Class 11 Biology · Chapter 13
Short answer: Class 11 Biology Chapter 13 "Plant Growth and Development" plant physiology unit ka sabse concept-heavy chapter hai — growth ki measurement (arithmetic vs geometric), sigmoid growth curve, 5 plant growth regulators (auxin, gibberellin, cytokinin, ethylene, ABA), aur photoperiodism/vernalisation is chapter me cover hote hain. NCERT ke end-of-chapter exercise me 11 questions hain (koi separate in-text question box nahi hai) — neeche step-by-step solutions, formulas table aur exam-ready FAQ diye gaye hain, jaisa "class 11 biology ncert solutions chapter wise pdf" search karne pe chahiye hota hai.
Agar Chapter 8 "Cell: The Unit of Life" Class 11 Biology ki neev hai, to Chapter 13 "Plant Growth and Development" us neev ke upar plant physiology unit ka climax hai — yahan pata chalta hai ki cell division aur differentiation actually ek poore plant ko kaise shape karte hain. 2026-27 ke rationalised (19-chapter) NCERT syllabus me ye chapter apni jagah pe hi hai; sirf Transport in Plants, Mineral Nutrition, aur Digestion and Absorption jaise standalone chapters is session ke "class 11 biology deleted syllabus 2026-27" list me the, Plant Growth and Development nahi. Is chapter me do bade ideas hain: (1) growth ko kaise measure/quantify karte hain — arithmetic growth, geometric growth aur us se banne waala sigmoid growth curve; aur (2) plant growth regulators (auxin, gibberellin, cytokinin, ethylene, abscisic acid) plant ke development ko kaise control karte hain, saath hi photoperiodism aur vernalisation jaise environment-triggered flowering mechanisms. Ye topics NCERT ke apne "class 11 biology syllabus 2026-27 ncert" document me plant physiology unit ka hissa hain aur "class 11 biology photosynthesis in higher plants important questions" ya "class 11 biology respiration in plants ncert solutions" ke saath hi revise karne chahiye kyunki teeno chapters ek hi unit (Plant Physiology) me aate hain.
Chapter 13 Summary — 5 Minute Revision
Growth ek irreversible, permanent increase hai jo meristem ki activity se hota hai — isse arithmetic (constant rate, sirf ek daughter cell divide karti hai) ya geometric (dono daughter cells divide karti hain, exponential rate) pattern me measure kiya ja sakta hai; natural environment me plants typically sigmoid (S-shaped) growth curve follow karte hain jisme lag, exponential aur stationary phase hoti hai. Development = Growth + Differentiation, aur plants me ye process "open" hota hai kyunki meristem life-bhar active rehta hai (indeterminate growth), jabki individual organs (leaf, flower) determinate growth dikhate hain. Development ko control karte hain paanch main plant growth regulators — Auxin (cell elongation, apical dominance, rooting), Gibberellins (bolting, stem elongation, seed germination), Cytokinins (cell division, delays senescence, overcomes apical dominance), Ethylene (fruit ripening, senescence — sirf gaseous PGR) aur Abscisic Acid (stress hormone — stomatal closure, seed dormancy, growth inhibitor). Flowering timing environment se bhi control hoti hai — Photoperiodism (day/night length ka response — SDP, LDP, DNP) aur Vernalisation (low-temperature-induced flowering).In-Text Questions — Solutions
Growth ko "irreversible" process kyun kaha jaata hai?
Ek baar cell/organ/plant size me permanently badh jaaye (jaise cell division ya cell enlargement se), to normal conditions me wo wapas apne pehle wale chhote size me nahi jaata. Isliye growth ko irreversible process kaha jaata hai — reversible changes (jaise wilting ke baad turgidity wapas aana) growth nahi kehlate.
Meristem kya hai aur plant me ye kahan-kahan paaya jaata hai?
Meristem woh tissue hai jiski cells me continuously divide karne ki capacity hoti hai, aur yehi cells poore plant ki growth ke liye responsible hoti hain.
Location: Root apex aur shoot apex pe apical meristem (primary growth ke liye), aur stem/root me lateral meristem — vascular cambium aur cork cambium (secondary growth, thickness badhane ke liye).
Differentiation aur dedifferentiation me farak spasht karo.
Differentiation: Jab meristem se bani naye cells mature hokar ek specific, permanent structure/function le leti hain (jaise xylem tracheary element banna) — is process me cells generally apni division karne ki capacity kho deti hain.
