Respiration in Plants: Class 11 Biology Chapter 12 Hinglish mein

Garden ki kyari se ek carrot ukhaado. Iski orange root ne apni poori zindagi zameen ke neeche andhere mein bitaayi hai, phir bhi iski cells divide hoti rahin, mineral ions sokhti rahin aur sugar store karti rahin. In sab kaamon mein energy lagti hai. Jo cell kabhi sunlight nahi dekhti, use yeh energy kahan se milti hai?

Jawab hai food, jo cell ke andar toota jaata hai. Kisi bhi food ko kaafi peeche tak trace karo to tum ek photosynthesise karne wali cell tak pahunch jaoge: bakri pattiyan khaati hai, leopard bakri ko khaata hai, aur mushroom gire hue patton aur sadti lakdi par jeeta hai. Plant ke andar bhi kahani wahi hai. Chloroplast wali cells zyaadatar leaves aur young stems ki bahari layers mein hoti hain, isliye carrot ki root, ek tree ki wood, uske flowers aur seeds ki tarah, leaves se phloem ke through aane wali sugar par jeeti hai.

Energy ke liye food ka use karna cellular respiration (श्वसन) kehlaata hai: cell energy se bhare molecules ko oxidise karti hai, unke carbon–carbon bonds ko ek-ek karke todti hai aur release hui energy ka kuch hissa ATP ke roop mein pakad leti hai. Cell is tarah jo bhi oxidise karti hai, woh respiratory substrate hai. Glucose aur doosre carbohydrates roz ka fuel hain; fats, proteins aur organic acids sirf kuch khaas plants ya situations mein kaam aate hain, jaise oil se bhara seed jab sprout hota hai. Jahan photosynthesis ko chloroplasts chahiye, wahin respiration cytoplasm mein aur eukaryotes mein mitochondria mein chalta hai.

Baaki chapter ke liye do baatein zaroori hain. Energy ek jhatke mein nahi, balki chhoti-chhoti doses mein nikalti hai, aur har step ko uska apna enzyme chalata hai. Isme se koi bhi energy seedhe kaam nahi karti: pehle yeh ATP ke roop mein jama hoti hai, aur ATP wahin kharch hota hai jahan koi kaam karna ho, jaise root hair mein ek pump ya protein banata hua ribosome. Aur aadhe toote hue molecules phenke nahi jaate. Unke carbon skeletons doosre compounds banane ka starting material bante hain, yeh idea Section 12.6 mein phir aayega.

12.1 Kya Plants Saans Lete Hain?

Ek tarah se, haan. Plant cells din-raat respire karti hain, O₂ leti hain aur CO₂ chhodti hain, isliye gases ka andar-bahar aana-jaana chalta rehna chahiye. Phir bhi plant ke paas na lungs hain, na gills, aur na hi saans lene ki movements. Gases stomata aur lenticels se andar aati hain aur phir sirf diffusion se phailti hain.

Tees metre ka neem ka tree yeh kaise sambhaalta hai? Ek aise city ko socho jahan central air-conditioning nahi hai, aur har ghar bas apni khidkiyan khol leta hai. Plants ke liye yeh teen reasons se kaam karta hai:

1. Koi commuting nahi. City mein hawa ko kabhi truck mein bhar kar shehar ke paar nahi le jaana padta. Isi tarah leaf, stem aur root har ek apne paas ki hawa se gases ka len-den karte hain; plant ke paas organs ke beech O₂ le jaane ke liye na blood hai na pipes, aur unki zaroorat bhi nahi.
2. Dheema metabolism. Weight ke hisaab se dekho to aam ke tree ki roots ya trunk bakri ki muscles se kahin zyada dheere O₂ use karte hain, isliye diffusion saath de paata hai. Leaves bade gas volumes sirf photosynthesis ke dauraan handle karti hain, aur tab unke apne chloroplasts wahin O₂ bana rahe hote hain.
3. Chhoti doori. Diffusion sirf bahut chhoti dooriyon par tez hota hai, aur lagbhag har living plant cell hawa ke paas hoti hai. Ek leaf sirf kuch cells moti hoti hai. Trunk solid dikhta hai, lekin uski living cells bark ke neeche sirf ek patli sleeve banati hain, jahan hawa lenticels se pahunchti hai; beech ka hissa dead wood hai jo bas tree ko khada rakhta hai. Har jagah loosely packed parenchyma ke beech gaps rehte hain jo judkar air passages ka network banate hain.

