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ExplorationCh 2 Cell: Jeevan ki Building Block

Cell: The Building Block of Life (Cell: Jeevan ki Building Block): Class 9 Science Chapter 2 Hinglish mein

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

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  • 100 min
  • 28 practice questions
  • 21 MCQs

Is chapter mein aap kya seekhenge

  • Samjhao ki cells dekhne ke liye microscope kyun chahiye, aur cell size aur total magnification ka estimate lagao
  • Cell membrane ki fluid mosaic structure describe karo, aur osmosis se predict karo ki isotonic, hypotonic aur hypertonic solutions mein cells kaisa behave karte hain
  • Plant, animal aur bacterial cells ki tulna karo, aur prokaryotic aur eukaryotic cells mein fark batao
  • Nucleus, ribosomes, ER, Golgi apparatus, lysosomes, mitochondria, plastids aur vacuoles ki structure aur kaam batao
  • Onion skin, cheek cells aur onion root tip ki temporary slides banao aur observe karo
  • Mitosis aur meiosis mein fark batao aur samjhao ki dono kyun zaroori hain
  • Cell theory batao aur samjhao ki controlled division, contact inhibition aur cell death tissues ko healthy kaise rakhte hain

NCERT Science Class 9, Chapter 2, pp. 8–27 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Talaab ke paani ki ek boond microscope ke neeche rakho aur ek poori bheed dikh jaati hai: ghoomte hue hare dhabbe, chappal jaise shape ke tairne wale, aur grey blobs jo apni shape badal-badal kar sarakte hain. Inmein se har ek ek poora living thing hai jo sirf ek cell (कोशिका) se bana hai. Ab apne haath ki peeth dekho. Woh bhi cells se bani hai, aur tumne aaj tak jo bhi living thing dekha hai, woh bhi.

Kuch organisms, jaise Amoeba, bread dough ko phulane wala yeast aur doodh ko dahi jamane wale bacteria, apni poori zindagi ek hi cell ke roop mein jeete hain. Inhe hum unicellular kehte hain. Aam ka ped, goraiya, rohu machhli aur tum khud multicellular ho: ek adult insaan ke body mein lagbhag 30 trillion cells hote hain. Dono cases mein cell woh sabse chhoti unit hai jo apne dum par zinda reh sakti hai.

Definition
Cell

Living things mein structure aur function ki sabse chhoti unit: sabse simple cheez jo materials andar le sakti hai, energy use kar sakti hai, grow kar sakti hai aur apne jaise aur bana sakti hai.

ExampleEk Amoeba ek single cell se bana poora organism hai; ek patti kai hazaar cells se bani hoti hai.

Multicellular body mein cells teams mein kaam karte hain. Ek tarah ke cells jo ek hi kaam karte hain, milkar tissue banate hain. Kuch tarah ke tissues milkar ek organ banate hain, aur jo organs ek bada kaam baant-te hain, woh organ system banate hain (Fig. 2.1). Jaise, tumhare stomach ki andar ki lining aise cells ka tissue hai jo digestive juice nikaalte hain. Muscle aur doosre tissues ke saath milkar yeh stomach banata hai, jo mouth, intestines aur liver ke saath digestive system ka hissa hai. Cells hata do, to kisi bhi level par kuch nahi bachta.

Fig. 2.1Body mein organisation ke levels: cells tissues banate hain, tissues organs banate hain aur organs organ systems banate hain.NCERT p. 8

Ek line mein chaar panels jo arrows se jude hain. Pehle mein ek single cell apne nucleus ke saath hai. Doosre mein bahut saare ek jaise cells ki ek sheet hai, yaani tissue. Teesre mein stomach hai, ek organ, jiski andar ki lining par tissue sheet mark ki gayi hai. Chauthe mein poora digestive system hai, food pipe se stomach aur intestines tak, aur stomach highlighted hai.

2.1 Cells ko kaise study karein?

Patle muslin kapde ka ek tukda haath ki doori par pakdo, to woh ek smooth sheet jaisa dikhta hai. Paas lao, to alag-alag dhaage dikhne lagte hain. Tumhari aankh do points ko tabhi alag pehchaan sakti hai jab unke beech ka gap kaafi bada ho. Sabse chhota gap jis par do points phir bhi alag dikhte hain, woh aankh ki limit of resolution hai. 25 cm door ki cheez dekhti normal aankh ke liye (yeh sabse kam doori hai jis par hum mein se zyadatar log saaf dekhte hain) yeh gap lagbhag 0.1 mm hota hai.

Zyadatar plant aur animal cells 10 se 100 micrometres chaude hote hain (1 µm ek millimetre ka hazaarvaan hissa hai). Zyadatar bacteria sirf 1 se kuch micrometres lambe hote hain. Matlab ek typical cell aankh ki 0.1 mm limit ke barabar ya usse chhota hai, aur bacterium usse bhi lagbhag sau guna chhota hai. Kuch cells exceptions hain: murgi ke ande ka yolk ek bahut bada single cell hai. Baaki sab ke liye madad chahiye, aur Fig. 2.2 dikhata hai ki kaun sa tool kya dekh sakta hai.

3/3Electron microscope 1 nm se bhi neeche pahunchta hai: viruses, ribosomes aur DNA ke strands tak.

Fig. 2.2Scale par har step neeche jaane par cheez das guna chhoti hoti hai. Har instrument scale ka ek naya hissa khol deta hai.NCERT Fig. 2.1 · p. 9

Ek horizontal scale left mein 1 centimetre se right mein 1 nanometre tak jaata hai, har mark pichhle se das guna chhota. Uske saath ek mustard seed, ek Amoeba, ek cheek cell, ek red blood cell, ek bacterium, ek virus, ek ribosome aur DNA ki chaudai rakhi hai. Step 1 woh hissa shade karta hai jo bina madad ki aankh dekh sakti hai, lagbhag 0.1 millimetre tak, jismein sirf seed aur Amoeba aate hain. Step 2 light microscope ki range jodta hai, lagbhag 0.2 micrometre tak, jismein cells aur bacterium aa jaate hain. Step 3 electron microscope ki range jodta hai, jo 1 nanometre se bhi neeche jaati hai, aur ismein virus, ribosome aur DNA aa jaate hain.

Tum convex lens ko magnifying glass ki tarah pehle use kar chuke ho. Compound microscope ek ke baad ek lenses ke do sets use karta hai. Specimen ke paas wala objective lens ek bada image banata hai, aur eyepiece us image ko phir se bada karta hai. 1665 mein Robert Hooke ne aisa instrument khud banaya. Usmein se dekhne par bottle cork ka ek patla tukda chhote-chhote khaali chambers ka honeycomb nikla. Unhone inhe cells naam diya, un chhote kamron ke naam par jinmein monks rehte the.

School ka microscope ek light microscope hota hai: yeh normal light ko ek patle, lagbhag transparent specimen se upar bhejta hai. Ismein aam taur par ek ghoomne wale nosepiece par do ya teen objectives hote hain, jaise 10X aur 40X, taaki tum wide view se closer view par switch kar sako. Use karne se pehle Fig. 2.3 mein iske parts seekh lo, aur hamesha pehle sabse low-power objective se focus karo.

2/3Light mirror se upar jaati hai, slide, objective aur eyepiece se hokar tumhari aankh tak.

Fig. 2.3Mirror se aane wali light specimen se hokar upar jaati hai aur phir do lenses se guzarti hai: objective aur eyepiece.NCERT Fig. 2.2 · p. 10

Compound light microscope ka side view. Step 1 parts ko label karta hai: body tube ke upar eyepiece, ghoomne wale nosepiece par objective lenses, clips se pakdi glass slide wala stage, stage ke neeche mirror, handle ki tarah use hone wala curved arm, arm par coarse aur fine focusing knobs, aur bhaari base. Step 2 light path ko arrows wali dashed line se dikhata hai: lamp ya khidki se mirror tak, stage ke ched aur slide se upar, objective mein, tube se upar aur eyepiece se bahar aankh tak. Step 3 dono knobs ko ghoomte arrows ke saath highlight karta hai, aur tube thoda neeche aati hai: coarse knob use zyada move karta hai, fine knob thoda sa, taaki image sharp ho.

Microscope ek bada kiya hua picture dikhata hai, to tum kaise jaanoge ki jo dikh raha hai uska asli size kya hai? Trick yeh hai ki eyepiece se dikhne wale light ke circle, yaani field of view, ko naapo, aur phir gino ki uske across kitne cells aate hain.

3/3Har cell ke liye 2000 μm÷8=250 μm.

Fig. 2.4Field ko ek baar ruler se naapo, phir uske across cells gino.NCERT Activity 2.1 · p. 10

Ek bright circle eyepiece se dikhne wala view dikhata hai. Step 1: ek ruler circle ke across rakha hai aur uske marks dikhate hain ki circle 2 millimetres chauda hai. Step 2: ruler hat gaya hai aur lambi bricks jaise onion peel cells circle mein bhare hain; beech mein 8 cells ki ek row par 1 se 8 tak number likhe hain. Step 3: circle ke paas calculation dikhti hai: 2 millimetres 2000 micrometres hai, aur 2000 ko 8 se divide karne par har cell ke liye 250 micrometres aata hai.

Cell size ka estimate
cell size=field widthcells across
(2.1)
jahan
field width
view wale circle ki chaudai, ruler se naapi gayi aur micrometres mein badli gayi
cells across
circle ke beech se jaati line par end to end pade cells ki sankhya

Cell kitna bada dikhta hai? Har lens ek fixed amount se magnify karta hai, jo us par 10X, 40X waghairah likha hota hai. Objective se bana image eyepiece phir se magnify karta hai, isliye dono numbers multiply hote hain, add nahi.

Total magnification
Mtotal=Me×Mo
(2.2)
jahan
Me
eyepiece par likha magnification, jaise 10X
Mo
use ho rahe objective lens par likha magnification, jaise 40X
Example 2.1

Cheek cells ka size naapna

Meera ruler se apna field of view naapti hai: woh 1.8 mm chauda hai. Cheek cells ki slide lagakar woh uske across 30 cells ginti hai. (a) Ek cheek cell ki chaudai ka estimate lagao. (b) Phir woh 10X eyepiece aur 40X objective se dekhti hai. Total magnification kitna hai, aur ek cell kitna chauda dikhta hai?

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

Example 2.2

Bacterium ko dikhne layak banana

Ek rod-shaped bacterium 2 μm lamba hai. Ek microscope mein 10X eyepiece aur 10X, 40X aur 100X ke objectives hain. Kaun sa objective bacterium ko kam se kam 1 mm lamba dikhayega?

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

Quick check
3 mein se 1
Onion peel ke alag-alag cells tum sirf aankhon se kyun nahi dekh sakte?
Answer dekho

Answer (B) Zyadatar cells aankh ki limit of resolution, lagbhag 0.1 mm, se chhote hote hain

Zyadatar cells 10–100 µm chaude hote hain, jo aankh ki 0.1 mm limit ke barabar ya usse kam hai, isliye paas-paas ke cells aapas mein ghul-mil kar dhundhle dikhte hain. Transparency contrast ki problem hai, jise stains theek karte hain; yeh microscope ko unhe dikhane se nahi rokti.

2.2 Cell ki Structure

Cell kabhi poori tarah band nahi hota. Root hair cell paani aur minerals kheenchta hai, nerve cell signals pakadta hai, aur Amoeba khana nigalta hai aur waste bahar dhakelta hai. Tissue ke cells bhi apne padosiyon ko materials aur messages bhejte hain. Yeh saara traffic ek hi jagah se guzarta hai, cell ka kinara, isliye hum wahi se shuru karte hain.

2.2.1 Cell membrane — Har cell ki common feature

Kisi bheed wale railway station ka security gate socho: kuch log seedhe nikal jaate hain, kuch ko check karke andar jaane diya jaata hai, aur kuch ko lauta diya jaata hai. Bacterium se lekar nerve cell tak, har cell ki ek boundary hoti hai jo is gate ki tarah kaam karti hai. Yeh cell membrane hai, jise plasma membrane (प्लैज़्मा झिल्ली) bhi kehte hain. Kyunki yeh chunti hai ki kya paar jaayega, hum ise selectively permeable kehte hain. Yeh cell ke andar ki cheezon ko saath bhi rakhti hai aur batati hai ki ek cell kahan khatam hota hai aur agla kahan shuru.

Definition
Cell membrane (plasma membrane)

Har cell ki patli, flexible, selectively permeable boundary, jo lipids aur proteins se bani hoti hai aur control karti hai ki cell mein kya aaye aur kya bahar jaaye.

