Organisms and Populations: Class 12 Biology Chapter 11 Hinglish mein

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

Published 12 Oct 2026 · Updated 12 Oct 2026

70 min
1 simulation
16 practice questions
24 MCQs

Is chapter mein aap kya seekhenge

Population ko define karo aur samjhao ki population ecology, ecology ko genetics aur evolution se kyun jodti hai
Per capita birth aur death rates calculate karo, aur sex ratios aur age pyramids ko interpret karo
Population density ka sahi measure chuno, jaise numbers, per cent cover, biomass aur indirect estimates
Natality, mortality, immigration aur emigration ke balance se population size ke changes predict karo
Exponential aur logistic growth equations derive aur apply karo, aur r aur carrying capacity K ka role samjhao
Breeding frequency aur offspring ki number aur size ke hisaab se life-history strategies compare karo
Interspecific interactions ko unke effects ke hisaab se classify karo, aur predation, competition, parasitism, commensalism aur mutualism ko examples ke saath samjhao

NCERT Biology Class 12, Chapter 11, pp. 188–204 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Ek peacock apni poonch phailata hai aur use itna kampata hai ki feathers khadakne lagte hain. Use dekh raha ek biologist do bilkul alag sawaal pooch sakta hai. Woh yeh kaise karta hai? Jawab muscles, nerves aur us tareeke mein hai jisse lambe train feathers skin se jude hote hain. Woh yeh kyun karta hai? Ab jawab peahens ke baare mein hai: kai generations tak, sabse shaandaar display wale males ne zyada chicks chhode. Pehli tarah ka sawaal mechanism dhoondhta hai; doosra poochta hai ki behaviour kis liye hai aur kaise aaya.

Dono tarah ke sawaal life ke organisation ke har level par pooche ja sakte hain, molecules aur cells se lekar poore landscapes tak. Book ki yeh aakhri unit us ladder ke top tak chadhti hai. Ecology (पारिस्थितिकी) yeh study karti hai ki organisms ek doosre ke saath aur apne non-living (abiotic) surroundings ke saath kaise interact karte hain: light, water, temperature aur soil. Ecologists chaar levels par kaam karte hain: akele organisms, ek species ki populations, kai species ki communities, aur biomes, yaani bade climatic zones jaise deserts, grasslands aur tropical forests Fig. 11.1.

4/4Ek biome: apni khaas tarah ki vegetation wala ek climatic zone.

Fig. 11.1Ecology chaar levels par kaam karti hai, aur har level apne pichhle level ko apne andar rakhta hai.NCERT p. 191

Rounded boxes, ek ke andar ek. Pehle step mein sirf sabse andar wala box bright hai: ek blackbuck, jis par organism likha hai. Doosre step mein agla box roshan hota hai: wahi blackbuck apni tarah ke teen aur ke saath, jis par population likha hai. Teesre step mein ek bada box unke aas-paas doosri species jodta hai, grass, ek tree aur ek wolf, jis par community likha hai. Aakhri step mein sabse bahar wale box par, jismein sun aur rain hain, biome: tropical grassland likha hai.

History seNCERT p. 189

Ramdeo Misra (1908–1998)

Ramdeo Misra ko aksar Indian ecology ka father kaha jaata hai. 1937 mein Leeds University se ecology mein doctorate karne ke baad woh Banaras Hindu University laut aaye aur wahan ek school banaya. Unke students ne naapa ki tropical grasslands aur forests kaise grow karte hain, disturbance ke baad kaise recover karte hain aur nutrients ko kaise recycle karte hain.

Indian ecologists ki kai generations apni training unhi se jodti hain: unhone desh ka pehla postgraduate ecology course banaya, aur unke pachaas se zyada doctoral students ne aage chalkar doosri jagahon par ecology teaching aur research shuru ki. Unhone government par environment ke liye planning karne ka zor bhi daala. 1972 mein bani National Committee for Environmental Planning and Coordination usi koshish se nikli aur usne 1980s mein ek poori environment ministry ki zameen taiyaar ki.

11.1 Populations

Hum ladder ke beech se shuru karte hain, yaani population (समष्टि) se. Population woh level hai jahan births, deaths aur evolution gine ja sakte hain, isliye yeh poochna shuru karne ki sabse natural jagah hai ki kisi jagah kitne organisms rehte hain aur woh number kyun badalta hai.

11.1.1 Population ke Attributes

Gujarat ke Velavadar National Park mein charte blackbuck socho, sheher ki jheel ko dhak leta water hyacinth, ya idli batter ke bowl mein badhte yeast cells. Har group ek population hai: ek species ke members jo ek hi jagah aur ek hi time par rehte hain, same food, water aur space use karte hain, aur kam se kam principle mein aapas mein breed kar sakte hain. Nature mein bilkul akele rehne wale organisms exception hain. Yeast zyadatar mating ke bajaye budding se badhta hai, phir bhi ecologists aise asexually bane groups ko bhi populations hi ginte hain.

Definition

Population

Ek species ke individuals ka group jo ek defined area mein same time par rehte hain, milte-julte resources use karte hain aur potentially interbreed kar sakte hain.

ExampleGir forest ke saare Asiatic lions.

Individuals ke bajaye populations ko kyun study karein? Kyunki evolution populations mein hota hai. Natural selection individuals ko chhaantta hai, lekin ek generation se agli generation tak jo badalta hai woh gene pool mein alleles ka mix hai, aur gene pool ek population ka hota hai (Chapter 6). Isse population ecology ek chauraahe par aa jaati hai: iske sawaal population genetics aur evolutionary biology ke saath share hote hain.

Kuch quantities sirf group ke liye hi matlab rakhti hain. Yeh poochna bekaar hai ki ek banyan tree kitni baar paida hota hai, lekin yeh poochna ki ek decade mein har maujooda banyan par kitne naye banyans aate hain, ek birth rate deta hai; deaths ke liye matching figure death rate hai. Ecologists dono ko per capita express karte hain, yaani pehle se maujood har individual ke hisaab se, taaki badi aur chhoti populations ko fairly compare kiya ja sake.

ExampleNCERT p. 191

Per capita birth aur death rates

Saal ki shuruaat mein ek forest herd mein 160 chital (spotted deer) hain. Saal bhar mein 48 fawns paida hote hain aur har umar ke 20 deer mar jaate hain. Saal ke liye per capita birth rate aur death rate nikaalo, aur per deer net change bhi.

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

Usi herd ke males aur females gino to tumhe uska sex ratio milta hai, ek aur number jo kisi ek deer ka nahi balki group ka hota hai. India ka census ise per 1000 males par females ke roop mein deta hai: 2011 mein 943. Kai deer aur antelope herds mein adult females males se zyada hote hain, kyunki young males zyada aksar herd chhod dete hain ya mar jaate hain.

Umar bhi alag-alag hoti hai. Ecologists aam taur par members ko teen classes mein baante hain: pre-reproductive (breed karne ke liye bahut chhote), reproductive aur post-reproductive. Har age group ka percentage ek horizontal bar ke roop mein banao, males left mein aur females right mein, bars ko sabse chhote age group ko neeche rakh kar stack karo, aur result ek age pyramid hai. Iski outline population ka future predict karti hai Fig. 11.2.

1/3Growing: bachchon ka chauda base jo jald breed karenge (triangle).

Fig. 11.2Ek pyramid, teen shapes: base ki width future bata deti hai.NCERT Fig. 11.1 · p. 192

Central line ke dono taraf chhe horizontal bars, males left mein aur females right mein, neeche 0–14 age se upar 75 aur usse zyada tak. Right side par brackets unhe pre-reproductive, reproductive aur post-reproductive mein group karte hain. Pehle step mein bars bahut chaude base se lagataar chhoti hoti jaati hain, yaani growing population. Doosre step mein neeche ki bars lagbhag barabar width ki hain, yaani stable population. Teesre step mein base beech ki bars se patla hai, yaani declining population.

