Class 10 Science · Chapter 13
Short answer:
Is chapter me NCERT ke saare 7 in-text questions (3 page-wise sets) aur saare 9 exercise questions step-by-step solve kiye gaye hain — NCERT ke exact order me. Iske alawa ek key concepts reference table (trophic levels, 10% law, biomagnification, ozone layer, biodegradable vs non-biodegradable), 6 common exam mistakes jo students har saal karte hain, 5 board-style practice questions (1, 2, 3, 5 marks), aur 6 FAQs bhi diye gaye hain. Coverage: ecosystem aur uske components, producers-consumers-decomposers, food chain aur food web, energy flow ka 10% law, biological magnification, ozone layer ka banna aur uska depletion (CFCs), aur waste management — biodegradable vs non-biodegradable.
Har trophic level par sirf 10% energy aage jati hai, isliye food chain me 4-5 se zyada levels bante hi nahi. Yahi ek line poore chapter ki aatma hai. "Our Environment" me hum dekhte hain ki hum jis duniya me rehte hain woh actually kaise chalti hai — sooraj se energy aati hai, plants use food me badalte hain, phir woh food ek jeev se doosre jeev tak jata hai, aur jo bacha-khucha hai use decomposers todkar wapas mitti me mila dete hain. Ye ek closed loop hai jisme matter cycle karta hai par energy sirf ek direction me behti hai — aur har step par bahut zyada waste hoti hai.
Problem tab shuru hoti hai jab insaan is loop me aisi cheezein daal deta hai jo loop tod deti hain — plastic jo decompose hi nahi hota, DDT jo har level par concentrate hota jata hai, aur CFCs jo 30 km upar jaakar ozone layer ko kha jate hain. Ye chapter sirf ratne wala nahi hai — board me isse energy flow calculations, food chain arrows, biomagnification reasoning aur ozone ke questions seedha aate hain, aur zyadatar marks isliye kat-te hain kyunki concept nahi, direction galat ho jati hai.
Chapter 13 Summary — 5 Minute Revision
1. Ecosystem kya hai?
Ek area ke saare living organisms (biotic components) + unke aas-paas ka physical environment (abiotic components) — dono milkar ek ecosystem banate hain. Dono ek doosre ke saath constantly interact karte hain.
- Biotic components: plants, animals, bacteria, fungi — yaani sab jeev.
- Abiotic components: temperature, rainfall, wind, soil, sunlight, minerals — non-living cheezein.
Ecosystem ke types
| Type | Kaise banta hai | Examples |
|---|---|---|
| Natural | Khud-ba-khud, bina insaan ke | Forest, pond, lake, sea, grassland, desert |
| Artificial (man-made) | Insaan banata aur maintain karta hai | Garden, crop field, aquarium |
↔ Table ko side me swipe karein
Note: Aquarium ek artificial ecosystem hai — isme humein khud feed dena padta hai aur paani saaf karna padta hai, kyunki isme complete natural cycle nahi hoti.
2. Ecosystem ke functional components
| Component | Kaam | Examples |
|---|---|---|
| Producers (Autotrophs) | Photosynthesis se sunlight ki energy ko chemical energy (food) me convert karte hain. Ye hi ecosystem me energy ka entry point hain. | Green plants, blue-green algae (cyanobacteria) |
| Consumers (Heterotrophs) | Directly ya indirectly producers par depend karte hain | Sab animals |
| Decomposers | Dead organisms aur waste ko todkar simple inorganic substances banate hain, jo wapas mitti me chale jate hain | Bacteria, fungi |
↔ Table ko side me swipe karein
Consumers ke 4 types
- Herbivores — sirf plants khate hain (cow, deer, goat)
- Carnivores — sirf dusre animals khate hain (lion, snake, frog)
- Omnivores — dono khate hain (human, crow, bear)
- Parasites — kisi living host par rehkar uska food lete hain (lice, leech, Cuscuta)
3. Food chain aur Trophic levels
Food chain = organisms ki ek series jisme har jeev agle jeev ka food banta hai. Har step ko ek trophic level kehte hain.
| Trophic level | Kaun | Example (grassland) |
|---|---|---|
| First (T1) | Producers | Grass |
| Second (T2) | Primary consumers — herbivores | Grasshopper / Deer |
| Third (T3) | Secondary consumers — small carnivores | Frog |
| Fourth (T4) | Tertiary consumers — large carnivores | Snake |
| Fifth (T5) | Quaternary consumers — top carnivores | Hawk / Eagle |
↔ Table ko side me swipe karein
Arrow ki direction: Arrow hamesha energy ke flow ki direction me hoti hai — khane wale ki taraf.