ExampleOxygen lung cell ki membrane se seedha nikal jaati hai, lekin glucose ko khaas protein darwazon ki zaroorat hoti hai.

Kaun se substances paar jaate hain, aur kis taraf jaate hain? Oxygen aur carbon dioxide aasaani se paar ho jaate hain, jaise tumhare lungs ke air sacs mein hota hai. Paani bhi paar jaata hai. Ek kaccha aloo tumhe dikha sakta hai ki paani kis taraf jaata hai, aur direction kaun tay karta hai.

Particles hamesha bheed wali jagah se kam wali jagah ki taraf phailne ki koshish karte hain. Paani ke glass mein thoda rooh afza syrup daalo aur laal rang dheere-dheere poore paani mein phail jaata hai; talte hue pakoras ki khushboo agle kamre tak pahunch jaati hai. Higher se lower concentration ki taraf yeh net movement diffusion (विसरण) hai, aur iske liye kisi membrane ki zaroorat nahi hoti.

Ab beech mein ek aisi membrane rakho jo water molecules ko jaane de, lekin zyadatar ghule hue particles (solute) ko rok le. Sirf paani phail sakta hai, isliye paani us side se jahan woh zyada hai (dilute solution) us side jaata hai jahan woh kam hai (concentrated solution). Yahi osmosis (परासरण) hai: selectively permeable membrane se paani ka diffusion (Fig. 2.5). Root hair cells geeli mitti se bilkul isi tarah paani lete hain.

Definition
Osmosis

Selectively permeable membrane ke across paani ka net movement, dilute solution (zyada paani, kam solute) se zyada concentrated solution (kam paani, zyada solute) ki taraf.

ExampleRaat bhar paani mein bhigoyi kishmish phool jaati hai, kyunki osmosis se paani unke cells mein jaata hai.

2/3Left se right zyada paani jaata hai, wapas kam; sugar particles ruk jaate hain.

Fig. 2.5Chhote water molecules membrane se nikal jaate hain; bade sugar particles nahi nikal paate.NCERT p. 12

Ek tank ek membrane se do hisson mein bata hai; membrane chhote pores wali dashed line ki tarah bani hai. Left hisse mein dilute solution hai, jismein bahut saare chhote water molecules aur sirf do bade sugar particles hain; right hisse mein concentrated solution hai jismein bahut saare sugar particles hain. Step 1 mein dono hisse same level tak bhare hain. Step 2 mein arrows water molecules ko pores se left se right le jaate hain, jabki membrane tak pahuncha ek sugar particle wahin ruk jaata hai aur us par cross laga hai. Step 3 result dikhata hai: ek dashed line shuruaati level dikhati hai; concentrated side ka liquid usse upar chadh gaya hai aur dilute side ka liquid usse neeche gir gaya hai.

Isse aloo ki strips samajh aati hain. Har aloo cell ke andar ka sap paani hai jismein sugars aur salts ghule hain. Bahar ka saada paani sap se zyada dilute hai, isliye cells mein jitna paani gaya utna bahar nahi aaya, aur strip phool kar stiff ho gayi. Strong sugar solution sap se zyada concentrated hai, isliye cells ne paani khoya aur strip dheeli pad gayi.

To cell ke saath kya hoga, yeh is baat par depend karta hai ki uske bahar ka solution andar ke solution se kaisa hai. Biologists teen words use karte hain, aur har word bahar ke solution ko describe karta hai, jaisa Fig. 2.6 aur Table 2.3 dikhate hain. Yaad rakhne ka tareeka: iso matlab barabar, hypo matlab kam (bahar kam solute) aur hyper matlab zyada (bahar zyada solute).

Table 2.3Teen tarah ke bahar ke solutions par cell kaise react karta hai
Bahar ka solutionAndar ke mukable bahar solutePaani ka net flowAnimal cellPlant cell
IsotonicBarabarKoi nahi (andar = bahar)Apni shape banaye rakhta haiApni shape banaye rakhta hai, thoda naram
HypotonicKamCell ke andarPhoolta hai aur phat sakta haiPhool kar sakht ho jaata hai; wall use phatne se rokti hai
HypertonicZyadaCell se baharSikud kar jhurridar ho jaata haiAndar ki cheezein sikud kar wall se door hat jaati hain

3/3Paani bahar jaata hai: animal cell sikud jaata hai; plant cell ki andar ki cheezein wall se door khinch jaati hain.

Fig. 2.6Wahi do cells teen solutions mein. Sirf plant cell ki wall use phatne ya pichakne se rokti hai.NCERT Fig. 2.6 · p. 12

Har step mein left mein ek animal cell aur right mein ek plant cell ek solution mein hain, solution ka naam batata ek label hai aur paani ke liye arrows hain. Step 1, isotonic: andar aur bahar barabar arrows, aur dono cells normal dikhte hain. Step 2, hypotonic: arrows andar ki taraf hain; animal cell phool kar ek badi gend jaisa ho gaya hai jo phatne ke kareeb hai, jabki plant cell ki andar ki cheezein apni wall par zor se dabti hain, aur wall mazbooti se tiki rehti hai. Step 3, hypertonic: arrows bahar ki taraf hain; animal cell sikud gaya hai aur uska kinara jhurridar hai, jabki plant cell ki andar ki cheezein wall se sikud kar door ho gayi hain aur beech mein gap hai, lekin wall apni shape banaye rakhti hai.

Hospitals har din is par bharosa karte hain. Patient ki vein mein lagayi jaane wali drip aam taur par 0.9 % salt solution hoti hai, jo blood ke saath isotonic hai, isliye red blood cells na phoolte hain na sikudte hain. Vein mein shuddh paani jaaye to red cells phool kar phat jaayenge.

InteractiveOsmosis lab

Osmosis ka ek interactive model. Learner red blood cell ya onion skin cell chunta hai, phir slider se bahar ka solution shuddh paani se lekar cell ke andar se teen guna concentrated tak set karta hai; background mein kam ya zyada solute dots dikhte hain. Start dabane par paani ke arrows andar ya bahar jaate hain aur cell badalta hai: red blood cell phoolta hai aur phat sakta hai, apni shape rakhta hai, ya sikud kar jhurridar ho jaata hai; plant cell sakht ho jaata hai, thoda naram rehta hai, ya uski andar ki cheezein wall se door khinch jaati hain. Labels solution ko hypotonic, isotonic ya hypertonic batate hain aur paani ka net flow describe karte hain.

Fig. 2.7Ek cell chuno, bahar ka solution kitna concentrated ho yeh set karo, phir Start dabao aur dekho ki paani kis taraf jaata hai.

Yeh choosy boundary kis cheez se bani hai? Yeh hairaan karne wali had tak patli hai, sirf lagbhag 7 se 10 nanometres: das hazaar membranes ka dher lagbhag ek kaagaz ki sheet jitna mota hoga. Yeh lipids (fat jaise molecules) aur proteins se bani hai, jo fluid mosaic model ke hisaab se arranged hain (Fig. 2.8).

Shuru karne ke liye sabun ka bulbula achhi jagah hai. Soap molecules ka ek head hota hai jo paani ki taraf khinchta hai aur ek tail jo paani se bachti hai, isliye woh line mein lag kar ek patli film bana lete hain jo mudti hai, hilti hai aur chhote ched bhi band kar deti hai. Membrane lipids bhi aisa hi behave karte hain. Woh ek lipid bilayer banate hain: molecules ki do sheets, jinke paani pasand karne wale heads cell ke bahar aur andar ke paani wale fluid ki taraf hote hain, aur paani se bachne wali tails beech mein chhupi rehti hain.

Proteins is bilayer mein aise tairte hain jaise samundar mein icebergs. Kuch ek surface par baithe hote hain. Kuch poori membrane ke aar-paar jaate hain aur channels aur carriers banate hain jo khaas substances ko jaane dete hain; isi tarah membrane chunaav karti hai. Lipids aur proteins milkar ek mosaic banate hain, yaani bahut saare alag-alag tukdon ka pattern. Yeh tukde ek jagah fixed nahi hote: woh ek doosre ke bagal se sarakte hain, ghoomte hain, aur kabhi-kabhi do layers ke beech palat jaate hain, isliye poori sheet fluid hai. Isi se naam pada fluid mosaic model.

4/4Channel protein chhote particle ko jaane deta hai; bade particle ko bahar rokta hai.

Fig. 2.8Fluid mosaic model: lipids ki double layer jismein proteins tairte hain.NCERT Fig. 2.7 · p. 12

Membrane ka ek chhota hissa side se dekha gaya, upar cell ka bahar aur neeche andar. Step 1 lipid bilayer dikhata hai: gol heads ki do rows bahar ki taraf, unki tails ke jode beech ki taraf, aur ek bracket motaai ko 7 se 10 nanometres batata hai. Step 2 proteins jodta hai: ek bada protein jo membrane ke aar-paar jaata hai aur usmein ek channel hai, aur chhote proteins jo surfaces par baithe hain. Step 3 fluid nature dikhata hai: lipids aur proteins bagal mein sarakte hain, jo double-headed arrows se dikhaya gaya hai. Step 4 protein channel ko kaam karte dikhata hai: ek chhota particle channel se neeche cell mein chala jaata hai, jabki bahar ka ek bada particle rok diya jaata hai.

Har cell mein membrane hoti hai. Plants, fungi aur zyadatar bacteria ke cells mein uske bahar ek doosri, zyada mazboot layer bhi hoti hai, cell wall. Wall se kya fark padta hai, yeh dekhne ke liye ek plant cell ko apne khud ke ek cell se compare karo.

2.2.2 Cell wall — Cells ka bahari aavaran

Phir se dekho ki Activity 2.3 mein strong sugar solution ne kya kiya. Dono tarah ke cells ne osmosis se paani khoya, phir bhi sirf cheek cell pichka. Onion cell ne apni outline isliye banaye rakhi kyunki uski membrane ke bahar ek mazboot layer hai, cell wall (कोशिका भित्ति). Wall sikud nahi sakti thi, isliye membrane aur uske andar ki har cheez wall se door khinch gayi. Ise plasmolysis kehte hain. Cell ko wapas saade paani mein rakho, to woh aam taur par theek ho jaata hai.

Plant cell walls zyadatar cellulose se bani hoti hain, jo glucose units ki lambi chains se bana ek carbohydrate hai. Hum cellulose digest nahi kar sakte, lekin phir bhi hamare khaane mein yeh fibre (roughage) ke roop mein kaam ka hai, jo khaane ko gut mein aasaani se aage badhne mein madad karta hai. Fungi aur zyadatar bacteria ki bhi walls hoti hain, jo doosre materials se bani hoti hain. Jaise, fungal walls mein chitin hota hai, wahi mazboot material jo insect ke bahari skeleton mein milta hai.

Jab hum bina walls ke kaam chala lete hain, to plants ko walls kyun chahiye? Ped toofan se bach kar chal nahi sakta, na chhaav mein ja sakta hai, aur use jab tak jeena hai apna wazan khud uthana hai. Ek doosre se dabe arabon walled cells tanon ko seedha aur pattiyon aur pankhudiyon ko shape mein rakhte hain. Animal ko iske badle skeleton sambhalta hai, aur uske cells ko shape badalni padti hai: muscle cells contract hote waqt chhote hote hain, aur white blood cells doosre cells ke beech ke gaps se nikal jaate hain. Rigid walls ke saath yeh dono namumkin hote.

Wall mazboot hai lekin choosy nahi. Paani aur ghule hue minerals isse aasaani se nikal jaate hain, jaise bed ki tokri ke gaps se. Chunaav uske theek andar wali membrane karti hai. Root ko dono chahiye: khuli wall mitti ke paani ko cell tak pahunchne deti hai, aur selective membrane tay karti hai ki asal mein andar kya jaayega.

Definition
Cell wall

Plant, fungal aur zyadatar bacterial cells ki cell membrane ke bahar ek rigid, freely permeable layer, jo unhe shape, support aur suraksha deti hai.

ExampleAnginat cells ki cellulose walls ganne ke tane ko seedha khada rakhti hain.