Definition

Age pyramid

Horizontal bars ka ek diagram jo population ke har age group ka percentage dikhata hai, aam taur par males ek taraf aur females doosri taraf; iski shape batati hai ki population growing, stable ya declining hai.

India ka apna pyramid badal raha hai. 1971 mein iska base tezi se badhti population jaisa chauda tha. Jab se families chhoti hui hain, sabse chhote bachchon ki bars ka chauda hona ruk gaya hai, aur pyramid dheere-dheere bell mein badal raha hai. Japan aur Europe ke zyadatar hisse mein pehle se urn shape dikhti hai.

Sabse badhkar, ecologists individuals ki number track karte hain, jise $N$ likhte hain. Yeh is subject ki common currency hai: yeh jaanne ke liye ki kisi drought, nayi disease ya dam ne kisi species ko nuksaan pahunchaya ya nahi, woh pehle aur baad ka $N$ compare karte hain. Real values ki range bahut badi hai. 2018 mein wild mein sirf lagbhag 150 Great Indian Bustards bache hone ka estimate tha, jabki pond water ke sirf ek litre mein millions algal cells ho sakte hain.

Size ko aam taur par population density ke roop mein report kiya jaata hai, yaani per unit area ya volume amount. Ise naapne ka natural tareeka sir ginna hai, lekin jab individuals ke size mein bahut fark ho to yeh mislead kar sakta hai, aur runners se phailne wali grasses ke liye yeh saaf nahi hota, jahan ek plant agle mein mil jaata hai. Ek purane neem tree aur chaalis grass tufts wala plot yeh problem dikhata hai Fig. 11.3: count mein grass chaalis ke muqable ek se jeetti hai, phir bhi neem kahin zyada zameen par chhaaya karta hai aur kahin zyada living matter rakhta hai. Aise plants ke liye per cent cover (zameen ka woh hissa jo ek species dhakti hai) ya biomass (uske living tissue ka mass) behtar paimaana hai.

2/3Per cent cover: neem das guna zyada zameen par chhaaya karta hai.

Fig. 11.3Same do populations ko naapne ke teen tareeke (illustrative numbers).NCERT p. 192

Upar se dekha gaya ek square plot. Pehle step mein ek bada gol neem canopy aur chaalis chhote grass tufts dikhte hain, aur ek panel par likha hai: count, neem 1, grass 40. Doosre step mein canopy aur tufts shaded hain aur panel par likha hai: cover, neem lagbhag 40 per cent, grass lagbhag 4 per cent. Teesre step mein do horizontal bars biomass compare karti hain: neem ki bar lambi hai, lagbhag 1.5 tonnes, aur grass ki bar bahut chhoti, lagbhag 8 kilograms.

Definition

Population density

Per unit area ya volume population ka size, jo numbers, per cent cover ya biomass mein naapa jaata hai, jo bhi us species ko sabse achhe se describe kare.

Petri dish par bacteria ki ghani film ko tum kaise report karoge? Cells ginna naamumkin hai, lekin tum naap sakte ho ki colonies dish ka kitna hissa dhakti hain, liquid culture kitna dhundhla hai, ya cells ka dry mass kitna hai. Bahut badi populations ke liye aksar relative density kaafi hoti hai. Jaise malaria workers ponds mein ek ladle daalte hain aur har dip mein mosquito larvae ginte hain; yeh number real population ke saath upar-neeche hota hai, isliye poori ginti ke bina bhi trend dikha deta hai.

Kai populations ka estimate indirectly lagaya jaata hai, har jaanwar ko dekhe bina. Tiger surveys pehle pugmarks aur scats par depend karte the. Aaj All India Tiger Estimation forest trails ke saath camera traps bhi lagata hai aur har tiger ko uski unique stripes se pehchaanta hai; 2022 ke round ne India ki tiger population lagbhag 3700 batayi. Plant ecologists bhi per cent cover ka estimate isi tarah indirectly lagate hain: plot par random points girakar aur yeh dekhkar ki har point ke neeche kya hai. Neeche ka simulation tumhe yeh try karne deta hai.

SimulationRandom points se per cent cover estimate karo

Ground cover ke proportion mein teen sectors mein bata ek spinner: neem canopy 45, grass 15 aur bare soil 40, jin par canopy, grass aur bare soil likha hai. Buttons ek baar mein 1, 10, 100 ya 1000 random points girate hain, 10000 tak. Ek line chart dikhata hai ki points badhne ke saath neem canopy ke neeche gire points ka fraction kitna hai, true cover 0.45 ke against.

Fig. 11.4Har spin ek plot par ek random point girata hai jahan neem canopy 45 % zameen dhakta hai, grass 15 % aur bare soil 40 %. Neem ke neeche aane wale points ka share uska cover estimate karta hai.

Try karo

Kuch baar 10 points girao. Ek chhota sample 45 % se kitna door ho sakta hai?
1000 points tak chalte raho. Kya tumhara estimate 0.45 ke paas tik jaata hai?
Field ecologists aksar har plot par lagbhag 100 points use karte hain. Woh 10 000 ke bajaye wahin kyun ruk jaate honge?

11.1.2 Population Growth

Ek hi population ko saal-dar-saal gino, to number lagbhag kabhi repeat nahi hota. Iske changes hi ecologist ko batate hain ki population phal-phool rahi hai ya musibat mein hai. Causes kitne bhi complicated hon, har badhat ya girawat sirf chaar tarah ke events ka net result hoti hai: individuals paida hote hain, marte hain, aate hain ya chale jaate hain.

Natality ( $B$ ): period mein kitne individuals paida hote hain; births $N$ mein judte hain.
Mortality ( $D$ ): period mein kitne members marte hain; deaths $N$ se ghatti hain.
Immigration ( $I$ ): species ke woh members jo period ke dauraan bahar se habitat mein aate hain.
Emigration ( $E$ ): woh members jo period ke dauraan habitat se bahar jaakar kahin aur bas jaate hain.

Inmein se do population mein jodte hain aur do ghatate hain. Inhe saath rakho to ek simple balance sheet ban jaati hai Fig. 11.5.

6/6Ek saal baad: 400 + 150 + 30 − 120 − 40 = 420.

Fig. 11.5Campus ki sparrow population ki ek saal ki balance sheet.NCERT Fig. 11.2 · p. 193

Ek sparrow population ke ek saal ka waterfall chart. Pehle step mein ek akeli bar 400 ki starting population dikhati hai. Doosre step mein births ke liye ek green bar uske upar 150 badhti hai. Teesre step mein ek aur green bar 30 immigrants jodti hai aur 580 tak pahunchti hai. Chauthe step mein deaths ke liye ek vermillion bar 120 girti hai. Paanchve step mein emigrants ke liye doosri vermillion bar 40 girti hai. Aakhri step mein final bar nayi population, 420, dikhati hai.

Population density mein change

\begin{aligned} N_{t + 1} = N_{t} & + (B + I) \\ - (D + E) \end{aligned}

jahan

$N_{t}$: time $t$ par population density
$N_{t + 1}$: ek time step baad ki population density
$B, I$: step ke dauraan births aur immigrants
$D, E$: step ke dauraan deaths aur emigrants

Jab koi reservoir bharta hai ya lava island thanda hota hai, tab wahan birth dene ke liye abhi koi nahi hota. Pehle members ko udkar, tairkar ya behkar aana padta hai, isliye naye habitat mein population ki shuruaati growth immigration se chalti hai. Population establish hone ke baad balance doosri taraf jhuk jaata hai: zyadatar change births aur deaths se aata hai, aur migration mainly special cases mein matter karti hai. Dono tarah se rule simple hai: jab $B + I$ , $D + E$ se zyada ho to $N$ badhta hai, aur jab kam ho to ghatta hai.