Grass → Grasshopper → Frog → Snake → Hawk
Food web
Real ecosystem me organisms ek se zyada food chains ka hissa hote hain. Jab bahut saari food chains aapas me interconnect ho jaati hain, to jo network banta hai use food web kehte hain. Food web zyada realistic hai — kyunki ek deer ko sirf sher hi nahi khata, aur sher sirf deer hi nahi khata.
4. Energy flow — 10% Law
Sun se energy plants me aati hai (~1% incident sunlight photosynthesis me convert hoti hai). Uske baad har trophic level par:
- Sirf 10% energy agle trophic level tak pahunchti hai
- 90% energy respiration, heat, movement, digestion aur life processes me kharch ho jaati hai
Do bahut important consequences:
- Food chain me 4-5 se zyada trophic levels nahi hote — kyunki 5th level tak energy itni kam bach jaati hai ki uspar koi population survive hi nahi kar sakti.
- Energy flow unidirectional hai — sun → producers → consumers. Ye kabhi wapas nahi jaati. Isliye ecosystem ko continuously sun se energy ki supply chahiye.
Isi wajah se upar ke trophic levels ke members sabse kam number me hote hain — 10,000 J grass sirf 10 J top carnivore support kar sakti hai.
5. Biological Magnification (Biomagnification)
Definition: Harmful non-biodegradable chemicals (jaise pesticides DDT, mercury) ka food chain ke har successive trophic level par concentration badhte jaana — isse biological magnification kehte hain.
Kyun hota hai? Ye chemicals na to break hote hain, na body se excrete hote hain — fat me store ho jate hain. Jab ek badi machhli 100 chhoti machhliyan khati hai, to 100 machhliyon ka poora DDT usme aa jata hai.
Sabse zyada concentration: highest trophic level par — aur bahut saari food chains me humans top par hote hain.
Path: Soil/Water (pesticide spray) → Plants → Herbivores → Carnivores → Humans (maximum concentration)
6. Ozone Layer
Ozone (O3) = oxygen ke 3 atoms ka molecule. Ground level par ye ek deadly poison hai, lekin atmosphere ke upper part (stratosphere) me ye ek protective shield ka kaam karta hai.
Ozone kaise banta hai
Higher levels par UV radiation O2 molecule ko todti hai, aur free oxygen atoms O2 se judkar O3 banate hain:
O2 (UV)→ O + O
O + O2 → O3 (ozone)
Ozone ka kaam
Ye Sun ki harmful ultraviolet (UV) radiation ko absorb karke Earth tak pahunchne se rokti hai. UV radiation se hoti hai — skin cancer, cataract (aankh ka motiyabind), immune system damage, aur plants/phytoplankton ko nuksaan.
Ozone depletion
- 1980s se ozone layer me tezi se kami dekhi gayi.
- Main culprit: CFCs (Chlorofluorocarbons) — refrigerators aur fire extinguishers me use hote the.
- UNEP ke through 1987 me consensus bana ki CFC production ko freeze kiya jaye (Montreal Protocol). Aaj kai countries me CFC-free refrigerators compulsory hain.
7. Waste Management — Biodegradable vs Non-biodegradable
| Point | Biodegradable | Non-biodegradable |
|---|---|---|
| Definition | Jo decomposers (bacteria/fungi) ke enzymes se break ho jate hain | Jo decomposers break nahi kar paate |
| Examples | Paper, vegetable peels, cow dung, wood, cotton, wool, leather | Plastic, polythene, DDT, glass, aluminium cans, radioactive waste |
| Time | Din se mahine | Saalon-saal, kabhi kabhi hazaar saal |
| Main problem | Foul smell, flies, disease-spread, decomposition ke dauraan | Soil fertility loss, drain blockage, animal deaths, biomagnification |
↔ Table ko side me swipe karein
Enzymes hi asli reason hain: Decomposers ke enzymes specific hote hain. Natural substances ke liye enzyme exist karta hai; man-made materials jaise plastic ke liye koi enzyme evolve hi nahi hua — isliye woh non-biodegradable hai.
Waste kam karne ke tarike
- Segregation — biodegradable aur non-biodegradable waste alag-alag dustbin me
- Composting / vermicomposting — kitchen aur garden waste se manure
- Recycling — paper, glass, metal, plastic
- Reuse aur Reduce — cloth bag carry karna, single-use plastic avoid karna
- Sewage treatment paani chhodne se pehle
In-Text Questions — Solutions
Q1. Why are some substances biodegradable and some non-biodegradable?
Iska poora answer decomposers ke enzymes me chhupa hai.
