Chapter ke text par jao
ScienceCh 8 Heredity

Heredity: Class 10 Science Chapter 8 Hinglish mein

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

Published · Updated

  • 50 min
  • 18 practice questions
  • 17 MCQs

Is chapter mein aap kya seekhenge

  • Samjhao ki asexual aur sexual reproduction mein generations ke saath variations kaise jama hote hain, aur variation kisi species ko survive karne mein kyun madad karta hai
  • Tall aur short pea plants ka Mendel wala cross describe karo, aur Punnett square se 3 : 1 aur 1 : 2 : 1 ratios samjhao
  • Dominant aur recessive traits mein, aur genotype aur phenotype mein fark batao, aur crosses ke results se gene pairs nikaalo
  • Dihybrid cross aur uska 9 : 3 : 3 : 1 ratio samjhao, is baat ke saboot ki tarah ki do traits ek doosre se independently aage jaati hain
  • Samjhao ki genes proteins ke through traits ko kaise control karte hain, aur chromosomes aur germ cells dono parents ke contribution ko barabar kaise rakhte hain
  • Samjhao ki insaanon mein sex kaise determine hota hai, aur kuch animals mein surroundings se hone wale sex determination se iski tulna karo

NCERT Science Class 10, Chapter 8, pp. 128–133 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Family ki kisi shaadi mein cousins ki ek line par nazar daalo. Kai cousins ki naak daadi jaisi tez hai ya baal dada jaise ghunghraale hain, phir bhi koi do chehre ek jaise nahi hain. Ab ek banana plantation socho jismein har plant ek hi parent plant se kaate gaye sucker se ugaya gaya hai: plants lagbhag ek doosre ki copy jaise dikhte hain. Do parents wala reproduction saaf dikhne wale differences banata hai; ek plant ke hisson se naye plants ugane par bahut kam differences aate hain.

Pichhle chapter mein tumne dekha ki reproduction DNA ko copy karta hai, aur copies kabhi perfect nahi hoti. Yeh chapter do sawaal poochta hai. Differences, yaani variations, kaise paida hote hain aur generations ke saath kaise jama hote hain? Aur kin rules se features parents se bachchon tak pahunchte hain?

8.1 Reproduction ke dauraan Variation ka jama hona

Socho ek family recipe jo ek cook se doosre cook tak aage badhti hai. Har cook use imaandaari se copy karta hai lekin ek chhota sa badlaav kar deta hai, ek chutki namak zyada ya thodi cheeni kam, aur agla cook badli hui recipe copy karta hai aur apna ek badlaav jod deta hai. Living things bhi apna design lagbhag isi tarah aage dete hain. Har generation ko ek kaam karne wala plan milta hai, saath mein parents ke chhote badlaav bhi, aur woh kuch naye badlaav jod deti hai, isliye generations ke saath differences jama hote jaate hain.

3/4Har cell apne parent ka change rakhta hai aur ek naya jodta hai, isliye chaaron alag hain.

Fig. 8.1Chhote changes generation dar generation jama hote hain, aur surroundings mein aaya change tay karta hai ki kaunse changes maayne rakhte hain.NCERT Fig. 8.1 · p. 128

Curd bacteria ki ek family line, left se right banayi gayi. Step 1 mein generation 1 ka ek akela rod-shaped cell hai. Step 2 mein generation 2 ke do daughter cells judte hain: ek par naya triangle mark hai aur doosre par naya square mark, dono DNA copy karte waqt aaye chhote change ko dikhate hain. Step 3 mein generation 3 ke chaar cells judte hain: har cell apne parent ka mark rakhta hai aur apna ek naya mark paata hai, isliye chaaron thode alag hain. Step 4 mein teesri generation mein medicine daali jaati hai: triangle mark wale do cells, jinka change medicine ko resist karta hai, par bacha likha hai, aur square mark wale do cells kaat diye gaye hain aur un par mara likha hai.

DNA copying kamaal ki accurate hoti hai, lekin laakhon copies mein kuch galtiyan aa hi jaati hain. Lactobacillus bacteria ko socho jo raat bhar mein doodh ko dahi bana dete hain, kuch cells se baar-baar double hote hue. Jis daughter cell ko copying ki galti milti hai, woh use apne saare descendants ko de deta hai, aur unmein se koi bhi apni ek nayi galti jod sakta hai. Ek family line ko teen generations tak follow karo (Fig. 8.1) aur tumhe aise cells milenge jo lagbhag, par poori tarah nahi, ek jaise hain; har cell mein apne ancestors ki galtiyan hain.

Sexual reproduction kahin zyada variety banata hai. Har offspring ko do alag parents se DNA milta hai, isliye woh features ke ek naye mixture ke saath zindagi shuru karta hai, jo bilkul isi roop mein kisi bhi parent mein nahi tha. Yeh mixing kaise hoti hai, yeh tum Section 8.2.2 mein Mendel ke experiments padhte waqt dekhoge.

Ab surroundings mein ek change jodo. Jab koi patient antibiotic leta hai, to woh gine-chune bacteria jinmein sanyog se aisa change hai jo medicine ko resist karne deta hai, survive karke multiply karte hain, aur baaki mar jaate hain. Kam baarish wale saal mein, bajre ke woh plants jinki roots sanyog se thoda zyada gehri jaati hain, seed banane ke sabse zyada chance rakhte hain. Jo difference aam dinon mein bekaar lagta tha, woh tay kar sakta hai ki kaun jiyega. Matlab variants barabar nahi hote: surroundings kuch ko doosron se zyada favour karti hain, aur isi chhantai se evolution ki kahani shuru hoti hai, jo tum oonchi classes mein padhoge.

Definition
Variation

Ek hi species ke individuals ke beech differences, jaise height, colour ya kisi disease ko resist karne ki ability mein. Variations reproduction ke dauraan paida hote hain, aur unmein se kai inherit hote hain.

ExampleBacteria ki ek colony mein kuch cells us antibiotic se bhi bach jaate hain jo unke padosiyon ko maar deta hai.

Quick check
3 mein se 1
Bacteria ki ek colony ek single cell se baar-baar split hokar badhti hai. Cells lagbhag ek jaise, lekin bilkul ek jaise kyun nahi hote?
Answer dekho

Answer (D) Har split se pehle hone wali DNA copying poori tarah accurate nahi hoti

Splitting parent ke DNA ko copy karti hai, aur kabhi-kabhi hone wali copying errors kuch daughter cells ko thoda alag DNA de deti hain. Mix karne ke liye koi doosra parent nahi hai, aur cells apne changes khud nahi chunte: variations sanyog se paida hote hain, aur baad mein hi surroundings unmein se kuch ko favour karti hain.
Practice · 2 questions

Practice 8.1 (NCERT in-text questions, p. 129): answers ke saath

  1. Short answerMediumNCERT in-text Questions p. 129, Q1

    Yeast ki ek population sirf budding se reproduce karti hai. Cell colour mein ek change, P, 8% cells mein milta hai, aur cell shape mein ek change, Q, 55% cells mein. Koi bhi change survival par asar nahi daalta. Kaunsa change shayad pehle aaya tha? Apna reason batao.