Food ko seedhe jala kyun na diya jaaye? Glucose poori tarah jalkar CO₂ aur paani ban jaata hai:

Flame mein lagbhag saari energy heat aur light ban kar nikal jaati hai, jo molecules banane ke kisi kaam ki nahi. Cell iske bajaye glucose ko kai chhote steps mein todti hai, jaise chhat se koodne ke bajaye seedhiyan utarna. Zyaadatar steps thodi heat dete hain, lekin kai steps par release hui energy ATP banane ki cost ke barabar hoti hai, aur dono reactions jud jaate hain (Fig. 12.2). Yahi step-by-step release respiration ka poora idea hai. Respiration aur combustion ke start aur end points same hain, isliye dono same total energy release karte hain; fark sirf itna hai ki cell kitni energy pakad paati hai.

Jalne ke liye oxygen chahiye, aur cell mein glucose ke complete breakdown ke liye bhi. Phir bhi talaab ke tale ki mud ya achaar ke jar ke andar ke baare mein socho: wahan free oxygen nahi hai, phir bhi microbes khoob panapte hain. Kuch, jaise yeast, facultative anaerobes hain, jo O₂ use karne aur uske bina kaam chalaane ke beech switch karte hain. Doosre, jaise gehri mud mein Clostridium bacteria, obligate anaerobes hain, jinhe oxygen se hi nuksaan hota hai. Life isi tarah shuru hui thi, kyunki Earth ke early atmosphere mein lagbhag koi free O₂ nahi thi. Aaj ka har organism, yeast se lekar banyan tak, abhi bhi glucose ke pehle, oxygen-free stage ke enzymes rakhta hai: use pyruvic acid mein todna, ek pathway jise glycolysis kehte hain.

12.2 Glycolysis

Yeh naam do Greek words ko jodta hai, ek sugar ke liye aur ek todne ke liye. Glycolysis har living cell ke cytoplasm mein hota hai aur oxygen use nahi karta; anaerobic organisms mein yahi ek maatra respiratory process hai. Ek glucose molecule (chhe carbons) aanshik roop se oxidise hokar pyruvic acid ke do molecules (har ek mein teen carbons) banata hai. Kyunki teen biochemists ne milkar yeh sequence jodi thi, ise EMP pathway bhi kehte hain.

Plant mein glucose sucrose se aata hai, jo sugar leaves export karti hain, ya stored starch se. Enzyme invertase sucrose ko glucose aur fructose mein todta hai. Phir enzyme hexokinase ATP use karke glucose par ek phosphate jodta hai, jisse glucose-6-phosphate banta hai, jo rearrange (isomerise) hokar fructose-6-phosphate ban jaata hai. Fructose bhi phosphorylate hota hai aur yahin pathway mein jud jaata hai, isliye fructose-6-phosphate se aage dono sugars ek hi raaste par chalti hain. Das enzyme-catalysed reactions glucose ko pyruvate tak le jaate hain. Scroll karte hue un steps par nazar rakho jo ATP kharch karte hain, ATP banate hain ya NADH + H⁺ banate hain.

12.3 Fermentation

Pyruvic acid ek chauraaha hai. Cell iske saath kya karti hai, yeh organism par aur is baat par depend karta hai ki oxygen milti hai ya nahi (Fig. 12.4). O₂ ke saath pyruvate aerobic respiration mein poori tarah oxidise hota hai. O₂ ke bina kai prokaryotes, unicellular eukaryotes aur germinate hote seeds bhi ise ya to ethanol aur CO₂ mein ya lactic acid mein badal dete hain. Dono fermentation ke prakaar hain, jisme glucose sirf aanshik roop se oxidise hota hai aur oxygen ka koi role nahi hota.