Compare

Cell membrane aur cell wall

Cell membrane

  • Har cell mein
  • Patli aur flexible
  • Selectively permeable: control karti hai ki kya paar jaaye
  • Lipids aur proteins se bani

Cell wall

  • Sirf plants, fungi aur zyadatar bacteria mein
  • Moti aur rigid
  • Paani aur ghule minerals ke liye freely permeable
  • Zyadatar cellulose se bani (plants mein)
Quick check
4 mein se 1
Ek red blood cell ko aise salt solution mein rakha gaya jo uske andar se zyada concentrated hai. Kya hota hai?
Answer dekho

Answer (D) Woh sikud jaata hai, kyunki osmosis se paani bahar nikalta hai

Bahar ke solution mein solute zyada hai, isliye paani cell se bahar jaata hai aur cell sikud jaata hai. Salt tezi se andar nahi aata: membrane zyadatar solute ko rok leti hai, aur isi wajah se jo cheez move karti hai woh paani hai.
Practice · 3 questions

Ruko aur socho: answers ke saath

  1. Short answerMediumPause and Ponder Q1

    Ek bargad ka ped sadiyon tak ek hi jagah rehta hai, jabki ek bakri din bhar ghoomti hai. In dono zindagiyon se tark do ki plant cells ko walls kyun chahiye aur animal cells bina walls ke kaise kaam chala lete hain.

    Solution dikhao

    AnswerPed ko bina hile hawa, baarish aur apne wazan ka saamna karna hai, isliye uske cells ko rigid walls chahiye; bakri ko chalna hai, isliye uske cells ko flexible hona chahiye.

    Bargad hawa, baarish ya sookhe se bhaag nahi sakta, aur use bahut lambe samay tak bhaari shaakhaon ko uthaye rakhna hai. Har cell ke around rigid walls uske body ko taakat deti hain aur use seedha rakhti hain, aur paani lene par cells ko phatne se rokti hain.

    Bakri apne body ko skeleton se sambhalti hai aur use chalna, mudna aur charna hai. Uske muscle cells contract hote waqt shape badalte hain, aur blood cells patli vessels se nikalte hain. Rigid walls ke saath yeh sab namumkin hota, isliye sirf membrane wale flexible cells animal ke liye theek hain.

  2. Short answerMediumPause and Ponder Q2

    Ek maali ko ek ajeeb paudha milta hai jiski cell walls cell membranes jitni naram aur khinchne wali hain. Is paudhe ki do problems predict karo, aur har ek ko samjhao.

    Solution dikhao

    AnswerPaudha jhuk jaayega aur seedha khada nahi reh paayega, aur paani lene par uske cells phool kar phat sakte hain.

    • Woh gir padega. Tane aur pattiyan apni shape isliye banaye rakhte hain kyunki rigid walls ek doosre par dabti hain. Naram walls paudhe ko uske wazan ya hawa ke against sambhal nahi paati.
    • Uske cells phat sakte hain. Plant cells aam taur par dilute paani mein rehte hain aur osmosis se paani lete hain. Sirf rigid wall unhe zyada phoolne se rokti hai. Khinchne wali wall ke saath, saade paani mein cell tab tak phool sakta hai jab tak phat na jaaye, jaise shuddh paani mein red blood cell.
  3. Short answerEasyPause and Ponder Q3

    Activity 2.2 mein Rani ne apni teen aloo strips do alag aloo se, alag-alag size mein kaati, aur glasses mein daalne se pehle unka wazan lena bhool gayi. Samjhao ki uske results par bharosa kyun nahi kiya ja sakta, aur use kya karna chahiye tha.

    Solution dikhao

    AnswerYeh fair test nahi tha, aur shuruaati mass ke bina woh koi change nahi nikaal sakti. Use ek hi aloo se barabar strips kaatni chahiye thi aur pehle unka wazan lena chahiye tha.

    Alag aloo ki strips ka sap shuru se alag strength ka ho sakta hai, aur alag size ki strips mein paani ke paar jaane ke liye alag surface hota hai. To result mein fark strip ki wajah se ho sakta hai, liquid ki wajah se nahi. Use ek hi aloo se barabar strips kaatni chahiye, taaki sirf liquid hi alag ho. Use har strip ka wazan pehle aur baad mein bhi lena chahiye, kyunki mass ka change hi dikhata hai ki kitna paani andar ya bahar gaya.

2.3 Cell ka andar — Ek coordinated working system

School microscope ke neeche ek stained cell sirf kuch features dikhata hai: kinare par membrane, use bharne wala jelly jaisa fluid jise cytoplasm (कोशिकाद्रव्य) kehte hain, aur ek gehra, gol nucleus. Electron microscope isse kahin zyada dikhata hai. Cytoplasm mein bahut saari chhoti structures lataki hoti hain, har ek ka apna kaam. Yeh organelles (कोशिकांग) hain, cell ke 'chhote organs'.

Fig. 2.9Bacterial cell: koi nucleus nahi, aur membranes mein lipte koi organelles nahi.NCERT Fig. 2.10 (a) · p. 14

Gol kinaron wala ek rod-shaped bacterium. Ek moti bahari line par cell wall label hai aur uske theek andar ek patli line par cell membrane label hai. Andar ke cytoplasm mein bahut saare chhote dots hain jin par ribosomes label hai, aur beech mein dhaage ka ek uljha hua loop hai jis par nucleoid (DNA) label hai, aur uske around koi membrane nahi hai. Ek end par ek lambi lehardar tail hai jis par flagellum label hai.

6/6Saare parts ek saath: wall, membrane, nucleus, ER, Golgi body, chloroplasts, mitochondria aur central vacuole.

Fig. 2.10Plant cell: membrane ke bahar wall, chloroplasts, aur ek bada central vacuole.NCERT Fig. 2.10 (b) · p. 14

Box jaisa ek plant cell, jiske saare parts uske around label kiye gaye hain: cell wall, cell membrane, cytoplasm, nucleolus wala nucleus, rough ER, ribosomes, Golgi body, mitochondria, chloroplasts aur ek bada central vacuole. Step 1 boundary highlight karta hai: moti cell wall aur uske theek andar patli cell membrane, aur beech ki jagah bharta cytoplasm. Step 2 ek taraf khiske nucleus ko uske gehre nucleolus ke saath highlight karta hai. Step 3 production line highlight karta hai: nucleus ke paas ribosomes wala rough ER aur uske kareeb Golgi body. Step 4 energy organelles highlight karta hai: hare oval chloroplasts aur chhote rod-shaped mitochondria. Step 5 bada central vacuole highlight karta hai jo cell ka zyadatar hissa bharta hai. Step 6 poora cell har label ke saath poori tarah dikhata hai.

5/5Saare parts ek saath: membrane, nucleus, ER, Golgi body, mitochondria, lysosomes aur ek chhota vacuole.

Fig. 2.11Animal cell: koi wall nahi, koi chloroplasts nahi, chhote vacuoles, aur lysosomes.NCERT Fig. 2.10 (c) · p. 14

Bina wall ka ek gol, be-dhang animal cell, jiske parts uske around label kiye gaye hain: cell membrane, cytoplasm, nucleolus wala nucleus, rough ER, smooth ER, ribosomes, Golgi body, mitochondria, lysosomes aur ek chhota vacuole. Step 1 flexible cell membrane aur cytoplasm highlight karta hai. Step 2 beech mein nucleus highlight karta hai. Step 3 rough aur smooth ER aur chhote vesicles wali Golgi body highlight karta hai. Step 4 mitochondria, lysosomes aur chhota vacuole highlight karta hai. Step 5 poora cell har label ke saath poori tarah dikhata hai.

Kya tumne sabse bada fark notice kiya? Biologists isi se saare cells ko do bade groups mein baant-te hain, jinke naam Greek karyon (yaani guthli, matlab nucleus) par rakhe gaye hain. Eukaryotic cells (eu, true) apna DNA ek true nucleus ke andar rakhte hain aur apne andar ki jagah ko membrane-bound organelles mein baant-te hain. Plant, animal aur fungal cells eukaryotic hain, aur Amoeba aur yeast jaise single-celled organisms bhi.

Prokaryotic cells (pro, pehle) zyada simple hote hain, aur jeevan ke itihaas mein yeh pehle aaye. Bacterium mein nucleus nahi hota: uska DNA cytoplasm ke ek region mein uljha pada rehta hai jise nucleoid kehte hain, uske kisi bhi part ki apni membrane nahi hoti, aur uski lagbhag saari chemistry seedhe cytoplasm mein hoti hai. Table 2.6 dono groups ko saath-saath rakhta hai.

Table 2.6Prokaryotic aur eukaryotic cells ki tulna
FeatureProkaryotic cellEukaryotic cell
Typical size1–10 µm10–100 µm
DNA kahan haiNucleoid mein ek circular molecule, uske around koi membrane nahiDouble membrane wale nucleus ke andar kai chromosomes
Membrane-bound organellesKoi nahiBahut saare: mitochondria, ER, Golgi apparatus aur bhi
RibosomesHote hain (chhote)Hote hain (bade)
Body planLagbhag hamesha single-celledSingle-celled (yeast, Amoeba) ya multicellular
ExamplesBacteria, jaise dahi mein LactobacillusPlants, animals, fungi aur Amoeba

Cell paani ke gubbare ki tarah latak kyun nahi jaata, aur ek package uske ek end se doosre end tak kaise pahunchta hai? Eukaryotic cells mein ek andar ka dhaancha hota hai, cytoskeleton: bahut patle protein fibres ka jaal jo cytoplasm mein phaila hota hai. Yeh ek saath tent ke bamboo aur railway ki patriyon jaisa kaam karta hai. Yeh cell ko shape aur taakat deta hai, kuch cells ko rengne ya shape badalne deta hai, aur apne fibres par organelles aur packages ko le jaata hai. Iske fibres itne patle hain ki electron microscope ke bina dikhte nahi.

Cytoplasm mein non-living stored material bhi ho sakta hai, jise cell inclusions kehte hain. Kai plant cells starch grains store karte hain. Kuch mein calcium oxalate ke sui jaise crystals hote hain, isi wajah se kacchi arbi (colocasia) ki pattiyan gale mein khujli kar sakti hain. Kuch apne tissues mein silica bhar lete hain, isi wajah se chawal ki bhoosi aur bamboo itne sakht aur khurdure lagte hain.

Quick check
3 mein se 1
Inmein se kaun sa cell prokaryotic hai?
Answer dekho

Answer (D) Dahi ka ek Lactobacillus cell

Lactobacillus ek bacterium hai, isliye uska DNA nucleoid mein hota hai. Amoeba single-celled hai lekin eukaryotic: unicellular hone se koi cell prokaryotic nahi ban jaata.

2.3.1 Eukaryotic cells ko yeh organelles kyun chahiye?

Cell ko ek saath kai kaam karne padte hain: proteins banana, energy release karna, waste saaf karna, khaana store karna aur apni instructions sambhalna. Kuch kaamon ko aisi conditions chahiye jo doosre kaamon ko bigaad dein. Jaise, digestive enzymes agar khule ghoomein to cell ke apne proteins ko tod denge. Membrane-bound organelles har kaam ko apna alag kamra dekar, jismein andar sahi conditions hon, yeh problem solve karte hain.

Kisi badi gurdwara ki langar kitchen socho, jo ek din mein das-hazaaron logon ko khaana khila sakti hai. Recipes ek jagah rakhi jaati hain, cooks apne-apne counters par kaam karte hain, khaana ek alag station par pack hota hai, chulhe jalte rehte hain, aur ek safai team sab kuch use karne layak rakhti hai. Eukaryotic cell ka har organelle aisa hi role nibhata hai (Table 2.7).

Table 2.7Cell ek community kitchen ki tarah
OrganelleKitchen mein roleCell mein kaam
NucleusRecipe book aur head cookDNA instructions rakhta hai aur cell ko control karta hai
RibosomesCooksBuilding blocks jodkar proteins banate hain
Endoplasmic reticulumTaiyaari ke counters aur raasteProteins aur lipids banata aur le jaata hai
Golgi apparatusPacking aur dispatch counterProteins aur lipids ko finish, sort aur pack karta hai
LysosomesSafai teamWaste aur ghise-pite parts ko todte hain
MitochondriaChulheKhaane se energy release karte hain
Plastids (plants)Solar cooker aur storeroomKhaana banate aur store karte hain
VacuolePaani ki tanki aur storeroomPaani, salts, sugars aur wastes store karta hai

Nucleus: control centre

Nucleus aam taur par sabse bada organelle hota hai. Yeh do membranes ke nuclear envelope mein lipta hota hai, jismein bahut saare nuclear pores hote hain; yeh aise khule raaste hain jo nucleus aur cytoplasm ke beech materials aur messages aane-jaane dete hain (Fig. 2.12). Andar ek ghana, gol hissa hota hai, nucleolus. Yeh woh do parts banata hai, ek bada aur ek chhota, jinse ribosomes bante hain. Yeh parts pores se bahar nikal kar cytoplasm mein judte hain aur kaam karne wale ribosomes ban jaate hain.