- Biodegradable substances: Ye woh substances hain jinhe bacteria aur fungi (saprophytes) apne enzymes ki madad se todkar simple harmless substances me convert kar dete hain. Reason ye hai ki in substances ke liye nature me pehle se hi specific enzymes maujood hain, kyunki ye substances khud nature ka hi hissa rahe hain — jaise vegetable peels, paper, cow dung, wood.
- Non-biodegradable substances: Ye mostly man-made (synthetic) materials hain jaise plastic, polythene, DDT. Enzymes bahut hi specific hote hain — ek enzyme sirf ek particular type ke chemical bond par kaam karta hai. In artificial materials ke chemical structure ko todne wala koi enzyme kisi bhi decomposer ke paas evolve hi nahi hua. Isliye ye environment me saalon tak waise ke waise pade rehte hain.
One-line answer: Jinke liye decomposers ke paas matching enzyme hai woh biodegradable hain; jinke liye nahi hai woh non-biodegradable hain.
Q2. Give any two ways in which biodegradable substances would affect the environment.
Biodegradable hone ka matlab ye nahi ki koi nuksaan nahi hota. Decomposition ke dauraan ye problems hoti hain:
- Foul smell aur unhygienic conditions: Jab biodegradable waste (kitchen waste, sewage, dead matter) bade amount me jama ho jata hai, to decomposition ke dauraan foul-smelling gases nikalti hain jo air pollution aur badbu paida karti hain.
- Disease-causing organisms ka breeding ground: Ye rotting waste flies, mosquitoes aur cockroaches ke liye perfect breeding place ban jata hai, jo cholera, dysentery, malaria jaisi diseases spread karte hain.
Extra points (agar zyada marks ka question ho):
- Water bodies me jaakar ye eutrophication karte hain — bacteria oxygen consume kar lete hain, jisse paani me dissolved oxygen girti hai aur machhliyan mar jaati hain.
- Decomposition se nikalne wali methane gas ek greenhouse gas hai.
Q3. Give any two ways in which non-biodegradable substances would affect the environment.
- Biological magnification: Non-biodegradable chemicals jaise pesticides (DDT) aur heavy metals food chain me enter karke har trophic level par concentrate hote jate hain. Sabse zyada concentration top consumers me hoti hai — aksar humans me. Isse serious health disorders hote hain.
- Soil aur water pollution: Plastic aur polythene mitti me pade rehne se soil ki fertility kam ho jati hai aur paani ka seepage rukta hai. Drains aur sewers block ho jate hain jisse waterlogging hoti hai.
Extra points:
- Animal deaths: Gaayein aur stray animals plastic bags nigal lete hain, jo unke digestive system me phans kar unki maut ka kaaran ban jata hai.
- Ye substances saalon tak accumulate hote rehte hain kyunki natural cycles inhe recycle nahi kar paate.
Q4. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Trophic level: Food chain me har ek step ya level jahan energy transfer hoti hai, use trophic level kehte hain. Ek trophic level me woh saare organisms aate hain jo food chain me producers se same number of steps door hain.
Example food chain (grassland ecosystem):
Grass → Grasshopper → Frog → Snake → Hawk
| Organism | Trophic level | Category |
|---|---|---|
| Grass | First | Producer (autotroph) |
| Grasshopper | Second | Primary consumer (herbivore) |
| Frog | Third | Secondary consumer (small carnivore) |
| Snake | Fourth | Tertiary consumer (large carnivore) |
| Hawk | Fifth | Quaternary consumer (top carnivore) |
↔ Table ko side me swipe karein
Yaad rakho: Arrow hamesha khaye jaane wale se khane wale ki taraf jaati hai — yaani energy flow ki direction me.
Q5. What is the role of decomposers in the ecosystem?
Decomposers (bacteria aur fungi) ecosystem ke recycling department hain. Unka role:
- Complex organic matter ko todna: Ye dead plants, dead animals aur unke waste products ko break karke simple inorganic substances me convert karte hain.
- Nutrients wapas mitti me lautana: Ye simple substances mitti aur paani me wapas mil jaate hain, jahan se plants unhe dobara absorb karke use karte hain. Isse nutrient cycling chalti rehti hai.
- Environment saaf rakhna: Agar decomposers na hote to Earth par dead bodies aur waste ke dher lag jaate, aur nutrients unme lock ho jate.
- Soil fertility maintain karna: Decomposition se humus banta hai jo mitti ko fertile banata hai.
Ek line me: Decomposers matter ka cycle poora karte hain — bina inke ecosystem ka material flow ruk jayega.
Q6. What is ozone and how does it affect any ecosystem?