Yeast jo alcoholic fermentation karta hai, usme har pyruvic acid par do enzymes kaam karte hain. Pyruvic acid decarboxylase ek CO₂ hataata hai, jisse acetaldehyde bachta hai, aur phir alcohol dehydrogenase NADH + H⁺ se hydrogen lekar acetaldehyde ko ethanol mein reduce karta hai. Lactic acid fermentation kuch bacteria karte hain (jaise dahi jamaane wala Lactobacillus), aur isme enzyme lactate dehydrogenase NADH + H⁺ ke saath pyruvic acid ko seedhe lactic acid mein reduce karta hai. Tumhari apni muscle cells bhi sprint ke dauraan yahi karti hain, jab O₂ itni tez nahi pahunch paati.

Aakhir yeh last step kyun? Glycolysis ko phir se dekho: PGAL → BPGA step ko NAD⁺ chahiye, aur cell ke paas iska sirf chhota sa stock hota hai. Oxygen ke bina NADH apna hydrogen respiratory chain ko nahi de sakta, to stock jaldi khatam ho jaata aur glycolysis ruk jaata. Fermentation hydrogen ko pyruvic acid (ya acetaldehyde) par utaar deta hai aur NAD⁺ wapas glycolysis ko de deta hai. Glycolysis ke baad koi ATP nahi banta, isliye fermentation se net sirf utne hi 2 ATP milte hain jo glycolysis kamaata hai.

Energy source ke roop mein yeh ghaate ka sauda hai. Glucose ki 7 per cent se kam energy hi bahar nikal paati hai, kyunki zyaadatar ethanol ya lactic acid mein band reh jaati hai, aur jo nikalti hai uska bhi sirf kuch hissa ATP ke roop mein pakda jaata hai. Products nuksaandeh bhi hain: acid ya alcohol unhi cells ke aas-paas jama hota hai jo use banati hain.

Glucose ki baaki energy tak pahunchne ka matlab hai use poori tarah, CO₂ aur paani tak, todna. Iske liye cell ko O₂ chahiye aur, agar woh eukaryotic hai, to uske mitochondria. Plants aur animals lagbhag hamesha isi tarah respire karte hain, aur yahi agle section ka topic hai.

12.4 Aerobic Respiration

Oxygen hone par pyruvic acid cytoplasm se nikal kar mitochondrion mein le jaaya jaata hai. Mitochondrion ko do kamron wala workshop samjho (Fig. 12.5). Matrix mein pyruvic acid ko khola jaata hai: uske hydrogen atoms thode-thode karke kheeche jaate hain, aur uske teen carbons teen CO₂ ban kar nikal jaate hain. Inner membrane par un hydrogens ke electrons aage-aage O₂ tak pahunchaaye jaate hain, aur raaste mein jo energy woh chhodte hain usse ATP banta hai.

Matrix ke andar har pyruvic acid pehle oxidative decarboxylation se guzarta hai. Ek bada enzyme complex, pyruvate dehydrogenase, ek carbon ko CO₂ ke roop mein aur do hydrogen atoms ko hataata hai, jo NAD⁺ ko milte hain. Jo do carbons bachte hain woh acetyl group hain, jo coenzyme A se jud kar acetyl CoA ke roop mein aage jaata hai. Is reaction ko NAD⁺, coenzyme A aur Mg²⁺ chahiye:

Ek glucose se do pyruvic acid bane the, isliye yeh step har glucose par 2 NADH + H⁺ aur 2 CO₂ deta hai. Ab acetyl CoA reactions ke ek loop mein jaata hai jise tricarboxylic acid cycle kehte hain, aur zyaadatar Krebs' cycle kehte hain, us biochemist ke naam par jisne ise samjha tha.