Nucleus ka zyadatar hissa lambe, patle dhaagon ke uljhe jaal se bhara hota hai jise chromatin kehte hain. Yeh dhaage cell ki instructions hain, jo DNA (deoxyribonucleic acid) ke lambe molecules mein likhi hain; yeh molecules proteins ke around lipte hote hain. Jab cell divide hone ki taiyaari karta hai, to yeh dhaage kas kar lipat jaate hain aur chhote, mote chromosomes (गुणसूत्र) ban jaate hain, jo microscope mein saaf dikhte hain. Ek lamba charger cable socho: khula ho to poori drawer mein ulajh jaata hai; lapet kar baandh do to kisi ko dena aasaan hai. DNA ko bhi isi wajah se do naye cells mein baantne se pehle lapeta jaata hai.

DNA ka woh hissa jo ek khaas kaam karta hai, jaise ek protein ka code rakhna, gene kehlata hai. Har chromosome par bahut saare genes hote hain. Genes maa-baap se bacchon mein jaate hain, isi tarah shayad tumhe apni maa ke dimples ya apne dada ke ghunghrale baal mile hon.

Definition
Chromosome

Nucleus mein DNA aur proteins se bani dhaage jaisi structure, jo cell ke genes rakhti hai; yeh saaf tabhi dikhti hai jab cell divide ho raha ho.

ExampleInsaan ke body cells mein 46 chromosomes hote hain; onion root cells mein 16.

4/4Chromosome proteins par lipta DNA hai; gene DNA ka ek kaam karne wala hissa hai.

Fig. 2.12Nucleus cell ka DNA store karta hai aur ribosome ke parts bahar bhejta hai.NCERT Figs. 2.11, 2.12 · p. 16

Left mein ek bada nucleus aur right mein ek zoom panel. Step 1 double nuclear envelope, ek nuclear pore, gehra nucleolus aur uljhe chromatin threads ko label karta hai. Step 2 chhote aur bade ribosome parts ko pores se cytoplasm mein nikalte dikhata hai, jahan ek chhota aur ek bada part judkar ribosome banate hain. Step 3 cell ko divide hone ki taiyaari karte dikhata hai: uljhe dhaage gayab ho gaye hain aur chaar chhote X-shaped chromosomes dikh rahe hain. Step 4 zoom panel bharta hai: ek chromosome bada banaya gaya hai, uski arm khul kar ek lamba DNA double strand ban jaati hai, aur DNA ke ek chhote rangeen hisse par gene label hai.

Prokaryotes bina nucleus ke kaam chala lete hain. Bacterium ka DNA aam taur par ek circular molecule hota hai, jis par kuch proteins jude hote hain, aur yeh nucleoid mein pada rehta hai.

Ribosomes: protein banane wale

Ribosomes sabse chhote organelles hain aur unke around koi membrane nahi hoti. Har ek ek chhoti si machine hai jo DNA se copy ki gayi instructions padhti hai aur amino acids naam ke building blocks ko jodkar protein chain banati hai. Kuch ribosomes cytoplasm mein khule tairte hain aur cell ke andar use hone wale proteins banate hain. Kuch endoplasmic reticulum par baithe hote hain aur aise proteins banate hain jo membranes mein jaayenge ya cell se bahar jaayenge. Bacteria mein bhi ribosomes hote hain, kyunki har cell ko proteins chahiye.

Endoplasmic reticulum: channels ka network

Endoplasmic reticulum (ER) membrane se bani tubes aur chapti theliyon ka ek bada system hai jo poore cytoplasm mein phaila hota hai. Iski membrane nuclear envelope ki bahari membrane se judi hoti hai. ER proteins aur lipids banata hai, unhe cell mein idhar-udhar le jaata hai, aur kuch cells mein hormones banata hai. Yeh do roop mein hota hai:

  • Rough ER (RER) par ribosomes ke dots hote hain, jo electron microscope mein ise daanedar look dete hain. Iske kai proteins export ke liye bante hain. Salivary glands ke cells, jo tumhare munh mein enzymes daalte hain, rough ER se bhare hote hain.
  • Smooth ER (SER) par ribosomes nahi hote. Yeh lipids banata hai, jinmein nayi membranes ke lipids bhi shaamil hain, aur kuch hormones bhi. Liver cells mein yeh drugs aur zehar ko todne mein bhi madad karta hai.

Golgi apparatus: sorting aur dispatch

Cell diagrams ko dhyaan se dekho to tumhe chapti, mudi theliyon ke stacks milenge, jaise chapatis ka dher katori ki shape mein daba diya ho. Yeh Golgi apparatus (गॉल्जी उपकरण) hai. ER mein bane proteins aur lipids chhote membrane bubbles mein stack ke ek face par pahunchte hain; in bubbles ko vesicles kehte hain. Theliyon se guzarte hue unhe finish kiya jaata hai, jaise unpar sugar chains jodi jaati hain, aur phir doosre face par sort karke naye vesicles mein pack kiya jaata hai.

Ek courier hub ki tarah jo har parcel par address ki mohar lagata hai, Golgi har package ko wahan bhejta hai jahan uski zaroorat hai: cell membrane tak, cell se bahar, ya lysosome mein. Fig. 2.13 is raaste par ek protein ka peecha karta hai.

5/5Vesicle membrane se jud kar protein ko bahar chhod deta hai. Ek aur vesicle lysosome ban jaata hai.

Fig. 2.13Cell se bahar jaane wale protein ki production line.NCERT Fig. 2.13 · p. 17

Left se right: nucleus ka kinara, ribosomes ke dots wala rough ER, Golgi theliyon ka ek muda stack, aur bilkul right mein cell membrane jiske paar cell ka bahar hai. Step 1: rough ER par ek ribosome protein banata hai, jo ek chhote rangeen bead ki tarah dikhaya gaya hai. Step 2: bead ER ke andar aage badhta hai. Step 3: bead ko le jaata ek vesicle ER se alag hota hai aur Golgi tak jaata hai. Step 4: Golgi ke andar bead par ek tag lagta hai, aur doosri side se do vesicles alag hote hain. Step 5: ek vesicle cell membrane se judkar bead ko cell ke bahar chhod deta hai; doosra andar hi lysosome ban kar reh jaata hai.

Lysosomes: safai karne wali team

Lysosome (लयनकाय) taakatwar digestive enzymes ki ek chhoti thaili hai jo ek single membrane mein lipti hoti hai. Yeh enzymes proteins, carbohydrates, fats aur poore organelles tak tod sakte hain. Membrane inhe cell ke baaki hisse se door rakhti hai. Agar cell bahut zyada damage ho jaaye, to uske lysosomes phat kar khud cell ko hi digest kar sakte hain, isiliye inhe cell ke 'suicide bags' kehte hain.

Aisi khatarnaak thaili rakhte hi kyun hain? Har vyast cell kachra banata hai: ghise-pite organelles, kharab proteins aur, kuch cells mein, bahar se nigle gaye bacteria. Lysosomes ise digest karte hain, aur jo simple tukde bachte hain woh cytoplasm mein chhod kar dobara use kiye jaate hain. Lysosome jitna dustbin hai, utna hi recycling unit bhi.

Mitochondria: jahan khaana kaam aane wali energy banta hai

Cell jo kuch bhi karta hai, protein banane se lekar ek chhote baal ko hilane tak, sab mein energy kharch hoti hai, aur cell ek hi currency mein bhugtaan karta hai: ek chhota molecule jise ATP (adenosine triphosphate) kehte hain. ATP ek prepaid card ki tarah kaam karta hai jise cell ki har machine accept karti hai. Iska zyadatar hissa mitochondria (सूत्रकणिका; singular mitochondrion) mein banta hai. Wahan glucose aur doosre food molecules oxygen ki madad se tode jaate hain; is process ko cellular respiration kehte hain, jisse tum pehle mil chuke ho, aur jo energy release hoti hai woh ATP mein store hoti hai.

Structure kaam ke hisaab se bani hai (Fig. 2.14). Mitochondrion mein do membranes hoti hain. Bahari membrane smooth hai aur chhote molecules ko jaane deti hai. Andar wali membrane bahut saari shelves mein mudi hoti hai jinhe cristae kehte hain; inse use ek bada surface milta hai jis par energy release karne wale reactions hote hain. Isiliye mitochondria ko powerhouses of the cell kehte hain, aur isiliye heart muscle cells mein, jo kabhi aaram nahi karte, inki hazaaron ki sankhya hoti hai.

Plastids: food factories aur rang ke store

Gaajar orange, aloo safed aur patti hari kyun hoti hai? Teeno rang plastids (लवक) se aate hain; yeh plants aur algae mein milne wale organelles hain jo khaana banate, use rang dete ya store karte hain. Chromoplasts (Greek chroma, rang) mein peele, orange ya laal pigments hote hain. Yeh genda ki pankhudiyon, pake aamon aur gaajar ko rang dete hain, aur yeh chamakdaar rang un insects ko kheenchte hain jo phoolon ko pollinate karte hain aur un pakshiyon aur jaanwaron ko jo phal khaakar uske beej phailate hain. Pakta hua tamatar ek switch dikhata hai: hare se laal hote hue uske chloroplasts chromoplasts mein badal jaate hain. Leucoplasts (leukos, safed) mein koi pigment nahi hota. Yeh khaana store karte hain: aloo ke tuber ya gehun ke daane mein starch, aur kuch beejon mein oils ya proteins.

Hare plastids chloroplasts hain, plant ki food factories. Inmein chlorophyll pigment hota hai, jo photosynthesis ke liye sunlight pakadta hai. Mitochondrion ki tarah chloroplast mein bhi do membranes hoti hain. Andar stroma naam ka ek fluid hota hai, jismein disc jaisi membrane theliyon ke stacks hote hain. Chlorophyll inhi discs mein hota hai, jahan light energy pakdi jaati hai. Bani hui sugar turant use hoti hai ya stroma mein starch grains ke roop mein store hoti hai.

3/3Har ek ka apna DNA loop aur apne ribosomes hote hain.

Fig. 2.14Dono organelles mein do membranes aur unka apna DNA aur ribosomes hote hain.NCERT Figs. 2.14, 2.15 · p. 18

Do cut-away organelles, upar mitochondrion aur neeche chloroplast. Step 1 mitochondrion ko label karta hai: smooth bahari membrane aur shelves mein mudi andar wali membrane jinhe cristae kehte hain. Step 2 chloroplast ko label karta hai: bahari aur andar wali membrane, fluid stroma, chlorophyll wali hari discs ke stacks, aur ek starch grain. Step 3 dikhata hai ki dono mein kya common hai: har ek mein apna DNA ka chhota loop aur apne chhote ribosomes hain, jinhe dono drawings mein rings se mark kiya gaya hai.

Mitochondria aur chloroplasts mein ek hairaan karne wali baat common hai: har ek ka apna DNA aur ribosomes hai aur woh apne kuch proteins khud bana sakte hain. Unka DNA circular hai, bacterium ki tarah, aur woh do mein bat kar multiply hote hain. Zyadatar biologists ise is baat ka mazboot saboot maante hain ki bahut pehle dono azaad rehne wale bacteria the jo bade cells ke andar rehne lage aur kabhi bahar nahi gaye.

Compare

Teen tarah ke plastids

Chloroplasts

  • Hare (chlorophyll)
  • Photosynthesis se khaana banate hain
  • Pattiyan aur naye tane

Chromoplasts

  • Peele, orange ya laal
  • Jaanwaron ko kheenchne ke liye phoolon aur phalon ko rang dete hain
  • Pankhudiyan, pake phal, gaajar

Leucoplasts

  • Rangheen
  • Starch, oils ya proteins store karte hain
  • Tubers, roots aur seeds

Vacuoles: storage ki tankiyan

Garmi ke din tulsi ke paudhe ko paani dena bhool jao, to shaam tak uski pattiyan latak jaati hain. Paani do, aur kuch hi ghanton mein woh phir khada ho jaata hai. Yeh badlaav uske vacuoles (रसधानी) mein hota hai. Ek mature plant cell mein ek bada central vacuole cell ka zyadatar hissa bhar sakta hai aur cytoplasm ko wall ke saath ek patli layer mein dhakel deta hai. Yeh ek single, selectively permeable membrane se ghiri thaili hai, jo paani jaise cell sap se bhari hoti hai jismein ghuli sugars, salts, pigments aur wastes hote hain.