Ozone (O3) oxygen ke teen atoms ka bana hua ek molecule hai, jabki humein saans lene wali normal oxygen (O2) do atoms ki hoti hai.
Ozone kaise banta hai: Atmosphere ke higher levels (stratosphere) par UV radiation oxygen molecule ko tod deti hai, aur free oxygen atoms O2 ke saath judkar ozone bana dete hain:
O2 (UV)→ O + O
O + O2 → O3
Ecosystem par effect — dono taraf:
- Ground level par ozone ek deadly poison hai — ye living tissues ko damage karta hai.
- Upper atmosphere me ozone ek protective shield hai. Ye Sun se aane wali harmful UV radiation ko absorb kar leti hai aur Earth tak nahi pahunchne deti.
Agar ozone layer damage ho jaye: Zyada UV radiation Earth par pahunchegi, jisse insaano me skin cancer aur cataract, plants me photosynthesis ka damage, aur oceans me phytoplankton ki death hogi. Phytoplankton marne ka matlab hai poori aquatic food chain ka base hil jaana.
Q7. How can you help in reducing the problem of waste disposal? Give any two methods.
- Waste segregation aur composting: Ghar par hi biodegradable (kitchen waste, vegetable peels, garden leaves) aur non-biodegradable (plastic, glass, metal) waste ko alag-alag dustbin me daalna. Biodegradable waste se ghar par hi compost / vermicompost banakar plants ke liye manure ki tarah use karna — isse landfill jaane wala waste kaafi kam ho jata hai.
- Reduce, Reuse aur Recycle: Shopping ke liye plastic bag ki jagah cloth ya jute ka bag le jaana, single-use plastic (straw, disposable cups, cutlery) avoid karna, aur paper, glass, metal aur plastic ko recycling ke liye alag dena.
Aur bhi tareeke:
- Paper ke dono sides par likhna aur old newspapers/notebooks recycle karna
- Disposable items ki jagah reusable steel/glass items use karna
- Waste ko khule me na jalana (isse toxic gases nikalti hain)
Poore Class 10 Science ke handwritten colour notes
IITian & district toppers ke banaye short notes — revision-ready, diagram ke saath. Board se pehle poora syllabus 3 din me revise.
Exercise Questions — Solutions (Q1–Q9)
Q1. Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass
Answer: (a), (c) and (d)
Reasoning:
- (a) Grass, flowers, leather — teeno natural origin ke hain, decomposers inhe tod sakte hain. ✓
- (b) Grass aur wood biodegradable hain, lekin plastic non-biodegradable hai. Isliye ye group qualify nahi karta. ✗
- (c) Fruit-peels, cake, lime-juice — sab food items, jaldi decompose ho jate hain. ✓
- (d) Cake, wood, grass — sab natural organic matter. ✓
Trick: Group me sirf ek non-biodegradable item bhi ho to poora group reject ho jata hai.
Q2. Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Answer: (b) Grass, goat and human
Reasoning:
- (a) Grass, wheat, mango — teeno producers hain. Koi kisi ko nahi khata, isliye food chain nahi banti. ✗
- (b) Grass → Goat → Human — producer → herbivore → omnivore. Energy transfer ka proper sequence hai. ✓
- (c) Goat, cow, elephant — teeno herbivores hain, same trophic level par. Ek doosre ko nahi khate. ✗
- (d) Grass, fish, goat — fish grass nahi khati (aur na hi goat fish khati hai). Ye logical sequence nahi hai. ✗
Rule: Food chain banne ke liye har organism ka agle organism ka food hona zaroori hai — aur chain hamesha ek producer se shuru hoti hai.
Q3. Which of the following are environment-friendly practices?
(a) Carrying cloth-bags to put purchases in while shopping
(b) Switching off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop you on her scooter
(d) All of the above
Answer: (d) All of the above
Reasoning:
- (a) Cloth bag reusable hai — isse plastic (non-biodegradable) waste generate hi nahi hota.
- (b) Bijli bachane ka matlab hai power plants me kam coal jalna — kam CO2 aur kam air pollution.
- (c) Paidal chalne se petrol nahi jalta — kam vehicular emissions, aur health ke liye bhi accha.
Teeno hi practices resource conservation aur pollution reduction me madad karti hain, isliye (d) sahi hai.
Q4. What will happen if we kill all the organisms in one trophic level?
Agar kisi ek trophic level ke saare organisms mar jaayein to poora ecosystem imbalance ho jayega, kyunki har level upar aur neeche dono se juda hua hai. Do cheezein ek saath hongi:
- Us level ke upar wale organisms bhookh se mar jayenge — unka food source hi khatam ho jayega.