    Solution dikhao

    AnswerQ shayad pehle aaya tha.

    Budding mein naya change pehle ek cell mein dikhta hai. Woh tabhi failta hai jab us cell ke descendants generation dar generation multiply karte hain. Kyunki koi bhi change survival mein na madad karta hai na nuksaan, isliye use rakhne wale cells ka hissa mainly is baat se badhta hai ki uske aane ke baad kitni generations beet chuki hain.

    To jo change kahin zyada cells mein hai, yaani 55% wala Q, use failne ke liye shayad zyada generations mili hain: woh shayad P se pehle aaya, jo abhi sirf 8% cells mein milta hai.

  2. Short answerMediumNCERT in-text Questions p. 129, Q2

    Gehoon ugane wale districts mein ek nayi fungal disease fail jaati hai. Field A mein ek hi variety boyi gayi thi jiske plants genetically lagbhag ek jaise hain; field B mein genetically alag-alag plants ka mixture boya gaya tha. Kis field mein kuch plants ke bachne ke chance zyada hain? Apne answer se samjhao ki variation kisi species ko survive karne mein kaise madad karta hai.

    Solution dikhao

    AnswerField B. Alag-alag individuals wali population mein shayad kuch aise individuals honge jo naye khatre se bach sakein.

    Field A mein, agar fungus ek plant par attack kar sakta hai to sab par kar sakta hai, isliye poori fasal barbaad ho sakti hai. Field B mein plants alag-alag hain, aur kuch mein sanyog se aisa variation ho sakta hai jo fungus ko resist kare. Woh plants survive karte hain aur seed banate hain.

    Ek species field B ki tarah behave karti hai. Jab uski surroundings badalti hain, kisi nayi disease, sookhe ya garam climate se, to alag-alag individuals wali population mein shayad kuch individuals nayi conditions ke laayak honge. Woh survive aur reproduce karte hain, isliye species chalti rehti hai. Variation ke bina ek hi change use khatam kar sakta hai.

8.2 Heredity

Variation kahani ka sirf aadha hissa hai. Dekho kya nahi badalta: aam ki guthli se hamesha aam ka ped ugta hai, kabhi neem nahi, aur billi ke bachche hamesha billi hi hote hain. Heredity parents se offspring tak features ka yahi aage jaana hai, aur iske rules samjhate hain ki yeh itna bharosemand kyun hai, aur phir bhi differences ki jagah kyun chhodta hai.

Definition
Heredity

Parents se unke offspring tak traits ka aage jaana. Heredity ke rules samjhate hain ki traits generation dar generation kaise inherit hote hain.

8.2.1 Inherited Traits

Kisi bheed bhare railway platform par khade hokar charon taraf dekho. Height, skin tone, baal aur aankhon ki shape mein bepanaah variety hai. Phir bhi wahan sab log ek hi human plan share karte hain: do aankhein, ek backbone aur paanch ungliyon wale haath, aur har insaan kisi ajnabi se zyada apne parents jaisa dikhta hai. Parents se bachchon tak aane wale features ko inherited traits kehte hain. Sabse aasaan traits jinhe study kiya ja sake, unke do saaf roop hote hain, jaise kaan ke earlobe ki shape.

3/3Attached lobe seedha chehre ke side mein mil jaata hai.

Fig. 8.2Earlobe sir se kahan milta hai?NCERT Fig. 8.2 · p. 129

Side se dikhte do kaan, har ek gaal aur jabde ki line ke paas. Step 1 mein dono saade outlines hain jin par question mark laga hai. Step 2 mein left kaan ka lobe shaded hai: woh us dot ke neeche latakta hai jahan kaan sir se judta hai, jise dashed line se mark kiya gaya hai, aur us par free lobe likha hai. Step 3 mein right kaan ka lobe bhi shaded hai: uska neeche wala edge seedha jabde ki line mein mil jaata hai, koi latakta hissa nahi hai, aur us par attached lobe likha hai.

8.2.2 Traits ki Inheritance ke Rules – Mendel ka Yogdaan

Maan lo tumhari mother ke earlobes free hain aur father ke attached. Tumhare andar dono ke instructions hain, kyunki har parent ne tumhe tumhare DNA ka lagbhag theek aadha diya. Matlab har trait ke liye tumhare paas do instructions hain. Jab dono alag baat kehte hain, to kaun jeetta hai, aur haarne wale ka kya hota hai? Gregor Mendel ne 1860s mein garden peas ki breeding karke aur results gin kar iska answer dhoondha.

Peas Mendel ke liye bilkul sahi the. Woh jaldi ugte hain, ek plant bahut saare seeds deta hai, aur har flower aam taur par khud ko pollinate karta hai, phir bhi pollen ko haath se ek plant se doosre tak le jaaya ja sakta hai. Sabse badi baat, peas mein kai characters ke saaf ya-yeh-ya-woh roop hote hain, beech ka kuch nahi: round ya wrinkled seeds, violet ya white flowers, tall ya short stems, aur chaar aur pairs jo Table 8.2 mein diye hain.

Mendel ne pure-breeding plants se shuruaat ki: tall plants jinke offspring generation dar generation hamesha tall hote the, aur short plants jo hamesha short offspring hi dete the. Unhone ek tarah ke plant ka pollen doosri tarah ke flowers par chhidak kar dono ko cross kiya. In parents ko P generation kehte hain, aur unke offspring ko first filial, yaani F1, generation.

Agar traits chai mein ghule doodh ki tarah blend hote, to tall × short se medium height ke plants aane chahiye the. Mendel ko aisa kuch nahi mila: har F1 plant apne tall parent jitna hi tall tha. Kya shortness khatam ho gayi thi? Unhone F1 plants ko khud pollinate hone diya aur unke seeds se doosri generation, F2, ugayi. Short plants wapas aa gaye, lagbhag har chaar mein se ek; ek experiment mein unhone 787 tall plants aur 277 short plants gine. Matlab F1 plants shortness ko shuru se apne andar liye hue the, bina use dikhaye.

Mendel ki explanation simple aur bold thi: ek plant mein height ke liye hereditary factors ka ek pair hota hai. Aaj hum in factors ko genes kehte hain. Tall version ko T likho aur short version ko t. Tab pure tall plant TT hai aur pure short plant tt. Har pollen grain ya egg cell mein sirf ek copy hoti hai. Isliye har F1 plant ko ek parent se T aur doosre se t mila: woh Tt hai, aur tall hai kyunki ek T hi kaafi hai.

