.

Compare

Waste ke do types

Biodegradable

  • bacteria aur fungi isse tod dete hain
  • chhilke, bacha hua khana, paper, cotton, lakdi, gobar
  • agar phenka jaaye: badbu, makkhiyan, bimaari, methane gas
  • compost ya biogas ban sakta hai

Non-biodegradable

  • living things isse nahi tod paate
  • polythene, PET bottles, glass, foil, batteries
  • saalon tak tikta hai, naaliyan block karta hai, animals ko nuksaan pahunchata hai
  • ise reuse, recycle ya safely dispose karna zaroori hai
Quick check
2 mein se 1
Saare biodegradable items chuno.
Saare sahi options chuno
Answer dekho
Answer
  • (A) aam ka chhilka
  • (B) cotton ka dhaaga
  • (D) purani notebook
Chhilka, cotton aur paper plants se aate hain, isliye microbes unhe digest kar sakte hain. Polythene aur aluminium par microbes kaam nahi karte.
Practice · 3 questions

Practice 13.2 (NCERT ke in-text questions, p. 214): answers ke saath

  1. Short answerEasyNCERT in-text Questions p. 214, Q1

    Geeli soil mein gaada gaya cotton ka rumaal kuch mahinon mein gal jaata hai, lekin nylon ka rumaal saalon baad bhi poora rehta hai. Samjhao kyun.

    Solution dikhao

    AnswerMicrobes ke paas cotton ke cellulose ko digest karne wale enzymes hain, lekin nylon, jo ek synthetic material hai, ke liye koi nahi.

    Decomposers materials ko enzymes se todte hain, aur har enzyme sirf kuch khaas substances par kaam karta hai. Cotton plant se aaya cellulose hai, aur soil ke bacteria aur fungi ke paas cellulose ke liye enzymes hain, isliye cotton biodegradable hai. Nylon ek synthetic polymer hai jiske liye microbes ke paas koi enzyme nahi, isliye yeh non-biodegradable hai aur tika rehta hai.

  2. Short answerEasyNCERT in-text Questions p. 214, Q2

    Ek market ka sabzi waste roz ek lake ke kinare phenka jaata hai. Yeh sadta hua waste kaun si do problems paida kar sakta hai, batao.

    Solution dikhao

    AnswerKoi bhi do: dher ke paas badbu, makkhiyan aur bimaari; lake mein sadne se oxygen khatam hoti hai aur fish mar jaati hain; dher se methane.

    • Sadte dher se badbu aati hai aur wahan makkhiyan, mosquitoes aur rats panapte hain jo bimaari phailaate hain.
    • Lake mein baha waste bacteria decompose karte hain jo dissolved oxygen ko khatam kar dete hain, isliye fish ka dam ghut jaata hai.
    • Bina hawa wale dher methane release karte hain, jo ek strong greenhouse gas hai.

    Sahi tarah handle kiya jaaye to yahi waste kaam ka hai: compost karne par yeh kheton ke liye manure ban jaata hai.

  3. Short answerEasyNCERT in-text Questions p. 214, Q3

    Ek town ki naaliyon aur kheton mein plastic packets baar-baar milte hain. Wahan woh kaun se do tarah ke nuksaan kar sakte hain?

    Solution dikhao

    AnswerKoi bhi do: yeh naaliyan block karke flooding karte hain; animals inhe nigal lete hain; yeh soil tak paani aur hawa pahunchne se rokte hain; yeh microplastics mein toot jaate hain.

    • Packets naaliyan jaam kar dete hain, isliye baarish ka paani waapas aakar sadkon par bhar jaata hai.
    • Gaay, kutte aur fish inhe nigal lete hain aur mar sakte hain.
    • Khet mein yeh soil tak paani aur hawa pahunchne se rokte hain, jisse crops ko nuksaan hota hai.
    • Saalon mein yeh toot kar microplastics ban jaate hain jo soil aur paani mein phail jaate hain.