- Us level ke neeche wale organisms ki population bepanaah badh jayegi — unhe khaane wala koi nahi bachega.
Example samajhne ke liye: Food chain — Grass → Deer → Lion. Agar saare deer maar diye jaayein:
- Lions ko food nahi milega → woh bhookh se mar jayenge ya migrate kar jayenge.
- Grass ko koi khane wala nahi bachega → grass overgrow karegi.
Important point: Aisa nuksaan irreversible ho sakta hai, kyunki nature me removed organism ki jagah lene wala turant koi nahi hota aur poora energy flow toot jata hai.
Q5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?
Pehla part — Haan, impact har level par alag hoga.
| Level hataya | Kya hoga |
|---|---|
| Producers | Sabse zyada catastrophic. Poora ecosystem collapse ho jayega, kyunki energy ka entry point hi khatam. Saare consumers marenge. |
| Herbivores | Carnivores food ke bina mar jayenge, aur plants uncontrolled badh jayenge. |
| Carnivores | Herbivores ki population explode karegi, jo saari vegetation kha jayegi — aakhir me vegetation aur khud herbivores dono khatam. |
| Top carnivores | Neeche wale levels ki population unchecked badhegi, food scarcity aur competition badhegi. |
↔ Table ko side me swipe karein
Doosra part — Nahi. Kisi bhi trophic level ke organisms ko bina ecosystem ko damage kiye nahi hataya ja sakta. Har trophic level ecosystem ke energy flow aur nutrient cycling ka ek zaroori link hai. Ek link tootne se poori chain disturb hoti hai. Isliye ecosystem ka balance banaye rakhne ke liye sabhi trophic levels zaroori hain.
Q6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Biological magnification (Biomagnification): Harmful non-biodegradable chemicals (jaise pesticides DDT, mercury) ka food chain ke har successive trophic level par concentration badhte jaana — isse biological magnification kehte hain.
Kaise hota hai: Crops par chhidke gaye pesticides mitti aur paani me chale jate hain. Wahan se plants unhe absorb kar lete hain. Ye chemicals na break hote hain, na excrete hote hain — body ke fatty tissues me store ho jate hain. Isliye jab ek consumer bahut saare organisms khata hai, to sabka pesticide usme jama ho jata hai.
Doosra part — Haan, magnification ka level har trophic level par alag hota hai.
- Concentration producers me sabse kam hoti hai.
- Har agle trophic level par ye badhti jaati hai.
- Highest trophic level par maximum hoti hai.
Chinta ki baat: Kyunki humans kai food chains me top par aate hain (aur omnivore hone ki wajah se ek se zyada chains se food lete hain), maximum concentration humans ke body me pahunchti hai.
Q7. What are the problems caused by the non-biodegradable wastes that we generate?
Non-biodegradable waste decomposers ke through break nahi hota, isliye ye environment me saalon tak jama hota rehta hai. Iski wajah se ye problems hoti hain:
- Biological magnification: Pesticides aur heavy metals food chain me enter karke har level par concentrate hote hain aur aakhir me humans me pahunchkar serious diseases karte hain.
- Soil pollution aur fertility loss: Plastic aur polythene mitti me layer bana lete hain, jisse paani aur air ka seepage ruk jata hai aur mitti infertile ho jaati hai.
- Water pollution: Rivers, lakes aur oceans me jaakar ye aquatic life ko maar dete hain.
- Drainage blockage: Plastic bags naaliyon aur sewers ko block kar dete hain, jisse waterlogging hoti hai aur mosquitoes ke breeding grounds banate hain.
- Animals ki death: Gaayein aur stray animals plastic nigal lete hain, jo unke stomach me jam kar unki maut ka kaaran banta hai.
- Toxic gases: Plastic jalane par dioxins aur furans jaisi harmful gases nikalti hain jo cancer-causing hoti hain.
Q8. If all the waste we generate is biodegradable, will this have no impact on the environment?
Nahi — biodegradable waste ka bhi environment par impact padta hai. Faayda sirf itna hai ki ye accumulate nahi hota, lekin nuksaan phir bhi hota hai:
- Decomposition me time lagta hai: Agar waste generation ki rate decomposition ki rate se zyada ho jaye, to waste jama hone lagega. Sirf 'biodegradable' hone se turant gayab nahi ho jata.
- Foul smell aur air pollution: Decomposition ke dauraan foul-smelling gases nikalti hain.
- Methane emission: Landfills me anaerobic decomposition se methane nikalti hai, jo ek powerful greenhouse gas hai aur global warming badhati hai.