Example

Balance equation ka use

Ek college campus par house sparrows ke survey mein March mein 400 birds milte hain. Agle saal campus par 150 young fledge hote hain, paas ki colonies se 30 birds aa jaate hain, 120 marte hain aur 40 chale jaate hain. Ek saal baad population kitni hai, aur processes ke kis pair ne zyada contribute kiya?

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

Growth ke models: exponential growth

Kya hum predict kar sakte hain ki time ke saath $N$ kaise badlega? Ecologists iska jawab simple mathematical models se dete hain. Do classic models, ek resources par bina limit ke aur ek limit ke saath, dikhate hain ki un limits se kya fark padta hai, aur yeh hamari apni species ke baare mein sochne mein bhi madad karte hain.

Maan lo kisi cheez ki kabhi kami nahi hoti: food, water aur space unlimited hain. Tab population ki growth sirf is par depend karti hai ki uske members kitni baar reproduce karte hain aur kitni baar marte hain. Maan lo $b$ per capita birth rate hai aur $d$ per capita death rate. Thode time mein har individual $b$ births aur $d$ deaths jodta hai, isliye poori population is rate se badalti hai

Exponential growth

\frac{d N}{d t} = (b - d) N = r N

jahan

$\frac{d N}{d t}$: time ke saath population size ke change ki rate
$r$: $b - d$ , intrinsic rate of natural increase (per unit time)

Yahan $r$ intrinsic rate of natural increase hai. Kyunki yeh births aur deaths ko ek number mein samet deta hai, ecologists isi paimaane ka use karte hain jab woh poochte hain ki koi pesticide, drought ya naya parasite kisi species ko nuksaan pahuncha raha hai ya nahi: jo bhi $b$ ko kam kare ya $d$ ko badhaye, woh $r$ ko kam karta hai. Insects aur bacteria jaisi chhoti, tezi se breed karne wali species ke $r$ values bade hote hain; elephants aur humans jaise bade, dheere breed karne walon ke chhote.

Definition

Intrinsic rate of natural increase (

r

)

Per capita birth rate minus per capita death rate, $r = b - d$ , jo per unit time naapa jaata hai; yeh population ki grow karne ki built-in capacity naapta hai.

Chalo explore kareinNCERT p. 194

Aaj India ka r kya hai?

Tumhe chahiye

latest Sample Registration System (SRS) bulletin, jo Registrar General of India se milta hai
ek calculator

Pehle guess karo

1981 se India ka birth rate lagataar gira hai. Tab ke muqable aaj uske

r

ke liye tum kya expect karte ho?

ChhotaBadaLagbhag same

Latest bulletin mein India ka crude birth rate aur crude death rate dhoondho. Dono per 1000 log per year diye gaye hain.
Har ek ko 1000 se divide karke per capita rate mein badlo.
Ghatao: $r = b - d$ . Apna answer per year note karo.
Apne state ke liye dohrao aur compare karo.

Table 11.1Tumhara calculation

	India	Mera state
Births per 1000
Deaths per 1000
$r$ per year

Tumhari entries apne aap save hoti hain.

Kyunki $d N / d t$ , $N$ ke proportional hai, population jitni badi hoti hai, utni tezi se badhti hai. Isliye time ke against $N$ ka graph lagataar zyada steep hokar upar mudta hai aur ek J-shaped curve banata hai Fig. 11.6. Yeh exponential growth hai, jise geometric growth bhi kehte hain. Thode calculus se hum $N$ ko hi time ke function ke roop mein likh sakte hain.

DerivationExponential growth equation ka integration

$\frac{d N}{d t} = r N$ mein variables alag karo, $N$ ko ek taraf aur $t$ ko doosri taraf rakho, aur time $0$ (size $N_{0}$ ) se time $t$ (size $N_{t}$ ) tak integrate karo:

\int_{N_{0}}^{N_{t}} \frac{d N}{N} = \int_{0}^{t} r d t

jisse milta hai

\ln N_{t} - \ln N_{0} = r t

Dono sides ka exponential lo:

Integral form

N_{t} = N_{0} e^{r t}

jahan

$N_{t}$: time $t$ ke baad population density
$N_{0}$: time zero par population density
$e$: natural logarithms ka base, lagbhag 2.718

$N_{t} = 2 N_{0}$ rakhne par doubling time milta hai, jo same rehta hai chahe population pehle se kitni bhi badi ho: $t_{d} = \ln 2 / r \approx 0.693 / r$ .

Example

Double hone wala weed

Garam, nutrient-rich paani mein water hyacinth ki mat ek-do hafte mein apna area double kar sakti hai. Maan lo yeh har 8 din mein double hoti hai, aur 2 m² dhakne wali ek mat 1 km² (1 000 000 m²) area wali jheel mein tairti hui aati hai. Exponential growth maan kar nikaalo (a) $r$ , (b) 64 din baad area aur (c) lagbhag kitne time mein mat poori jheel dhak legi.

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

Quick check

3 mein se 1

Bacteria ka ek culture

r = 0.035

per minute ke saath exponentially grow karta hai. Minutes mein iska doubling time kya hai?

min

Answer dekho

Answer 19.8 min

t_{d} = \ln 2 / r = 0.693 / 0.035 \approx 19.8

min, jo achhe se khilaye gaye E. coli ke 20-minute doubling ke kareeb hai. 1 ko

r

se divide karna (lagbhag 28.6) aam galti hai.

Logistic growth

Real habitats mein jagah khatam ho jaati hai. Sugar solution ke flask mein yeast ya fenced island par deer socho: der-saber har naya member baaki sab ke liye kam food ka matlab hai. Bheed same species ke members ke beech competition tez karti hai, isliye births girte hain aur deaths badhti hain. Population dheere-dheere habitat ke resources se tay ek ceiling ki taraf badhti hai, jo uski carrying capacity, $K$ , hai.

Definition

Carrying capacity (

K

)

Kisi species ki sabse badi population jise ek habitat apne available resources se hamesha ke liye support kar sakta hai.

Aisi population ko time ke against plot karo to ek S-shaped (sigmoid) curve dikhta hai, jise logistic growth kehte hain, ya Verhulst–Pearl logistic growth, us mathematician aur biologist ke naam par jinhone ise describe kiya. Iske stages ke naam hain. Lag phase mein kuch founders bas rahe hote hain, isliye numbers dheere badhte hain. Acceleration phase mein zyada breeders hote hain aur food abhi bhi kaafi hota hai, isliye growth tez hoti hai. Aadhe raaste ke baad kami mehsoos hone lagti hai aur growth decelerate hoti hai. Aakhir mein $N$ , $K$ ke kareeb ek asymptote ke saath level off ho jaata hai.

Logistic growth

\frac{d N}{d t} = r N (\frac{K - N}{K})

jahan

$N$: time $t$ par population density
$r$: intrinsic rate of natural increase
$K$: carrying capacity

Bracket ko ek brake ki tarah padho. Jab $N$ bahut chhota ho, $(K - N) / K$ lagbhag 1 hota hai aur growth lagbhag exponential hoti hai. Jab $N = K / 2$ , brake growth ko aadha kar deta hai, lekin kyunki ab $N$ bada hai, per unit time judne wali number, $r K / 4$ , apne sabse zyada par hoti hai. Jaise-jaise $N$ , $K$ ke paas aata hai, bracket zero ki taraf girta hai aur growth ruk jaati hai. Agar $N$ kabhi $K$ se aage nikal jaaye, to bracket negative ho jaata hai aur population wapas ghat jaati hai.

3/4Lag, acceleration, deceleration aur $K$ par asymptote.

Fig. 11.6Same start se exponential (J) aur logistic (S) growth.NCERT Fig. 11.3 · p. 194

Time ke against population size ke axes. Pehle step mein sirf ek J-shaped exponential curve bana hai, jo lagataar zyada steep hokar upar jaata hai, aur dots har doubling mark karte hain. Doosre step mein ek dashed horizontal line carrying capacity K mark karti hai aur ek S-shaped logistic curve upar uthkar uske thoda neeche level off ho jaata hai. Teesre step mein chaar labels S-curve ke saath phases ke naam batate hain: lag, acceleration, deceleration aur asymptote. Aakhri step mein ek tangent line S-curve ko K ke aadhe par chhooti hai, jahan woh sabse steep hai, aur us par fastest growth likha hai.