Kitna waste, aur woh jaata kahan hai?

Yeh problem kisi bhi bus ki khidki se aasaani se dikhti hai: bhare hue community bins, baadon mein phansi plastic, shehar ke kinare sulagta hua dher. Central Pollution Control Board (CPCB) ke 2021–22 ke data ke hisaab se India ke towns aur cities roz lagbhag 1.7 lakh tonnes solid waste paida karte hain. Iska sirf aadhe se thoda zyada process hota hai, aur baaki ka bada hissa khule dumps aur landfills mein pahunchta hai.

Example 13.3

Ek parivaar ka waste audit padhna

Chaar logon ka ek parivaar ek din ke waste ka weight karta hai: kitchen waste 0.90 kg, paper 0.20 kg, plastic packets aur bottles 0.35 kg, aur glass aur baaki items 0.15 kg. Nikaalo (a) biodegradable waste ka percentage, (b) har vyakti ka roz ka waste, aur (c) parivaar ka ek saal ka total waste.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Aaj ki grocery shopping ko apne dada-dadi ki shopping se compare karo. Woh kapde ka thaila le jaate the, dukaandar dal ko newspaper mein lapetta tha aur dahi steel ke tiffin mein ghar aata tha. Aaj wahi cheezein plastic pouches mein aati hain, jinmein se kai plastic aur foil ki chipki hui layers se bane hote hain jinhe recycle karna bahut mushkil hai. Hum zyada khareedte bhi hain, aur usmein se zyada cheezein ek hi baar use karne ke liye bani hoti hain: paper plates, plastic spoons, shampoo sachets, single-serve snacks, delivery boxes aur bubble wrap. Isliye dher badhta jaata hai, aur uska bada hissa kabhi nahi sadega.

Hum kya kar sakte hain

Saaf mahaul ghar se shuru hota hai. Sabse kaam ki aadat hai segregation at source: alag-alag tarah ke waste ko phenkte hi alag rakhna, taaki har ek ko sahi tarah treat kiya ja sake. India ke Solid Waste Management Rules, 2026, jo 1 April 2026 se laagu hain, har ghar ke liye apna waste chaar streams mein alag karna zaroori banate hain (Fig. 13.10):

  • Wet waste: kitchen waste, chhilke, bacha hua khana, phool. Yeh composting ya biogas ke liye jaata hai.
  • Dry waste: plastic, paper, metal, glass, lakdi, rubber. Yeh sorting aur recycling ke liye material recovery facilities mein jaata hai.
  • Sanitary waste: use kiye diapers aur sanitary pads. Ise achhi tarah lapet kar alag rakha jaata hai.
  • Special care waste: paint ke dibbe, bulbs, mercury thermometers, purani dawaiyan. Ise authorised agencies collect karti hain, ya tum ise collection centre par de aate ho.

3/3Alag rakhne par har stream ko compost, recycle ya safely dispose kiya ja sakta hai.

Fig. 13.10Segregation at source: India ke Solid Waste Management Rules, 2026 ke tahat chaar streams.

Ek row mein chaar bins khade hain, jin par wet, dry, sanitary aur special care likha hai. Step 1 mein bins khaali hain. Step 2 mein items andar girte hain: banana peel wet mein, plastic bottle dry mein, ek mudha hua pad sanitary mein, aur ek battery aur ek bulb special care mein. Step 3 mein har bin ke neeche arrows aate hain jo batate hain ki stream kahan jaati hai: compost ya biogas; sorting aur recycling; lapet kar alag rakha jaata hai; aur ek collection centre.

