Class 11 Biology · Chapter 7
Short answer: Chapter 7 Class 11 Biology mein tum seekhte ho ki cells kaise tissues banate hain, aur teen model organisms — earthworm, cockroach, aur frog — ke through poori body organisation (tissue se organ-system level tak) kaise samajhi jaati hai; ye diagram-heavy, definition-heavy chapter NEET/board dono ke liye high-yield hai.
Chapter 7 "Structural Organisation in Animals" Class 11 Biology syllabus 2026-27 NCERT ke Unit 2 ka doosra chapter hai (Unit 2 ka pehla chapter — Morphology aur Anatomy of Flowering Plants — plants cover karta hai, ye chapter animals cover karta hai). Ye chapter do parts mein divide ho sakta hai: pehla part animal tissues (epithelial, connective, muscular, neural) ka detailed study hai, aur doosra part teen representative organisms — earthworm (Pheretima), cockroach (Periplaneta americana), aur frog (Rana tigrina) — ki morphology aur anatomy ka case-study hai.
Ye chapter Chapter 4 (Animal Kingdom) ke classification knowledge par build karta hai — wahan tum Annelida, Arthropoda, aur Chordata phyla ke characters padhe the, yahan un tino ke ek-ek representative organism ka poora body plan detail mein dekhte ho. Isi wajah se agar Chapter 4 ke concepts weak hain, to pehle 'class 11 biology animal kingdom important questions' revise karna helpful rahega.
Diagram-based questions (earthworm reproductive organs, cockroach alimentary canal, frog digestive/circulatory system) is chapter ka backbone hain — CBSE board exams mein labelled-diagram questions is chapter se frequently aate hain, isliye inhe practice karna zaroori hai.
Chapter 7 Summary — 5 Minute Revision
Is chapter ke core takeaways:
- Tissue = similar cells ka group jo specific function ke liye kaam karta hai; 4 main animal tissue types: epithelial, connective, muscular, neural.
- Epithelial tissue — simple (squamous/cuboidal/columnar/ciliated/glandular, single layer, secretion-absorption-filtration) aur compound (multi-layer, sirf protection).
- Connective tissue — loose (areolar, adipose), dense (regular — tendon/ligament; irregular — dermis), aur specialised (cartilage, bone, blood).
- Muscular tissue — skeletal (voluntary, striated), smooth (involuntary, unstriated), cardiac (involuntary, striated, branched).
- Neural tissue — neuron (cyton + dendrites + axon) impulse conduct karta hai.
- Earthworm (Annelida) — metameric segmentation, closed circulatory system (4 pairs lateral hearts), 3 types nephridia, hermaphrodite reproduction with 4 pairs spermathecae.
- Cockroach (Arthropoda) — head-thorax(3)-abdomen(10 segments), Malpighian tubules for excretion, gastric caeca for digestion.
- Frog (Chordata, Amphibia) — poikilothermic, dual (skin+lung) respiration, complete digestive-circulatory-excretory-reproductive systems.
In-Text Questions — Solutions
Tissue ki definition kya hai, aur multicellular organisms mein tissue banne ki zaroorat kyun padi?
A tissue is a group of similar cells (along with intercellular substances) that work together to perform a specific function. Unicellular organisms perform all life processes with one cell, but as organisms became multicellular, individual cells started to specialise for specific jobs — division of labour — resulting in different cells grouping into tissues, tissues into organs, and organs into organ systems. Ye NCERT ke earlier chapters (living world, classification) ke baad next logical step hai — Class 11 Biology syllabus 2026-27 NCERT ke Unit 2 ka core idea yahi hai.
Earthworm (Pheretima) kis phylum mein aata hai, aur uski body segmentation (metamerism) ka kya fayda hai?
Pheretima phylum Annelida mein aata hai. Iski body metamerically segmented hoti hai — body ko repeating segments mein divide karne se locomotion (burrowing), regeneration, aur internal organs ka repetition (jaise nephridia har segment mein) efficiently ho paata hai. Ye body plan directly Chapter 4 (Animal Kingdom) ke Annelida phylum ke characters se link hota hai.