Example

Brake sabse strong kahan hai?

Water fleas (Daphnia) ki ek pond population ka $r = 0.4$ per week aur carrying capacity 1000 hai. $N$ = 100, 500 aur 900 par $d N / d t$ nikaalo.

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

InteractiveGrowth model explorer

Time ke against population size ka graph, jismein same starting size se do curves hain: ek exponential J-curve aur ek logistic S-curve jo dashed carrying-capacity line par level off hota hai. Sliders intrinsic rate of increase r, carrying capacity K aur starting size set karte hain. Buttons koi ek curve ya dono dikhate hain, aur Play time ke saath ek marker chalata hai, jise ek time slider bhi control karta hai. Readouts chune gaye time par dono population sizes, logistic growth rate dN/dt aur uska brake factor, doubling time aur woh time dete hain jab logistic population K ke aadhe tak pahunchti hai. Ek status line samjhati hai ki kya ho raha hai.

Fig. 11.7Starting size,

r

aur

K

set karo, phir Play dabao aur ek exponential aur ek logistic population ko saath-saath grow hote dekho.

Dono models mein se logistic model nature mein behtar fit hota hai, kyunki har real population der-saber kisi limit se takraati hai. Phir bhi yeh ek simplification hai. Koi herd $K$ se aage nikal kar crash ho sakta hai, numbers $K$ ke aas-paas cycle kar sakte hain, aur $K$ khud wet season mein badhta hai aur dry season mein ghatta hai.

Try karke dekhoNCERT p. 196

India par kaun sa curve fit hota hai?

Tumhe chahiye

graph paper ya spreadsheet
neeche diye census totals (millions)

Pehle guess karo

Plot karne se pehle guess karo: 1901 se 2011 tak India ki population ka curve kaun si shape dikhayega?

J-curve jo lagataar steep hota ja raha haiJ-curve jo mudna shuru ho raha haiFlat line

Table 11.2Har census par India ki population (millions, rounded)

Year	Population
1901	238
1921	251
1941	319
1961	439
1981	683
2001	1029
2011	1211

Year ke against population plot karo.
Har 20-saal ke gap mein growth ko percentage mein nikaalo.
Tay karo ki curve kis model jaisa dikhta hai, aur kin saalon mein.

Table 11.320 saal mein growth

Period	% growth
1921–41
1961–81
1981–2001

Tumhari entries apne aap save hoti hain.

1921 tak growth dheemi aur uneven thi (famine aur epidemic wale ek decade mein to dip bhi aaya). Tab se lagbhag 1981 tak curve exponential dikhta hai: 1921–41 mein lagbhag 27 % growth aur 1961–81 mein 56 %. Uske baad percentage gira hai (1981–2001 mein 51 %, 2011 tak ke ek hi decade mein lagbhag 18 %), isliye curve mudna shuru ho raha hai. Lekin insaanon ke liye yeh brake mainly choice se aaya hai, kyunki families chhoti hui, kisi fixed carrying capacity se nahi.

Quick check

3 mein se 1

Logistic equation mein, jab population apni carrying capacity tak pahunchti hai to

d N / d t

ka kya hota hai?

Yeh zero ho jaata haiYeh apne maximum par pahunchta haiYeh

r

ke barabar hota haiYeh negative ho jaata hai

Answer dekho

Answer (A) Yeh zero ho jaata hai

N = K

par factor

(K - N) / K

zero hai, isliye growth ruk jaati hai. Maximum growth rate pehle aata hai,

N = K / 2

par. Yeh negative tabhi hota hai jab

N

K

se aage nikal jaaye.

11.1.3 Life History mein Variation

Har organism ke paas energy ka limited budget hota hai, jise use zinda rehne, grow karne aur reproduce karne ke beech baantna padta hai. Natural selection us batwaare ko favour karta hai jo sabse zyada surviving descendants chhode, yaani sabse high reproductive ya Darwinian fitness (population ke liye high $r$ ). Isse growth, breeding aur death ka jo pattern banta hai, woh species ki life history hai, aur yeh ek species se doosri species mein kamaal ka alag hota hai.

Ek fark yeh hai ki species kitni baar breed karti hai. Kerala aur Tamil Nadu ki pahadiyon par Neelakurinji shrubs baarah saal mein ek baar dhalaanon ko neele rang se dhak dete hain aur phir mar jaate hain; kai bamboos decades baad ek baar flower karke mar jaate hain; Pacific salmon ek baar nadi mein upar ki taraf tairti hain, spawn karti hain aur mar jaati hain. Aisi species sab kuch ek hi breeding event par daav par lagati hain. Doosri species, jaise mango trees aur zyadatar birds aur mammals, season-dar-season breed karti hain.

Doosra choice yeh hai ki offspring ke liye available energy ko kaise baanta jaaye. Ek oyster millions chhote eggs chhodta hai aur unhe samundar ke bharose chhod deta hai; orchids dhool jaise baareek seeds bikherte hain. Doosri extreme par ek elephant cow ek calf ko lagbhag 22 mahine pet mein rakhti hai aur phir saalon tak use doodh pilaati hai, aur ek coconut har seed mein bada food store bhar deta hai. Kam survival wale kai saste offspring, ya achhe survival wale kuch mehenge offspring Fig. 11.8?

3/3Number versus size: same energy se kai chhote ya kuch bade offspring milte hain.

Fig. 11.8Do choices jo har life history karti hai.NCERT p. 196

Ek grid jismein do rows hain, breed once aur breed many times, aur do columns, many small offspring aur few large offspring. Pacific salmon aur bamboo breed-once, many-small cell mein hain; breed-once, few-large cell par rare likha hai. Oysters aur orchids breed-many-times, many-small cell mein hain; elephants, humans aur coconut palms breed-many-times, few-large cell mein. Pehle step mein upar wali row highlight hoti hai, doosre step mein neeche wali row, aur teesre step mein columns ke beech ek do-muhi arrow number aur size ke beech trade-off dikhata hai.

Koi bhi strategy har jagah nahi jeetti. Kai saste offspring wahan faayde mein rehte hain jahan conditions unpredictable hon aur parents kuch bhi karein, zyadatar young mar hi jaate hain, jaise khule samundar mein spawn karne wale oysters. Kuch young par bhaari investment bheed wale, stable habitats mein faayda deta hai, jahan achhe se khilaya-pilaya aur well-protected bachcha doosron ko competition mein pachhaad sakta hai. Isliye kisi species ki life history uske habitat ki physical conditions aur wahan rehne wali doosri species, dono ko reflect karti hai, aur khaas cases ko samjhaana abhi bhi research ka ek lively field hai.

Quick check

2 mein se 1

Har organism ko uske life-history pattern se match karo.

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

Answer dekho

Answer

Pacific salmon : ek baar breed karti hai, kai eggs
Oyster : aksar breed karta hai, millions chhote eggs
Elephant : aksar breed karta hai, ek bada calf

Salmon ek baar spawn karke mar jaati hai; oysters baar-baar bahut saare chhote eggs ke saath spawn karte hain; elephants kai baar breed karte hain lekin har calf par bhaari investment karte hain.

11.1.4 Population Interactions

Ek bageeche ke ek mango tree ko dhyaan se dekho. Caterpillars uski leaves chabate hain, bees aur flies uske flowers par aati hain, birds aur bats uske fruit le jaate hain, aur fungi aur bacteria uski giri hui leaves ko break down karte hain, jisse minerals nikalte hain jinhe uski roots phir se le leti hain. Koi bhi species akele nahi reh sakti; ek green plant bhi, jo apna food khud banata hai, nutrients recycle karne ke liye decomposers par aur aksar apna pollen le jaane ke liye animals par depend karta hai. Ek jagah share karne wali populations ek community banati hain, jo kai links se judi hoti hai, kuch saaf dikhte hain aur kuch chhupe hue.