Sorting ke aage, teen Rs ko unki value ke order mein follow karo. Reduce: kam khareedo, single-use items ko mana karo, kapde ka thaila aur paani ki bottle saath rakho. Reuse: jars dobara bharo, kapde aur books doosron ko do, nayi lene se pehle repair karo. Recycle: paper, metal, glass aur saaf plastic ko nayi cheezein banane ke liye bhejo. Wet waste garden ke gaddhe ya khamba (mitti ke matkon ka stack) mein compost ban sakta hai, ya khaana pakane ke liye biogas. India ne 1 July 2022 se kai single-use plastic items, jaise plastic cutlery, straws aur plastic-stick earbuds, par ban bhi lagaya hai.

Step by step

Bottle se T-shirt tak

Step 1 / 5

Collect karo

Rag-pickers, kabadiwale aur collection drives use ki hui PET bottles ikattha karte hain (jin par triangle mein number 1 bana hota hai).

1 / 5
Quick check
4 mein se 1
India ke Solid Waste Management Rules, 2026 ke tahat use kiya hua diaper kis stream mein jaata hai?
Answer dekho

Answer (C) sanitary waste

Use kiye diapers aur sanitary pads sanitary waste hain, jinhe lapet kar alag rakha jaata hai. Geele hone ke bawajood yeh wet kitchen waste ke saath nahi jaate.
Practice · 2 questions

Practice 13.3 (NCERT ke in-text questions, p. 216): answers ke saath

  1. Short answerMediumNCERT in-text Questions p. 216, Q1

    Ozone ko pollutant bhi kaha jaata hai aur protector bhi. Samjhao ki yeh kya hai, aur kisi samundar ke upar bahut patli ozone layer us samundar ke ecosystem par kaise asar daal sakti hai, uske producers se shuru karke.

    Solution dikhao

    AnswerOzone OX3 hai, oxygen ka ek form. Zyada UV tairti algae ko nuksaan pahunchayegi, isliye har consumer level tak kam food aur energy pahunchegi.

    Ozone teen oxygen atoms ka molecule hai, OX3. Atmosphere mein bahut upar yeh Sun ki zyadatar UV radiation absorb karti hai.

    Agar layer patli ho jaaye, to zyada UV samundar ki surface tak pahunchegi aur tairti algae, yaani producers, ko nuksaan pahunchayegi. Kam producers hone se food chain mein kam energy aayegi, isliye tiny animals, fish, aur fish khaane wale birds aur mammals, sabke paas kam food hoga. Kyunki har chain producers se shuru hoti hai, base ka nuksaan poore ecosystem mein phail jaata hai.

  2. Short answerEasyNCERT in-text Questions p. 216, Q2

    Do cheezein suggest karo jo tumhara school landfill mein bheje jaane wale waste ko kam karne ke liye kar sakta hai.

    Solution dikhao

    AnswerKoi bhi do: wet aur dry waste alag karo; canteen aur garden waste ko compost karo; paani ki bottles refill karo; paper reuse karo aur baaki recycling ke liye bhejo; single-use plastic se bacho.

    • Har corridor aur canteen mein wet aur dry waste ke liye alag bins rakho.
    • Canteen ke bache tukdon aur giri hui leaves ko ek gaddhe mein compost karo aur compost ko school garden mein use karo.
    • Students se kaho ki packets ke bajaye refillable bottles aur steel lunch boxes laayein.
    • Use kiya paper recycling ke liye collect karo aur har sheet ke dono taraf likho.
Recap