Dedifferentiation: Jab already-differentiated, living cells jo divide karna band kar chuki thi, certain conditions me dobara meristematic ban kar division ki capacity regain kar leti hain — example: interfascicular cambium aur cork cambium, jo mature parenchyma cells se bante hain.
"Bolting" kya hota hai plant growth ke context me?
Bolting ka matlab hai kisi rosette-form plant (jisme leaves compact cluster me close together hoti hain, internodes bahut chhote hote hain) me achanak internode elongation ho jaana — stem rapidly lamba ho jaata hai, generally flowering se pehle. Ye effect Gibberellins (GA3) treatment se induce kiya ja sakta hai.
Photoperiodism kya hai — basic definition do.
Photoperiodism plant ka flowering response hai light aur dark duration (day-length) ke prati. Is response ke basis pe plants Short-Day, Long-Day ya Day-Neutral categories me classify hote hain, aur ye stimulus leaves me perceive hota hai.
Vernalisation ka basic matlab kya hai?
Vernalisation wo phenomenon hai jisme low temperature exposure se flowering promote/induce hoti hai — ye premature reproductive development ko rok kar flowering ko favourable (spring) season ke saath synchronise karta hai. Example: winter wheat varieties.
Poore Class 11 Biology ke handwritten colour notes
IITian & district toppers ke banaye short notes — revision-ready, diagram ke saath. Board se pehle poora syllabus 3 din me revise.
Exercise Questions — Solutions (Q1–Q11)
1. Define growth, differentiation, development, dedifferentiation, redifferentiation, determinate growth, meristem and growth rate.
Growth: Irreversible, permanent increase in size of a cell, organ, or plant part, generally along with increase in dry weight — ek quantitative, measurable process hai.
Differentiation: Root apical meristem, shoot apical meristem ya cambium se banne waali cells jab mature hoke specific structure/function le leti hain, use differentiation kehte hain (e.g. ek meristematic cell xylem tracheary element bankar apni protoplast kho deti hai).
Development: Seed germination se lekar senescence tak, organism ke poore life-cycle me hone waale saare changes ka sum — Development = Growth + Differentiation.
Dedifferentiation: Living differentiated cells jo divide karna band kar chuki thi, certain conditions me dobara division capacity regain kar leti hain — e.g. interfascicular cambium aur cork-cambium, jo parenchyma cells se bante hain.
Redifferentiation: Dedifferentiation se bani cells jab dobara divide karna band karke ek naya specific function perform karne ke liye mature ho jaati hain.
Determinate growth: Plant ke kisi specific part (leaf, flower) ka growth ek definite period tak hota hai aur maturity pe ruk jaata hai — poore plant pe nahi, sirf organs pe apply hota hai.
Meristem: Woh tissue jiski cells me continuously divide karne ki ability hoti hai — root tips, shoot tips aur lateral buds pe present hoti hai, growth ke liye responsible hai.
Growth rate: Unit time me hone waali growth ki quantity — Absolute Growth Rate (AGR) ya Relative Growth Rate (RGR) ke roop me express hoti hai.
2. Why is not any one parameter good enough to demonstrate growth throughout the life of a flowering plant?
Growth ek multifaceted (bahu-aayaami) phenomenon hai — ise length, area, volume, fresh weight, dry weight ya cell number, kisi bhi ek parameter se poori tarah nahi dikhaya ja sakta, kyunki har parameter alag stage/organ pe sahi fit karta hai:
- Root ya pollen tube jaisi structures ke liye increase in length best measure hai.
- Meristematic tissue (jahan cells chhoti hoti hain) ke liye increase in cell number zyada meaningful hai.
- Parenchyma cells jo size me badhti hain, unke liye increase in volume/area better hai.
- Leaves ke liye fresh/dry weight aksar use hota hai.
Iske alawa, growth hamesha weight badhne ke saath nahi hota — e.g. germinating seed me starch/food reserve tootne se shuru me dry weight kam hota hai jabki embryo ki length badh rahi hoti hai. Isliye life-cycle ke different stages me sahi parameter alag-alag hota hai, ek single universal parameter kaafi nahi hai.
3. Describe briefly: (a) Arithmetic growth (b) Geometric growth (c) Sigmoid growth curve (d) Absolute and relative growth rates
(a) Arithmetic growth: Mitotic cell division ke baad sirf ek daughter cell continuously divide karti rehti hai, doosri differentiate/mature ho jaati hai (jaise root ka constant elongation). Growth rate constant rehta hai, isliye graph pe plot karne par ek straight line milti hai.