Ecologists in links ko ek simple code se sort karte hain. Interaction mein shaamil dono species mein se har ek ke liye poocho: kya use faayda (+) hota hai, nuksaan (−) hota hai, ya koi effect nahi (0)? Tab har interspecific interaction, yaani alag species ki populations ke beech ka interaction, ko signs ka ek pair milta hai Fig. 11.9.

4/4Ek par koi effect nahi: commensalism (+, 0) aur amensalism (−, 0).

Fig. 11.9Interaction ka naam har partner par uske effect se rakho.NCERT Table 11.1 · p. 197

Ek grid jismein species A par effect rows hain (plus, zero, minus) aur species B par effect columns (plus, zero, minus). Diagonal ke neeche ke cells mirror images hone ki wajah se grey hain. Pehle step mein sirf signs dikhte hain. Doosre step mein plus-plus cell mein mutualism aur minus-minus cell mein competition aata hai. Teesre step mein plus-minus cell mein predation aur parasitism aate hain. Aakhri step mein plus-zero cell mein commensalism, zero-minus cell mein amensalism aur zero-zero cell mein neutralism aata hai.

Sign pairs se definitions yaad rakhna aasaan ho jaata hai: mutualism (+, +), competition (−, −), predation aur parasitism (+, −), commensalism (+, 0) aur amensalism (−, 0). Amensalism sabse kam jaana-pehchaana hai. Blue-green mould Penicillium penicillin chhodta hai, jo uske aas-paas ke bacteria ko maar deta hai, jabki mould ko koi saaf faayda nahi hota. Yeh bhi dekho ki partners kitne paas hote hain: predators, parasites aur commensals aam taur par us species ke direct contact mein rehte hain jise woh exploit karte hain ya jiske peechhe chalte hain, jabki competitors shayad kabhi milte bhi nahi.

Predation

Predator kisi doosre living organism, yaani apne prey, ko khata hai. Definition jitni lagti hai usse zyada broad hai: hedge charne wali goat aur grain khane wala field mouse bhi living cheezein khate hain, isliye ecologists herbivores ko plants ke predators maante hain. Predation (परभक्षण) community ke liye teen tarah se important hai. Pehla, yeh energy ko food chain mein upar le jaata hai: plants sunlight se jo energy pakadte hain, woh plant tissue mein hi band rehti agar unhe koi na khata.

Doosra, predators prey numbers ko regulate karte hain. Apne dushmanon se azaad hokar ek prey species itna badh sakti hai ki poore ecosystem ko destabilise kar de. Isiliye kisi nayi jagah le jaayi gayi species itni aksar invasive ban jaati hai. Australia ne yeh mushkil se seekha: colonial era mein laaya gaya prickly pear cactus (Opuntia) 1920s ke beech tak lagbhag 24 million hectares farmland par chha gaya tha. 1926 mein scientists ne ek South American cactus moth chhoda jiske caterpillars cactus pads mein surang banate hain, aur kuch hi saalon mein zyadatar infested zameen saaf ho gayi.

Yahi biological control ka basis hai: kisi pest ko regulate karne ke liye uske natural predator ya parasite ka use karna. India ne weed Parthenium (congress grass) ke khilaaf Mexican beetle Zygogramma bicolorata chhoda, aur water hyacinth ke khilaaf genus Neochetina ke weevils. Aphids ko chat kar jaane wale ladybird beetles kheton aur gardens mein yahi kaam karte hain.

Teesra, predators apne aas-paas ki species ki variety ko bacha sakte hain. 1960s mein Washington state ke rocky shores par Robert Paine shore ke ek hisse se starfish Pisaster ko baar-baar hatate rahe. Apne main predator se azaad hokar mussels rock par phail gaye aur un barnacles, limpets aur doosre animals ko bahar kar diya jo pehle use share karte the Fig. 11.10. Sabse strong competitor ko khakar predator baaki species ke liye jagah bana raha tha.

3/3Mussels jagah par kabza kar lete hain; species ki number 15 se girkar 8 ho jaati hai.

Fig. 11.10Ek predator jo ek strong competitor ko control mein rakhta hai (Paine ke experiment par based).NCERT p. 198

Mussels, barnacles, limpets, chitons aur algae wala rocky shore ka ek strip, aur mussels kha rahi ek starfish; ek counter par 15 species likha hai. Doosre step mein starfish par cross lagta hai aur use hata diya jaata hai. Aakhri step mein, kuch saal baad, mussels zyadatar rock ko dhak lete hain, kai tarah ke animals gayab ho jaate hain aur counter par 8 species likha hai.

Prey passive nahi hote. Kai generations mein woh dhoondhe jaane, pakde jaane ya khaye jaane se bachne ke tareeke evolve karte hain. Indian dead-leaf butterfly apne wings ko mod kar bilkul sookhe patte jaisi dikhti hai, aur stick insects aur leaf-litter frogs apne background mein gayab ho jaate hain: woh camouflaged (cryptically coloured) hote hain. Kuch doosre prey poisonous ya bure taste wale hote hain, aur jo bird ek ko try karta hai woh shayad hi doosra try kare. India ki plain tiger butterfly iska example hai: iske caterpillars Calotropis khate hain aur plant ke toxins ko apne andar rakh lete hain, jaise Americas ki mashhoor Monarch butterfly milkweed ke saath karti hai. Predators bhi control mein rehte hain, kyunki itna efficient predator jo apne prey ko khatam kar de, jald hi bhookha mar jaayega; nature mein successful predators 'prudent' (samajhdaar) hote hain.

Herbivores plant world ke predators hain, aur insects inka sabse bada group hain. Ek jagah jadon se bandha plant bhaag nahi sakta, isliye use khud ko khaane mein mushkil banana padta hai. Sabse common physical defences thorns aur spines hain, jaise babul (Acacia), ber aur cacti par; chubhne wale hairs aur sakht, silica-rich leaves bhi madad karte hain. Kai defences dikhte nahi: aise chemicals jo animal ko beemar kar dein, uska khaana ya digest karna rok dein, uski breeding mein dakhal dein ya use maar dein comparison dekho.

Compare

Prey aur plants kaise jawab dete hain

Prey animals

Camouflage: dead-leaf butterfly, stick insects aur leaf-litter frogs
Poison ya bura taste: Monarch aur plain tiger butterflies
Chamakdaar warning colours jo poison ka elaan karte hain
Speed, alertness aur herds mein rehna

Plants

Thorns aur spines: babul, ber, cacti
Leaves par chubhne wale ya chipchipe hairs
Poisons: Calotropis cardiac glycosides banata hai, isliye goats aur cattle use nahi khate
Kadve ya toxic chemicals: nicotine, caffeine, quinine, strychnine, opium alkaloids

Kisi chhode hue khet ke paas se guzro to shayad tumhe chari hui thoonth ke beech Calotropis (aak) bina chhue khada dikhe: iske cardiac glycosides itne poisonous hain ki cattle aur goats ise chhod dete hain. Log jo kai plant products ikattha karte hain, jaise tea aur coffee ki caffeine, tobacco ki nicotine aur cinchona bark ki quinine, unki shuruaat isi tarah ke deterrents ke roop mein hui thi.

Definition

Predation

Ek interaction jismein ek species (predator) doosri species (prey) ko maarkar khati hai ya us par feed karti hai; herbivory, yaani animals ka plants khana, iska ek form hai.

Competition

South-western United States ke deserts mein seed khane wale ants aur seed khane wale rodents same seeds ikattha karte hain. Jab ecologists ne kuch plots se rodents ko fence lagakar bahar rakha, to wahan ant colonies badh gayi; jab unhone ants ko hataya, to rodents badh gaye. Ants aur rodents ek doosre se lagbhag utne hi unrelated hain jitne do animals ho sakte hain, phir bhi har ek doosre ko rok raha tha. Yeh competition (प्रतिस्पर्धा) hai, aur yeh roz ki us picture se zyada broad hai jismein do kareebi relatives kisi kam resource ke liye ladte hain.