Ek Tt plant barabar sankhya mein do tarah ke germ cells banata hai: aadhe mein T hota hai aur aadhe mein t. Jab woh khud ko pollinate karta hai, to koi bhi pollen grain kisi bhi egg se mil sakta hai, isliye chaar pairings ke chance barabar hain. Punnett square naam ka ek grid in sabko list karta hai (Fig. 8.3): TT, Tt, tT aur tt. Chaar mein se teen mein kam se kam ek T hai aur woh tall hain; sirf tt short hai.

5/5Teen tall aur ek short; TT, Tt aur tt ka ratio 1 : 2 : 1.

Fig. 8.3Tall × short: short trait F1 mein chhup jaata hai aur F2 ke ek chauthai mein wapas aata hai.NCERT Fig. 8.3 · p. 130

Step 1: ek pure tall pea plant (TT) ko pure short plant (tt) se cross kiya jaata hai. Step 2: tall parent ke germ cells mein T hai aur short parent ke germ cells mein t; dono milkar ek F1 plant, Tt, dete hain, aur saare F1 plants tall hain. Step 3: ek F1 plant self-pollinate hota hai, aur ek do-by-do grid uske germ cells, T aur t, ko upar aur side mein list karta hai. Step 4: grid TT, Tt, Tt aur tt se bhar jaata hai; teen squares mein ek chhota tall plant hai aur tt square mein ek short plant. Step 5: tt square ko outline kiya gaya hai aur ratios diye gaye hain: 3 tall aur 1 short, aur 1 TT : 2 Tt : 1 tt.

Ek trait ka F2: jo hum dekhte hain
tall:short=3:1
(8.1)
Ek trait ka F2: gene pairs
TT:Tt:tt=1:2:1
(8.2)

Aisa experiment, jo contrasting traits ke ek pair ko follow karta hai, monohybrid cross kehlata hai. Dhyaan do ki do plants ek jaise dikh sakte hain phir bhi unke genes alag ho sakte hain: TT aur Tt dono tall hain. Isliye hum kisi organism ke phenotype, yaani trait ka woh roop jo hum dekh sakte hain, ko uske genotype, yaani uske gene copies ke pair, se alag rakhte hain.

Definition
Dominant trait

Aisi trait jo tab bhi dikhti hai jab uske gene version ki sirf ek copy maujood ho.

ExamplePeas mein tallness: TT aur Tt dono plants tall hote hain.

Definition
Recessive trait

Aisi trait jo sirf tab dikhti hai jab gene ki dono copies usi version ki hon.

ExamplePeas mein shortness: sirf tt plants short hote hain.

Dominant hone se koi trait zyada strong, behtar ya zyada common nahi ho jaati. Iska matlab bas itna hai: jab dono copies alag hon, to dominant copy tay karti hai ki hum kya dekhte hain. Recessive trait chhupne par khatam nahi hoti; woh Tt plants mein intezaar karti hai aur jab bhi do t copies milti hain, phir se dikh jaati hai.

Example 8.1

Kaunsi trait dominant hai?

Inflated (bhari hui) pods wale pure-breeding pea plants ko constricted (pichki hui) pods wale pure-breeding plants se cross kiya jaata hai. Har F1 plant ki pods inflated hain. Jab F1 plants ko self-pollinate kiya gaya, to Mendel ne inflated pods wale 882 F2 plants aur constricted pods wale 299 plants gine. Kaunsi trait dominant hai, aur kya yeh counts 3 : 1 ratio mein fit hote hain?

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

Table 8.2Garden peas mein Mendel ne jin saat characters ko follow kiyaNCERT p. 130
CharacterDominant roopRecessive roop
Seed shaperoundwrinkled
Seed colouryellowgreen
Flower colourvioletwhite
Pod shapeinflated (bhari hui)constricted (pichki hui)
Pod colourgreenyellow
Flower positionaxial (stem ke saath-saath)terminal (tip par)
Stem heighttallshort (dwarf)
LawLaw of dominance

Jab kisi organism mein ek gene ke do alag versions hote hain, to unmein se ek (dominant version) tay karta hai ki hum kaunsi trait dekhte hain, aur doosra (recessive version) chhupa rehta hai.

LawLaw of segregation

Germ cells bante waqt gene ki dono copies alag ho jaati hain, isliye har germ cell mein har gene ki sirf ek copy hoti hai. Fertilisation do copies ko phir se saath le aata hai.

3/3Sirf tall offspring ka matlab TT; kuch short offspring ka matlab Tt.

Fig. 8.4Tall plants ek jaise dikhte hain; unke offspring TT aur Tt ka fark batate hain.NCERT Activity 8.2 · p. 130

Step 1: teen F2 plants ek line mein khade hain: do tall plants jin par question marks hain aur ek short plant jis par tt likha hai. Step 2: har plant ke seeds alag tray mein boye jaate hain: pehla tall plant chaar tall offspring deta hai, doosra teen tall aur ek short, aur short plant chaar short offspring deta hai. Step 3: question marks ki jagah TT aur Tt aa jaate hain, Tt plant ke short offspring ko outline kiya jaata hai, aur trays par sab tall, 3 tall : 1 short aur sab short likha hota hai.

Example 8.2

Ratio se asli numbers tak

School ka eco-club F1 (Tt) pea plants ko self-pollinate karta hai aur 480 F2 plants ugata hai. (a) Kitne tall aur kitne short hone chahiye? (b) Tall plants mein se kitne Tt hone ki ummeed hai?

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

Quick check
4 mein se 1
Pure tall pea plants ko pure short plants se cross kiya jaata hai. F1 plants kaise dikhte hain?
Answer dekho

Answer (C) Sab tall

Har F1 plant Tt hai, aur ek akela T hi poori height de deta hai. Traits blend nahi hoti, isliye koi medium plant nahi hota, aur 3 : 1 ka split sirf F2 mein dikhta hai.

Ek saath do traits

Mendel ka agla step aur bhi bold tha: ek hi cross mein do characters ko follow karo aur dekho ki woh saath rehte hain ya alag-alag raaste jaate hain. Unhone round, yellow seeds (RRYY) wale ek pure-breeding plant ko wrinkled, green seeds (rryy) wale plant se cross kiya. Saare F1 seeds round aur yellow the (RrYy), isliye round aur yellow dominant roop hain.

Surprise F2 mein aaya. Parents mein dikhe do tarah ke seeds, round yellow aur wrinkled green, ke alawa do naye combinations bhi the: round green seeds aur wrinkled yellow seeds. Chaaron tarah ke seeds lagbhag 9 : 3 : 3 : 1 ke ratio mein aaye.

Punnett square iski wajah dikhata hai (Fig. 8.5). Ek RrYy plant barabar sankhya mein chaar tarah ke germ cells banata hai, RY, Ry, rY aur ry, kyunki germ cell ko jo shape copy milti hai, uska us colour copy par koi asar nahi padta jo use milti hai. Chaar tarah ke pollen ke chaar tarah ke eggs se milne par 16 barabar chance wali pairings banti hain. Aisa cross, jo traits ke do pairs ko saath-saath follow karta hai, dihybrid cross kehlata hai.