Lt = L0 + rt
Yahan Lt = time t pe length, L0 = time zero pe length, r = growth rate/elongation per unit time.
(b) Geometric growth: Shuru me growth slow hoti hai (lag phase) — usme cells nayi environment ke adjust hoti hain, phir dono daughter cells divide karne ki capacity retain karti hain to growth rapid/exponential ho jaati hai (log/exponential phase).
W1 = W0 ert
Yahan W1 = final size, W0 = initial size, r = growth rate (efficiency index), t = time, e = natural log base.
(c) Sigmoid growth curve: Geometric (exponential) growth phase ke baad, limited nutrient supply ki wajah se growth slow ho jaati hai aur eventually stationary phase aa jaati hai. Growth vs time plot karne pe typical S-shaped (sigmoid) curve milta hai — jisme lag, exponential aur stationary — teeno phases hote hain. Ye curve natural environment me har living organism ka characteristic hai.
(d) Absolute aur relative growth rate: Absolute Growth Rate (AGR) = total growth ki quantity per unit time. Relative Growth Rate (RGR) = growth per unit time, ek common/initial base pe expressed (i.e. growth ÷ initial value). Example: Leaf A (5 cm² initial) aur Leaf B (50 cm² initial), dono ek hi time me 5 cm² badhte hain — AGR dono ka same (5 cm²) hai, lekin RGR bahut alag hai: Leaf A = 5/5 = 1, Leaf B = 5/50 = 0.1 — matlab Leaf A, Leaf B se zyada efficiently grow kar rahi hai.
4. List five main groups of natural plant growth regulators. Write a note on the discovery, physiological functions and agricultural/horticultural applications of any one of them.
Paanch main groups: Auxins, Gibberellins, Cytokinins, Ethylene, Abscisic Acid (ABA).
Note on Auxin:
Discovery: Charles Darwin aur unke bete Francis Darwin ne canary grass ke coleoptiles me observe kiya ki unilateral light ki taraf plant bend hota hai (phototropism) aur ye bending sirf tab hoti hai jab coleoptile tip present ho. Baad me Boysen-Jensen ne dikhaya ki tip ka influence agar ek agar block ke through transmit ho to bhi bending hoti hai. Finally F. W. Went ne oat (Avena) coleoptile tips se ek growth-promoting substance isolate ki aur uska naam "auxin" rakha, Avena curvature test se uska effect measure kiya.
Physiological functions: Cell elongation ko promote karta hai; apical dominance maintain karta hai (terminal bud lateral/axillary buds ki growth inhibit karta hai); adventitious root formation induce karta hai; parthenocarpy (bina fertilization ke fruit development, jaise tomato) induce karta hai; early stage me fruit/leaf drop prevent karta hai, lekin later stage me promote karta hai; xylem differentiation induce karta hai.
Agricultural/horticultural applications: Nursery me stem cuttings me rooting induce karne ke liye (IAA/IBA/NAA use hote hain); premature fruit aur leaf drop rokne ke liye; pineapple jaisi crops me flowering induce karne ke liye; 2,4-D jaisa synthetic auxin selective weedicide ke roop me dicot weeds maarne ke liye use hota hai.
5. What do you understand by photoperiodism and vernalisation? Describe their significance.
Photoperiodism: Plants ka flowering response light aur dark duration (day-length) ke prati hota hai, isse photoperiodism kehte hain — sabse pehle Garner aur Allard ne discover kiya. Is response ke basis pe plants teen categories me baante jaate hain:
- Short-Day Plants (SDP): Flower tabhi karte hain jab continuous dark period ek critical duration se zyada mile.
- Long-Day Plants (LDP): Flower tabhi karte hain jab light period critical photoperiod se zyada mile (matlab dark period short ho).
- Day-Neutral Plants (DNP): Inki flowering photoperiod se affect nahi hoti.
Photoperiodic stimulus leaves me perceive hoti hai. Significance: Ye ensure karta hai ki flowering season/environment ke hisaab se sahi time pe ho (pollinators available hon, favourable temperature ho); agriculture me off-season flowering induce karne ke liye bhi use hota hai.
Vernalisation: Low temperature exposure se flowering ko promote karna vernalisation kehlata hai — ye premature reproductive development ko rokta hai aur flowering ko spring ke saath synchronise karta hai. Example: winter wheat varieties agar seedha spring me boyi jaayen to der se aur poor flower/grain deti hain, lekin agar germinating seeds ko pehle low temperature expose karke phir boya jaaye to woh normal time pe hi flower kar deti hain. Significance: Farmers ek hi growing season me winter varieties bhi ugaa paate hain, aur vegetative phase shorten hokar flowering jaldi ho jaati hai.