Frog (Rana tigrina) ko poikilothermic ('cold-blooded') kyun kaha jaata hai?
Frog ka body temperature environment ke temperature ke saath change hota rehta hai kyunki iske paas internal temperature-regulation mechanism nahi hota (unlike homeothermic mammals/birds). Isi wajah se frog winter mein hibernation (mud mein) aur summer mein aestivation karta hai — dono behaviours extreme temperature avoid karne ke liye.
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–Q14)
Q1. Answer in one word or one line:
- (a) Which of the following is not a tissue level of organisation — Hydra, sponges, or Periplaneta?
- (b) How many spermathecae are present in Pheretima (earthworm)?
- (c) Where are the ovaries located in an earthworm?
- (d) How many segments form the abdomen in a cockroach?
- (e) Where are the Malpighian tubules located in a cockroach?
In sab one-word/one-line answers hain, seedha exam mein aise hi likho:
(a) Sponges — sponges show cellular level of organisation (cells act somewhat independently); Hydra shows tissue level, and Periplaneta (cockroach) shows organ-system level, which is more advanced than tissue level.
(b) 4 pairs — located in the intersegmental grooves of segments 6/7, 7/8, 8/9 and 9/10.
(c) A pair of ovaries is present in the 13th segment, attached to the anterior septum (12/13 septum) of that segment.
(d) 10 segments form the abdomen of a cockroach (the 10th is reduced/vestigial).
(e) Malpighian tubules are located at the junction of the midgut (mesenteron) and hindgut (proctodaeum), arising as thin, yellow, filamentous outgrowths, 100–150 in number.
Q2.
- (a) What is the function of nephridia?
- (b) Name the different types of nephridia found in Pheretima.
Dono parts ka jawab niche diya gaya hai:
(a) Nephridia are the excretory and osmoregulatory organs of the earthworm — they remove nitrogenous waste (mainly urea) and help regulate water/ion balance in the body.
(b) Three types of nephridia are found:
- Septal nephridia — present on both sides of septa from the 15th/16th segment backward, open into the alimentary canal (enteronephric).
- Integumentary nephridia — attached to the inner body wall in most segments (except a few anterior/posterior ones), open directly to the outside (exonephric).
- Pharyngeal nephridia — present as paired tufts in the 4th, 5th and 6th segments, attached to the wall of the pharynx.
Q3. Draw a labelled diagram of the reproductive organs of an earthworm.
Exam mein neat labelled diagram banao, in structures ko clearly dikhao (anterior to posterior order):
- 1 pair testes (segments 10, 11) with testes sacs
- 1 pair seminal vesicles (segments 11, 12) — store and mature sperm
- 1 pair ovaries (segment 13)
- 1 pair oviducal funnels + oviducts (segment 13/14) opening on segment 14
- 4 pairs spermathecae (segments 6–9) — store sperm received during copulation
- Male genital pore on the 18th segment; female genital pore on the 14th segment
Study tip: Diagram ke saath jitne zyada correct labels utna behtar — kam se kam 6 labels include karne ki koshish karo.
Q4. Draw a labelled diagram of the alimentary canal of a cockroach.
Cockroach ke alimentary canal ko teen regions mein samjho:
Sequence of parts to label (mouth → anus), divided into 3 regions:
Foregut (stomodaeum): mouth → buccal cavity → pharynx → oesophagus → crop (food storage) → gizzard/proventriculus (grinding, has 6 chitinous teeth).
Midgut (mesenteron): stomach, with 6–8 finger-like gastric/hepatic caeca at the junction with foregut (secrete digestive juices).
Hindgut (proctodaeum): ileum → colon → rectum → anus; Malpighian tubules open at the midgut–hindgut junction (excretory, not digestive, but must be labelled).
