Class 11 Biology · Chapter 17
Short answer:
Class 11 Biology Chapter 17 Locomotion and Movement — 2026-27 ke rationalised (19-chapter) syllabus me yahi number hai; purani numbering me ye Chapter 20 tha. Yahan milega: sliding filament theory, muscle contraction ke steps, skeletal system (axial + appendicular), joints, aur poore NCERT exercise ke 10 questions ka step-by-step solution — wahi format jo "class 11 biology ncert solutions chapter wise pdf" aur "class 11 biology important questions with answers pdf" dhoondhne wale students chahte hain.
Locomotion and Movement, Class 11 Biology ki Human Physiology unit ka chapter hai — sequence me Chapter 16 "Excretory Products and their Elimination" ke baad aur Chapter 18 "Neural Control and Coordination" se pehle aata hai. Simple sawaal se shuru hoti hai ye chapter: hum chalte-phirte kaise hain? Jawab teen systems ke coordination me hai — muscular system (force generate karta hai), skeletal system (support + lever provide karta hai), aur joints (movement possible banate hain jahan do bones milte hain).
Is chapter ka core concept hai sliding filament theory — muscle contraction actually filaments ke chhote hone se nahi, balki actin (thin filament) ke myosin (thick filament) ke upar "slide" karne se hota hai. Ye high-yield concept hai jo NCERT exercise aur exams dono me repeat hota hai. Doosra bada hissa hai skeletal system — 206 bones, unki classification (axial 80 + appendicular 126), aur alag-alag joint types (pivot, hinge, ball-and-socket, saddle, gliding, fibrous, cartilaginous).
Neeche poora chapter breakdown hai — quick summary, NCERT ke saare 10 exercise questions (step-by-step, exam-style explanations), key-facts table, common mistakes, expected exam-pattern questions, aur FAQ.
Chapter 17 Summary — 5 Minute Revision
Types of movement: Human body ki cells teen tarah ki movement dikhati hain — amoeboid (macrophages, leucocytes — pseudopodia se), ciliary (trachea, oviduct/fallopian tube — particles ya ovum move karne ke liye), aur muscular (limbs, jaw, tongue, heart — poore body ki locomotion).
Muscle structure aur contraction: Skeletal muscle striated, voluntary hota hai; smooth muscle non-striated, involuntary; cardiac muscle striated par involuntary. Har muscle fibre me myofibrils hote hain jo sarcomere units me bante hain — thin filament (actin + troponin + tropomyosin) aur thick filament (myosin) ke alternate bands se A-band, I-band, H-zone, Z-line banti hai. Sliding filament theory ke mutabik: motor neuron se signal → acetylcholine release → sarcolemma me action potential → sarcoplasmic reticulum se Ca2+ release → Ca2+ troponin se bind hoke tropomyosin ko hata deta hai → myosin head actin se bind karke cross-bridge banata hai → ATP hydrolysis se power stroke hota hai aur actin andar khinch jaata hai → sarcomere shorten hota hai (filament ki length same rehti hai, sirf overlap badhta hai) → naya ATP bind hote hi cross-bridge tootta hai aur cycle repeat hota hai jab tak Ca2+ aur stimulus rehte hain.
Skeletal system: Total 206 bones — axial skeleton (80 bones: skull, vertebral column, sternum, ribs) aur appendicular skeleton (126 bones: limbs + girdles). Cranium 8 bones se banta hai, facial skeleton 14 bones se. Vertebral column me 26 vertebrae (7 cervical, 12 thoracic, 5 lumbar, 1 sacrum(fused), 1 coccyx(fused)). 12 pairs ribs — 7 true, 3 false, 2 floating (11th-12th). Pectoral girdle = clavicle + scapula (glenoid cavity → shoulder ka ball-and-socket joint humerus se). Pelvic girdle = ilium + ischium + pubis fused = coxal bone, dono halves pubic symphysis pe milte hain, acetabulum femur se ball-and-socket joint banata hai.