12.4.1 Tricarboxylic Acid Cycle

Is cycle ka naam iske pehle product, citric acid, par hai, jisme teen carboxyl (–COOH) groups hote hain. Ek four-carbon acceptor har two-carbon acetyl group ko pakadta hai, jude hue molecule ko phir se toda jaata hai, aur aakhir mein acceptor agle round ke liye taiyaar nikalta hai. Fig. 12.6 par Play dabao aur uske neeche diye numbered steps follow karo.

1. Entry. Acetyl group (2C) ek water molecule ke saath oxaloacetic acid, OAA (4C), se judta hai, aur citric acid (6C) banta hai. Enzyme citrate synthase hai, aur CoA free ho jaata hai taaki agla acetyl group la sake.
2. Do CO₂ nikalte hain. Citric acid rearrange (isomerise) hokar isocitrate banta hai. Phir lagaataar do oxidative decarboxylations hote hain, har ek ek carbon ko CO₂ ke roop mein hataata hai aur hydrogen NAD⁺ ko deta hai: isocitrate α-ketoglutaric acid (5C) banta hai, jo succinyl-CoA (4C) banta hai. Jitne carbons acetyl group laaya tha, utne nikal chuke hain.
3. Substrate se seedha phosphate. Jab succinyl-CoA succinic acid banta hai, to release hui energy GDP se GTP banati hai. Kyunki phosphate group electron transport system ki madad ke bina transfer hota hai, yeh substrate-level phosphorylation hai. Phir GTP woh phosphate ADP ko de deta hai, isliye cycle ki energy aakhir mein ATP mein pahunchti hai.
4. Ek alag hydrogen carrier. Succinic acid oxidise hokar fumaric acid banta hai, lekin is baar hydrogen FAD ko jaata hai, aur FADH₂ banta hai. Fumaric acid paani lekar malic acid banata hai.
5. Wapas start par. Malic acid oxidise hokar OAA banta hai, aur teesra NAD⁺ reduce hota hai. Acceptor phir se ban gaya hai aur agla acetyl group utha sakta hai.
6. Ek round. Har acetyl group 2 CO₂, 3 NADH + H⁺, 1 FADH₂ aur 1 ATP deta hai. Do cheezein is pahiye ko ghumaate rehti hain: har round ke end mein fresh OAA, aur NADH aur FADH₂ ke khaali hone ke baad khaali carriers (NAD⁺ aur FAD) ki lagaataar wapsi. Unhe khaali karna agle stage ka kaam hai.

Link reaction ko cycle ke ek round mein jodne se matrix mein ek pyruvic acid ki balance sheet milti hai:

Ek glucose ke liye ise double karo. Ab har carbon CO₂ ban kar nikal chuka hai, aur matrix mein 8 NADH + H⁺, 2 FADH₂ aur sirf 2 ATP hain. Dhyaan do kya missing hai: ek bhi O₂ use nahi hui, aur ATP ki ginti abhi bhi bahut chhoti hai. Dono paheliyan un bhare hue carriers, NADH aur FADH₂, se sulajhti hain.

12.4.2 Electron Transport System (ETS) aur Oxidative Phosphorylation

NADH aur FADH₂ high-energy electrons le jaate hain. Woh energy nikaalne ka matlab hai unhe oxidise karna, aur cell yeh unke electrons ko inner mitochondrial membrane mein carriers ki ek chain se guzaar kar karti hai, jab tak woh O₂ tak nahi pahunch jaate, jo protons bhi leti hai aur paani ban jaati hai. Electrons jis raaste se jaate hain woh electron transport system (ETS) hai.