Q5. Distinguish between:
- (a) Prostomium and peristomium
- (b) Septal nephridia and pharyngeal nephridia
Dono distinctions table format mein niche diye gaye hain:
| Basis | Prostomium | Peristomium |
|---|---|---|
| Position | First, small lobe at the extreme anterior end of the earthworm, overhangs the mouth | First true segment, immediately behind the prostomium, contains the mouth |
| Function | Sensory in function (helps in burrowing/testing surroundings) | Encloses the buccal cavity/mouth opening |
↔ Table ko side me swipe karein
| Basis | Septal nephridia | Pharyngeal nephridia |
|---|---|---|
| Location | On both sides of intersegmental septa, from 15th/16th segment backward | Paired tufts on the wall of the pharynx, in segments 4, 5, 6 |
| Opening | Open into the alimentary canal (enteronephric) | Open into the alimentary canal (enteronephric) |
↔ Table ko side me swipe karein
Q6. What are the cellular components of blood?
Blood ke teen cellular components ye hain:
Blood is a fluid connective tissue with a liquid matrix (plasma) and three types of formed (cellular) elements suspended in it:
- Erythrocytes (RBCs) — biconcave, anucleate (in mammals), carry O₂/CO₂ via haemoglobin.
- Leucocytes (WBCs) — nucleated, colourless, defence function; further divided into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).
- Platelets (thrombocytes) — small cell fragments, help in blood clotting.
Q7. Where do you find the following:
- (a) Chondrocytes
- (b) Axons
- (c) Ciliated epithelium
In teeno structures ki location niche batayi gayi hai:
(a) Chondrocytes — found in small cavities called lacunae within the matrix of cartilage tissue (e.g., nose, ear pinna, trachea rings).
(b) Axons — long, cylindrical process arising from the cyton (cell body) of a neuron; found in nerve tissue throughout the nervous system.
(c) Ciliated epithelium — found lining the inner surface of hollow organs like the trachea, bronchioles, and fallopian tubes, where its beating cilia move particles/gametes in a particular direction.
Q8. Describe various types of epithelial tissues with the help of labelled diagrams.
1. Simple epithelium (single layer, lines cavities/tubes/ducts, thin — good for filtration/absorption/secretion):
- Squamous — flat, irregular cells; lines blood vessels, alveoli (diffusion).
- Cuboidal — cube-shaped cells; lines kidney tubules, salivary gland ducts (secretion/absorption).
- Columnar — tall, pillar-like cells; lines stomach/intestine (secretion/absorption).
- Ciliated — columnar/cuboidal cells with cilia; lines trachea, fallopian tube.
- Glandular — modified columnar cells specialised for secretion (unicellular, e.g. goblet cells, or multicellular glands).
2. Compound epithelium (multiple cell layers, mainly protective, found where wear-and-tear is high — e.g. skin epidermis, buccal lining, oesophagus lining).
Diagram me har type ko alag row me draw karo with clear cell-shape outline + basement membrane label.
Q9. Distinguish between:
- (a) Simple epithelium and compound epithelium
- (b) Cardiac muscle and skeletal muscle
- (c) Dense regular and dense irregular connective tissue
- (d) Adipose tissue and blood tissue
- (e) Exocrine gland and endocrine gland
Paanchon distinctions table format mein niche diye gaye hain:
| Basis | Simple epithelium | Compound epithelium |
|---|---|---|
| Layers | Single layer of cells | Two or more layers of cells |
| Function | Filtration, secretion, absorption | Mainly protection (mechanical/chemical stress) |
↔ Table ko side me swipe karein
| Basis | Cardiac muscle | Skeletal muscle |
|---|---|---|
| Cell shape | Branched, cylindrical, uninucleate | Long, cylindrical, unbranched, multinucleate |
| Control | Involuntary, rhythmic, has intercalated discs | Voluntary, striated, attached to bones by tendons |
↔ Table ko side me swipe karein
| Basis | Dense regular CT | Dense irregular CT |
|---|---|---|
| Fibre arrangement | Collagen fibres in parallel bundles | Fibres arranged irregularly |
| Example | Tendons (muscle–bone), ligaments (bone–bone) | Dermis of skin |
↔ Table ko side me swipe karein
| Basis | Adipose tissue | Blood tissue |
|---|---|---|
| Matrix | Cells (adipocytes) filled with fat globules | Fluid matrix — plasma |
| Function | Fat storage, insulation, shock absorption | Transport of gases, nutrients, wastes, hormones |
↔ Table ko side me swipe karein
| Basis | Exocrine gland | Endocrine gland |
|---|---|---|
| Secretion route | Through a duct (e.g. salivary, sweat gland) | Ductless, secretes hormone directly into blood (e.g. thyroid) |
↔ Table ko side me swipe karein
Q10. Mark the odd one in each of the following groups on the basis of tissue type, and give a reason:
- (a) Squamous epithelium, cuboidal epithelium, columnar epithelium, cardiac muscle
- (b) Blood, lymph, cartilage, bone
- (c) Nephridia, Malpighian tubules, kidney, typhlosole
- (d) Prostomium, peristomium, clitellum, ootheca
- (e) Axon, dendrite, cyton, sarcomere
Har group ka odd-one-out aur reason niche diya gaya hai:
(a) Odd: Cardiac muscle — it is muscular tissue; the other three are all types of epithelial tissue.