Joints: Fibrous (immovable — skull sutures), cartilaginous (slightly movable — pubic symphysis, vertebrae ke beech), synovial (freely movable — ball-and-socket at shoulder/hip, hinge at elbow/knee/phalanges, pivot at atlas-axis, saddle at thumb carpal-metacarpal, gliding between carpals).
Disorders: Myasthenia gravis (autoimmune, neuromuscular junction affect hota hai), muscular dystrophy (progressive muscle degeneration), tetany (Ca2+ deficiency se rapid muscle contractions), arthritis (joint inflammation — osteoarthritis, rheumatoid arthritis), osteoporosis (age-related — bone mass kam hoti hai, estrogen fall se), gout (uric acid crystals joints me jama ho jaate hain).
In-Text Questions — Solutions
Locomotion aur movement me kya farak hai?
Movement ek broad term hai — body ke kisi bhi part ka position/shape badalna movement kehlata hai (jaise cilia beating, blood flow, muscle twitch).
Locomotion ek special type ka movement hai jisme poora organism apni ek jagah se doosri jagah shift hota hai (jaise chalna, tairna, udna) — food, shelter, mate ki talaash ya danger se bachne ke liye.
Striated aur non-striated muscle me farak batao.
Striated muscle: Microscope me alternate light aur dark bands (striations) dikhti hain — skeletal aur cardiac muscle striated hote hain.
Non-striated (smooth) muscle: Koi banding pattern nahi dikhta, spindle-shaped uninucleate cells hoti hain — alimentary canal aur blood vessels ki wall me paayi jaati hai, involuntary hoti hai.
Myofibril kya hota hai?
Myofibril ek muscle fibre (cell) ke andar present thread-jaisi structure hai, jo bahut saari sarcomere units se milkar bani hoti hai. Har myofibril me thin (actin) aur thick (myosin) filaments ka alternate arrangement hota hai, jo striated pattern (A-band, I-band) create karta hai — yehi contraction ki basic functional unit hai.
Skeletal system ke koi do main functions batao.
- Body ko structural support aur definite shape deta hai, aur muscles ko attachment surface provide karke movement/locomotion possible banata hai (lever system ki tarah).
- Vital organs (brain — cranium, heart/lungs — rib cage) ko protect karta hai, aur bone marrow me RBC production (haematopoiesis) ke liye site provide karta hai.
Axial aur appendicular skeleton me farak batao.
Axial skeleton (80 bones): body ki main axis banata hai — skull, vertebral column, sternum, ribs.
Appendicular skeleton (126 bones): limbs aur unki girdles (pectoral + pelvic) se milkar banta hai — movement/locomotion me directly involved hota hai.
Joint kya hota hai aur iske main types kya hain?
Joint wo point hai jahan do ya zyada bones (ya bone-cartilage) mile hote hain. Movement ke basis pe teen main types hote hain:
- Fibrous joint: immovable (jaise skull sutures)
- Cartilaginous joint: slightly movable (jaise pubic symphysis)
- Synovial joint: freely movable (jaise ball-and-socket, hinge, pivot, saddle, gliding)
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–Q10)
1. Draw the diagram of a sarcomere of skeletal muscle showing different regions.
Ye ek diagram-based question hai — paper pe banate waqt in regions ko clearly label karo (edge-to-edge ek sarcomere = do consecutive Z-lines ke beech ka hissa):
- Z-line: sarcomere ki dono boundaries — thin (actin) filaments yahan anchor hote hain.
- I-band: light zone — sirf thin (actin) filaments, Z-line ke dono taraf.
- A-band: dark zone — poori thick (myosin) filament ki length, jahan actin aur myosin overlap karte hain (edges pe) — A-band ki length contraction me constant rehti hai.
- H-zone: A-band ke beech ka lighter central hissa — sirf thick (myosin) filaments, actin overlap nahi karta.
- M-line: sarcomere ke bilkul center me — thick filaments ko jodta hai.
