This MCQ module is based on: NCERT Exercises and Solutions: Structural Organisation in Animals
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NCERT Exercises and Solutions: Structural Organisation in Animals
🎓 Class 11
Biology
CBSE
Theory
Ch 7 – Structural Organisation in Animals
⏱ ~8 min
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NCERT Exercises and Solutions: Structural Organisation in Animals
7.7 Chapter Summary
- Animal tissues are of four basic types: epithelial, connective, muscular and neural.
- Epithelium covers/lines surfaces. Simple epithelium (squamous, cuboidal, columnar) is a single layer; compound epithelium has multiple layers (protection). Glandular epithelium (exocrine, endocrine) is secretory.
- Cell junctions — tight, adhering, gap — link adjacent cells.
- Connective tissue has cells + matrix + fibres. Loose (areolar, adipose), dense (regular = tendon/ligament; irregular = dermis), and specialised (cartilage, bone, blood).
- Muscle is three types: skeletal (striated, voluntary, multinucleate), smooth (non-striated, involuntary, fusiform), cardiac (striated, branched, intercalated discs).
- Neural tissue = neurons (excitable) + neuroglia (support).
- Cells → Tissues → Organs → Organ Systems → Organism (hierarchy of organisation).
- Earthworm (Pheretima) — long segmented worm with clitellum on 14-16; closed circulation; cutaneous respiration; nephridia (excretion); hermaphrodite with cross-fertilisation; direct development.
- Cockroach (Periplaneta) — chitinous exoskeleton; 3 thoracic + 10 abdominal segments; open circulation; tracheal respiration (10 pairs spiracles); Malpighian tubules (uricotelic); dioecious with ootheca; paurometabolous.
- Frog (Rana tigrina) — moist skin; cutaneous + buccal + pulmonary respiration; 3-chambered heart (closed); kidneys + ureotelic; 10 cranial nerves; dioecious; external fertilisation; tadpole undergoes metamorphosis.
7.8 Key Terms (Glossary)
| Term | Definition |
|---|---|
| Epithelium | Tissue covering free surfaces; protects/lines. |
| Connective tissue | Supportive tissue with cells in matrix. |
| Tendon | Muscle-to-bone connector. |
| Ligament | Bone-to-bone connector. |
| Clitellum | Reproductive band of earthworm (14-16). |
| Typhlosole | Absorption-increasing fold in earthworm intestine. |
| Ootheca | Cockroach egg capsule. |
| Haemocoel | Open body cavity in cockroach. |
| Malpighian tubules | Insect excretory tubules (uric acid). |
| Nictitating membrane | Third transparent eyelid of frog. |
| Tympanum | Frog's eardrum. |
| Poikilotherm | Cold-blooded animal (frog). |
7.9 NCERT Exercises
Q1. Answer in one word or one line.
(i) Give the common name of Periplaneta americana.
(ii) How many spermathecae are found in earthworm?
(iii) What is the position of ovaries in cockroach?
(iv) How does fertilisation take place in frogs?
(v) What is the function of the nictitating membrane in frogs?
(i) American cockroach.
(ii) Four pairs (in segments 6, 7, 8 and 9).
(iii) The ovaries lie laterally in the 2nd-6th abdominal segments. Each ovary is made up of 8 ovarioles.
(iv) Fertilisation is external — it occurs in water. The male grasps the female (amplexus); as she releases ova, the male releases sperms over them.
(v) The nictitating membrane (third eyelid) protects the eye from injury and dirt while in water and keeps the cornea moist on land.
(ii) Four pairs (in segments 6, 7, 8 and 9).
(iii) The ovaries lie laterally in the 2nd-6th abdominal segments. Each ovary is made up of 8 ovarioles.
(iv) Fertilisation is external — it occurs in water. The male grasps the female (amplexus); as she releases ova, the male releases sperms over them.
(v) The nictitating membrane (third eyelid) protects the eye from injury and dirt while in water and keeps the cornea moist on land.
Q2. Mention the function of the following.
(i) Ureters of frog
(ii) Malpighian tubules
(iii) Body wall of earthworm
(i) Ureters of frog: Carry urine from the kidneys to the urinary bladder/cloaca. In males they also serve as the urinogenital duct (carrying both urine and sperms).
(ii) Malpighian tubules: Excretory organs of cockroach. They absorb nitrogenous wastes from the haemolymph and convert them into uric acid for excretion via the hindgut.
(iii) Body wall of earthworm: (a) Provides outer protective covering (cuticle), (b) houses the circular and longitudinal muscle layers that drive locomotion, (c) maintains a moist surface for cutaneous respiration, and (d) contains setae for grip with the soil.