(b) Odd: Blood — it is a fluid connective tissue; lymph, cartilage and bone all have a comparatively solid/semi-solid matrix (lymph is closer to fluid too, but blood is the only true circulating fluid CT with all three formed elements — accept blood as best-fit odd one on fluid-matrix logic).
(c) Odd: Typhlosole — it is a digestive adaptation (increases absorptive surface area of the earthworm's intestine); the other three are all excretory structures.
(d) Odd: Ootheca — it is the egg case of a cockroach; the other three (prostomium, peristomium, clitellum) are all external body parts of the earthworm.
(e) Odd: Sarcomere — it is the contractile unit of a muscle fibre; axon, dendrite and cyton are all parts of a neuron.
Q11. Match the terms in column I with those in column II:
Column I Column II (i) Typhlosole (a) Increases absorptive surface area of intestine (earthworm) (ii) Nephridia (b) Excretory organ of earthworm (iii) Malpighian tubules (c) Excretory organ of cockroach (iv) Ootheca (d) Egg case of cockroach (v) Spermatheca (e) Stores sperm received during copulation (earthworm) (vi) Gastric caeca (f) Aid digestion, at foregut–midgut junction (cockroach) (vii) Clitellum (g) Glandular, reproductive segments (14–16) of earthworm
↔ Table ko side me swipe karein
| Column I | Column II |
|---|---|
| (i) Typhlosole | (a) Increases absorptive surface area of intestine (earthworm) |
| (ii) Nephridia | (b) Excretory organ of earthworm |
| (iii) Malpighian tubules | (c) Excretory organ of cockroach |
| (iv) Ootheca | (d) Egg case of cockroach |
| (v) Spermatheca | (e) Stores sperm received during copulation (earthworm) |
| (vi) Gastric caeca | (f) Aid digestion, at foregut–midgut junction (cockroach) |
| (vii) Clitellum | (g) Glandular, reproductive segments (14–16) of earthworm |
Sahi matching: (i)–(a), (ii)–(b), (iii)–(c), (iv)–(d), (v)–(e), (vi)–(f), (vii)–(g).
Q12. Mention the circulatory system of earthworms briefly.
Earthworm ka circulatory system samajhne ke liye ye points yaad rakho:
Earthworm has a closed type of circulatory system (blood flows within vessels):
- A dorsal blood vessel (above alimentary canal) carries blood backward.
- A ventral blood vessel (below alimentary canal) carries blood forward.
- 4 pairs of lateral hearts (in segments 7, 9, 12, 13) connect the dorsal and ventral vessels and pump blood.
- Blood contains plasma, amoebocytes (colourless corpuscles), and dissolved haemoglobin (not inside cells, so blood appears red/pale).
Q13. Draw a neat diagram of the digestive system of a frog.
Frog ke digestive system ke parts is order mein label karo, mouth se cloaca tak:
- Buccal cavity (with tongue, teeth) → Oesophagus → Stomach (curved, with cardiac and pyloric ends) → Small intestine (duodenum + ileum) → Large intestine (rectum) → Cloaca → Cloacal aperture.
- Associated glands: Liver (bile via gall bladder into duodenum) and Pancreas (pancreatic juice into duodenum) — must be shown attached near the duodenum.