- Disease vectors: Rotting waste par flies, mosquitoes, rats aur cockroaches panapte hain, jisse cholera, typhoid aur dysentery jaisi bimariyan phailti hain.
- Water bodies ka damage (eutrophication): Biodegradable waste jab paani me jata hai to decomposer bacteria tezi se badhte hain aur paani ki dissolved oxygen khatam kar dete hain, jisse machhliyan aur baaki aquatic organisms mar jate hain.
Conclusion: Biodegradable waste non-biodegradable se behtar hai, lekin harmless nahi. Iska bhi proper management (composting, biogas plants, sewage treatment) zaroori hai.
Q9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Concern kyun hai:
Ozone layer atmosphere ke upper part (stratosphere) me ek shield ki tarah kaam karti hai jo Sun ki harmful ultraviolet (UV) radiation ko absorb kar leti hai. Agar ye layer damage ho jaye to zyada UV radiation Earth ki surface tak pahunchegi, jiske ye effects honge:
- Humans me: Skin cancer, cataract (aankhon ka motiyabind), aur immune system ka weak hona
- Plants me: Photosynthesis ka damage, crop yield me kami
- Aquatic life me: Phytoplankton ki death, jisse poori marine food chain ka base hil jata hai
- Overall genetic mutations aur DNA damage
Damage ka main karan: CFCs (Chlorofluorocarbons) — jo refrigerators aur fire extinguishers me use hote the. Ye stratosphere me pahunchkar ozone molecules ko tod dete hain. 1980s se ozone layer me tezi se kami dekhi gayi.
Damage rokne ke liye kya kadam uthaye gaye:
- UNEP (United Nations Environment Programme) ke prayaso se 1987 me international consensus bana ki CFC production ko 1986 ke level par freeze kiya jaye.
- Aaj kai countries me refrigerators aur air conditioners ka CFC-free hona compulsory hai — CFCs ki jagah safer alternatives use kiye ja rahe hain.
- Aerosol sprays aur fire extinguishers me CFCs ka use band ya kam kiya gaya hai.
Important Equations — Ek Nazar Me
Key Concepts — Quick Reference Table
| Concept | Matlab kya hai | Exam-relevant example |
|---|---|---|
| Ecosystem | Ek area ke saare biotic (living) + abiotic (non-living) components jo aapas me interact karte hain | Natural: forest, pond, lake · Artificial: aquarium, garden, crop field |
| Trophic level | Food chain me energy transfer ka har ek step. Ek trophic level = producers se same distance par khade organisms | Grass (T1) → Grasshopper (T2) → Frog (T3) → Snake (T4) → Hawk (T5) |
| Producers | Autotrophs — photosynthesis se solar energy ko chemical energy me convert karte hain. Ecosystem ka energy entry point | Green plants, blue-green algae — hamesha first trophic level |
| Consumers | Heterotrophs — producers par directly/indirectly depend karte hain | Herbivore (deer), Carnivore (lion), Omnivore (human), Parasite (lice) |
| Decomposers | Dead matter aur waste ko todkar simple inorganic substances banate hain jo mitti me wapas jate hain. Ye producers NAHI hain | Bacteria aur fungi — nutrient cycling complete karte hain |
| Food chain | Organisms ki linear series jisme har jeev agle ka food banta hai. Arrow hamesha energy flow ki direction me (khaye jaane wale se khane wale ki taraf) | Grass → Deer → Lion (arrow lion ki taraf, deer ki taraf nahi) |
| Food web | Kai interconnected food chains ka network — real ecosystems isi tarah kaam karte hain | Deer ko sher, cheetah aur wild dog teeno kha sakte hain |
| 10% Law (energy flow) | Ek trophic level se agle level tak sirf 10% energy transfer hoti hai; 90% respiration aur heat me lost ho jati hai | 10,000 J grass → 1,000 J deer → 100 J lion. Isliye food chain me 4-5 se zyada trophic levels nahi bante |
| Unidirectional energy flow | Energy sirf ek direction me chalti hai: Sun → Producers → Consumers. Kabhi wapas nahi aati | Isliye ecosystem ko Sun se continuous energy supply chahiye. (Matter cycle karta hai, energy nahi) |
| Biological magnification | Non-biodegradable harmful chemicals ka har successive trophic level par concentration badhna, kyunki ye break ya excrete nahi hote — fat me store ho jate hain | DDT: Water → Plankton → Small fish → Large fish → Bird/Human. Concentration maximum top level par |
| Ozone (O3) | Oxygen ke 3 atoms ka molecule. Ground level par deadly poison, stratosphere me protective shield | Formation: UV se O2 tootkar O + O, phir O + O2 → O3 |
| Ozone depletion | 1980s se ozone layer ka tezi se patla hona. Main culprit: CFCs (refrigerators, fire extinguishers) | Effects: skin cancer, cataract. Step: 1987 UNEP consensus — CFC production 1986 level par freeze |
| Biodegradable | Jinhe decomposers ke enzymes tod sakte hain, kyunki matching enzyme nature me exist karta hai | Paper, vegetable peels, cow dung, wood, cotton, leather, wool |
| Non-biodegradable | Jinke liye kisi decomposer ke paas matching enzyme nahi hai (mostly man-made) — saalon tak jama rehte hain | Plastic, polythene, DDT, glass, aluminium cans, radioactive waste |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Food chain me arrow ki direction ulti banana. Sabse common galti. Students likh dete hain Lion → Deer → Grass ye sochkar ki 'sher deer ko khata hai'. Arrow khane ki direction nahi, energy flow ki direction dikhati hai — yaani jo khaya ja raha hai usse jo kha raha hai uski taraf. Sahi hai: Grass → Deer → Lion. Ek galat arrow poore diagram ke marks kha jata hai.