4/4Naye combinations (outlined) dikhte hain, aur chaaron tarah ke seeds 9 : 3 : 3 : 1 ke ratio mein aate hain.

Fig. 8.5Independently sort hui do traits 16 barabar chance wali pairings aur 9 : 3 : 3 : 1 ratio deti hain.NCERT Fig. 8.5 · p. 131

Step 1: ek round yellow seed (RRYY) ko wrinkled green seed (rryy) se cross kiya jaata hai, jisse ek F1 seed milta hai jo round aur yellow hai (RrYy). Step 2: ek chaar-by-chaar grid aata hai, jiske upar aur side mein woh chaar tarah ke germ cells likhe hain jo F1 plant banata hai, RY, Ry, rY aur ry. Step 3: saare 16 squares gene pairs aur ek seed drawing se bhar jaate hain: round seeds gol circles hain, wrinkled seeds ki outline sikudi hui hai, aur andar ka rang yellow ya green dikhata hai. Step 4: naye combinations wale chhe squares, round green aur wrinkled yellow, outline kiye jaate hain, aur ek tally 9 round yellow, 3 round green, 3 wrinkled yellow aur 1 wrinkled green list karti hai.

Do traits ka F2
9:3:3:1
(8.3)

Ek baar mein ek hi trait dekho, to purana pattern laut aata hai. Round seeds 16 mein se 9 + 3 = 12 squares bharte hain aur wrinkled seeds 3 + 1 = 4, yaani 3 : 1 ka ratio. Yellow aur green bhi 12 : 4, yaani 3 : 1 hai. Har trait apna 3 : 1 rule aise follow karti hai jaise doosri wahan ho hi nahi, isiliye (8.3) mein probabilities seedhe multiply hoti hain. Seed shape aur seed colour independently inherit hote hain.

LawLaw of independent inheritance (independent assortment)

Alag-alag traits ke genes ki copies ek doosre se independently germ cells mein sort hoti hain, isliye offspring mein traits naye combinations mein dikh sakti hain.

Example 8.3

Dihybrid F2 mein expected numbers

Ek RrYy pea plant ko self-pollinate karke 1,120 F2 seeds ikatthe kiye jaate hain. Har tarah ke kitne seeds ki ummeed karoge?

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

InteractiveCross lab

Teen modes: One trait (height, seed shape ya flower colour, jismein har parent ko do dominant copies, har ek ki ek copy, ya do recessive copies par set kiya ja sakta hai), Two traits (har parent ke liye seed shape aur seed colour), aur Boy or girl (ek mother XX aur ek father XY). Chune gaye parents ke liye panel har parent ke banaye germ cells unke fractions ke saath list karta hai, Punnett square ke har square mein gene pair aur dikhne wali traits bharta hai, aur offspring types aur gene pairs ka expected ratio batata hai. Buttons germ cells ke random pairs se 20, 200 ya 2000 offspring ugate hain aur bars ke saath expected aur actual counts ki table dikhate hain, taaki dikhe ki chhote batches ratio se bhatak jaate hain aur bade batches uske kareeb aa jaate hain.

Fig. 8.6Parents ki gene copies chuno aur unke germ cells, Punnett square aur expected ratio dekho. Phir chance se 20, 200 ya 2000 offspring ugao aur tulna karo.
Quick check
3 mein se 1
Ek RrYy plant kitni alag tarah ke germ cells banata hai?
Answer dekho

Answer (B) 4

Har germ cell ko ek shape copy (R ya r) aur ek colour copy (Y ya y) milti hai: RY, Ry, rY aur ry, yaani 2 × 2 = 4 tarah. Solah Punnett square ke squares ki sankhya hai, germ cells ki tarah ki sankhya nahi.

8.2.3 Yeh Traits Express Kaise Hoti Hain?

Ab tak genes grid mein bas letters the. Ek living cell ke andar woh kya hain? Har cell mein DNA hota hai, jo proteins banane ke instructions ka store hai, aur gene us DNA ka bas ek hissa hai.

Definition
Gene

DNA ka ek hissa jismein ek khaas protein banane ke instructions hote hain. Genes parents se offspring tak jaate hain aur traits ko control karte hain.

ExamplePea ka woh gene jo ek enzyme banata hai, jo growth hormone banane mein madad karta hai.

Genes proteins ke through kaam karte hain. Ek pea plant mein ek chain ko follow karo, us end se shuru karke jo tum dekh sakte ho. Stem lamba isliye badhta hai kyunki uske cells ek growth hormone, gibberellin, par respond karte hain. Plant yeh hormone kai steps mein banata hai, aur ek step ko ek khaas enzyme chahiye, jo ek protein hai. Us enzyme ke instructions ek gene hain. To chain aise chalti hai: gene → enzyme → hormone → height (Fig. 8.7). Agar gene copy working version hai, to uska enzyme tezi se kaam karta hai, hormone bharpoor banta hai aur stem tall ho jaata hai. Jis copy ke DNA mein chhota sa change hai, woh sust enzyme deti hai, thoda hormone banta hai aur plant short rehta hai.

3/3Ek working copy kaafi enzyme bana deti hai, isliye plant phir bhi tall hai.

Fig. 8.7Gene us protein ke through kaam karta hai jiske instructions usmein hain.NCERT 8.2.3 · p. 131

Left se right banayi gayi ek chain: DNA par ek gene ki do copies (mother ki aur father ki), har copy ka banaya enzyme, growth hormone ke dots, aur plant. Step 1 (TT): dono copies T hain, dono enzymes kaam karte hain, hormone ke bahut saare dots bante hain aur plant tall hai. Step 2 (tt): dono copies t hain, dono enzymes dashed outlines ke saath bane hain aur un par weak likha hai, thoda hi hormone banta hai aur plant short hai. Step 3 (Tt): ek copy T hai aur ek t, isliye ek enzyme kaam karta hai aur ek weak hai; hormone phir bhi bharpoor hai aur plant tall hai.

Yahi chain dominance ko bhi samjhati hai. Tt plant mein ek working copy aur ek kharaab copy hai. Akeli working copy hormone ka level banaye rakhne ke liye kaafi enzyme bana deti hai, isliye plant TT plant jitna hi tall hota hai. Sirf tt plant, jismein koi working copy nahi, short rehta hai.

Ab thoda arithmetic karo. Ek pea plant mein har gene ki do copies hoti hain, har parent se ek, jaisa Mendel ke results maangte hain. Agar pollen aur eggs mein bhi do copies hoti, to unke offspring mein chaar hoti, agli generation mein aath, aur aise hi aage. Isliye har germ cell mein har gene ki sirf ek copy honi chahiye: ek single complete set.

Germ cell ko theek ek set kaise milta hai? Maan lo har parent apne saare genes ek hi package mein aage deta. Hamare dihybrid cross mein R aur Y ek parent se saath aaye the aur r aur y doosre se. Agar woh saath bandhe rehte, to F1 plant sirf RY aur ry germ cells bana paata, aur round green ya wrinkled yellow seeds kabhi nahi dikhte. Lekin woh dikhte hain, isliye genes ek package ki tarah travel nahi kar rahe.