Jab paani bharpoor hota hai, to vacuole phool kar cytoplasm ko wall par dabata hai, jaise hawa football ko phulati hai. Yeh pressure cell ko sakht rakhta hai, aur sakht cells naram tanon aur pattiyon ko khada rakhte hain. Paani kam ho to vacuoles sikud jaate hain, pressure gir jaata hai aur paudha murjha (wilt) jaata hai. Animal cells mein, agar hon bhi, to sirf chhote, temporary vacuoles hote hain jo materials store karne ya le jaane ke kaam aate hain, jaise Amoeba ke food vacuoles.

Quick check
4 mein se 1
Har organelle ko uske khaas kaam se match karo.

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

Answer dekho
Answer
  • Ribosome : Proteins banata hai
  • Mitochondrion : Khaane se energy release karta hai
  • Golgi apparatus : Materials pack karke bhejta hai
  • Lysosome : Waste aur ghise-pite parts digest karta hai
  • Chloroplast : Sunlight se khaana banata hai
Har organelle ka apna kamra aur apna kaam hai; milkar woh cell ko chalate rehte hain.
Flash cards · 12

Organelles ke flash cards

1 / 12
Practice · 2 questions

Ruko aur socho: answers ke saath

  1. Short answerMediumPause and Ponder Q4

    Chameli ka phool bilkul safed hai. Kya iska matlab hai ki uski pankhudiyon mein koi pigment hi nahi hai? Kaaran do.

    Solution dikhao

    AnswerZaroori nahi. Safed pankhudiyon mein rangeen chromoplast pigments nahi hote, lekin unmein aksar halke pigments hote hain jinhe hum rang ke roop mein nahi dekh paate.

    Safed pankhudiyon ke plastids mein peela, orange ya laal pigment bahut kam ya bilkul nahi hota, isliye yeh zyadatar chromoplasts nahi balki rangheen leucoplasts hote hain, aur inmein woh laal, baingani aur neele pigments bhi nahi hote jo kuch phool apne vacuoles mein rakhte hain. Inka safed rang cells ke beech ke air spaces se light ke bikharne se aata hai, bilkul waise jaise jhaag safed dikhta hai.

    Kai safed phoolon mein phir bhi halke pigments hote hain jo ultraviolet light absorb karte hain. Hum ultraviolet nahi dekh sakte, lekin bees dekh sakti hain, isliye bee ko ek 'safed' phool par pattern dikh sakta hai. To safed phool hamesha pigment-free nahi hota; bas usmein woh pigments nahi hote jo humein rangeen dikhte hain.

  2. DiagramMediumPause and Ponder Q5

    In clues se plant cell ka ek labelled schematic diagram banao: (i) ek rectangular outline jiski bahari border moti aur andar wali patli ho; (ii) beech mein sap se bhari ek badi jagah; (iii) ek taraf khiska hua ek gehra, gol hissa; (iv) cytoplasm ki patli layer mein hare oval hisse aur chhote sausage jaise hisse. Jo bhi part banao, uska naam likho.

    Solution dikhao

    AnswerCell wall aur cell membrane; central vacuole; nucleus; chloroplasts aur mitochondria.

    • Clue (i): moti bahari border cell wall hai; uske theek andar ki patli line cell membrane hai.
    • Clue (ii): sap se bhari badi jagah central vacuole hai.
    • Clue (iii): gehra, gol hissa nucleus hai (nucleolus ke liye uske andar ek aur gehra dot banao).
    • Clue (iv): hare ovals chloroplasts hain; chhote sausage jaise hisse mitochondria hain.
    • Extra marks ke liye nucleus ke paas ER ke liye lines ka ek network aur Golgi apparatus ke liye mudi theliyon ka ek chhota stack banao, aur patli layer ko cytoplasm label karo.

2.4 Normal cells kaise grow aur divide hote hain?

Chhila hua ghutna lagbhag ek hafte mein bhar jaata hai. Chhote kate baal ek-do mahine mein badh jaate hain. 3 kg ka navjaat baccha 50 kg ya usse zyada ka adult ban jaata hai. Har baar naye cells ban rahe hote hain. Growth zyadatar cells ke bade hone se nahi hoti: ek cell ek had tak hi bada ho sakta hai, aur phir woh do mein divide ho jaata hai.

Had kyun hai? Cell jo kuch bhi andar leta hai ya bahar nikaalta hai, sab uske surface se guzarna chahiye. Jaise-jaise cell bada hota hai, uska volume, yaani woh living material jise supplies chahiye, uske surface area se zyada tezi se badhta hai, jabki supplies surface area se hi aati hain. Bahut bada cell beech mein bhookha mar jaayega. Do mein divide hone se behtar balance wapas aa jaata hai, jaisa Example 2.3 dikhata hai.

Example 2.3

Cells chhote kyun rehte hain

Do cube-shaped cells socho, ek ki sides 10 μm ki aur ek ki 20 μm ki. (a) Har ek ka surface area aur volume nikaalo, aur volume ke har cubic micrometre ke liye surface area nikaalo. (b) Bade cube ka volume aath chhote cubes ke barabar hai. Aath chhote cubes ke total surface ko bade cube ke surface se compare karo.

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

Tumhara body lagaataar cells badalta rehta hai: ek saavdhaan estimate ke hisaab se har din kuch sau billion, yaani tumhare saare cells ka lagbhag 1 %. Inmein zyadatar blood cells aur gut ki lining ke cells hote hain. Bacteria bhi multiply hote hain, bas apna DNA copy karke aur do mein bat kar. Lekin eukaryotic cell sirf kas kar control kiye gaye stages ki ek series ke aakhir mein divide hota hai, jise cell cycle kehte hain. Cell bada hota hai, apna DNA copy karta hai, copy ko check karta hai, aur tabhi divide hota hai. Stages tum oonchi classes mein padhoge.

2.4.1 Cell division

Tumhare body ke kuch cells kabhi divide hona band nahi karte: tumhari skin ki sabse gehri layer ke cells zindagi bhar naye cells banate hain. Kuch, jaise zyadatar nerve cells, ek baar banne ke baad phir kabhi divide nahi hote. Jab bhi koi cell do mein batta hai, is process ko cell division kehte hain. Yeh badhte body ko banata hai, chot lagne par use theek karta hai, aur woh cells banata hai jo agli generation shuru karte hain. Yeh do tarah ka hota hai, aur dono ke result bahut alag hote hain.

Mitosis (समसूत्री विभाजन) do daughter cells banata hai jo parent cell ki copies hote hain. Divide hone se pehle cell har chromosome ki copy banata hai. Phir dono copies alag kheenchi jaati hain, taaki har daughter cell ko ek poora set mile: parent jitne hi chromosomes aur parent jaisa hi DNA (Fig. 2.15).

Tumhari zindagi ek fertilised egg se shuru hui thi. Baar-baar hone wale mitosis ne use trillions cells mein badal diya, jin sab mein same instructions hain. Mitosis ghise-pite cells ko badalta hai aur zakhm bhi bharta hai. Yeh kuch organisms ko bina seeds ya gametes ke naye individuals banane deta hai (asexual reproduction), jaise jab aloo ka tuber ankurit hota hai ya Bryophyllum ki patti ke kinare par naye chhote paudhe ugte hain.

5/5Do daughter cells, har ek mein parent ki tarah 4 chromosomes.

Fig. 2.154 chromosomes wale cell mein mitosis: har chromosome copy hota hai, aur har daughter cell ko har ek ki ek copy milti hai.NCERT Figs. 2.17, 2.18 · p. 21

Ek cell paanch palon par banaya gaya hai. Uske chromosomes mein do lambe aur do chhote hain, taaki unhe length se pehchaana ja sake. Step 1: dheele, uljhe dhaagon se bhare nucleus wala cell. Step 2: dhaage lipat kar chaar X-shaped chromosomes ban gaye hain, har X do ek jaisi copies hai jo beech mein judi hain. Step 3: chaaron chromosomes cell ke beech mein line mein lag jaate hain. Step 4: copies cell ke opposite ends ki taraf kheenchi jaati hain, har end par do lambe aur do chhote. Step 5: cell sikud kar do daughter cells ban gaya hai, har ek ke nucleus mein do lambe aur do chhote chromosomes hain, parent jaisa hi set.

Meiosis (अर्धसूत्री विभाजन) woh division hai jo gametes banata hai, yaani woh sex cells jo fertilisation par judte hain. Iska result mitosis se bahut alag hai: ek cell lagaataar do baar divide hota hai aur chaar cells ban jaata hai, har ek mein sirf aadhe chromosomes (Fig. 2.16). Kyunki gametes sirf reproductive organs mein bante hain, meiosis bhi sirf wahin hota hai: animals ke testes aur ovaries mein, jo sperm aur eggs banate hain, aur phool ke anthers aur ovary mein, jinse pollen grains aur egg cell bante hain. Dono divisions alag-alag kaam karte hain:

  • Pehla division: chromosome number aadha ho jaata hai. Dono naye cells mein se har ek ko har matching pair se ek chromosome milta hai.
  • Doosra division: un do cells mein se har ek phir divide hota hai, kaafi had tak mitosis ki tarah. Result chaar cells hain, har ek mein parent ke aadhe chromosomes.

4/4Do parents ke do gametes judte hain: zygote mein phir se 4 chromosomes.

Fig. 2.16Meiosis chromosome number aadha karta hai; fertilisation use wapas poora karta hai.NCERT Fig. 2.19 · p. 22

Step 1 mein upar ek parent cell hai jismein chaar X-shaped chromosomes hain: ek lamba pair aur ek chhota pair. Step 2 pehla division dikhata hai: arrows neeche do cells tak jaate hain, har ek mein ek lamba aur ek chhota X-shaped chromosome, yaani number aadha ho gaya. Step 3 doosra division dikhata hai: un cells mein se har ek batta hai, aur neeche chaar gametes ki row banti hai, har ek mein ek lamba aur ek chhota single chromosome. Step 4 fertilisation dikhata hai: inmein se ek gamete, jis par ghera bana hai, doosre parent ke ek gamete se judta hai (jo dashed outline se bana hai) aur upar right mein ek zygote banata hai jismein phir se chaar chromosomes hain, do lambe aur do chhote.

Number aadha kyun karna? Fertilisation par ek sperm aur ek egg judte hain. Agar dono mein poora set hota, to bacche mein uske parents se dugne chromosomes hote, aur har generation mein number double hota jaata. Meiosis mein aadha hona aur fertilisation mein judna number ko steady rakhta hai: insaanon mein 23 + 23 = 46. Meiosis chromosomes ko phent bhi deta hai, isliye har gamete ko alag mixture milta hai. Isiliye bhai-behen apne parents se, aur ek doosre se, milte-julte hote hain lekin bilkul copy nahi hote, jab tak woh identical twins na hon. Chapter 11 ise aur aage le jaata hai.

Example 2.4

Pyaaz mein chromosomes ginna

Pyaaz ke body cells mein 16 chromosomes hote hain. (a) Root tip ke har daughter cell mein kitne chromosomes hote hain? (b) Anther ka ek cell meiosis se divide hota hai. Kitne cells bante hain, aur har ek mein kitne chromosomes hote hain? (c) Root tip ka ek cell mitosis se divide hota hai, phir dono daughters divide hote hain, aur aise hi kul paanch baar. Aakhir mein kitne cells hote hain?

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

Compare

Mitosis aur meiosis

Mitosis

  • Poore body ke body cells mein
  • Ek division
  • 2 daughter cells
  • Chromosome number same (pyaaz: 16 → 16)
  • Daughter cells parent jaise bilkul same
  • Growth, marammat aur asexual reproduction ke liye

Meiosis

  • Sirf reproductive organs mein
  • Do divisions, ek ke baad ek
  • 4 cells
  • Chromosome number aadha (pyaaz: 16 → 8)
  • Cells parent se aur ek doosre se alag
  • Sexual reproduction ke liye gametes banata hai
Practice · 2 questions

Ruko aur socho: answers ke saath

  1. Short answerHardPause and Ponder Q6

    Ek liver cell mein ek bade mitochondrion ki jagah hazaar ya usse zyada chhote mitochondria hote hain. Surface area ke idea se samjhao ki yeh arrangement cell ke liye behtar kyun hai.