Resource ka kam hona bhi zaroori nahi. Interference competition mein ek species doosri ko seedhe rokti hai, use bhaga kar, uske aas-paas ko ganda karke ya bas raaste mein aakar, isliye victim kam efficiently feed karta hai, tab bhi jab food aur space bharpoor hon. Kyunki competition in sab tareekon se kaam kar sakta hai, ecologists ise uske result se define karte hain, yaani usse hone wala fitness ka nuksaan.

Definition

Competition

Species ke beech ek interaction jismein ek ki maujoodgi doosre ki fitness ko saaf taur par kam karti hai, jo uske intrinsic rate of increase $r$ mein girawat se naapi jaati hai.

Darwin ne species ke beech competition ko evolution ki ek powerful force maana, aur Russian ecologist G. F. Gause ne 1930s mein is idea ko experiment se test kiya. Unhone Paramecium ki do species ko same bacterial food wali tubes mein grow kiya. Akele har ek achhe se badhi; saath mein, ek ne hamesha doosri ko extinct kar diya. Wild mein yahi baat saabit karna kahin mushkil hai, lekin kuch cases bahut kuch kehte hain. Galápagos ke Pinta (Abingdon) Island par giant tortoises, jo whalers ki wajah se pehle hi kam ho chuke the, unka saamna 1959 mein chhodi gayi goats se hua jinhone woh vegetation saaf kar di jise tortoises khate the. 1971 mein dhoondhne walon ko sirf ek survivor mila, 'Lonesome George', aur 2012 mein uske saath hi species khatam ho gayi.

Scotland ke rocky coast par Joseph Connell ke experiments ne zyada saaf evidence diya Fig. 11.11. Chhota barnacle Chthamalus shore par upar, bade Balanus se upar rehta hai, halaanki iske larvae neeche bhi settle hote hain. Jahan Connell ne Balanus ko rock se khurach kar hataya, wahan young Chthamalus neeche wale zone mein bhi survive karke bade hue. Jo species kisi stronger competitor ke hatne par phail jaati hai, woh competitive release dikhati hai. Is tarah ki field studies yeh bhi batati hain ki competition ka asar carnivores se zyada plants aur herbivores par padta hai.

4/4Balanus ko hatao to Chthamalus neeche bhi achhe se badhta hai: competitive release.

Fig. 11.11Connell ke barnacles: ek species ko doosri species neeche wale shore se bahar rakhti hai.NCERT p. 199

High-tide aur low-tide lines ke beech ek rocky shore. Pehle step mein chhote Chthamalus barnacles upar wale zone mein aur bade Balanus barnacles neeche wale zone mein hain. Doosre step mein young Chthamalus dono zones mein settle hote hain. Teesre step mein neeche wale zone ke young Chthamalus Balanus se kuchal kar dab jaate hain aur gayab ho jaate hain. Aakhri step mein neeche wale zone ke ek patch se Balanus khurach kar hata diya gaya hai aur ab wahan bhi Chthamalus badh rahe hain, jis par competitive release likha hai.

PrincipleGause ka Competitive Exclusion Principle

Do kareebi related species jo same limiting resources ke liye compete karti hain, hamesha ke liye saath nahi reh sakti; kamzor competitor aakhir mein khatam ho jaata hai.

Agar yeh principle hamesha sach hota, to North American forests mein paanch bahut milti-julti warbler species same spruce trees kaise share kar paati? Robert MacArthur ne 1950s mein unhe dhyaan se dekha aur paaya ki har species zyadatar tree ke apne hisse mein insects ka shikaar karti thi Fig. 11.12, isliye unki diets ka overlap pehli nazar se kahin kam tha. Kisi resource ko is tarah jagah, time ya feeding method ke hisaab se baantna resource partitioning kehlata hai; hawks aur owls din ke alag-alag time par shikaar karke rodent prey share karte hain. Exclusion tabhi expected hai jab resources limiting hon aur baaki kuch na badle, aur nayi studies dikhati hain ki competitors aksar aise differences evolve kar lete hain jinse woh saath reh paate hain.

2/3Har species zyadatar tree ke apne hisse mein shikaar karti hai.

Fig. 11.12Paanch warblers, ek tree, paanch zones (MacArthur ki study ke aadhaar par).NCERT p. 199

Trunk ke saath stacked triangles ke roop mein bana ek lamba conifer. Pehle step mein uske bagal mein paanch warbler species ki list hai, jo sab same tree mein feed karti hain. Doosre step mein tree A se E label wale feeding zones mein bat jaata hai: top, upper crown ki bahari branches, beech ka bahari hissa, trunk ke paas beech ka andar wala hissa, aur sabse neeche ki branches. Aakhri step mein ek note kehta hai ki har species zyadatar apne zone mein feed karti hai, isliye unke beech competition kam hota hai.

Quick check

3 mein se 1

Nature mein competition ka sabse achha evidence kaun sa observation hai?

Do species laboratory tube mein same food khati hainCompetitor ko hatane ke baad ek species naye zone mein phail jaati haiDo related species ek jaisi dikhti hainEk species doosri se badi hai

Answer dekho

Answer (B) Competitor ko hatane ke baad ek species naye zone mein phail jaati hai

Competitive release dikhata hai ki competitor doosri species ki range ko limit kar raha tha. Laboratory tube artificial conditions mein competition dikhati hai, nature mein nahi.

Parasitism

Kisi doosre organism ke upar ya andar rehne se parasite ko food aur shelter pakka mil jaata hai, aur parasitism (परजीविता) plants, fungi, protists, worms, insects aur yahan tak ki birds mein bhi alag-alag, independently paida hua hai. Kai parasites sirf ek host species ka use kar sakte hain. Aise pairs ek evolutionary arms race, yaani co-evolution, mein fanse hote hain: host jo bhi naya defence evolve karta hai, jaise parasite ko pehchaanne ki koi immune trick, woh un parasites ko select karta hai jo usse bach sakein, aur yeh silsila chalta rehta hai.

Tapeworm dikhata hai ki yeh lifestyle body ke saath kya karta hai. Yeh hooks aur suckers se gut wall se chipka rehta hai, iski koi eyes ya doosre sense organs nahi hote, aur iska gut bilkul nahi hota, kyunki yeh host ka pehle se digest kiya hua food soakh leta hai. Iski zyadatar body eggs se bhare segments ki ek chain hoti hai. Parasites mein bahut zyada output common hai: ek female roundworm (Ascaris) ek din mein lagbhag 200 000 eggs de sakti hai, kyunki unka sirf ek chhota sa hissa hi kabhi naye host tak pahunchega.

Naye host tak pahunchna parasite ki life ka sabse mushkil hissa hai, aur kai parasites ise complicated life cycles se solve karte hain. Kuch main host tak pahunchne se pehle ek ya do intermediate hosts se guzarte hain. Jaise Chinese liver fluke ko pehle ek snail aur phir ek fish chahiye, aur yeh un logon ko infect karta hai jo woh fish kachchi ya adhpaki khate hain Fig. 11.13. Kuch doosre ek vector par depend karte hain jo unhe hosts ke beech le jaata hai, jaise malaria parasite mosquitoes par depend karta hai (Chapter 7).

4/5Larvae snail ko chhodkar ek fish (second intermediate host) mein cysts banate hain.

Fig. 11.13Do intermediate hosts liver fluke ko wapas uske main host tak le jaate hain.NCERT p. 200

Arrows se jude paanch stations ka ek gol cycle. Pehla, adult flukes human liver ki bile ducts mein rehte hain. Doosra, unke eggs faeces ke saath bahar nikal kar fresh water tak pahunchte hain. Teesra, ek snail, yaani first intermediate host, eggs kha leta hai aur larvae uske andar multiply hote hain. Chautha, free-swimming larvae snail ko chhodkar ek fish, yaani second intermediate host, mein ghus jaate hain, jahan woh uske flesh mein cysts banate hain. Paanchva, koi insaan woh fish kachchi ya adhpaki khata hai aur young flukes liver tak pahunch jaate hain, aur cycle poora ho jaata hai.