Cell ke genes ko ek encyclopaedia samjho jo ek bahut badi kitaab ki jagah kai volumes mein chhapi hai. Har volume ek chromosome hai. Body cell har volume ki do copies rakhta hai, ek mother se aur ek father se mili hui. Germ cell ko har volume ki ek copy milti hai, aur har volume ke liye chance tay karta hai ki woh mother ki copy hogi ya father ki (Fig. 8.8). Isliye alag-alag volumes ke genes independently sort hote hain, bilkul waise hi jaise Mendel ke results maangte hain.

Definition
Chromosome

Nucleus mein DNA ka ek alag dhaage jaisa tukda jismein kai genes hote hain. Body cells mein chromosomes pairs mein hote hain, har pair ka ek member har parent se.

3/3Doosri tarah se sort hone par woh Ry aur rY hain: kul chaar tarah.

Fig. 8.8Har germ cell ko har pair se ek chromosome milta hai; kaunsa member milega, yeh chance hai.NCERT 8.2.3 · p. 132

Step 1: ek body cell mein chromosomes ke do pairs hain. Har pair mein ek member mother se aaya (solid outline) aur ek father se (dashed outline). Lamba pair seed-shape gene rakhta hai, mother ki copy par R aur father ki par r; chhota pair colour gene rakhta hai, mother ki par Y aur father ki par y. Step 2: ek tarah se sort hone par mother ke dono chromosomes ek germ cell (RY) mein jaate hain aur father ke doosre (ry) mein. Step 3: pairs utni hi aasaani se doosri tarah bhi sort ho sakte hain, jisse germ cells Ry aur rY bante hain, isliye chaar tarah ke germ cells barabar sankhya mein bante hain.

Fertilisation par ek male aur ek female germ cell fuse hote hain. Har ek har pair ka ek member laata hai, isliye zygote mein phir se poore pairs aur apne parents jitne hi chromosomes hote hain. Jaise, ek human body cell mein 23 pairs (46 chromosomes) hote hain, jabki human egg ya sperm mein 23. Is tarah DNA ki maatra ek generation se agli tak steady rehti hai.Germ cells bante waqt chromosomes ki sankhya aadhi karne wala khaas cell division meiosis kehlata hai. Tum ise Class 11 mein padhoge.

Quick check
4 mein se 1
Pea plant ko tall banane wali chain ki kadiyon ko DNA se shuru karke sahi order mein lagao.
  1. Stem tall hota hai
  2. Enzyme ka gene
  3. Enzyme banta hai
  4. Growth hormone banta hai
Answer dekho
Answer
  1. Enzyme ka gene
  2. Enzyme banta hai
  3. Growth hormone banta hai
  4. Stem tall hota hai
Gene mein enzyme ke instructions hain; enzyme hormone banane mein madad karta hai; hormone stem ko badhata hai.

8.2.4 Sex Determination

Ek baby ladka aur doosra ladki kyun hota hai? Nature ke paas ise tay karne ke ek se zyada tareeke hain, jaisa neeche ki tulna dikhati hai.

Compare

Sex tay hone ke teen tareeke

Surroundings se

  • Kai turtles, jinmein woh olive ridleys bhi hain jo Odisha ke beaches par bhaari sankhya mein ande dete hain.
  • Ande develop hote waqt ret ka temperature ise tay karta hai: garam nests se zyadatar females nikalti hain, thande nests se zyadatar males.

Baad mein badal sakta hai

  • Kuch sea snails, jaise slipper limpet, zindagi males ki tarah shuru karte hain aur badhne ke saath females ban jaate hain.
  • Clownfish ke group mein sabse badi fish female ban jaati hai.

Chromosomes se

  • Insaan aur zyadatar doosre mammals.
  • Parents se inherit hue genes fertilisation ke waqt sex tay kar dete hain.

Insaan aakhri group mein hain: fertilisation par mile chromosomes tay karte hain ki baby ladke ki tarah develop hoga ya ladki ki tarah. Lekin humne abhi dekha ki chromosomes matching pairs mein aate hain, har parent se ek member. To phir woh do tarah ke bachche kaise bana sakte hain?

Human body cell ke chromosomes gino to 46 milte hain, jo 23 pairs mein hain. Pairs ko size ke hisaab se line mein lagao, to unmein se 22 pairs men aur women mein ek jaise dikhte hain. Aakhri pair, yaani sex chromosomes, raaz khol deta hai. Woman mein iske dono members ek jaise hote hain, dono X chromosomes (XX). Man mein ek member X hota hai aur doosra ek kahin chhota chromosome jise Y kehte hain (XY).

Definition
Sex chromosomes

Chromosomes ka woh pair jo insaanon mein sex tay karta hai: females mein do X chromosomes (XX), aur males mein ek X aur ek Y (XY).

Ab germ cells ko follow karo (Fig. 8.9). Har egg ko X milta hai, kyunki woman ke paas dene ke liye aur kuch nahi hai. Man ke sperm barabar sankhya mein do tarah ke hote hain: aadhe mein X hota hai aur aadhe mein Y. Agar X wala sperm egg ko fertilise kare, to bachcha XX hota hai, yaani ladki. Agar Y wala sperm fertilise kare, to bachcha XY hota hai, yaani ladka. Har pregnancy ek fair sikke ke toss jaisi hai, isliye paida hone wale lagbhag aadhe babies ladkiyan aur aadhe ladke hote hain.

4/4Father ka sperm tay karta hai: ladkiyan aur ladke 1 : 1 ke ratio mein.

Fig. 8.9Har egg mein X hota hai; X ya Y wala sperm tay karta hai.NCERT Fig. 8.6 · p. 132

Step 1: mother ka cell jismein chromosomes ke 22 pairs aur do X chromosomes (XX) hain, aur father ka cell jismein 22 pairs aur ek X aur ek chhota Y (XY) hai. Step 2: arrows germ cells tak jaate hain: har egg mein X hai, jabki sperm mein ya to X hai ya Y; yeh ek do-by-do grid ki rows aur columns ke upar likhe hain. Step 3: grid bhar jaata hai: X sperm aur X egg se XX, yaani girl, aur Y sperm aur X egg se XY, yaani boy, dono do-do squares mein. Step 4: Y sperm wale column ko outline kiya gaya hai yeh dikhane ke liye ki father ka sperm sex tay karta hai, aur ratio girl : boy = 1 : 1 dikhaya gaya hai.

Example 8.4

Do betiyon ke baad

Ek couple ki pehle se do betiyan hain. Unka agla bachcha ladka hone ka chance kya hai?