Summary aur key points

  1. Ecosystem kisi area ke organisms aur unka non-living mahaul hai, jo sab ek doosre par asar daalte hain (Section 13.1).
  2. Producers sunlight se food banate hain; consumers (herbivores, carnivores, omnivores, parasites) use khaate hain; decomposers minerals ko soil mein waapas laate hain (Producers, consumers, decomposers).
  3. Food chain dikhati hai ki kaun kise khaata hai; har step ek trophic level hai, aur arrow khaane wale ki taraf point karta hai (Section 13.1.1).
  4. Plants sunlight ka lagbhag 1 % store karte hain, aur lagbhag 10 % energy ek level se agle level tak jaati hai (Law).
  5. Energy ek taraf behti hai aur har level par ghatti hai, isliye food chains chhoti hoti hain, aam taur par teen ya chaar links ki (How energy flows).
  6. Food chains aapas mein judkar food webs banati hain, jo ecosystem ko zyada stable banate hain (Fig. 13.6).
  7. Pesticides jaise non-degradable chemicals food chain mein upar jaate hue concentrate hote hain: biological magnification (Harmful chemicals).
  8. Ozone layer harmful UV absorb karti hai; CFCs ne ise patla kiya, aur 1987 ka Montreal Protocol ise recover hone mein madad kar raha hai (Section 13.2.1).
  9. Waste biodegradable ya non-biodegradable hota hai, is par depend karta hai ki microbes ke paas use todne wale enzymes hain ya nahi (Section 13.2.2).
  10. Segregation at source, composting aur reduce–reuse–recycle se waste ko manage karna aasaan hota hai (What we can do).
Practice · 14 questions

Practice questions answers ke saath (NCERT “Exercises”)

  1. Quick answerEasyNCERT Exercises Q1

    Kis group mein sirf biodegradable items hain?

    Answer dekho

    Answer (B) jute ki bori, cotton ka kapda, banana peel

    Jute, cotton aur banana peel teeno plants se aate hain. Baaki har group mein ek aisa item hai jise microbes tod nahi sakte: polythene, glass ya aluminium.
  2. Quick answerEasyNCERT Exercises Q2

    Inmein se kaun sa set food chain banata hai?

    Answer dekho

    Answer (C) algae, water fleas, small fish

    Water fleas algae khaate hain aur small fish water fleas ko khaati hain. Pehle set mein sab producers hain, doosre mein sab herbivores, aur aakhri mein do producers aur ek consumer hai.
  3. Quick answerEasyNCERT Exercises Q3

    Inmein se kaun si environment-friendly aadatein hain? Jo bhi sahi hon, sab chuno.

    Saare sahi options chuno
    Answer dekho
    Answer
    • (A) bottled water khareedne ke bajaye school steel ki bottle le jaana
    • (C) paas mein dost ke ghar cycle se jaana
    • (D) sabziyon ke chhilke compost pit mein daalna
    Bottle refill karne se plastic waste nahi banta, cycling mein koi fuel nahi lagta aur composting nutrients ko recycle karti hai. Khaali kamre mein chalta AC bijli barbaad karta hai, aur plastic jalaane se toxic dhuaan nikalta hai.
  4. Long answerMediumNCERT Exercises Q4

    Ek spray ek bade khet ke saare herbivorous insects ko maar deta hai, aur poora second trophic level khatam ho jaata hai.

    1. In insects ko khaane wale frogs aur birds ka kya hota hai?

      Solution dikhao

      AnswerUnka food chhin jaata hai, isliye woh bhookhe marte hain, kahin aur chale jaate hain ya ghat jaate hain.

      Level II khatam hone se koi energy upar nahi jaati, isliye secondary consumers ka food chhin jaata hai. Unki sankhya ghatti hai, ya woh khet chhod dete hain; phir unke predators, jaise snakes, ko bhi nuksaan hota hai.

    2. Shuru mein plants ka kya hota hai?

      Solution dikhao

      AnswerUnhe koi khaane wala nahi hota, isliye kuch samay tak woh bina roktok badhte hain.

      Herbivores nahi, to grazing nahi, isliye plants shuru mein bina roktok badhte aur phailte hain. Kuch plants ko pollinate karne wale insects na hone se baad mein kuch species ke kam seeds ban sakte hain.

    3. Poora ecosystem kam stable kyun ho jaata hai?

      Solution dikhao

      AnswerEk level par energy flow kat jaata hai aur levels ke beech ka balance toot jaata hai.

      Har level energy ke liye apne neeche wale level par depend karta hai aur use khaakar neeche wale level ko control mein rakhne mein madad karta hai. Ek level hataane se upar ke saare levels ki energy supply kat jaati hai aur neeche wale level par roktok khatam ho jaati hai, isliye ecosystem ka balance bigad jaata hai.