6. Why is Abscisic acid also known as a stress hormone?
Abscisic Acid (ABA) ko "stress hormone" isliye kaha jaata hai kyunki ye plant ko adverse/stressful environmental conditions (jaise water deficit/drought) se survive karne me madad karta hai:
- ABA leaf epidermis ki stomata ko band karne ko stimulate karta hai, jisse transpiration kam hota hai — is wajah se ise antitranspirant bhi kaha jaata hai — aur plant water stress ke waqt paani bacha paata hai.
- ABA generally growth ko inhibit karta hai — seed germination aur seedling growth ko slow/dormant karta hai, taaki unfavourable conditions me plant "wait" kar sake.
- Seed maturation aur seed dormancy induce karne me role hai, jisse seeds desiccation (sookhne) ko tolerate kar paate hain.
Isliye ABA ko general growth inhibitor aur stress-response hormone dono maana jaata hai.
7. 'Both growth and differentiation in higher plants are open.' Comment.
Animals ke unlike, higher plants me growth aur differentiation life-bhar continue ho sakte hain kyunki plants me apical meristems (root apex, shoot apex) aur lateral meristems (vascular cambium, cork cambium) hote hain, jinki cells hamesha divide karne ki capacity retain karti hain. Ye meristems naye cells, tissues aur organs (leaves, branches, flowers) continuously produce karte rehte hain jab tak plant zinda hai.
Isi wajah se plants ka growth indeterminate hota hai (poore plant ka), jabki individual organs (jaise ek leaf ya flower) determinate growth dikhate hain. Ye life-bhar naye organs banane ki ability hi "open growth" ya "open form of development" kehlati hai — ye plants ki ek unique aur distinguishing feature hai jo unhe environment ke hisaab se plastic (adaptable) banaati hai.
8. 'Both a short-day plant and a long-day plant can produce flowers simultaneously in a given place.' Explain.
Ye is liye possible hai kyunki har species ka "critical photoperiod" fixed absolute duration nahi hai — ye species-specific hota hai. SDP aur LDP ka classification sirf ye batata hai ki flowering ke liye unhe apne critical photoperiod se kam ya zyada light duration chahiye, na ki ek fixed universal cutoff.
Isliye agar kisi jagah ka actual day-length aisa ho ki wo ek SDP ke critical photoperiod se kam bhi ho, aur saath hi wahi day-length kisi LDP ke apne (kam) critical photoperiod se zyada bhi ho — to dono species ki apni-apni condition simultaneously satisfy ho jaati hai, aur dono ek hi jagah, ek hi samay flower kar sakti hain.
9. Which one of the plant growth regulators would you use if you are asked to:
(a) Induce rooting in a twig: Auxin (jaise IBA/NAA) — adventitious root formation induce karta hai, isliye nursery cuttings me use hota hai.
(b) Quickly ripen a fruit: Ethylene — fruit ripening ka main hormone hai, ripe fruits se release hoke nearby unripe fruits ko bhi ripen karwa deta hai.
(c) Delay leaf senescence: Cytokinin — senescence (leaf ageing) ko delay karta hai, isliye cut flowers/vegetables freshness badhaane me use hota hai.
(d) Induce growth in axillary buds: Cytokinin — apical dominance ko overcome karke lateral/axillary buds ki growth promote karta hai.
(e) 'Bolt' a rosette plant: Gibberellin (GA3) — internode elongation induce karke rosette plants me bolting (stem elongation before flowering) laata hai.
(f) Induce immediate stomatal closure in leaves: Abscisic Acid (ABA) — stomata ko turant close karwa deta hai, transpiration kam karta hai.
10. Would a defoliated plant respond to photoperiodic cycle? Why?
Nahi, ek defoliated (leaves-less) plant photoperiodic cycle ko normally respond nahi karega. Isliye kyunki photoperiod ka perception site leaves hoti hain — leaves me present phytochrome pigment hi light/dark duration detect karta hai aur us signal ko flowering ke liye responsible region tak transmit karta hai. Leaves ke absent hone par plant photoperiodic stimulus ko perceive hi nahi kar payega, isliye us cycle ke response me flowering trigger nahi hogi.