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

Quick check
3 mein se 1
Har bachcha, ladka ho ya ladki, mother se kaunsa sex chromosome paata hai?
Answer dekho

Answer (A) X

Mother XX hai, isliye har egg mein X hota hai. Chance wala step father ki taraf hota hai, jahan sperm mein X ya Y hota hai.
Practice · 4 questions

Practice 8.2 (NCERT in-text questions, p. 133): answers ke saath

  1. Short answerEasyNCERT in-text Questions p. 133, Q1

    Violet flowers wale pure-breeding pea plants ko white flowers wale pure-breeding plants se cross kiya jaata hai, aur phir F1 plants ko self-pollinate kiya jaata hai. F1 aur F2 ke results describe karo, aur samjhao ki woh kaise dikhate hain ki ek flower colour dominant hai aur doosra recessive.

    Solution dikhao

    AnswerF1: sab violet. F2: lagbhag 3 violet : 1 white. Isliye violet dominant hai aur white recessive.

    F1: har plant ke flowers violet hain (VV × vv se Vv milta hai). White blend hokar halka shade nahi bana; woh nazar se gayab ho gaya hai.

    F2: white flowers lagbhag har chaar mein se ek plant mein wapas aate hain, aur baaki violet hain (VV, Vv, Vv, vv). Matlab har F1 plant white ka instruction bina dikhaye apne andar liye hue tha.

    Jo colour sirf ek copy se dikh jaata hai, yaani violet, woh dominant hai. Jo colour sirf tab dikhta hai jab dono copies uski hon, yaani white, woh recessive hai.

  2. Short answerMediumNCERT in-text Questions p. 133, Q2

    Samjhao ki round yellow seeds wale pure plants aur wrinkled green seeds wale pure plants ke cross ka F2 kaise dikhata hai ki seed shape aur seed colour independently inherit hote hain.

    Solution dikhao

    AnswerNaye combinations (round green aur wrinkled yellow) dikhte hain, F2 9 : 3 : 3 : 1 hai, aur har trait akele 3 : 1 hai.

    F1 seeds sab round aur yellow hain (RrYy). Agar shape aur colour aapas mein bandhe hote, to F2 mein sirf parents wale seeds, round yellow aur wrinkled green, 3 : 1 ke ratio mein hote.

    Iske bajaye round green aur wrinkled yellow seeds bhi dikhte hain, aur chaaron tarah ke seeds lagbhag 9 : 3 : 3 : 1 mein aate hain. Akele lein to round : wrinkled = 12 : 4 = 3 : 1 aur yellow : green = 3 : 1. Har trait aise aage jaati hai jaise doosri ho hi nahi: woh independently inherit hoti hain.

  3. Short answerHardNCERT in-text Questions p. 133, Q3

    Ek mother jiska blood group B hai aur ek father jiska blood group O hai, unka ek beta hai jiska group O hai. B aur O ko ek gene ke do versions maan kar, kya yeh tay karne ke liye kaafi hai ki inmein se kaunsa dominant hai? Samjhao.

    Solution dikhao

    AnswerNahi. Family dono possibilities mein fit hoti hai.

    Maan lo B dominant hai. Aadmi O dikhata hai, isliye woh OO hi hoga. Woman BO ho sakti hai. Bete ko dono parents se O mil sakta hai, jisse woh OO hoga, yaani blood group O. Yeh fit hota hai.

    Maan lo O dominant hai. Tab woman, jo B dikhati hai, BB hogi, aur bete ko usse B aur father se O milta hai. Woh BO hai, jo O dikhata hai kyunki O dominant hai. Yeh bhi fit hota hai.

    Kyunki dono explanations fit hoti hain, akeli yeh family faisla nahi kar sakti. Humein aur saboot chahiye, jaise same blood group wale do parents jinka bachcha doosre group ka ho.

  4. Short answerEasyNCERT in-text Questions p. 133, Q4

    Ek newborn baby ke sex chromosomes XY hain. Har chromosome kis parent se aaya, aur kisne baby ka sex tay kiya?

    Solution dikhao

    AnswerX mother se aur Y father se. Father ke Y wale sperm ne baby ko ladka banaya.

    Mother XX hai, isliye uske banaye har egg mein X hota hai: baby ka X usi se aaya.

    Father XY hai aur barabar sankhya mein X wale aur Y wale sperm banata hai, isliye Y sirf usi se aa sakta hai.

    Egg mein to har haal mein X hi hota. Sex is baat se tay hua ki use kis sperm ne fertilise kiya: Y wale sperm ne XY diya, yaani ladka.

Recap

Summary aur key points

  1. Har generation ko chhote changes ke saath ek kaam karne wala body plan milta hai aur woh naye changes jodti hai, isliye variations jama hote jaate hain (Section 8.1).
  2. Asexual reproduction mein variation kam hota hai, sirf kabhi-kabhi hone wali DNA-copying errors se; sexual reproduction mein kahin zyada hota hai, kyunki har offspring do parents ka DNA milata hai.
  3. Variants ke survive karne ke chance alag hote hain, aur surroundings unmein se kuch ko doosron se zyada favour karti hain.
  4. Heredity traits ka bharosemand tareeke se aage jaana hai. Bachche ko har parent se barabar DNA milta hai, isliye usmein har gene ki do copies hoti hain (Section 8.2).
  5. Mendel ke monohybrid cross mein tall × short se saare tall F1 milte hain aur F2 mein 3 tall : 1 short, gene pairs 1 TT : 2 Tt : 1 tt ke saath (Section 8.2.2).
  6. Dominant trait ek copy se dikh jaati hai; recessive trait sirf do copies se dikhti hai. Genotype copies ka pair hai; phenotype woh hai jo hum dekhte hain.
  7. Dihybrid cross mein F2 9 : 3 : 3 : 1 hota hai aur usmein naye combinations hote hain; har trait akele phir bhi 3 : 1 hai, isliye har trait independently aage jaati hai (Ek saath do traits).
  8. Gene DNA ka woh hissa hai jo ek protein ko code karta hai; enzymes aur hormones ke through genes height jaisi traits ko control karte hain (Section 8.2.3).
  9. Genes chromosomes par hote hain, jo body cells mein pairs mein hote hain. Har germ cell ko chance se har pair ka ek member milta hai, aur fertilisation pairs ko wapas bana deta hai.
  10. Kuch turtles ka sex nest ke temperature se tay hota hai aur kuch snails sex badal lete hain, lekin insaanon mein women XX aur men XY hote hain, aur father ka X ya Y wala sperm bachche ka sex tay karta hai (Section 8.2.4).
Practice · 12 questions

Practice questions answers ke saath (NCERT “Exercises”)

  1. Quick answerMediumNCERT Exercises Q1

    Peas mein round seeds (R) wrinkled seeds (r) par dominant hain, aur violet flowers (V) white flowers (v) par. Round seeds aur violet flowers wale ek plant ko wrinkled seeds aur white flowers wale plant se cross kiya jaata hai. Saare offspring ke seeds round hain, lekin unmein se lagbhag aadhe ke flowers white hain. Us round, violet parent ka gene make-up sabse zyada kya ho sakta hai?