  5. Long answerMediumNCERT Exercises Q5

    Kisi forest se (i) uske saare producers aur (ii) uske saare top carnivores hataane ke effect ko compare karo. Kya koi aisa trophic level hai jiske khatam hone se koi nuksaan na ho?

    Solution dikhao

    AnswerProducers hataane se sab kuch dhah jaata hai; top carnivores hataane se herbivores badh jaate hain aur zaroorat se zyada charte hain. Koi bhi level bina nuksaan ke hataaya nahi ja sakta.

    (i) Producers hi woh akela raasta hain jisse energy ecosystem mein aati hai. Unke bina har consumer aur aakhir mein decomposers bhi bhookhe marte hain: ecosystem dhah jaata hai.

    (ii) Tigers ya leopards ke bina deer aur doosre herbivores badh jaate hain, chhote plants ko zaroorat se zyada char jaate hain aur jhaadiyan saaf kar dete hain. Forest dheere-dheere kharab hota hai, aur phir herbivores khud bhookhe marte hain.

    To asar har level par alag hota hai, lekin kabhi zero nahi hota. Decomposers ko bhi hataaya nahi ja sakta: dead matter ke dher lag jaate aur soil ke minerals khatam ho jaate.

  6. Short answerMediumNCERT Exercises Q6

    Spray kiye kheton ke paas ki ek lake ke tests yeh pesticide concentrations dete hain (parts per million): paani 0.0005, algae 0.04, small fish 0.5, big fish 2, heron 25.

    1. Biological magnification ko define karo.

      Solution dikhao

      AnswerHar oonche trophic level par kisi non-degradable chemical ke concentration ka badhna.

      Yeh aise chemical ka jama hona hai jo na toot sakta hai na excrete ho sakta hai, isliye food chain ke har agle trophic level par uska concentration badhta jaata hai.

    2. Data se batao ki pesticide har step par barabar jama hota hai ya nahi.

      Solution dikhao

      AnswerNahi: yeh har step par badhta hai, paani mein 0.0005 ppm se heron mein 25 ppm tak.

      Nahi. Har consumer neeche wale level ke bahut saare organisms khaata hai aur unka pesticide apne paas rakhta hai. Isliye concentration har step par chadhta jaata hai: algae mein paani se 80 guna zyada hai, aur heron mein small fish se 50 guna zyada.

    3. Heron mein pesticide small fish se kitne guna zyada concentrated hai?

      guna
      Answer dekho

      Answer 50 guna

      25÷0.5=50.

    4. Paas rehne wale logon ko iski chinta kyun karni chahiye?

      Solution dikhao

      AnswerLake ki fish khaane wale log chain ke top par hain aur sabse zyada dose lete hain.

      Lake ki fish khaane wale log heron ki tarah is chain ke top par hain. Woh sabse zyada concentrated pesticide lete hain, jo saalon mein unke body fat mein jama hota jaata hai.

  7. Short answerEasyNCERT Exercises Q7

    Ek shehar ka plastic, glass aur metal waste kabhi nahi sadta. Isse paida hone wali chaar problems batao.

    Solution dikhao

    AnswerBlock naaliyan aur flooding; animals ka plastic nigalna; zehreeli ya banjar soil; lagaataar badhte landfills aur microplastics.

    • Plastic bags aur wrappers naaliyan block kar dete hain, isliye tez baarish mein sadkon par paani bhar jaata hai.
    • Aawara gaay aur kutte khaane ke tukdon ke saath plastic kha lete hain aur beemar pad jaate hain ya mar jaate hain.
    • Batteries aur e-waste se toxic metals soil aur groundwater mein ris jaate hain.
    • Yeh kabhi nahi sadta, isliye landfills badhte rehte hain, aur plastics dheere-dheere microplastics mein toot jaate hain.
  8. Short answerMediumNCERT Exercises Q8

    Tumhara dost kehta hai, "Agar hamara saara waste biodegradable hota, to waste se koi problem hi nahi hoti." Kya tum sehmat ho? Kaaran do.