11. What would be expected to happen if: (a) GA3 is applied to rice seedlings (b) Dividing cells stop differentiating (c) A rotten fruit gets mixed with unripe fruits (d) You forget to add cytokinin to the culture medium
(a) GA3 rice seedlings pe apply karne se: Internode/stem elongation badh jaayega — seedlings abnormally lambi ho jaayengi (bolting-jaisa effect), plant height significantly increase hogi.
(b) Dividing cells differentiate karna band kar dein to: Cells continuously divide to karti rahengi lekin mature/specialise nahi hongi — result me ek undifferentiated cell mass (callus-jaisi structure) ban jaayegi, aur normal tissues/organs (leaf, root, flower) develop nahi ho paayenge, plant ka proper development ruk jaayega.
(c) Rotten fruit ko unripe fruits ke saath mix karne se: Rotten/ripe fruit se release hone waali ethylene gas nearby unripe fruits tak diffuse ho jaayegi aur unme bhi ripening trigger/accelerate kar degi — isi wajah se ek kharab fruit poori basket ko jaldi pakaa deta hai.
(d) Culture medium me cytokinin add karna bhool jaayein to: Cells normal rate se divide (cytokinesis) nahi kar paayengi — cell enlargement to ho sakta hai lekin cell division badly affect hoga, callus growth ruk jaayega aur shoot-bud differentiation (jo cytokinin-dependent hoti hai) properly induce nahi hogi.
Important Equations — Ek Nazar Me
| Concept | Formula / Rule | Terms |
|---|---|---|
| Arithmetic growth | Lt = L0 + rt | Lt = length at time t, L0 = length at time 0, r = constant growth rate, t = time |
| Geometric (exponential) growth | W1 = W0 ert | W1 = final size, W0 = initial size, r = growth rate (efficiency index), t = time, e = base of natural log |
| Growth phases (sigmoid curve) | Lag phase → Exponential/log phase → Stationary phase | Plot of growth vs time gives an S-shaped (sigmoid) curve |
| Absolute Growth Rate (AGR) | Total growth quantity produced per unit time | Not normalised to initial size |
| Relative Growth Rate (RGR) | Growth per unit time expressed relative to the initial value (per unit initial parameter) | Better measure of growth "efficiency" between two unequal-sized systems |
| 5 Plant Growth Regulator groups | Auxin, Gibberellin, Cytokinin, Ethylene, Abscisic Acid (ABA) | Auxin/Gibberellin/Cytokinin = mostly growth-promoting; Ethylene = ripening/senescence; ABA = growth-inhibiting/stress hormone |
| Photoperiod categories | SDP / LDP / DNP | Short-Day Plant, Long-Day Plant, Day-Neutral Plant — perception site = leaves |
| Vernalisation | Low-temperature exposure → earlier/promoted flowering | Shortens vegetative phase; synchronises flowering with favourable season |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Plant growth regulators ke effects aapas me confuse kar dena — e.g. Cytokinin ko senescence-delay ki jagah Auxin se, ya Gibberellin ke bolting effect ko Auxin se jod dena; har hormone ka function alag-alag yaad rakhna zaroori hai.
- Ye sochna ki growth hamesha weight increase ke saath hota hai — jabki germinating seed me shuru me reserve food consume hone se dry weight kam hota hai, phir bhi embryo grow kar raha hota hai.
- SDP/LDP ko galat samajhna ki 'Short-Day' ka matlab hai 'chhota din chahiye' — actual critical factor continuous DARK period ki length hai, na ki sirf light duration, isliye SDP ko technically 'Long-Night Plant' bhi kaha ja sakta hai.
- Dedifferentiation aur redifferentiation ka order ulta likh dena — pehle differentiated cell dobara divide karne layak banti hai (dedifferentiation), phir wahi cells dobara mature hoti hain (redifferentiation) — sequence yaad rakhein.
- Arithmetic aur Geometric growth ke formulas (L_t = L_0 + rt vs W_1 = W_0 e^rt) ko exam me swap kar dena — arithmetic linear hai, geometric exponential.
- Determinate growth ko poore plant pe apply kar dena — jabki ye sirf specific organs (leaf, flower) pe hota hai; poora plant meristem ki wajah se indeterminate (open) growth dikhata hai.
Board-Style Important Questions
- Auxin ka discovery kis scientist duo ne, kis plant material pe experiment karke kiya tha?
- Kaunsa plant growth regulator ekmatra gaseous PGR hai aur ye kis process ke liye jaana jaata hai?
- Absolute Growth Rate aur Relative Growth Rate me antar spashta kijiye, ek numerical example ke saath.