- Ozone depletion aur greenhouse effect ko ek hi cheez samajhna. Ye do bilkul alag phenomena hain. Ozone depletion stratosphere me hoti hai, CFCs se hoti hai, aur isse zyada UV radiation aati hai (skin cancer, cataract). Greenhouse effect / global warming troposphere me hota hai, CO2 aur methane se hota hai, aur isse temperature badhta hai. Ozone hole se global warming nahi hoti — exam me ye reasoning maangi jati hai.
- Decomposers ko producers ya consumers ke saath mila dena. Decomposers (bacteria, fungi) na producers hain na normal consumers — ye ek alag functional category hai jo dead organic matter ko todti hai. 'Decomposers photosynthesis karte hain' ya 'decomposers first trophic level me aate hain' likhna seedha galat hai. Ye food chain ke bahar nahi hain, par unhe alag category me hi likho.
- 10% law ko galat direction me lagana ya percentage ulti karna. 10% woh energy hai jo aage transfer hoti hai, 90% lost hoti hai — ulta nahi. Aur numerical me students calculation ulti kar dete hain: agar producers me 10,000 J hai to herbivores me 1,000 J (10,000 × 10/100), carnivores me 100 J. Bahut log 10,000 ÷ 10% ya ×90% kar dete hain. Bas yaad rakho — har step par ek zero kam.
- Biomagnification me maximum concentration producers me batana. Concentration producers me sabse KAM aur top trophic level (aksar humans) me sabse ZYADA hoti hai. Reason bhi likhna zaroori hai — ye chemicals biodegradable nahi hain, body se excrete nahi hote aur fatty tissues me accumulate hote rehte hain. Sirf 'concentration badhti hai' likhne se full marks nahi milte, kyun badhti hai woh likho.
- Biodegradable waste ko 'bilkul harmless' maan lena. Q8 exactly yahi test karta hai. Biodegradable hone ka matlab safe nahi hai — foul smell, disease-spreading flies aur mosquitoes, landfills se methane (greenhouse gas), aur paani me jaane par eutrophication (dissolved oxygen khatam → machhliyan marti hain). Answer me 'no impact' likhna seedha zero. Aur agar generation rate decomposition rate se zyada ho to ye bhi accumulate hota hai.
Board-Style Important Questions
- 1 mark: Ek terrestrial food chain me kis trophic level ke organisms ki sankhya sabse kam hoti hai, aur kyun? (Hint: 10% law)
- 2 marks: Kisi ecosystem me energy ka flow unidirectional kyun hota hai, jabki matter (nutrients) cycle karta hai? Ek example se samjhaiye.
- 3 marks: Ek food chain: Grass → Grasshopper → Frog → Snake → Hawk. (a) Grasshopper aur Snake ka trophic level batao. (b) Agar grass me 20,000 J energy available hai to hawk ko kitni energy milegi? (c) Is chain me chhathwa (sixth) trophic level kyun nahi ban sakta?
- 3 marks: Biological magnification kya hai? Kaunse organisms is se sabse zyada affect hote hain aur kyun? Kisaano dwara pesticides ka excessive use isse kaise juda hai — samjhaiye.
- 5 marks: (a) Ozone kya hai aur upper atmosphere me ye kaise banta hai — chemical equations ke saath likho. (b) Ozone layer ka damage humans aur plants ke liye kyun khatarnaak hai — do-do effects likho. (c) Is damage ko rokne ke liye international level par kya kadam uthaya gaya?
Quick Quiz — Score Check Karein
Q1. Ek food chain me arrow ki direction kis cheez ko dikhati hai?