    Solution dikhao

    AnswerNahi: bahut zyada maatra mein phenka jaaye to biodegradable waste bhi badbu karta hai, bimaari phailaata hai, methane chhodta hai aur paani ko polluted karta hai.

    Nahi. Biodegradable waste lambe samay ki kam problems paida karta hai, lekin bade dheron mein yeh phir bhi sadta aur badbu karta hai, makkhiyan, mosquitoes aur rats paida karta hai, aur methane, ek greenhouse gas, release karta hai. Pond mein beh jaaye to ise bacteria decompose karte hain jo dissolved oxygen khatam kar dete hain, aur fish mar jaati hain. Yeh tabhi harmless hai jab ise sahi tarah handle kiya jaaye, jaise compost karke ya biogas banakar.

  9. Long answerMediumNCERT Exercises Q9

    Ozone hole Antarctica ke upar banta hai. Iske patle hone ki chinta India ke logon ko bhi kyun karni chahiye? Ozone layer ko theek karne ke liye duniya bhar mein aur India mein kya kiya gaya hai?

    Solution dikhao

    AnswerZyada UV se har jagah skin cancer aur cataract badhenge aur crops aur plankton ko nuksaan hoga. 1987 ke Montreal Protocol ne CFCs ko phase out kiya, aur India ne 2008 mein CFCs ka use khatam kiya.

    Ozone layer poore planet ko gherti hai, aur ozone khatam karne wale chemicals poore atmosphere mein phail jaate hain, isliye patla hona sirf Antarctica tak seemit nahi hai. Zyada UV se skin cancer aur cataract ke cases badhenge, immunity kamzor hogi, crop yields ghatengi aur ocean food chains ko food dene wali tairti algae ko nuksaan hoga.

    Uthaaye gaye kadam: UNEP ki pehal par 1987 ke Montreal Protocol ke tahat deshon ne pehle CFCs, halons aur doosre ozone-depleting chemicals ka production roka aur phir unhe phase out kiya. Companies ne fridges, air conditioners aur sprays ko ozone-safe gases par shift kiya, aur ab har UN member ne treaty ratify kar di hai. India ne August 2008 mein CFCs ka production aur use band kiya aur HFCs ko phase down karne wala 2016 ka Kigali Amendment ratify kiya hai. Ab ummeed hai ki ozone layer Antarctica ke upar lagbhag 2066 tak apne 1980 ke level par recover ho jaayegi, aur baaki jagah usse pehle.

  10. Quick answerEasy

    Ek food chain mein producers ke paas 40 000 kJ energy hai. 10 per cent law use karke batao ki tertiary consumers tak kitni energy pahunchti hai?

    kJ
    Answer dekho

    Answer 40 kJ

    40 000 → 4000 (primary) → 400 (secondary) → 40 kJ (tertiary).
  11. Quick answerMedium

    Assertion (A): Nature mein food chains mein shayad hi kabhi chaar ya paanch se zyada trophic levels hote hain. Reason (R): Har transfer par energy ka sirf lagbhag 10 % agle level tak jaata hai.

    Answer dekho

    Answer (A) A aur R dono sahi hain, aur R, A ko samjhaata hai

    Dono sahi hain, aur R mein bataya gaya energy ka bhaari loss hi wajah hai ki chaar ya paanch levels ke baad itni kam energy bachti hai.
  12. Quick answerEasy

    Har organism ko us tareeke se match karo jisse woh food paata hai.

    Left mein koi item tap karo, phir right mein uska match.