Matrix mein bane NADH se electrons ke ek pair ko follow karo. Complex I (NADH dehydrogenase) NADH ko oxidise karta hai aur electrons ubiquinone (UQ) ko deta hai, jo ek chhota carrier hai aur membrane ke andar ghoomta hai. FADH₂, jo cycle mein succinate ke oxidation se banta hai, apne electrons complex II (succinate dehydrogenase) ke through ubiquinone ko deta hai. Reduced ubiquinone, jise ubiquinol kehte hain, electrons ko complex III (cytochrome bc₁ complex) ko deta hai. Wahan se woh cytochrome c tak jaate hain, jo ek chhota protein hai aur inner membrane par intermembrane space ki taraf wali side se dheela juda hota hai, aur electrons ko complex III se complex IV tak le jaata hai. Complex IV (cytochrome c oxidase, jisme cytochromes a aur a₃ aur do copper centres hote hain) aakhir mein unhe O₂ ko de deta hai (Fig. 12.7).

Complex V, ATP synthase, chain mein release hui energy ko cash karta hai, ADP aur inorganic phosphate ko jod kar ATP banata hai. Yield entry point par depend karti hai. NADH ka electron pair complex I se poora raasta tay karta hai aur 3 ATP ke barabar hai; FADH₂ ka pair ubiquinone par enter karta hai, complex I ko miss karta hai, aur sirf 2 ATP ke barabar hai.

Oxygen bilkul aakhir mein aati hai, phir bhi uske bina kuch kaam nahi karta. Final acceptor na ho to carriers electrons se bhare rehte hain, NADH oxidise nahi ho paata, NAD⁺ aur FAD khatam ho jaate hain, aur Krebs' cycle aur link reaction ruk jaate hain. Oxygen final hydrogen acceptor hai, expressway ke end ka exit: use block karo to traffic entry ramps tak jam ho jaata hai.

Process ka naam batata hai ki uski energy kahan se aati hai. Chloroplasts bhi isi kit (ek membrane, ek proton gradient, ek ATP synthase) se ATP banate hain, lekin wahan light gradient ko power deti hai, isliye woh photophosphorylation hai. Yahan power redox reactions se aati hai, yaani NADH aur FADH₂ ke oxidation se, isliye yeh oxidative phosphorylation hai.

Is mechanism, chemiosmosis, se tum Chapter 11 mein mil chuke ho. Yahan complexes I, III aur IV electron flow ki energy se protons ko matrix se bahar intermembrane space mein pump karte hain, aur unhe dam ke peeche paani ki tarah jama karte hain. ATP synthase us dam par lagi panchakki hai (Fig. 12.8). Iska F₀ part, membrane mein dhansa ek integral protein complex, sluice gate hai: woh akela darwaaza jisse protons matrix mein wapas aa sakte hain. Iska F₁ part, matrix ki taraf ek peripheral headpiece, chakki ka pathar hai, jisme woh site hai jahan ADP aur inorganic phosphate jude jaate hain. F₀ se apne electrochemical gradient ke neeche daudte protons F₁ mein catalysis chalaate hain; NCERT ke hisaab se har ATP ke liye 4 H⁺ ka guzarna zaroori hai.

12.5 Respiratory Balance Sheet

Kya hum gin sakte hain ki ek glucose kitne ATP ke barabar hai? Gin sakte hain, lekin sirf ek idealised cell ke liye, jaise ek auditor kisi factory ki value yeh maan kar lagaaye ki har machine poori speed par bina kuch waste kiye chal rahi hai. Yeh ginti tabhi sahi hai jab hum maan lein ki:

• pathway ek saaf-suthri assembly line ki tarah chalta hai, pehle glycolysis, phir Krebs' cycle, phir ETS, aur har product agle step ko milta hai;
• glycolysis ke dauraan cytoplasm mein bana NADH mitochondria mein pahunchta hai aur baaki ki tarah ETS se oxidise hota hai;
• koi bhi intermediate kisi doosre compound ko banane ke liye nikaala nahi jaata;
• glucose hi akela fuel hai, aur koi doosra substrate beech mein pathway mein nahi judta.