Q2. Grassland food chain 'Grass → Grasshopper → Frog → Snake → Hawk' me Frog kis trophic level par hai?
Q3. Agar producers me 10,000 J energy available hai, to 10% law ke according herbivores (second trophic level) tak kitni energy pahunchegi?
Q4. Food chain me 4-5 se zyada trophic levels kyun nahi bante?
Q5. Biological magnification (biomagnification) me chemicals ki concentration sabse zyada kahan hoti hai?
Q6. Ozone (O3) atmosphere ke upper part (stratosphere) me kis role me kaam karti hai?
Q7. Ozone layer depletion ka main culprit kaun sa chemical hai?
Q8. Nurserylive jaise substances jo decomposers ke enzymes se break nahi hote unhe kya kehte hain, aur inka example kya hai?
Q9. Agar kisi food chain me saare herbivores (primary consumers) hata diye jayein, to sabse pehle kya hoga?
Q10. Kya sirf biodegradable waste hone se environment par koi impact nahi padta?
Aksar Poochhe Jaane Wale Sawaal
Trophic level aur food chain me kya farak hai?
Food chain poora sequence hai — jaise Grass to Deer to Lion. Trophic level us chain ka ek particular step hai. Grass first trophic level par hai, deer second par, lion third par. Yaani ek food chain kai trophic levels se milkar banti hai. Ek hi trophic level par kai alag-alag organisms ho sakte hain — jaise deer, goat aur rabbit sab second trophic level par aate hain kyunki teeno herbivores hain.
Food chain me 4-5 se zyada trophic levels kyun nahi hote?
10% law ki wajah se. Har trophic level par sirf 10 percent energy aage jati hai, baaki 90 percent respiration, heat aur life processes me kharch ho jati hai. Agar producers me 10,000 J energy hai to second level par 1,000 J, third par 100 J, fourth par 10 J aur fifth par sirf 1 J bachti hai. Chhathwe level par itni kam energy bachegi ki uspar koi population survive hi nahi kar sakti. Isliye nature khud hi chain ko 4-5 levels par rok deti hai.
Ozone layer ka damage aur global warming ek hi problem hai kya?
Nahi, ye do bilkul alag problems hain aur exam me inhe mix karna badi galti hai. Ozone depletion stratosphere me hoti hai, CFCs ki wajah se hoti hai, aur iska result hai zyada UV radiation ka Earth par pahunchna jisse skin cancer aur cataract hote hain. Global warming troposphere me hoti hai, CO2 aur methane jaisi greenhouse gases ki wajah se, aur iska result hai Earth ka temperature badhna. Alag cause, alag jagah, alag effect.
Biological magnification me humans sabse zyada affected kyun hote hain?
Do reasons hain. Pehla, humans zyadatar food chains me sabse upar wale trophic level par aate hain, aur ye chemicals har level par concentrate hote jate hain. Doosra, humans omnivore hain — hum plants bhi khate hain aur animals bhi, yaani ek se zyada food chains se food lete hain. Isliye alag-alag chains se aane wale pesticides sab hamare body me jama ho jate hain. Ye chemicals non-biodegradable hain, body inhe excrete nahi kar paati aur ye fatty tissues me store hote rehte hain.
Agar saara waste biodegradable ho jaye to kya problem khatam ho jayegi?
Nahi. Biodegradable waste bhi environment ko nuksaan pahunchata hai. Decomposition me time lagta hai — agar hum waste decomposition se zyada speed se paida karein to woh bhi jama hoga. Iske alawa decomposition se foul smell aati hai, flies aur mosquitoes panapte hain jo bimariyan phailate hain, landfills se methane nikalti hai jo greenhouse gas hai, aur paani me jaane par eutrophication hoti hai jisse dissolved oxygen khatam hokar machhliyan mar jaati hain. Biodegradable behtar hai, harmless nahi.
Aquarium ko natural ecosystem kyun nahi kehte?
Kyunki aquarium ek artificial ya man-made ecosystem hai jise insaan banata aur maintain karta hai. Ismein natural cycles complete nahi hoti — humein khud fish ko food dena padta hai, paani time-time par saaf karna padta hai aur oxygen ki supply arrange karni padti hai. Natural ecosystem jaise pond ya lake me producers, consumers aur decomposers khud apna balance banaye rakhte hain aur nutrient cycling apne aap chalti rehti hai, bina kisi bahari madad ke.
Class 10 Science — Saare Chapters
Board exam tak sirf revision karna hai?
Class 10 Science ke saare chapters ke colour handwritten short notes — diagrams, formulas aur important points ek jagah.
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