Diagram me thin lines (actin) aur thick lines (myosin) parallel banao, Z-line se Z-line tak, upar diye gaye regions label karo.
2. Define sliding filament theory of muscle contraction.
Sliding filament theory ke mutabik, muscle contraction actin (thin) filaments ke myosin (thick) filaments ke upar slide karne se hota hai — na ki filaments ki length chhoti hoke. Jab myosin head, ATP hydrolysis se energy leke actin filament ko sarcomere ke center ki taraf khinchta hai, to Z-lines paas aati hain, I-band aur H-zone chhote ho jaate hain, jabki A-band ki length constant rehti hai. Isse poora sarcomere shorten ho jaata hai aur muscle contract hoti hai, filaments ki apni length badalti nahi.
3. Describe the important steps in muscle contraction.
Muscle contraction step-by-step (neural signal se relaxation tak):
- Motor neuron se signal neuromuscular junction pe pahunchta hai, jahan acetylcholine release hota hai.
- Isse sarcolemma me action potential (muscle action potential) generate hota hai, jo T-tubules ke through andar spread hota hai.
- Isse sarcoplasmic reticulum se Ca2+ ions sarcoplasm me release hote hain.
- Ca2+ troponin se bind hota hai, jisse actin filament pe se tropomyosin hat jaata hai aur myosin-binding sites expose ho jaate hain.
- Myosin head (jisme ADP + Pi already bound hai) actin ke exposed site se bind karke cross-bridge banata hai.
- Cross-bridge ka angle badalta hai (power stroke) — actin filament sarcomere ke center ki taraf khinchta hai, ADP aur Pi release hote hain.
- Naya ATP myosin head se bind hote hi cross-bridge actin se detach ho jaata hai.
- ATP hydrolysis (myosin ATPase) se myosin head wapas apni original position me "re-cock" ho jaata hai, next cycle ke liye ready.
- Jab tak Ca2+ aur stimulus present hai, ye cycle repeat hota hai aur sarcomere shorten hota rehta hai.
- Stimulus rukte hi Ca2+ wapas sarcoplasmic reticulum me pump ho jaata hai, tropomyosin dobara binding site cover kar leta hai — muscle relax ho jaati hai.
4. Write true or false. If false change the statement so that it is true.
- (a) Actin is present in thin filament.
- (b) H-zone of striated muscle fibre represents both thick and thin filaments.
- (c) Human skeleton has 206 bones.
- (d) There are 11 pairs of ribs in man.
- (e) Sternum is present on the ventral side of the body.
(a) True. Actin thin filament ka main protein hai.
(b) False. Corrected: H-zone of striated muscle fibre represents only thick (myosin) filaments — actin (thin filament) H-zone me overlap nahi karta.
(c) True. Human skeleton 206 bones ka hota hai (axial 80 + appendicular 126).
(d) False. Corrected: There are 12 pairs of ribs in man (7 true + 3 false + 2 floating).
(e) True. Sternum body ke ventral (front) side pe midline me present hota hai.
5. Write the differences between:
- (a) Actin and Myosin
- (b) Red and White muscles
- (c) Pectoral and Pelvic girdle
(a) Actin vs Myosin:
| Actin | Myosin |
|---|---|
| Thin filament banata hai | Thick filament banata hai |
| Do F-actin strands ki helix + troponin + tropomyosin | Head aur tail region hota hai — head me ATPase activity |
| I-band banata hai | A-band banata hai |
| Z-line se anchored | M-line se juda hota hai |
↔ Table ko side me swipe karein
(b) Red vs White muscles:
| Red muscle | White muscle |
|---|---|
| Myoglobin zyada — dark red colour | Myoglobin kam — pale colour |
| Mitochondria zyada, mainly aerobic respiration | Mitochondria kam, mainly anaerobic (glycolysis) |
| Slow contracting, fatigue-resistant (postural muscles) | Fast contracting, jaldi fatigue hoti hai |
↔ Table ko side me swipe karein
(c) Pectoral vs Pelvic girdle:
| Pectoral girdle | Pelvic girdle |
|---|---|
| Har half me clavicle + scapula | Har half me ilium + ischium + pubis (fused = coxal bone) |
| Glenoid cavity, humerus se articulate | Acetabulum, femur se articulate |
| Vertebral column se direct fuse nahi | Sacrum se fused, dono halves pubic symphysis pe midline me milte hain |