Asli cells in sab rules ko todti hain. Glycolysis, cycle aur ETS sab ek saath chalte hain, baari-baari nahi. Intermediates lagaataar doosre pathways se aate rehte hain ya unki taraf nikaale jaate hain. ATP kabhi jama nahi hota, kyunki bante hi use ho jaata hai, aur har enzyme ki speed kai controls se adjust hoti hai. Phir bhi yeh audit karna faydemand hai: nayi car ke liye bataaye gaye mileage ki tarah, yeh dikhata hai ki machine zyada se zyada kya kar sakti hai. In assumptions par ek glucose se net gain 38 ATP hota hai (Fig. 12.9).

Ab fermentation ko aerobic respiration ke saath rakh kar dekho:

12.6 Amphibolic Pathway

Respiratory pathway ko ek highway samjho jiske start par glucose hai. Starch aur sucrose glucose mein badalne ke baad wahin judte hain, isiliye glucose ko preferred fuel maana jaata hai. Fats aur proteins bhi respire ho sakte hain, lekin woh aage ke on-ramps use karte hain (Fig. 12.11).

• Fats pehle glycerol aur fatty acids mein tootte hain. Glycerol PGAL mein badal kar glycolysis ke beech mein judta hai. Fatty acids do-carbon wale tukdon mein kaate jaate hain jo acetyl CoA bante hain.
• Proteins ko proteases amino acids mein kaatte hain. Har amino acid apna amino group kho deta hai (deamination), aur jo bachta hai woh ek carbon skeleton hai jiski structure tay karti hai ki woh kaun sa on-ramp lega: kuch ke liye pyruvic acid, kuch ke liye acetyl CoA, aur baaki ke liye Krebs' cycle ka koi acid.

Respiration ko paramparik roop se catabolic pathway kaha jaata hai, kyunki yeh substrates ko todta hai. Lekin darwaaze dono taraf khulte hain. Jab sarson ka seed pak raha hota hai aur oil se bhar raha hota hai, tab acetyl CoA ko pathway se bahar nikaal kar fatty acids banaye jaate hain; jab woh seed germinate hota hai, to fatty acids wapas toot kar acetyl CoA bante hain aur respire hote hain. Isi tarah pyruvic acid, α-ketoglutaric acid aur OAA naye amino acids ke liye carbon skeletons ke roop mein nikaale jaate hain. Todna catabolism hai aur banana anabolism. Jo pathway dono kaam kare woh amphibolic pathway (amphi, dono) hai, aur respiratory pathway ke liye yeh naam catabolic se behtar hai.

12.7 Respiratory Quotient

Respire karte seed ke aas-paas ki gases naapo aur tum bata sakte ho ki woh kya jala raha hai. Trick yeh hai ki same time period mein do volumes ko compare karo: bahar di gayi CO₂ aur andar li gayi O₂. Inka ratio respiratory quotient (RQ) hai, jise respiratory ratio bhi kehte hain:

Poori tarah jale carbohydrate ke liye dono volumes barabar hote hain aur RQ 1 hota hai. (12.1) ko phir dekho: chhe O₂ andar jaati hain aur chhe CO₂ bahar aati hain, aur gas molecules ki barabar sankhya barabar volume gherti hai. Fats mein carbohydrates ke mukaable oxygen kam hoti hai, isliye sirf unke hydrogen ko paani banane ke liye hi bahut saari extra O₂ chahiye: unka RQ 1 se kam, lagbhag 0.7, hota hai. Proteins lagbhag 0.9 dete hain (Fig. 12.12).

Gas volumes respirometer mein naape jaate hain. Jis flask mein potassium hydroxide (KOH) bhi hota hai, woh seeds dwara chhodi gayi saari CO₂ sokh leta hai, isliye uska gas volume theek utna ghatta hai jitni O₂ use hui. Bina KOH wale jode ke flask ka volume use hui O₂ aur release hui CO₂ ke fark jitna badalta hai.

Asli tissues shaayad hi kabhi ek hi fuel par chalte hain. Jaise, naapa gaya RQ 0.85 ka matlab hai ki carbohydrate aur fat ka mix jal raha hai; koi bhi cell sirf pure fat ya sirf pure protein par nahi jeeti.