Q14. Mention the function of the following:
- (a) Ureters in frog
- (b) Malpighian tubules
- (c) Body wall in earthworm
Teeno structures ke functions niche diye gaye hain:
(a) Ureters (frog): Carry urine from the kidneys to the cloaca; in the male frog, the same ureter also carries sperm (acts as a urinogenital duct).
(b) Malpighian tubules (cockroach): Excretory structures — absorb nitrogenous waste (mainly uric acid) from the haemolymph and pass it into the hindgut for elimination; help maintain ionic/osmotic balance.
(c) Body wall (earthworm): Provides protection (cuticle + epidermis), helps in locomotion (circular + longitudinal muscle layers produce peristaltic waves), and acts as the main site of respiration (moist, vascular skin allows gaseous exchange since earthworm has no separate respiratory organ).
Important Equations — Ek Nazar Me
| Concept | Key fact |
|---|---|
| Epithelial tissue — single layer | Squamous (flat, filtration/diffusion) · Cuboidal (secretion/absorption) · Columnar (secretion/absorption) · Ciliated (movement of particles) · Glandular (secretion) |
| Compound epithelium | Multiple layers — protective function only (skin, buccal cavity) |
| Connective tissue types | Loose (areolar, adipose) · Dense regular (tendon, ligament) · Dense irregular (dermis) · Specialised (cartilage, bone, blood) |
| Muscle tissue | Striated/skeletal (voluntary) · Smooth (involuntary, unstriated) · Cardiac (involuntary, striated, branched, intercalated discs) |
| Neural tissue | Neuron = cyton + dendrites + axon; conducts nerve impulses |
| Earthworm (Pheretima) — Phylum Annelida | Metameric segments · closed circulatory system with 4 pairs lateral hearts · 3 types of nephridia (septal, integumentary, pharyngeal) · hermaphrodite, cross-fertilisation, 4 pairs spermathecae · typhlosole increases intestinal absorption area |
| Cockroach (Periplaneta americana) — Phylum Arthropoda | Body: head, thorax (3 segments), abdomen (10 segments) · Malpighian tubules at midgut-hindgut junction (excretion) · gastric caeca aid digestion · ootheca = egg case |
| Frog (Rana tigrina) — Phylum Chordata, Class Amphibia | Poikilothermic · dual respiration (skin + lungs) · digestive tract: buccal cavity → oesophagus → stomach → intestine → cloaca · 3-chambered heart |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Nephridia (earthworm) aur Malpighian tubules (cockroach) ko mix-up kar dena — dono excretory structures hain lekin alag-alag phylum/organism ke liye specific hain, exam mein swap mat karo.
- Spermathecae ka count galat likhna — sahi answer 4 pairs hai (segments 6–9), na ki 4 ya 3 pairs.
- Simple aur compound epithelium ki function confuse karna — simple epithelium secretion/absorption/filtration karta hai, compound sirf protection deta hai, isse ulta mat likho.
- Cardiac muscle ko voluntary muscle samajh lena — cardiac muscle striated dikhta hai isliye students isse skeletal (voluntary) samajh lete hain, lekin ye involuntary hota hai.
- Cockroach ke abdomen ke segments ki ginti mein galti — abdomen mein 10 segments hote hain, thorax ke 3 segments ke saath confuse mat karo.
- Frog ke digestive system ka diagram banate waqt liver-pancreas ko alimentary canal ka hi part maan lena — ye associated (accessory) glands hain, canal ka direct part nahi.
Board-Style Important Questions
- Very short answer: Cockroach mein Malpighian tubules kahan open hote hain?
- Short answer: Simple epithelium aur compound epithelium mein antar likho (koi do points).
- Short answer: Earthworm mein paaye jaane wale teen prakar ke nephridia ka naam aur unka location likho.
- Short answer: Cardiac muscle aur skeletal muscle ke beech kisi teen aadhar par antar likho.
- Long answer: Frog ke digestive system ka labelled diagram banao aur uske major parts describe karo.
Aksar Poochhe Jaane Wale Sawaal
Class 11 Biology Chapter 7 ke saath Chapter 8 Cell: The Unit of Life kaise connect hota hai?