Parasite ka faayda uske host ka nuksaan hai. Infected hosts dheere grow kar sakte hain, kam breed kar sakte hain aur kam umar mein mar sakte hain, aur parasites se kamzor hua host predator ke liye pakadna aasaan hota hai. Isliye bhaari parasite load host population ki density ko neeche kheench sakta hai.

Parasites ko is hisaab se group kiya ja sakta hai ki woh kahan rehte hain. Ectoparasites host ke bahar rehte hain: insaanon ke baalon mein head lice, dogs aur cattle par ticks, aur woh copepods jo kai marine fish ki skin aur gills se chipke rehte hain. Plants bhi ectoparasites ho sakte hain. Dodder (Cuscuta, अमरबेल), yaani hedges ko dhak dene wale bina leaves ke peele dhaage, ne evolution ke dauraan apna chlorophyll kho diya hai aur haustoria naam ke suckers se apna saara food host se leta hai.

Tapeworms, liver flukes aur malaria parasite jaise endoparasites host ke andar rehte hain, gut aur liver se lekar lungs aur red blood cells tak ke organs mein. Yeh sabse specialised parasites hain, jinki body sabse zyada simplified hai, egg output sabse zyada hai aur life cycles sabse elaborate hain.

Har spring aur summer mein Indian towns mein female Asian koel house crows ke nests mein tab chupke se ghus jaati hai jab maalik bahar hote hain, aur wahan apne eggs de deti hai. Phir crows un eggs ko sete hain aur koel chicks ko apna samajh kar khilate hain. Yeh brood parasitism hai: parasite apne host ki body ke bajaye uski parental care ka exploit karta hai. Kai generations mein koel ke eggs crow ke eggs jaise dikhne lage hain, isliye crows shayad hi in ghuspaithiyon ko pehchaan kar bahar phenkte hain.

Chalo explore kareinNCERT p. 201

Brood parasite ko kaam karte dekho

Tumhe chahiye

ek notebook
binoculars, agar tumhare paas hon

March aur July ke beech koi park ya campus dhoondho jahan house crows aur koels dono common hon. Male koel ki upar uthti ku-oo call suno.
Crow nests ko door se note karo. Unpar chadho mat aur unhe disturb mat karo.
Record karo ki koels (kaala male ya chitkabri bhoori female) kitni baar crow nest ke paas aate hain, aur crows kaise react karte hain.
Summer mein thoda baad, aise crows dekho jo kisi fledgling ko khila rahe hon jo unse bada ho ya alag tarah se bolta ho.

Quick check

3 mein se 1

Gut mein rehne wale tapeworm mein tum kaun sa feature expect nahi karoge?

Hooks aur suckersBahut saare eggsAchhe se developed digestive systemComplex life cycle

Answer dekho

Answer (C) Achhe se developed digestive system

Tapeworm host ka pehle se digest kiya hua food absorb karta hai, isliye usne apna digestive system kho diya hai. Hooks, suckers, bahut zyada egg output aur complex cycles typical parasite adaptations hain.

Commensalism

Commensalism (सहभोजिता) ek-tarfa partnership hai: ek species ko faayda hota hai, aur uske partner ka na kuch bhala hota hai na bura. Table mein kuch jaane-pehchaane cases hain.

Table 11.4Commensals aur unke hostsNCERT p. 201

Commensal aur host	Iska faayda
Mango tree par orchid	roshni mein baithne ki jagah; yeh apna water khud ikattha karta hai
Whale par barnacles	food-rich water mein free ki sawaari
Cattle ke paas cattle egret	cattle ke pairon se udne wale insects
Sea anemone mein clownfish	dank maarne wale tentacles ke beech shelter
Shark par remora	transport aur khaane ke tukde

Har case mein host ko na madad milti hai na nuksaan: gaay apne pairon ke paas egret se pareshaan nahi hoti, aur mango tree orchid ki wajah se kuch nahi khota, kyunki orchid usse koi food nahi leta. Clownfish ek borderline case hai. Tumhari textbook ise commensalism maanti hai, kyunki anemone ko koi saaf faayda nahi hota; kuch haal ki studies batati hain ki fish ke wastes aur anemone khane wali fish ko bhagana anemone ki bhi madad kar sakta hai, jisse yeh mutualism ban jaayega.

Definition

Commensalism

Do species ke beech ek-tarfa association: ek partner ko faayda hota hai, jabki doosre ka na kuch bhala hota hai na bura.

ExampleCharte hue buffaloes se udne wale insects ko pakadte cattle egrets.

Mutualism

Mutualism (सहोपकारिता) mein har partner woh cheez deta hai jo doosre ke paas nahi hoti. Purani deewar ya tree trunk par grey-green crust dekho: yeh ek lichen hai, yaani ek fungus aur ek photosynthetic alga ya cyanobacterium jo ek ki tarah rehte hain. Photosynthetic partner sugars banata hai; fungus water rokta hai, minerals absorb karta hai aur use shelter deta hai. Zameen ke neeche zyadatar plants mycorrhizae mein fungi ke saath len-den karte hain. Fungal threads roots se kahin door tak phail kar plant ko minerals, khaas kar phosphorus, dete hain, aur plant fungus ko sugars se payment karta hai.

Flowering plants kuch sabse elaborate saude un animals ke saath karte hain jo unke pollen aur seeds ko le jaate hain. Nectar aur extra pollen pollinators ki mazdoori hain; meetha, gooddaar fruit us bird ya bat ki fees hai jo seeds nigal kar unhe door gira deta hai. Aisa har deal cheaters ko kheenchta hai: carpenter bee flower ke base mein kaat kar pollen ko chhuye bina nectar pee sakti hai. Plants aise flower shapes se jawab dete hain jo sirf sahi visitors ko andar aane dein, aur pollinators bhi unse match karne ke liye evolve hote hain, isliye plant aur animal co-evolve karte hain.

Fig poori tarah fruit nahi hai: yeh ek khokhli, lagbhag band ball hai jiske andar saikdon chhote flowers lage hote hain. Iske tip par bane patle opening se sirf ek chhota wasp hi andar ja sakta hai, aur kai fig species mein har fig ki apni partner wasp species hoti hai, jo kahin aur breed nahi kar sakti Fig. 11.14. Pollen se lipti ek female andar reng kar jaati hai, eggs dene ki jagah dhoondhte hue flowers ko pollinate karti hai, aur kuch flowers mein eggs de deti hai. Uske larvae un flowers mein ban rahe seeds kha jaate hain, jabki baaki flowers seeds banate hain. Fig kuch seeds se keemat chukata hai; wasp pollination se.

2/4Woh flowers ko pollinate karti hai aur unmein se kuch mein eggs deti hai.

Fig. 11.14Fig aur fig wasp: dono ek doosre par depend karte hain.NCERT Fig. 11.4 · p. 202

Beech se kata ek fig, andar chhote flowers se bhare khokhle urn jaisa, upar ek patle opening ke saath. Pehle step mein pollen se lipti ek female wasp opening se andar aati hai. Doosre step mein woh flowers par chalti hai, un par pollen chhodti hai aur kuch mein eggs deti hai. Teesre step mein pollinated flowers seeds ban gaye hain, jo dots se mark hain, aur eggs wale flowers galls ban gaye hain jinmein wasp larvae hain. Aakhri step mein pollen le jaane wali nayi female wasps doosre fig ke liye opening se bahar nikalti hain.