| Zyada mobility, kam load-bearing | Kam mobility, zyada body-weight support |
↔ Table ko side me swipe karein
6. Match Column I with Column II.
Column I Column II (a) Smooth muscle (i) Involuntary, non-striated (b) Tropomyosin (ii) Thin filament ka regulatory protein (c) Red muscle (iii) Myoglobin-rich (d) Skull (iv) Cranium + facial bones se banta hai
↔ Table ko side me swipe karein
| Column I | Column II |
|---|---|
| (a) Smooth muscle | (i) Involuntary, non-striated |
| (b) Tropomyosin | (ii) Thin filament ka regulatory protein |
| (c) Red muscle | (iii) Myoglobin-rich |
| (d) Skull | (iv) Cranium + facial bones se banta hai |
Matching: (a) → (i) smooth muscle involuntary aur non-striated hoti hai (alimentary canal, blood vessels ki wall me). (b) → (ii) tropomyosin thin filament (actin) ka protein hai jo resting state me myosin-binding site cover karke rakhta hai. (c) → (iii) red muscle me myoglobin zyada hoti hai jo O2 store karta hai. (d) → (iv) skull cranium (8 bones) + facial skeleton (14 bones) se milkar banta hai.
7. What are the different types of movements exhibited by the cells of human body?
Human body ki cells teen tarah ki movement dikhati hain:
- Amoeboid movement: pseudopodia (finger-like projections) ke through — macrophages aur leucocytes (WBCs) me, jaise ye blood vessels se bahar nikal ke infection site tak pahunchte hain.
- Ciliary movement: cilia ki coordinated beating se — trachea (dust particles bahar nikalna) aur fallopian tube/oviduct (ovum ko move karna) jaisi jagah.
- Muscular movement: skeletal, smooth aur cardiac muscles ki contraction se — limbs move karna, jaw se chewing, heart ka pumping, alimentary canal ki peristalsis.
8. How do you distinguish between a skeletal muscle and a cardiac muscle?
| Skeletal muscle | Cardiac muscle |
|---|---|
| Voluntary control (nervous system se conscious control) | Involuntary (khud apni rhythm me contract karta hai — myogenic) |
| Fibres lambe, cylindrical, multinucleate | Fibres branched, cylindrical, uninucleate/binucleate |
| Bones se tendons ke through attached | Heart wall (myocardium) banata hai |
| Intercalated discs nahi hote | Intercalated discs hote hain jo cells ko connect karte hain, jaldi fatigue nahi hote |
| Fast contract, jaldi fatigue hoti hai | Rhythmic aur untiring contraction, poori zindagi non-stop |
↔ Table ko side me swipe karein
Dono hi striated (cross-striped) hote hain, lekin control aur structure me upar diye antar hote hain.
9. Name the type of joint between the following:
- (a) atlas/axis
- (b) carpal-metacarpal of thumb
- (c) between phalanges
- (d) femur/acetabulum
- (e) between cranial bones
- (f) between the pubic bones in the pelvic girdle
(a) atlas/axis: Pivot joint (head ka rotation possible karta hai).
(b) carpal-metacarpal of thumb: Saddle joint.
(c) between phalanges: Hinge joint.
(d) femur/acetabulum: Ball and socket joint (hip joint).
(e) between cranial bones: Fibrous joint (sutures — immovable).
(f) between pubic bones (pelvic girdle): Cartilaginous joint (pubic symphysis — slightly movable).
10. Fill in the blank spaces:
- (a) All mammals (except a few) have ______ cervical vertebra.
- (b) The number of phalanges in each limb of human is ______.