    Solution dikhao

    AnswerBahut saare chhote mitochondria ka total surface (aur andar wali membrane) same volume ke ek bade mitochondrion se kahin zyada hota hai, isliye zyada reactions aur exchange ho sakte hain, aur woh poore cell mein phaile ho sakte hain.

    Ek volume ko chhote tukdon mein baantne se total surface badhta hai: aath chhote cubes ka surface same volume ke ek bade cube ka dugna hota hai. Energy release karne wale reactions andar wali membrane par hote hain, aur khaane aur oxygen ko bahari membrane se guzarna padta hai. Isliye bahut saare chhote mitochondria utne hi material mein kahin zyada kaam karne wala surface dete hain.

    Chhote mitochondria poore cytoplasm mein bikhre bhi ho sakte hain, har us jagah ke paas jahan energy chahiye. Ek bade mitochondrion ke saath ATP ko cell ki door wali side tak pahunchne ke liye lamba safar karna padta.

  2. Short answerMediumPause and Ponder Q7

    Maan lo kate hue hisse ke aas-paas ke skin cells mitosis ki jagah meiosis se divide hote. Predict karo ki bharti hui skin ka kya hota, aur samjhao kyun.

    Solution dikhao

    AnswerZakhm theek se nahi bharta: naye cells mein aadhe chromosomes hote, woh ek doosre se alag hote aur normal skin cells ki tarah kaam ya divide nahi kar paate.

    Bharne ke liye aise naye cells chahiye jo un skin cells ki bilkul copy hon jinki jagah woh le rahe hain. Meiosis aise cells deta jinmein sirf aadha chromosome number aur genes ka phenta hua mixture hota. Har naye cell mein skin cell ke liye zaroori aadhi instructions gaayab hoti.

    Aise cells normal tareeke se kaam nahi karte, aur meiosis ka doosra round number ko phir aadha kar deta, jo chal hi nahi sakta. Kata hua hissa dheere ya kharab tareeke se bharta, abnormal tissue ke saath. Isiliye body cells mitosis se divide hote hain aur sirf reproductive organs meiosis use karte hain.

Quick check
4 mein se 1
20 chromosomes wala ek cell mitosis se divide hota hai. Har daughter cell mein kitne chromosomes hote hain?
Answer dekho

Answer (C) 20

Mitosis number same rakhta hai: har daughter cell mein 20. 10 tak aadha karna meiosis ka kaam hai.

2.5 Cell Theory — Biology ka jodne wala principle

1830s tak behtar microscopes ki madad se biologists kai tarah ke tissues jaanch paaye, aur ek pattern saamne aaya. 1838 mein German botanist Matthias Schleiden is nateeje par pahunche ki plant ka har hissa cells se bana hai. Ek saal baad German zoologist Theodor Schwann animals ke liye bhi isi nateeje par pahunche. 1855 mein German doctor Rudolf Virchow ne chhoota hua hissa joda: cells kahin se bhi achaanak nahi aa jaate, balki hamesha pehle se maujood cells se aate hain. Unka Latin motto tha omnis cellula e cellula, 'har cell ek cell se'.

PrincipleCell theory

(1) Har living thing ek cell ya bahut saare cells se bana hai. (2) Cell sabse chhoti unit hai jo jeevan ki banawat aur activities dono dikhati hai. (3) Har cell apne se pehle maujood ek cell se banta hai.

Yeh teen baatein poori biology ko jodti hain. Ek bacterium, ek bargad ka ped aur ek insaan ek hi plan par bane hain, aur unke cells milte-julte tareekon se badhte aur divide hote hain. Teesri baat jeevan ki continuity bhi samjhati hai: tumhare body ka har cell, division dar division, us fertilised egg tak jaata hai jisse tumhari shuruaat hui thi, aur woh egg tumhare parents ke cells se aaya tha.

Timeline

Cells ki study ke milestones

  1. 1665

    Hooke ne 'cells' naam diya

    Robert Hooke ko cork ke patle tukde mein box jaisi jagahein dikhti hain.

  2. 1670s

    Leeuwenhoek ne living cells dekhe

    Unke single-lens microscopes baarish ke paani aur daanton se khurchi cheez mein bacteria aur protists dikhate hain.

  3. 1831

    Brown ne nucleus describe kiya

    Robert Brown ko orchid ki patti ke har cell mein ek gehra hissa dikhta hai.

  4. 1838–1839

    Schleiden aur Schwann

    Saare plants, aur saare animals, cells se bane hain.

  5. 1855

    Virchow

    Har cell ek cell se aata hai.

  6. 1898

    Golgi ka network

    Camillo Golgi woh organelle dekhte hain jo ab unke naam se jaana jaata hai.

  7. 1902

    Haberlandt ki prediction

    Ek single plant cell badh kar poora paudha ban sakta hai.

  8. 1931

    Electron microscope

    Ernst Ruska aur Max Knoll pehla electron microscope banate hain.

  9. 2010

    Lab mein bana DNA

    Ek bacterium chemicals se bane DNA par chalta hai.

2.5.1 Kya cells hamesha badhte aur reproduce karte rehte hain?

Culture dish mein badhte animal cells dekho, to ek built-in brake dikhta hai. Woh tab tak divide hote hain jab tak tali ko ek single layer mein dhak na lein aur har taraf padosiyon ko chhoo na lein, aur phir ruk jaate hain. Ise contact inhibition (Fig. 2.17) kehte hain. Cancer cells ka yeh brake kho chuka hota hai. Woh bheed mein bhi divide hote rehte hain, ek doosre ke upar chadh jaate hain aur tumour bana lete hain.

Division balance ka sirf aadha hissa hai; baaki aadha hai death. Healthy cell apna kaam karta hai aur samay poora hone par mar jaata hai, aur uski jagah naya cell aa jaata hai. Umr mein bahut fark hota hai: gut ki lining ke cells sirf kuch din chalte hain, red blood cells lagbhag chaar mahine, aur zyadatar nerve cells tumhari poori zindagi. Agar cells bahut kam divide hon ya bahut jaldi mar jaayein, to tissue kamzor hokar ghat jaata hai; agar woh bahut zyada divide hon ya marne se inkaar karein, to woh wahan jama ho jaate hain jahan unki zaroorat nahi.

3/3Cancer cells signal ko ignore karte hain aur ek gaanth mein jama ho jaate hain.

Fig. 2.17Normal cells chhoone par divide hona band kar dete hain; cancer cells nahi.NCERT p. 23

Do culture dishes side se dekhi gayi, upar wali dish mein normal cells aur neeche wali mein cancer cells. Step 1: har dish ki tali par kuch alag-alag cells hain. Step 2: dono divide ho gaye hain; upar wali dish mein cells ab tali ko ek saaf layer mein dhak rahe hain, har ek apne padosiyon ko chhoo raha hai, aur ek stop sign hai; neeche wali dish bhi dhak gayi hai. Step 3: upar wali dish waisi hi hai, ab bhi ek layer, jabki neeche wali dish mein cancer cells divide hote rehte hain aur ek dher ban gaye hain jis par tumour label hai.

Plant cells apni walls ki wajah se apni jagah tike rehte hain aur kabhi ek doosre par nahi rengte, isliye unmein contact inhibition ka koi role nahi hai. Plants growth ko doosre tareeke se control karte hain: sirf khaas growing regions, jaise Activity 2.5 mein padhi root tip aur shoot ki tip, divide hote rehte hain, jabki zyadatar doosre cells mature hone ke baad divide hona band kar dete hain.

Agli baar jab ghutne ki kharonch bhare, to socho ki papdi ke neeche kya ho raha hai. Gap ke kinare ke cells mitosis se divide hote hain, apne ribosomes par naye proteins banate hain, apne mitochondria ke ATP se kaam ko power dete hain, aur gap band hote hi divide hona band kar dete hain. Is chapter ki lagbhag har cheez skin ke us chhote se hisse mein kaam kar rahi hoti hai.

Quick check
3 mein se 1
Kaun si baat cell theory ka hissa hai?
Answer dekho

Answer (C) Saare cells pehle se maujood cells se aate hain

'Har cell ek cell se' cell theory ki teesri baat hai. Bacteria aur red blood cells mein nucleus nahi hota, animal cells ki wall nahi hoti, aur kai organisms unicellular hote hain.
Recap

Summary aur key points

  1. Har organism cells se bana hai, jo sabse chhoti zinda units hain; organisms unicellular ya multicellular hote hain, aur multicellular organisms mein cells tissues, organs aur organ systems banate hain.
  2. Zyadatar cells aankh ki limit of resolution (lagbhag 0.1 mm) se chhote hain, isliye hum unhe light aur electron microscopes se study karte hain; total magnification = eyepiece × objective (Section 2.1).
  3. Cell membrane proteins wali ek selectively permeable lipid bilayer hai (fluid mosaic model) aur har cell ko gherti hai (Section 2.2.1).
  4. Osmosis selectively permeable membrane ke across dilute se concentrated solution ki taraf paani ka movement hai: hypotonic mein cells phoolte hain, isotonic mein apni shape rakhte hain aur hypertonic solutions mein sikudte hain.
  5. Plants, fungi aur zyadatar bacteria mein membrane ke bahar ek rigid, freely permeable cell wall hoti hai; plant walls mainly cellulose ki hoti hain, aur strong solutions mein plant cells plasmolysis dikhate hain (Section 2.2.2).
  6. Prokaryotic cells (bacteria) mein true nucleus nahi, sirf nucleoid hota hai, aur koi membrane-bound organelles nahi hote; eukaryotic cells bade hote hain aur unmein dono hote hain (Section 2.3).
  7. Nucleus chromosomes mein DNA rakhta hai; genes DNA ke kaam karne wale hisse hain; nucleolus ribosome ke parts banata hai (nucleus).
  8. Ribosomes proteins banate hain; rough ER proteins banata aur le jaata hai, smooth ER lipids banata hai; Golgi apparatus finish, sort aur dispatch karta hai; lysosomes digest aur recycle karte hain (Section 2.3.1).
  9. Mitochondria khaane se energy ATP ke roop mein release karte hain; plastids (chloroplasts, chromoplasts, leucoplasts) banate, rang dete aur store karte hain; mitochondria aur chloroplasts ka apna DNA hota hai (mitochondria, plastids).
  10. Bada central vacuole cell sap store karta hai aur plant cells ko sakht rakhta hai; animal cells mein chhote vacuoles hote hain ya hote hi nahi (vacuoles).
  11. Mitosis growth, marammat aur asexual reproduction ke liye do ek jaise daughter cells deta hai (Section 2.4.1).
  12. Meiosis, jo sirf reproductive organs mein hota hai, aadhe chromosome number wale chaar gametes deta hai; fertilisation use wapas poora karta hai.
  13. Cell theory: saare living things cells se bane hain, cell jeevan ki basic unit hai, aur saare cells pehle se maujood cells se aate hain (Section 2.5).
  14. Normal cells balance mein badhte, kaam karte aur marte hain; contact inhibition bheed wale animal cells ko divide hone se rokta hai, aur jo cancer cells ise kho dete hain woh tumours banate hain (Section 2.5.1).
Practice · 21 questions

Practice questions answers ke saath (NCERT “Dohraao, socho, sudhaaro”)

  1. Short answerEasyNCERT Revise, Reflect, Refine Q1

    Har pair ke terms mein fark batao, bracket mein diye sawaal ka jawaab dekar.

    1. Cell wall aur cell membrane (kaun si paani mein ghuli lagbhag har cheez ko jaane deti hai, aur kaun si chunti hai?)

      Solution dikhao

      Cell membrane selectively permeable hai: yeh kuch substances ko jaane deti hai aur kuch ko rok leti hai. Cell wall freely permeable hai: paani aur ghule minerals isse aasaani se nikal jaate hain.

    2. Rough ER aur smooth ER (electron microscope mein yeh alag kaise dikhte hain, aur har ek mainly kya banata hai?)

      Solution dikhao

      Rough ER ki surface par ribosomes hote hain aur yeh mainly proteins banata hai. Smooth ER par ribosomes nahi hote aur yeh mainly lipids aur kuch hormones banata hai.

    3. Chromoplasts aur leucoplasts (har ek ka rang kya hai, aur har ek kis kaam ka hai?)

      Solution dikhao

      Chromoplasts mein peele, orange ya laal pigments hote hain aur yeh phoolon aur phalon ko rang dete hain. Leucoplasts rangheen hote hain aur starch, oils ya proteins jaisa khaana store karte hain.