- Photoperiodism kya hai? SDP, LDP aur DNP me antar kijiye aur photoperiod perceive karne wala plant part bataiye.
- Arithmetic growth aur Geometric growth me antar, respective formulas ke saath samjhaiye.
- Auxin, Gibberellin, Cytokinin, Ethylene aur Abscisic acid — in paanch plant growth regulators ka ek-ek mukhya physiological function likhiye.
Aksar Poochhe Jaane Wale Sawaal
Class 11 Biology ke saare chapters ke NCERT solutions chapter-wise PDF format me kahan milte hain?
Har chapter ke solutions is style me tayyar kiye jaate hain jaisa aap upar dekh rahe hain — 'class 11 biology ncert solutions chapter wise pdf' search karne pe generally aapko unit-wise breakdown milta hai: Diversity in Living World (Ch 1-4, jisme 'class 11 biology chapter 1 the living world notes' bhi shaamil hai), Structural Organisation (Ch 5-7), Cell Structure and Function (Ch 8-10, jisme 'class 11 biology chapter 8 cell the unit of life important questions' ek high-search topic hai), Plant Physiology (Ch 11-13, jisme ye Chapter 13 aata hai), aur Human Physiology (Ch 14-19, jisme Excretory Products, Neural Control jaise chapters hain). Poore syllabus ke 'class 11 biology important questions with answers pdf' collect karte waqt unit-wise revise karna sabse efficient hota hai.
2026-27 session ke Class 11 Biology syllabus me kaunse chapters delete/hata diye gaye hain?
'class 11 biology deleted syllabus 2026-27' se related jo verified ho paaya hai wo ye hai: rationalisation ke baad Transport in Plants, Mineral Nutrition, aur Digestion and Absorption — teeno standalone chapters is 19-chapter list se hata diye gaye hain (in teeno ka core content jaise osmosis/diffusion basics aur macro-micronutrients ab summative assessment ke scope se bahar maane jaate hain). Plant Growth and Development is list me hata nahi gaya — ye 2026-27 session ke 'class 11 biology syllabus 2026-27 ncert' me Chapter 13 ke roop me poora retained hai.
NEET ke liye Class 11 Biology chapter-wise weightage me Plant Growth and Development kitna important hai?
NCERT/NTA koi official chapter-wise percentage weightage publish nahi karti, isliye 'class 11 biology chapter wise weightage neet' ke liye koi specific number claim karna galat hoga. Jo bataya ja sakta hai wo ye hai ki ye chapter conceptually Plant Physiology unit ka core hai — phytohormones, growth curves aur photoperiodism jaise topics regularly diagram-based aur assertion-reason MCQs me poochhe jaate hain, isliye conceptual clarity yahan high-value hai, chahe exact weightage number verified na ho.
Plant Growth and Development ko baaki plant physiology chapters ke saath kaise link karke revise karein?
Ye chapter khade-akele padhne se zyada tab click karta hai jab 'class 11 biology photosynthesis in higher plants important questions' aur 'class 11 biology respiration in plants ncert solutions' ke saath revise kiya jaaye — teeno hi ek hi Plant Physiology unit ka hissa hain aur cell-level energy/metabolism (Photosynthesis, Respiration) ultimately isi growth aur development ko fuel karta hai jo is chapter me discuss hota hai. Cell division/differentiation ka base samajhne ke liye Chapter 8 Cell: The Unit of Life bhi ek baar refresh kar lena helpful rehta hai.
Photoperiodism aur Vernalisation me exact difference kya hai?
Photoperiodism plant ka response hai light aur dark duration (day-night length) ke prati — isse SDP/LDP/DNP categories banti hain aur leaves is stimulus ko perceive karti hain. Vernalisation is bilkul alag trigger hai — ye low temperature exposure se flowering promote hone ka phenomenon hai (jaise winter wheat varieties). Dono hi environment-controlled flowering mechanisms hain, lekin ek light-based hai aur doosra temperature-based.
Growth aur Development me kya farak hai, exam me kaise likhein?
Growth ek quantitative process hai — size, weight ya cell number me irreversible increase. Development ek broader term hai jisme Growth + Differentiation dono shaamil hain, plus dedifferentiation aur redifferentiation jaisi processes bhi — matlab seed germination se lekar senescence tak ke poore changes. Exam me likhte waqt formula-style likhna helpful hai: Development = Growth + Differentiation, aur ek example (jaise ek seedling ka poora life-cycle) add karna.
Class 11 Biology — Saare Chapters
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