Chapter 7 tissue-se-organism level ki organisation dikhata hai (cells → tissues → organs → organ systems), jabki agla chapter — Cell: The Unit of Life — us organisation ki sabse chhoti unit, yaani cell, ko detail mein cover karta hai. Bahut students Chapter 8 ke liye 'class 11 biology chapter 8 cell the unit of life important questions' aur 'class 11 biology chapter 8 notes pdf' dhundhte hain, kyunki weightage-wise ye NEET ka ek high-yield chapter hai — Chapter 7 ka tissue-level foundation clear hone ke baad ye padhna easier ho jaata hai.
Kya is chapter (ya nearby chapters) mein Transport in Plants ya Digestion and Absorption bhi cover hote hain?
Nahi. 2023-24 rationalisation ke baad — jo 2026-27 session mein bhi wahi chali aa rahi hai — Transport in Plants, Mineral Nutrition, aur Digestion and Absorption teeno chapters hata diye gaye the. Isliye jab kisi student ko 'class 11 biology deleted syllabus 2026-27' search karna ho, ye teen chapters hi wo topics hain jo ab standalone chapter ke roop mein nahi padhaye jaate — unka core content (jaise digestive enzymes) ab kisi bhi remaining chapter mein summative assessment scope se bahar maana jaata hai.
Class 11 Biology ke saare NCERT solutions chapter wise PDF ek jagah mil sakte hain?
Haan, 'class 11 biology ncert solutions chapter wise pdf' search karne par aksar full-syllabus bundle milte hain — lekin quality-wise verify karo ki wo current 19-chapter rationalised list (Ch1 The Living World se lekar Ch19 Chemical Coordination and Integration tak) follow kar rahe hain, kyunki purani (pre-2023) 22-chapter PDFs abhi bhi internet par circulate ho rahi hain aur unmein deleted chapters shaamil hote hain.
Chapter 7 ka NEET weightage kitna hai?
Official NTA syllabus document mein chapter-wise exact weightage percentage publish nahi hoti, isliye 'class 11 biology chapter wise weightage neet' search karne par jo bhi numbers milein unhe estimate maano, official confirmed figure nahi. Jo confirm hai wo ye hai ki Structural Organisation in Animals ek diagram-heavy, definition-heavy chapter hai jahan se 1-3 direct questions frequently practice-question banks mein dikhte hain — isliye labelled diagrams (earthworm reproductive organs, cockroach alimentary canal, frog digestive system) exam-ready practice zaroor karo.
Is chapter ke baad next kaunse Class 11 Biology chapters padhne chahiye jinka pattern similar hai?
Structural Organisation in Animals ke turant baad syllabus Unit 3 (Cell Structure and Function) mein jaata hai — Cell: The Unit of Life aur Biomolecules. Aage Unit 5 (Human Physiology) mein similar animal-system-based chapters aate hain jaise Excretory Products and their Elimination, Neural Control and Coordination — in dono ke liye bhi 'class 11 biology excretory products and their elimination ncert solutions' aur 'class 11 biology neural control and coordination notes pdf' jaisi searches common hain, aur wahan bhi isi tarah ka labelled-diagram-plus-definition approach kaam aata hai.
Exam ke liye 'important questions with answers' kaise practice karein?
'class 11 biology important questions with answers pdf' dhundhne ke bajaye, is chapter ke andar diye gaye 14 exercise questions (especially distinguish-between aur labelled-diagram wale) ko khud se likh kar practice karo — CBSE marking scheme step-by-step answers maangti hai, sirf one-word answers nahi. Diagram + correct labels + short functional explanation, ye combination zyada marks deta hai.
Class 11 Biology — Saare Chapters
Board exam tak sirf revision karna hai?
Class 11 Biology ke saare chapters ke colour handwritten short notes — diagrams, formulas aur important points ek jagah.
NCERT Kaksha ek swatantra shaikshik platform hai aur NCERT ya CBSE se aadhikarik roop se sambaddh (officially affiliated) nahi hai. Kisi galti ki jaankari dene ke liye contact kijiye.