    4. Diffusion aur osmosis (kise membrane chahiye?)

      Solution dikhao

      Diffusion kisi bhi particles ka higher se lower concentration ki taraf phailna hai aur ise membrane nahi chahiye. Osmosis sirf paani ka diffusion hai, selectively permeable membrane ke across.

  2. Quick answerMediumNCERT Revise, Reflect, Refine Q2

    Ek hi blood ki do boondein milayi jaati hain, ek distilled water ke saath (tube P) aur ek 3 % salt solution ke saath (tube Q). Microscope mein P ke red cells phool gaye hain aur kai phat gaye hain, jabki Q ke cells sikud gaye hain aur jhurridar dikhte hain. Kaun si explanation sahi hai?

    Answer dekho

    Answer (D) P ke cells mein paani gaya, aur Q ke cells se paani nikla, unki membranes ke across

    Distilled water hypotonic hai, isliye osmosis se paani P ke cells mein gaya jab tak kuch phat nahi gaye. 3 % salt solution hypertonic hai, isliye paani Q ke cells se bahar gaya. Salt ne kuch 'dabaya' nahi: woh zyadatar ruka rehta hai, isiliye move karne wali cheez paani hai.
  3. Quick answerEasyNCERT Revise, Reflect, Refine Q3

    Fig. 2.10 ke steps dekho aur har labelled part dhoondho. Phir us part ka naam batao jo har kaam karta hai.

    1. Cell ki saari activities control karta hai

      Answer dekho

      Answer (D) Nucleus

      Nucleus mein DNA instructions hoti hain jo cell ke banaye aur kiye har kaam ko direct karti hain.

    2. Cellular respiration ki jagah

      Answer dekho

      Answer (A) Mitochondrion

      Mitochondria oxygen ke saath khaana todte hain aur release hui energy ko ATP ke roop mein store karte hain.

    3. ER se mile materials pack karta hai

      Answer dekho

      Answer (B) Golgi apparatus

      Golgi apparatus ER se aaye proteins aur lipids ko finish, sort aur vesicles mein pack karta hai.

    4. Cell sap store karta hai aur cell ko sakht rakhta hai

      Answer dekho

      Answer (C) Central vacuole

      Central vacuole mein paani, sugars aur salts hote hain; bhara hone par yeh cytoplasm ko wall par dabata hai aur cell ko sakht rakhta hai.
  4. Quick answerMediumNCERT Revise, Reflect, Refine Q4

    Inmein se kaun se pairs ke dono parts plant cells mein milte hain lekin animal cells mein nahi?

    Saare sahi options chuno
    Answer dekho
    Answer
    • (A) Cell wall aur chloroplast
    • (C) Bada central vacuole aur leucoplast
    Walls, chloroplasts, leucoplasts aur bada central vacuole plant features hain. Mitochondria, ribosomes, Golgi apparatus, nuclei aur membranes animal cells mein bhi hote hain, aur lysosomes animal cells ki typical pehchaan hain.
  5. Short answerMediumNCERT Revise, Reflect, Refine Q5

    Arjun kehta hai ki gaajar mein koi plastids ho hi nahi sakte, kyunki woh zameen ke neeche ugti hai jahan photosynthesis ke liye light nahi hai. Kavya kehti hai ki woh galat hai. Kaun sahi hai? Plastids ke naam lekar samjhao.

    Solution dikhao

    AnswerKavya. Zameen ke neeche wale hisson mein kaam karne wale chloroplasts nahi hote, lekin doosre plastids hote hain: gaajar mein chromoplasts aur aloo mein leucoplasts.

    Kavya sahi hai. Arjun sirf chloroplasts ke baare mein soch raha hai, jinhe sach mein light chahiye. Lekin plastids aur tarah ke bhi hote hain. Gaajar ka orange rang orange pigment se bhare chromoplasts se aata hai. Aloo ke tuber ke cells starch store karne wale leucoplasts se bhare hote hain.

    To zameen ke neeche ugne wale hisson mein bhi plastids hote hain, bas hare nahi. Asal mein, agar gaajar ka upar wala hissa light mein chhod do, to wahan chloroplasts banne se woh dheere-dheere hara ho jaata hai.

  6. Long answerMediumNCERT Revise, Reflect, Refine Q6

    Mitochondria aur chloroplasts dono leaf cell mein milte hain.

    1. Structure mein dono ke do milte-julte points batao.

      Solution dikhao
      • Dono do membranes se ghire hain.
      • Dono mein apna DNA (ek chhota loop) aur apne ribosomes hote hain, isliye dono apne kuch proteins khud bana sakte hain.

    2. Structure mein dono ke do fark batao.

      Solution dikhao
      • Mitochondrion mein andar wali membrane cristae mein mudi hoti hai; chloroplast mein andar wali membrane smooth hoti hai, aur stroma mein alag discs ke stacks hote hain.
      • Chloroplast mein hara pigment chlorophyll hota hai; mitochondrion mein nahi hota. Chloroplasts aam taur par bade bhi hote hain.

    3. Dono ke kaam kaise jude hain?

      Solution dikhao

      Chloroplast light energy pakadta hai aur use photosynthesis se bani sugar mein store karta hai. Mitochondrion cellular respiration mein us sugar ko todta hai aur release hui energy ko ATP ke roop mein store karta hai, jise cell apne kaam par kharch karta hai. Ek energy ko khaane mein store karta hai; doosra use release karta hai.

  7. Quick answerMediumNCERT Revise, Reflect, Refine Q7

    Leaf cell ki har woh structure select karo jismein DNA hai.

    Saare sahi options chuno
    Answer dekho
    Answer
    • (A) Nucleus
    • (B) Chloroplast
    • (C) Mitochondrion
    Nucleus mein chromosomes hote hain, aur mitochondria aur chloroplasts dono mein apne DNA ka ek chhota loop hota hai. Ribosomes DNA se copy ki gayi instructions padhte hain, lekin unmein khud DNA nahi hota.
  8. Short answerMediumNCERT Revise, Reflect, Refine Q8

    Priya ek kacchi radish (mooli) se do barabar strips kaatti hai. Woh strip A ko nal ke paani mein aur strip B ko strong namak wale paani mein daalti hai. Agle din A kurkuri hai aur modne par toot jaati hai, jabki B naram hai aur rubber ki tarah mud jaati hai.

    1. Priya kaun sa hypothesis test kar rahi thi?

      Solution dikhao

      Ki mooli ke cells dilute solution mein paani lete hain aur concentrated solution mein paani khote hain, osmosis se, aur isse mooli ki sakhti badal jaati hai.

    2. Uske experiment ko behtar banane ka ek tareeka batao.

      Solution dikhao

      Har strip ka pehle aur baad mein wazan lo (ya naapo), taaki change ko number mein bataya ja sake. Woh har liquid mein kai strips bhi use kar sakti thi, aur comparison ke liye ek teesri strip hawa mein chhod sakti thi, taaki result zyada bharosemand ho.

    3. Samjhao ki strip A kurkuri aur strip B dheeli kyun hai.

      Solution dikhao

      Nal ka paani mooli ke cells ke liye hypotonic hai, isliye osmosis se paani unke andar gaya. Unke vacuoles phool kar walls par dabe aur cells sakht ho gaye, isliye strip kurkuri hai. Namak wala paani hypertonic hai, isliye paani cells se bahar nikla. Sikude vacuoles ke saath cells ki sakhti chali gayi, aur strip dheeli pad gayi.

  9. Quick answerMediumNCERT Revise, Reflect, Refine Q9

    Inmein se kya bacterial cell aur plant leaf cell dono mein hota hai?

    Saare sahi options chuno
    Solution dikhao
    Table 2.8
    StructureBacterial cellPlant ki patti ka cell
    RibosomesHaiHai
    Cell wallHaiHai
    Nuclear membraneNahi haiHai
    ChloroplastsNahi haiHai
    DNAHai (nucleoid)Hai (nucleus, aur mitochondria aur chloroplasts mein bhi)
    MitochondriaNahi haiHai
  10. ActivityHardNCERT Revise, Reflect, Refine Q10

    Kabir sweet potato (shakarkandi) ke teen aadhe tukdon ko khokhla karke cups banata hai. Cup X kaccha hai, aur uske khokhle hisse mein ek teaspoon cheeni hai. Cup Y kaccha hai, aur khokhla hissa khaali hai. Cup Z pehle ubala gaya tha aur uske khokhle hisse mein ek teaspoon cheeni hai. Har cup paani ki ek plate mein khada hai. Teen ghante baad sirf cup X ke khokhle hisse mein liquid jama hota hai.

    1. Cup X mein liquid kahan se aaya, aur woh kyun move hua?

      Solution dikhao

      Yeh plate ka paani hai. Khokhle hisse ki cheeni ne ek concentrated solution banaya, jabki plate mein saada paani tha. Paani cup ki wall ke living cells se hokar, dilute side se concentrated side ki taraf, osmosis se gaya.

    2. Cup Z mein liquid kyun jama nahi hota?

      Solution dikhao

      Ubalne se cells mar gaye aur unki membranes kharab ho gayi. Mare hue cells selectively permeable nahi rehte, isliye woh osmotic membrane ki tarah kaam nahi karte; cheeni aur paani bas aar-paar mil jaate hain, aur khokhle hisse mein paani jama nahi hota.

    3. Cup Y kis liye hai?

      Solution dikhao

      Yeh control hai. Yeh dikhata hai ki kacche cup ke khokhle hisse mein paani tab tak jama nahi hota jab tak usmein cheeni na ho, isliye cup X mein cheeni hi kaaran hai.

    4. Predict karo ki kya hoga agar cheeni plate ke paani mein ghol di jaaye, aur cup X ka khokhla hissa saade paani se bhara ho.

      Solution dikhao

      Khokhle hisse mein paani ka level gir jaayega. Ab concentrated solution bahar hai, isliye paani khokhle hisse se cup ki wall se hokar plate mein jaayega.

  11. Quick answerMediumNCERT Revise, Reflect, Refine Q11

    Organelle aur function ka kaun sa joda galat hai?

    Answer dekho

    Answer (B) Rough ER: cell ke zyadatar lipids banata hai

    Lipids mainly smooth ER banata hai. Rough ER, apne ribosomes ke saath, mainly proteins banata hai. Baaki teen jode sahi hain.
  12. Short answerMediumNCERT Revise, Reflect, Refine Q12

    Cyanide ek zehar hai jo mitochondria ko oxygen use karne se rok deta hai. Predict karo ki cyanide ke sampark mein aaye heart muscle cell ka kya hota hai, aur samjhao ki heart aur brain ko itni jaldi nuksaan kyun hota hai.

    Solution dikhao

    AnswerCell ab kaafi ATP nahi bana paata, isliye apna kaam nahi kar paata aur jaldi mar jaata hai; heart aur brain, jo sabse tezi se energy use karte hain, sabse pehle fail hote hain.

    Mitochondria oxygen se khaana todte hain aur release hui energy ko ATP ke roop mein store karte hain. Agar woh kaam karna band kar dein, to cell ki ATP supply dhah jaati hai. Heart muscle cell ko contract hone ke liye ATP ki lagaataar dhaara chahiye, isliye woh kamzor hokar ruk jaata hai, aur marammat ke liye energy na hone se jaldi mar jaata hai.

    Heart aur brain ke cells bina ruke kaam karte hain aur unmein bahut saare mitochondria hote hain, isliye woh zyadatar cells se tezi se energy use karte hain. Unki energy sabse pehle khatam hoti hai, isiliye cyanide poisoning itni jaldi khatarnaak ho jaati hai.

  13. Short answerHardNCERT Revise, Reflect, Refine Q13

    Culture dish mein badhte normal cells ek doosre ko chhoone par divide hona band kar dete hain.

    1. Is property ka naam batao aur samjhao ki ise khone se tumour kaise ban sakta hai.

      Solution dikhao

      Yeh contact inhibition hai. Jin cells ne ise kho diya hai woh bheed mein bhi divide hote rehte hain, isliye ek doosre ke upar jama hokar extra tissue ki ek gaanth, yaani tumour, bana lete hain.

    2. Plant cells yeh property nahi dikhate. Kya iska matlab hai ki plants mein kabhi tumours nahi ho sakte? Samjhao.

      Solution dikhao

      Nahi. Plants growth ko alag tareeke se control karte hain: sirf root aur shoot tips jaise growing regions divide hote rehte hain. Plants mein phir bhi tumour jaisi soojan ban sakti hai jise galls kehte hain, jaise jab kuch bacteria ya insects plant cells ko abnormal tareeke se divide karwa dete hain. Kyunki rigid walls plant cells ko apni jagah tikaye rakhti hain, yeh growths body mein us tarah nahi phailti jaise malignant animal cancers phailte hain.