- (c) Thin filament of myofibril contains two 'F' actins and two other proteins namely ______ and ______.
- (d) In a muscle fibre Ca2+ is stored in ______.
- (e) ______ and ______ pairs of ribs are called floating ribs.
- (f) The human cranium is made of ______ bones.
(a) Seven (7) cervical vertebra — sabhi mammals me (jiraffe se leke insan tak), kuch apwaad (jaise sloth, manatee) chhodkar.
(b) 14 phalanges har limb me (thumb/big toe me 2, baaki 4 digits me 3-3 = 2 + 12 = 14).
(c) Troponin aur Tropomyosin — dono actin filament pe regulatory proteins hain jo contraction control karte hain.
(d) Sarcoplasmic reticulum — yahan se Ca2+ stimulus milne pe release hota hai.
(e) 11th aur 12th pairs ribs floating ribs kehlate hain — inka sternum se koi connection nahi hota.
(f) 8 bones se cranium banta hai (jo brain ko protect karta hai).
Important Equations — Ek Nazar Me
| Fact / Rule | Value |
|---|---|
| Total bones in human skeleton | 206 (Axial 80 + Appendicular 126) |
| Cranium bones | 8 |
| Facial bones | 14 |
| Vertebral column | 26 vertebrae — 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum (fused), 1 coccyx (fused) |
| Ribs | 12 pairs — 7 true, 3 false, 2 floating (11th–12th) |
| Phalanges per limb | 14 (thumb/big toe: 2, baaki 4 digits: 3 each) |
| Pectoral girdle components | Clavicle + Scapula (har side) |
| Pelvic girdle components | Ilium + Ischium + Pubis (fused = coxal bone) |
| Thin filament proteins | F-actin (2 strands) + Troponin + Tropomyosin |
| Thick filament protein | Myosin (head = ATPase activity + actin binding) |
| Ca2+ storage site | Sarcoplasmic reticulum |
| Sliding filament rule | A-band constant; I-band aur H-zone shorten hote hain jab actin myosin ke upar slide karta hai |
| Joint types (movable) | Ball-and-socket (shoulder/hip), Hinge (elbow/knee/phalanges), Pivot (atlas-axis), Saddle (thumb), Gliding (carpals) |
| Joint types (immovable / limited) | Fibrous (skull sutures — immovable), Cartilaginous (pubic symphysis — slightly movable) |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
H-zone ko galat samajhna: students likh dete hain H-zone me actin + myosin dono hain — actually H-zone sirf myosin (thick filament) ka central area hai, actin overlap nahi karta.
Ribs ki ginti me galti: 11 nahi, 12 pairs ribs hote hain (7 true + 3 false + 2 floating) — NCERT ka exact true/false question isi pe hai.
Sliding filament theory me filament length badalna likhna: galat hai — actin/myosin filaments ki apni length same rehti hai, sirf unka overlap badhta hai aur sarcomere shorten hota hai.
Joint types me confusion: atlas-axis pivot joint hai, shoulder/hip ball-and-socket hai — dono ko mix mat karo, exercise Q9 exactly isi pe test karta hai.
Pectoral aur pelvic girdle ki bones mix karna: Pectoral = clavicle + scapula; Pelvic = ilium + ischium + pubis (fused = coxal bone) — alag-alag yaad rakho.
Ca2+ ka role/location galat likhna: Ca2+ sarcoplasmic reticulum me store hota hai (sarcolemma me nahi), aur ye directly myosin se nahi, troponin se bind hota hai.
Board-Style Important Questions
- Define sliding filament theory of muscle contraction.
- Name the type of joint present between the atlas and axis.
- Differentiate between red and white muscle fibres.
- Describe the important steps involved in muscle contraction.
- Differentiate between pectoral girdle and pelvic girdle.
- Draw and label a sarcomere, and explain how it shortens during muscle contraction according to the sliding filament theory.
Aksar Poochhe Jaane Wale Sawaal
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Class 11 Biology — Saare Chapters
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