    Answer dekho

    Answer (B) RRVv

    Saare offspring round: yeh parent sirf R deta hai, isliye RR hai. Aadhe white: yeh V aur v barabar deta hai, isliye Vv hai. RRVv × rrvv barabar sankhya mein RrVv aur Rrvv deta hai: sab round, aadhe violet aur aadhe white. RrVV se aadhe offspring wrinkled hote, aur RRVV se koi white nahi hota.
  2. Short answerMediumNCERT Exercises Q2

    Ek survey mein pata chalta hai ki dimples wale bachchon ke aam taur par kam se kam ek parent ke dimples hote hain. Sirf isse kya hum keh sakte hain ki dimples hona dominant trait hai ya recessive? Kis tarah ki family yeh sawaal suljha degi?

    Solution dikhao

    AnswerNahi. Aisi family jismein bachcha ek jaise dikhne wale do parents se alag ho, yeh suljha degi.

    Nahi. Bachche ko har parent se har gene ki ek copy milti hai, isliye dono cases mein, dominant ho ya recessive, bachche apne parents jaise dikhte hain. Akela yeh pattern dono cases mein fark nahi bata sakta.

    Faisla aisa bachcha karta hai jo dono parents se alag ho. Agar dimples ke bina wale do parents ka bachcha dimples wala hai, to dimples trait dono parents mein chhupi thi, isliye woh recessive hai. Agar dimples wale do parents ka bachcha dimples ke bina hai, to "no dimples" chhupa tha, aur dimples hona dominant hai.

  3. Long answerHardNCERT Exercises Q3

    Rabbits mein kaunsa fur colour, black ya white, dominant hai, yeh pata karne ke liye ek project ki outline banao.

    Solution dikhao

    AnswerPure black rabbits ko pure white rabbits se cross karo; saare F1 rabbits ka colour dominant wala hai, aur lagbhag 3 : 1 wala F2 ise confirm karta hai.

    1. Pure-breeding black rabbits aur pure-breeding white rabbits lo. Do-teen generations tak check karo ki black × black se sirf black bachche aate hain, aur white × white se sirf white.
    2. Black ko white se cross karo. Cross dono taraf se karo (black male ke saath white female, aur white male ke saath black female), yeh check karne ke liye ki result is par depend nahi karta ki kaun sa parent kaun hai.
    3. F1 bachchon ka fur colour record karo. Agar sab black hain, to black dominant hai; agar sab white hain, to white dominant hai.
    4. F1 rabbits ko aapas mein mate karao aur kai litters mein F2 bachche gino. Lagbhag 3 dominant colour aur 1 recessive colour do versions wale ek single gene ko confirm karta hai.
    5. Badi sankhya use karo, har animal ka record rakho, aur poore samay animals ka achche se dhyaan rakho.

    Agar F1 bachche beech ke grey nikle, to koi bhi colour poori tarah dominant nahi hoga, aur project yahi report karega.

  4. Short answerMediumNCERT Exercises Q4

    Samjhao ki har parent bachche ke theek aadhe chromosomes kaise deta hai.

    Solution dikhao

    AnswerGerm cells mein har pair se ek chromosome hota hai, aur fertilisation har parent ka ek set jodta hai.

    Body cells mein chromosomes pairs mein hote hain (insaanon mein 23 pairs). Germ cells bante waqt har ek ko har pair se sirf ek chromosome milta hai, isliye egg aur sperm dono mein 23 hote hain, body cell ke aadhe.

    Fertilisation par sperm aur egg fuse hote hain. Zygote mein 23 chromosomes father se aur 23 mother se hote hain, jo milkar phir se 23 pairs banate hain. Har parent ne har pair ka ek member diya hai: theek aadha.

  5. Quick answerMedium

    F1 (Tt) pea plants ko self-pollinate karke 1,200 F2 plants ugaye jaate hain. Inmein se kitne pure-breeding tall (TT) hone ki ummeed hai?

    plants
    Answer dekho

    Answer 300 plants

    TT Punnett square ke 4 mein se 1 square bharta hai: 1200 × 1/4 = 300. Kul 900 tall plants hain, lekin unmein se 600 Tt hain.
  6. Quick answerEasy

    Ek tall pea plant (Tt) ko short plant (tt) se cross kiya jaata hai. Tall aur short offspring ka kya ratio expect karoge?

    Answer dekho

    Answer (D) 1 : 1

    Tt T ya t deta hai; tt sirf t deta hai. Offspring barabar sankhya mein Tt ya tt hain: 1 tall : 1 short. 3 : 1 ratio ke liye do Tt parents chahiye.
  7. Quick answerEasy

    Assertion (A): Jab pure tall aur pure short pea plants cross kiye jaate hain, to koi F1 plant medium height ka nahi hota. Reason (R): Tallness dominant hai, isliye pair mein ek T hi poori height ke liye kaafi hai.

    Answer dekho

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

    Dono sahi hain. Har F1 plant Tt hai, aur kyunki ek T kaafi hai, sab poore tall hain: R, A ko samjhata hai.
  8. Quick answerHard

    Assertion (A): Pure round yellow aur pure wrinkled green pea plants ke cross ke F2 mein round green seeds dikhte hain. Reason (R): Round seed shape wrinkled par dominant hai.

    Answer dekho

    Answer (B) A aur R dono sahi hain, lekin R, A ko nahi samjhata

    Dono statements sahi hain, lekin naya combination isliye dikhta hai kyunki shape aur colour ke genes independently germ cells mein sort hote hain. Wrinkled par round ki dominance ise nahi samjhati.
  9. Short answerMedium

    Case study. Ek student stem ke saath-saath flowers wale (axial) pure-breeding pea plants ko sirf tip par flowers wale (terminal) pure-breeding plants se cross karti hai. Saare F1 plants ke flowers axial hain. F2 mein woh 648 axial aur 222 terminal plants ginti hai.

    1. Kaunsa roop dominant hai? Tumhe kaise pata?

      Solution dikhao

      AnswerAxial.

      Axial, kyunki F1 mein sirf yahi roop dikhta hai, jahan har plant mein har version ki ek copy hai.

    2. Axial plants ki sankhya ko terminal plants ki sankhya se divide karo. Result ek decimal place tak do.

      Answer dekho

      Answer 2.9

      648 ÷ 222 ≈ 2.92, jo round karke 2.9 hota hai: monohybrid F2 mein expected 3 : 1 ke kareeb.

    3. Axial version ke liye A aur terminal version ke liye a use karke, F1 plants aur terminal F2 plants ke gene pairs likho.

      Solution dikhao

      AnswerF1: Aa. Terminal wale F2 plants: aa.

      F1 plants ko axial parent se A aur terminal parent se a mila, isliye woh Aa hain. Recessive trait sirf do copies se dikhti hai, isliye terminal F2 plants aa hain.