Orchid flowers ki shapes mein kamaal ki variety hoti hai, aur kai ek hi tarah ki bee ke liye bani hoti hain. Kuch orchids apne pollinators ko bilkul kuch nahi dete. Mediterranean orchid Ophrys mein ek petal shape, colour, texture aur yahan tak ki smell mein bhi female bee ki nakal karta hai. Male bees spring mein females se pehle nikalti hain, pehle in 'females' ko paati hain aur unse mate karne ki koshish karti hain; is behaviour ko pseudocopulation kehte hain. Har koshish mein bee par pollen chipak jaata hai, jise woh agle flower tak pahuncha deti hai jo use bewakoof banata hai. Yeh trick tabhi tak kaam karti hai jab tak petal asli female se match kare, isliye bee mein hone wala koi bhi evolutionary change orchid ko bhi follow karna padta hai: yeh phir se co-evolution hai.

Definition

Mutualism

Do species ke beech ek interaction jismein dono ko faayda hota hai.

ExampleLichen ke roop mein saath rehte ek fungus aur ek alga.

Quick check

3 mein se 1

Cattle egrets charti hui cattle ke peechhe chalte hain. Signs ka kaun sa pair is interaction (egret, cattle) ko describe karta hai?

(+, +)(+, 0)(+, −)(0, 0)

Answer dekho

Answer (B) (+, 0)

Egret ko grass se udne wala aasaan prey milta hai; cattle par koi effect nahi hota. Yeh commensalism hai. (+, +) ke liye cattle ko bhi faayda hona chahiye.

Recap

Summary aur key points

Ecology yeh study karti hai ki organisms ek doosre ke saath aur apne abiotic surroundings ke saath kaise interact karte hain, organisms, populations, communities aur biomes ke levels par.
Population ek defined area mein ek species ka group hai jo resources share karta hai aur interbreed kar sakta hai; natural selection populations par kaam karta hai (Section 11.1.1).
Populations ke kuch attributes hote hain jo individuals mein nahi hote: per capita birth aur death rates, sex ratio aur age distribution, jo age pyramid se dikhaya jaata hai (Section 11.1.1).
Population density ko numbers, per cent cover ya biomass mein naapa ja sakta hai, ya indirectly aur relative density ke roop mein estimate kiya ja sakta hai (Section 11.1.1).
Density natality aur immigration (gains) aur mortality aur emigration (losses) se badalti hai: $N_{t + 1} = N_{t} + [(B + I) - (D + E)]$ (Section 11.1.2).
Unlimited resources ke saath growth exponential hoti hai: $d N / d t = r N$ , $N_{t} = N_{0} e^{r t}$ , yaani J-shaped curve (exponential growth).
Limited resources ke saath growth logistic hoti hai: $d N / d t = r N (K - N) / K$ , ek S-shaped curve jo carrying capacity $K$ par level off hota hai (logistic growth).
Life histories is baat mein alag hoti hain ki organisms kitni baar breed karte hain aur unke offspring ki number aur size kya hai, aur inhe habitat shape karta hai (Section 11.1.3).
Interspecific interactions ke naam unke effects se rakhe jaate hain: mutualism (+, +), competition (−, −), predation aur parasitism (+, −), commensalism (+, 0) aur amensalism (−, 0) (Section 11.1.4).
Predators energy transfer karte hain, prey ko regulate karte hain (biological control ka basis) aur diversity bana kar rakh sakte hain; prey aur plants ne physical aur chemical defences evolve kiye hain (predation).
Gause ka competitive exclusion principle tab laagu hota hai jab resources limiting hon; competitive release aur resource partitioning dikhate hain ki nature mein competition kaise kaam karta hai (competition).
Parasites co-evolution, simplified bodies aur complex life cycles dikhate hain; commensals ko host ko koi nuksaan pahunchaye bina faayda milta hai; figs aur fig wasps jaise mutualists ek doosre par depend karte hain (parasitism, mutualism).

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 mein	Yahan practice question
NCERT Exercises Q1	Practice Q1
NCERT Exercises Q2	Practice Q2
NCERT Exercises Q3	Practice Q3
NCERT Exercises Q4	Practice Q4
NCERT Exercises Q5	Practice Q5
NCERT Exercises Q6	Practice Q6
NCERT Exercises Q7	Practice Q7
NCERT Exercises Q8	Practice Q8
NCERT Exercises Q9	Practice Q9
NCERT Exercises Q10	Practice Q10

Quick check: MCQs

11.1.1 Population ke Attributes4 questions
Growth ke models: exponential growth3 questions
Logistic growth3 questions
11.1.3 Life History mein Variation2 questions
Predation3 questions
Competition3 questions
Parasitism3 questions
Mutualism3 questions

Glossary · 15

Key terms (English + Hindi)

age pyramid: Har age group mein population ka share dikhane wala bar diagram; iski shape growth, stability ya decline batati hai.Chapter mein pehli baar yahan aaya →

carrying capacity: Kisi species ki sabse badi population jise ek habitat hamesha ke liye support kar sakta hai.Chapter mein pehli baar yahan aaya →
commensalismसहभोजिताsahbhojita: Ek-tarfa association: ek partner ko faayda hota hai aur doosre par koi effect nahi (+, 0).Chapter mein pehli baar yahan aaya →
competitionप्रतिस्पर्धाpratispardha: Ek interaction jo same resource use karne wali ek ya dono species ki fitness kam karta hai (−, −).Chapter mein pehli baar yahan aaya →

ecologyपारिस्थितिकीparisthitiki: Is baat ki study ki organisms ek doosre ke saath aur apne physical surroundings ke saath kaise interact karte hain.Chapter mein pehli baar yahan aaya →

intrinsic rate of natural increase: Per capita birth rate minus per capita death rate, $r = b - d$ .Chapter mein pehli baar yahan aaya →

logistic growth: Aisi growth jo numbers ke carrying capacity ke paas aane par dheemi ho jaati hai, $d N / d t = r N (K - N) / K$ , aur S-shaped curve deti hai.Chapter mein pehli baar yahan aaya →

mortalityमृत्यु दरmrityu dar: Diye gaye time mein population ke kitne members marte hain.Chapter mein pehli baar yahan aaya →
mutualismसहोपकारिताsahopkarita: Ek interaction jismein dono species ko faayda hota hai (+, +).Chapter mein pehli baar yahan aaya →

natalityजन्म दरjanm dar: Diye gaye time mein population mein kitne naye individuals paida hote hain.Chapter mein pehli baar yahan aaya →

parasitismपरजीविताparjivita: Ek interaction jismein ek species host ke upar ya andar rehkar usse food leti hai aur use nuksaan pahunchati hai (+, −).Chapter mein pehli baar yahan aaya →
populationसमष्टिsamashti: Ek defined area mein ek species ke saare individuals jo resources share karte hain aur interbreed kar sakte hain.Chapter mein pehli baar yahan aaya →
population densityसमष्टि घनत्वsamashti ghanatva: Per unit area ya volume population ka size, numbers, per cent cover ya biomass mein.Chapter mein pehli baar yahan aaya →
predationपरभक्षणparbhakshan: Ek interaction jismein ek species doosri ko maarkar khati hai ya us par feed karti hai (+, −).Chapter mein pehli baar yahan aaya →

resource partitioning: Shared resource ko time, jagah ya feeding method ke hisaab se baantna, jisse competing species saath reh paati hain.Chapter mein pehli baar yahan aaya →

Organisms and Populations: Class 12 Biology Chapter 11 Hinglish mein

Is chapter mein aap kya seekhenge

11.1 Populations

11.1.1 Population ke Attributes

11.1.2 Population Growth

Growth ke models: exponential growth

Logistic growth

11.1.3 Life History mein Variation

11.1.4 Population Interactions

Predation

Competition

Parasitism

Commensalism

Mutualism

Summary aur key points

Practice questions answers ke saath (NCERT “Exercises”)

Apna NCERT exercise question dhoondo

Quick check: MCQs

Key terms (English + Hindi)

Tum chapter ke end tak pahunch gaye