  14. DiagramHardNCERT Revise, Reflect, Refine Q14

    Badhte cell ko zyada cell membrane chahiye, jo lipids aur proteins se bani hoti hai.

    1. Nayi membrane ke lipids aur proteins kaun se organelles banate hain?

      Solution dikhao

      Smooth ER lipids banata hai. Rough ER par ribosomes membrane proteins banate hain.

    2. Batao ki yeh materials cell membrane tak kis raaste se jaate hain.

      Solution dikhao

      Naye lipids aur proteins ER membrane mein jama hote hain. Chhote vesicles ER se alag hokar unhe Golgi apparatus tak le jaate hain, jo unhe finish aur sort karta hai. Golgi se naye vesicles alag hote hain, cell membrane tak jaate hain aur usse fuse ho jaate hain, isliye unki membrane cell membrane ka hissa ban jaati hai.

    3. Is raaste ko ek labelled flow diagram mein dikhao.

      Solution dikhao

      Arrows se jude boxes banao: rough ER par ribosomes (proteins) aur smooth ER (lipids) → vesicle → Golgi apparatus → vesicle → cell membrane. Har arrow par 'vesicle' likho, aur membrane par 'fuses' likho.

  15. Short answerMediumNCERT Revise, Reflect, Refine Q15

    Fruit fly ke body cells mein 8 chromosomes hote hain. Maan lo fruit flies apne gametes meiosis ki jagah mitosis se banate.

    1. Agli generation ke fertilised egg mein kitne chromosomes hote?

      chromosomes
      Answer dekho

      Answer 16 chromosomes

      Har gamete mein poore 8 rehte, isliye fertilised egg ko 8+8=16 milte.

    2. Teesri generation mein kitne hote? Asli zindagi mein aisa kyun nahi hota?

      Solution dikhao

      Number har generation mein double hota: 16, phir 32, phir teesri generation mein 64. Cells lagaataar badhte chromosome sets ko sambhal nahi paate, isliye flies normal tareeke se develop nahi ho paati. Meiosis gametes mein number aadha karke ise rokta hai, aur fertilisation use wapas poora karta hai, isliye yeh 8 hi rehta hai.

  16. Long answerHardNCERT Revise, Reflect, Refine Q16

    Konkan coast ke ek machhuaaron ke gaon mein Shabana ka self-help group do products bechta hai. Ek hai bahut saare namak mein lapet kar dhoop mein sukhayi machhli. Doosra hai kacche aam ka murabba: gaadhe sugar syrup mein rakhe aam ke tukde. Dono mahinon tak bina kharab hue chalte hain, aur group ab un machhliyon aur aamon se kamaata hai jo pehle barbaad ho jaate the.

    1. Us process ka naam batao jisse namak aur cheeni preservatives ki tarah kaam karte hain.

      Solution dikhao

      Osmosis.

    2. Samjhao ki namak ya cheeni ka high concentration bacteria aur fungi ko badhne se kaise rokta hai.

      Solution dikhao

      Namak ya cheeni ki gaadhi parat khaane par girne wale kisi bhi bacterium ya fungus ke cells ke liye bahut hypertonic hoti hai. Osmosis se microbe ke cells se paani nikal jaata hai, isliye woh sikud jaate hain aur badh ya multiply nahi kar paate, aur kai mar jaate hain. Namak machhli se bhi paani kheench leta hai, jisse microbes ke use ke liye bahut kam khula paani bachta hai.

    3. Syrup patla nahi, gaadha kyun hona chahiye?

      Solution dikhao

      Patla syrup microbial cells ke liye isotonic ke kareeb, ya hypotonic bhi ho sakta hai, isliye unka paani nahi nikalega aur woh phir bhi badh sakte hain. Sirf bahut concentrated syrup hi unse kaafi paani kheench paata hai.

    4. Kam cheeni ke saath phal preserve karne ka ek tareeka batao, aur batao ki kya usmein bhi yahi idea hai.

      Solution dikhao

      Phal ke patle slices ko dhoop mein sukhana (jaise kam cheeni wala aam papad) seedhe paani hata deta hai. Ismein milta-julta idea hai: paani ke bina microbes badh nahi sakte. Sukhana bina hypertonic solution daale kaam karta hai, isliye ismein kam cheeni lagti hai.

  17. Quick answerEasy

    Inhe sabse bade se sabse chhote ke order mein lagao.

    1. Amoeba
    2. Bacterium
    3. Virus
    4. Red blood cell
    5. Cheek cell
    Answer dekho
    Answer
    1. Amoeba
    2. Cheek cell
    3. Red blood cell
    4. Bacterium
    5. Virus
    Lagbhag 0.5 mm, 60 µm, 8 µm, 2 µm aur 0.1 µm.
  18. Quick answerEasy

    Plant cell walls mainly se bani hoti hain, jo hamare khaane mein fibre ka kaam karta hai.

    Answer dekho

    Answer cellulose

    Cellulose glucose units ki ek lambi chain hai jise hum digest nahi kar sakte, isliye yeh roughage ki tarah aage nikal jaata hai.
  19. Quick answerEasy

    Har living cell mein nucleus hota hai.

    Answer dekho

    Answer Galat

    Bacteria mein sirf nucleoid hota hai, aur insaan ke mature red blood cells apna nucleus kho dete hain.
  20. Quick answerMedium

    Ek cell 80 μm chauda hai. 10X eyepiece aur 10X objective se dekhne par woh millimetres mein kitna chauda dikhta hai?

    mm
    Answer dekho

    Answer 8 mm

    Total magnification 10×10=100 hai, isliye image 80×100=8000 μm=8 mm chauda hai.
  21. Quick answerEasy

    Genda ki pankhudiyan chamakdaar orange hoti hain. Unmein kaun se plastids bharpoor hote hain?

    Answer dekho

    Answer (C) Chromoplasts

    Chromoplasts mein peele, orange aur laal pigments hote hain. Chloroplasts pankhudiyon ko hara bana dete; leucoplasts rangheen hote hain.

Apna NCERT exercise question dhoondo

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

Tumhari NCERT textbook meinYahan practice question
Pause and Ponder Q1Ruko aur socho · Q1
Pause and Ponder Q2Ruko aur socho · Q2
Pause and Ponder Q3Ruko aur socho · Q3
Pause and Ponder Q4Ruko aur socho · Q4
Pause and Ponder Q5Ruko aur socho · Q5
Pause and Ponder Q6Ruko aur socho · Q6
Pause and Ponder Q7Ruko aur socho · Q7
NCERT Revise, Reflect, Refine Q1Dohraao, socho, sudhaaro · Q1
NCERT Revise, Reflect, Refine Q2Dohraao, socho, sudhaaro · Q2
NCERT Revise, Reflect, Refine Q3Dohraao, socho, sudhaaro · Q3
NCERT Revise, Reflect, Refine Q4Dohraao, socho, sudhaaro · Q4
NCERT Revise, Reflect, Refine Q5Dohraao, socho, sudhaaro · Q5
NCERT Revise, Reflect, Refine Q6Dohraao, socho, sudhaaro · Q6
NCERT Revise, Reflect, Refine Q7Dohraao, socho, sudhaaro · Q7
NCERT Revise, Reflect, Refine Q8Dohraao, socho, sudhaaro · Q8
NCERT Revise, Reflect, Refine Q9Dohraao, socho, sudhaaro · Q9
NCERT Revise, Reflect, Refine Q10Dohraao, socho, sudhaaro · Q10
NCERT Revise, Reflect, Refine Q11Dohraao, socho, sudhaaro · Q11
NCERT Revise, Reflect, Refine Q12Dohraao, socho, sudhaaro · Q12
NCERT Revise, Reflect, Refine Q13Dohraao, socho, sudhaaro · Q13
NCERT Revise, Reflect, Refine Q14Dohraao, socho, sudhaaro · Q14
NCERT Revise, Reflect, Refine Q15Dohraao, socho, sudhaaro · Q15
NCERT Revise, Reflect, Refine Q16Dohraao, socho, sudhaaro · Q16

Quick check: MCQs

  1. 2.1 Cells ko kaise study karein?3 questions
  2. 2.2.2 Cell wall — Cells ka bahari aavaran4 questions
  3. 2.3 Cell ka andar — Ek coordinated working system3 questions
  4. Vacuoles: storage ki tankiyan4 questions
  5. 2.4.1 Cell division4 questions
  6. 2.5.1 Kya cells hamesha badhte aur reproduce karte rehte hain?3 questions
Glossary · 19

Key terms (English + Hindi)

cellकोशिकाkoshika
Living things mein structure aur function ki sabse chhoti unit.Chapter mein pehli baar yahan aaya →
cell membraneप्लैज़्मा झिल्लीplasma jhilli
Har cell ki patli, selectively permeable boundary, proteins wali ek lipid bilayer.Chapter mein pehli baar yahan aaya →
cell wallकोशिका भित्तिkoshika bhitti
Plants (mainly cellulose), fungi aur zyadatar bacteria mein membrane ke bahar ek rigid, freely permeable layer.Chapter mein pehli baar yahan aaya →
chromosomeगुणसूत्रgunsutra
Nucleus mein DNA aur proteins ka ek dhaaga jo genes rakhta hai.Chapter mein pehli baar yahan aaya →
contact inhibition
Padosiyon ko chhoote hi animal cells ke division ka ruk jaana; cancer cells ise kho dete hain.Chapter mein pehli baar yahan aaya →
endoplasmic reticulumअंतर्द्रव्यी जालिकाantardravyi jalika
Membrane tubes aur theliyon ka network jo proteins (rough ER) aur lipids (smooth ER) banata aur le jaata hai.Chapter mein pehli baar yahan aaya →
eukaryotic cellयूकैरियोटी कोशिकाyukairiyoti koshika
Aisa cell jismein membrane-bound nucleus aur organelles hote hain, jaise plants, animals aur fungi mein.Chapter mein pehli baar yahan aaya →
Golgi apparatusगॉल्जी उपकरणgolji upkaran
Chapti theliyon ka stack jo proteins aur lipids ko finish, sort aur vesicles mein pack karta hai.Chapter mein pehli baar yahan aaya →
limit of resolution
Sabse chhota gap jis par do points phir bhi alag dikhte hain; 25 cm par aankh ke liye lagbhag 0.1 mm.Chapter mein pehli baar yahan aaya →
lysosomeलयनकायlayankay
Digestive enzymes ki single-membrane thaili jo waste todti aur recycle karti hai.Chapter mein pehli baar yahan aaya →
meiosisअर्धसूत्री विभाजनardhsutri vibhajan
Reproductive organs mein do divisions jo aadhe chromosome number wale chaar gametes dete hain.Chapter mein pehli baar yahan aaya →
mitochondrionसूत्रकणिकाsutrakanika
Double-membrane wala organelle jo cellular respiration se khaane ki energy ATP ke roop mein release karta hai.Chapter mein pehli baar yahan aaya →
mitosisसमसूत्री विभाजनsamsutri vibhajan
Cell division jo parent jaise bilkul same do daughter cells deta hai.Chapter mein pehli baar yahan aaya →
organelleकोशिकांगkoshikang
Cell ke andar ek khaas kaam wali structure, jaise mitochondrion.Chapter mein pehli baar yahan aaya →
osmosisपरासरणparasaran
Selectively permeable membrane ke across dilute se zyada concentrated solution ki taraf paani ka movement.Chapter mein pehli baar yahan aaya →
plastidलवकlavak
Plant ka organelle jo khaana banata hai (chloroplast), rang rakhta hai (chromoplast) ya khaana store karta hai (leucoplast).Chapter mein pehli baar yahan aaya →
prokaryotic cellप्रोकैरियोटी कोशिकाprokairiyoti koshika
Aisa cell jismein true nucleus nahi hota (uska DNA nucleoid mein hota hai) aur koi membrane-bound organelles nahi hote, jaise bacterium.Chapter mein pehli baar yahan aaya →
ribosomeराइबोसोमraibosom
Bina membrane ka ek chhota organelle jo proteins banata hai.Chapter mein pehli baar yahan aaya →
vacuoleरसधानीrasdhani
Cell sap ki membrane wali thaili; plant cells mein badi aur beech mein, jahan yeh cell ko sakht rakhti hai.Chapter mein pehli baar yahan aaya →

Tum chapter ke end tak pahunch gaye