    Answer dekho
    Answer
    • algae : producer
    • bakri : herbivore
    • kingfisher : carnivore
    • amarbel : parasite
    • mushroom : decomposer
    Algae photosynthesis karti hain; bakriyan plants khaati hain; kingfishers fish khaate hain; amarbel apne host plant se food kheenchti hai; mushrooms dead matter par jeete hain.
  13. Quick answerEasy

    Pesticide logon tak jin steps se pahunchta hai, unhe order mein lagao.

    1. Fish plankton ko khaati hain
    2. Baarish use lake mein baha le jaati hai
    3. Crops par pesticide spray hota hai
    4. Log fish khaate hain
    5. Plankton use le lete hain
    Answer dekho
    Answer
    1. Crops par pesticide spray hota hai
    2. Baarish use lake mein baha le jaati hai
    3. Plankton use le lete hain
    4. Fish plankton ko khaati hain
    5. Log fish khaate hain
    Pesticide khet se paani mein jaata hai, phir food chain mein upar hote hue hum tak.
  14. Short answerMedium

    Case study: Pune ki ek housing society Solid Waste Management Rules, 2026 ke tahat apna waste sort karna shuru karti hai. Neeche ke sawaalon ke jawab do.

    1. Toota hua CFL bulb kis stream mein jaata hai?

      Answer dekho

      Answer (D) special care

      CFLs mein mercury hota hai, isliye bulbs special care waste hain jo authorised collector ke paas jaate hain.

    2. Aam ke chhilke aur baasi chapatiyan kis stream mein jaati hain?

      Answer dekho

      Answer (A) wet

      Kitchen waste wet waste hai, jise compost kiya ja sakta hai.

    3. Purane newspapers aur ek tadki hui plastic bucket kis stream mein jaate hain?

      Answer dekho

      Answer (B) dry

      Paper aur plastic dry waste hain, jo sorting aur recycling ke liye bheje jaate hain.

    4. Waste ko landfill ke bajaye ghar par sort karne ke do fayde batao.

      Solution dikhao

      AnswerSaaf streams compost ya recycle ho sakti hain; landfill tak kam waste pahunchta hai aur workers ko ganda, khatarnaak mixed waste chhoona nahi padta.

      Ghar par sort karne se wet waste itna saaf rehta hai ki compost ho sake aur dry waste itna saaf ki recycle ho sake, isliye landfill mein bahut kam pahunchta hai. Isse bulbs aur dawaiyon jaisi khatarnaak cheezein waste workers se door rehti hain, jinhe warna ek mile-jule, gande dher mein se cheezein beenni padti.

Flash cards · 8

Key terms

1 / 8

Apna NCERT exercise question dhoondo

Hamare practice questions ncert.ai ke liye likhe gaye hain aur NCERT exercises ko follow karte hain. Apni textbook ke question se match karne wala question dhoondo; uska answer uske saath hai.

Tumhari NCERT textbook meinYahan practice question
NCERT in-text Questions p. 212, Q1Practice 13.1 (NCERT ke in-text questions, p. 212) · Q1
NCERT in-text Questions p. 212, Q2Practice 13.1 (NCERT ke in-text questions, p. 212) · Q2
NCERT in-text Questions p. 214, Q1Practice 13.2 (NCERT ke in-text questions, p. 214) · Q1
NCERT in-text Questions p. 214, Q2Practice 13.2 (NCERT ke in-text questions, p. 214) · Q2
NCERT in-text Questions p. 214, Q3Practice 13.2 (NCERT ke in-text questions, p. 214) · Q3
NCERT in-text Questions p. 216, Q1Practice 13.3 (NCERT ke in-text questions, p. 216) · Q1
NCERT in-text Questions p. 216, Q2Practice 13.3 (NCERT ke in-text questions, p. 216) · Q2
NCERT Exercises Q1Exercises · Q1
NCERT Exercises Q2Exercises · Q2
NCERT Exercises Q3Exercises · Q3
NCERT Exercises Q4Exercises · Q4
NCERT Exercises Q5Exercises · Q5
NCERT Exercises Q6Exercises · Q6
NCERT Exercises Q7Exercises · Q7
NCERT Exercises Q8Exercises · Q8
NCERT Exercises Q9Exercises · Q9