    4. 648 axial F2 plants mein se lagbhag kitne pure-breeding (AA) hone ki ummeed hai?

      plants
      Answer dekho

      Answer 216 plants

      Axial F2 plants mein AA : Aa = 1 : 2, isliye unmein se ek-tihaai AA hain: 648 ÷ 3 = 216.
  10. Quick answerMedium

    Ek RrYy pea plant ko self-pollinate kiya jaata hai. F2 mein kitne alag gene combinations (genotypes) aur kitne alag dikhne wale tarah ke seeds (phenotypes) aate hain?

    Answer dekho

    Answer (D) 9 genotypes aur 4 phenotypes

    Har gene 3 genotypes deta hai (RR, Rr, rr aur YY, Yy, yy), isliye 16 squares mein 3 × 3 = 9 genotypes hain. Yeh 4 phenotypes ki tarah dikhte hain: round yellow, round green, wrinkled yellow aur wrinkled green.
  11. Quick answerEasy

    Human egg mein 22 chromosomes aur ek chromosome hota hai, isliye usmein kul chromosomes hote hain.

    Answer dekho

    Answer (1) X, (2) 23

    Woman XX hai, isliye har egg ko baaki 22 pairs mein se har ek ke ek member ke saath ek X milta hai: 23 chromosomes.
  12. DiagramMedium

    Insaanon mein bachche ka sex kaise tay hota hai, yeh dikhane ke liye ek labelled Punnett square banao. Isse samjhao ki ladke aur ladkiyan lagbhag barabar sankhya mein kyun paida hote hain.

    Solution dikhao

    AnswerSaare eggs X hain; sperm barabar sankhya mein X ya Y hain, isliye aadhe zygotes XX (ladkiyan) aur aadhe XY (ladke) hote hain.

    Table 8.4
    X wala spermY wala sperm
    X wala eggXX (ladki)XY (ladka)
    X wala eggXX (ladki)XY (ladka)

    Mother (XX) sirf X wale eggs banati hai. Father (XY) barabar sankhya mein X wale aur Y wale sperm banata hai. Chaar mein se do squares XX hain aur do XY, isliye har bachche ke ladki ya ladka hone ka chance barabar hai, aur bahut saare births mein sankhya lagbhag barabar aati hai.

Apna NCERT exercise question dhoondo

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

Tumhari NCERT textbook meinYahan practice question
NCERT in-text Questions p. 129, Q1Practice 8.1 (NCERT in-text questions, p. 129) · Q1
NCERT in-text Questions p. 129, Q2Practice 8.1 (NCERT in-text questions, p. 129) · Q2
NCERT in-text Questions p. 133, Q1Practice 8.2 (NCERT in-text questions, p. 133) · Q1
NCERT in-text Questions p. 133, Q2Practice 8.2 (NCERT in-text questions, p. 133) · Q2
NCERT in-text Questions p. 133, Q3Practice 8.2 (NCERT in-text questions, p. 133) · Q3
NCERT in-text Questions p. 133, Q4Practice 8.2 (NCERT in-text questions, p. 133) · Q4
NCERT Exercises Q1Exercises · Q1
NCERT Exercises Q2Exercises · Q2
NCERT Exercises Q3Exercises · Q3
NCERT Exercises Q4Exercises · Q4

Quick check: MCQs

  1. 8.1 Reproduction ke dauraan Variation ka jama hona3 questions
  2. 8.2.2 Traits ki Inheritance ke Rules – Mendel ka Yogdaan4 questions
  3. Ek saath do traits3 questions
  4. 8.2.3 Yeh Traits Express Kaise Hoti Hain?4 questions
  5. 8.2.4 Sex Determination3 questions
Glossary · 15

Key terms (English + Hindi)

chromosomeगुणसूत्रgunsootra
Nucleus mein DNA ka dhaage jaisa tukda jismein kai genes hote hain. Body cells mein chromosomes pairs mein hote hain.Chapter mein pehli baar yahan aaya →
dihybrid cross
Aisa cross jo contrasting traits ke do pairs ko ek saath follow karta hai; uske F2 mein 9 : 3 : 3 : 1 ratio dikhta hai.Chapter mein pehli baar yahan aaya →
dominant traitप्रभावी लक्षणprabhavi lakshan
Aisi trait jo tab bhi dikhti hai jab uske gene version ki sirf ek copy ho, jaise Tt peas mein tallness.
geneजीनjeen
DNA ka ek hissa jismein ek protein ke instructions hain. Genes traits ko control karte hain aur pairs mein inherit hote hain.Chapter mein pehli baar yahan aaya →
genotypeजीनप्ररूपjeenprarup
Kisi trait ke liye organism ka gene make-up, jo uski gene copies ke pair ki tarah likha jaata hai, jaise TT, Tt ya tt.Chapter mein pehli baar yahan aaya →
germ cellजनन कोशिकाjanan koshika
Reproductive cell (egg, sperm ya pollen) jismein har chromosome pair ka ek member hota hai: body cell ka aadha.Chapter mein pehli baar yahan aaya →
heredityआनुवंशिकताaanuvanshikta
Parents se offspring tak traits ka aage jaana, aise rules se jinki wajah se offspring bharosemand tareeke se parents jaise dikhte hain.Chapter mein pehli baar yahan aaya →
monohybrid cross
Aisa cross jo contrasting traits ke ek pair, jaise tall aur short, ko follow karta hai; uske F2 mein 3 : 1 ratio dikhta hai.Chapter mein pehli baar yahan aaya →
phenotypeलक्षणप्ररूपlakshanprarup
Trait ka woh roop jo hum dekh sakte hain, jaise tall ya short. Yeh genotype par depend karta hai.Chapter mein pehli baar yahan aaya →
Punnett square
Ek grid jo ek parent ke har tarah ke germ cell ko doosre parent ke har tarah ke germ cell se jodta hai, taaki expected offspring dikhein.Chapter mein pehli baar yahan aaya →
pure-breeding
Aise plants jo self-pollinate hone par kisi trait ke liye generation dar generation apne jaise offspring dete hain.Chapter mein pehli baar yahan aaya →
recessive traitअप्रभावी लक्षणaprabhavi lakshan
Aisi trait jo sirf tab dikhti hai jab dono gene copies usi version ki hon, jaise tt peas mein shortness.
sex chromosomesलिंग गुणसूत्रling gunsootra
Woh chromosome pair jo insaanon mein sex tay karta hai: females mein XX aur males mein XY.Chapter mein pehli baar yahan aaya →
traitलक्षणlakshan
Kisi organism ka feature, jaise height, seed shape ya earlobe type. Inherited traits parents se offspring tak jaati hain.Chapter mein pehli baar yahan aaya →
variationविभिन्नताvibhinnata
Ek hi species ke individuals ke beech differences, jaise height ya colour mein. Kai reproduction ke dauraan paida hote hain aur inherit hote hain.Chapter mein pehli baar yahan aaya →

Tum chapter ke end tak pahunch gaye