Quick check: MCQs

  1. Producers, consumers aur decomposers4 questions
  2. Energy kaise flow hoti hai4 questions
  3. Food chain mein harmful chemicals3 questions
  4. 13.2.1 Ozone Layer aur yeh kaise Deplete ho rahi hai4 questions
  5. 13.2.2 Hamare Banaye Garbage ko Manage karna2 questions
  6. Hum kya kar sakte hain4 questions
Glossary · 15

Key terms (English + Hindi)

10 per cent lawदस प्रतिशत नियमdas pratishat niyam
Average mein ek trophic level ki energy ka sirf lagbhag 10 % agle level tak jaata hai.Chapter mein pehli baar yahan aaya →
abiotic componentअजैव घटकajaiv ghatak
Ecosystem ka non-living part, jaise soil aur uske minerals, paani, sunlight, hawa aur temperature.Chapter mein pehli baar yahan aaya →
biodegradableजैव निम्नीकरणीयjaiv nimnikaraniya
Jise bacteria, fungi aur doosre living things simple substances mein tod sakte hain.
biological magnificationजैव आवर्धनjaiv aavardhan
Food chain ke har oonche trophic level par kisi non-degradable chemical ke concentration ka badhna.Chapter mein pehli baar yahan aaya →
biotic componentजैव घटकjaiv ghatak
Ecosystem ka living part: plants, animals aur microorganisms.Chapter mein pehli baar yahan aaya →
chlorofluorocarbons (CFCs)क्लोरोफ्लोरोकार्बनchlorofluorocarbon
Chlorine, fluorine aur carbon ke insaan ke banaye compounds, jo kabhi fridges aur sprays mein use hote the, aur atmosphere mein bahut upar ozone khatam karne wala chlorine release karte hain.Chapter mein pehli baar yahan aaya →
consumerउपभोक्ताupbhokta
Aisa organism jo producers ya doosre consumers ko khaakar food paata hai.Chapter mein pehli baar yahan aaya →
decomposerअपघटकapghatak
Ek microorganism, mainly bacterium ya fungus, jo dead matter aur wastes ko khaata hai aur is tarah unke minerals waapas soil aur paani mein chhod deta hai.Chapter mein pehli baar yahan aaya →
ecosystemपारितंत्रparitantra
Kisi area ke saare organisms aur unka non-living mahaul, jo ek unit ki tarah ek doosre par asar daalte hain.Chapter mein pehli baar yahan aaya →
food chainआहार श्रृंखलाaahaar shrinkhala
Organisms ka aisa sequence jismein har ek ko agla khaata hai, aur jo producer se shuru hota hai.Chapter mein pehli baar yahan aaya →
food webआहार जालaahaar jaal
Ecosystem mein aapas mein judi food chains ka network.Chapter mein pehli baar yahan aaya →
non-biodegradableअजैव निम्नीकरणीयajaiv nimnikaraniya
Jise living things nahi tod paate, isliye yeh saalon ya sadiyon tak bana rehta hai.Chapter mein pehli baar yahan aaya →
ozone layerओज़ोन परतozone parat
Upper atmosphere ka lagbhag 15–35 km upar wala hissa, jismein ozone (OX3) zyada hoti hai aur jo Sun ki zyadatar ultraviolet radiation absorb karta hai.Chapter mein pehli baar yahan aaya →
producerउत्पादकutpaadak
Aisa organism jo sunlight ki madad se simple substances se apna food khud banata hai, jaise green plant ya alga.Chapter mein pehli baar yahan aaya →
trophic levelपोषी स्तरposhi star
Food chain mein khaane ka ek step; producers pehla level banate hain.Chapter mein pehli baar yahan aaya →

Tum chapter ke end tak pahunch gaye

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