(ii) Malpighian tubules: Excretory organs of cockroach. They absorb nitrogenous wastes from the haemolymph and convert them into uric acid for excretion via the hindgut.
(iii) Body wall of earthworm: (a) Provides outer protective covering (cuticle), (b) houses the circular and longitudinal muscle layers that drive locomotion, (c) maintains a moist surface for cutaneous respiration, and (d) contains setae for grip with the soil.
Q3. Draw a labelled diagram of the reproductive organs of an earthworm.
Q4. Draw a labelled diagram of the digestive system of frog.
Q5. What are the differences between hermaphrodite and unisexual animal?
| Feature | Hermaphrodite (Bisexual) | Unisexual (Dioecious) |
|---|---|---|
| Sex organs | Both male and female sex organs in the same individual | Either male or female organs in one individual |
| Fertilisation | Self or cross-fertilisation | Always cross-fertilisation |
| Examples | Earthworm, leech, Taenia, Hydra | Cockroach, frog, all higher vertebrates including humans |
| Sexual dimorphism | Generally absent | Often present |
Q6. State two differences between cartilage and bone.
| Feature | Cartilage | Bone |
|---|---|---|
| Matrix | Solid but pliable (made of chondroitin); no calcium | Hard and non-pliable (rich in calcium salts + collagen) |
| Cells | Chondrocytes in lacunae | Osteocytes in lacunae, arranged around Haversian canal |
| Blood supply | Avascular (no blood vessels); heals slowly | Highly vascular; heals well |
| Location | Tip of nose, ear pinna, between vertebrae | Limb bones, skull, vertebral column |
Q7. Distinguish between the following: (a) Simple epithelium and Compound epithelium (b) Cardiac muscle and Striated muscle (c) Dense regular and Dense irregular connective tissues (d) Adipose and Blood tissue (e) Simple gland and Compound gland.
(a) Simple vs Compound epithelium: Simple = single cell layer (squamous, cuboidal, columnar) — secretion/absorption/diffusion; Compound = many layers — protection (skin, buccal cavity).
(b) Cardiac vs Striated (skeletal) muscle: Cardiac is branched, single nucleus, has intercalated discs, involuntary, never fatigues, only in heart; Skeletal is unbranched cylindrical, multinucleate, no discs, voluntary, fatigues, attached to bones.
(c) Dense regular vs irregular connective: Regular = fibres in parallel bundles (tendon, ligament); Irregular = fibres in many directions (dermis of skin).
(d) Adipose vs Blood: Adipose = loose connective with fat-storing adipocytes; Blood = fluid connective tissue with plasma matrix carrying RBCs, WBCs, platelets — transport.
(e) Simple vs Compound gland: Simple = unbranched duct (sweat gland); Compound = branched duct system (salivary gland, pancreas).
(b) Cardiac vs Striated (skeletal) muscle: Cardiac is branched, single nucleus, has intercalated discs, involuntary, never fatigues, only in heart; Skeletal is unbranched cylindrical, multinucleate, no discs, voluntary, fatigues, attached to bones.
(c) Dense regular vs irregular connective: Regular = fibres in parallel bundles (tendon, ligament); Irregular = fibres in many directions (dermis of skin).
(d) Adipose vs Blood: Adipose = loose connective with fat-storing adipocytes; Blood = fluid connective tissue with plasma matrix carrying RBCs, WBCs, platelets — transport.
(e) Simple vs Compound gland: Simple = unbranched duct (sweat gland); Compound = branched duct system (salivary gland, pancreas).
Q8. Mark the odd one in each series:
(a) Areolar tissue; blood; neuron; tendon
(b) RBC; WBC; platelets; cartilage
(c) Exocrine; endocrine; salivary gland; ligament
(d) Maxilla; mandible; labrum; antennae
(e) Protonema; mesothorax; metathorax; prothorax
(a) Neuron — the others are connective tissues; neuron is a nerve cell.
(b) Cartilage — the others are blood components.
(c) Ligament — the others relate to glands; ligament is a dense connective tissue connecting bones.
(d) Antennae — the others are mouth parts of cockroach (also: antennae are sensory appendages, not mouth parts).
(e) Protonema — that's a juvenile stage of a moss (plant), not a part of cockroach thorax.
(b) Cartilage — the others are blood components.
(c) Ligament — the others relate to glands; ligament is a dense connective tissue connecting bones.
(d) Antennae — the others are mouth parts of cockroach (also: antennae are sensory appendages, not mouth parts).
(e) Protonema — that's a juvenile stage of a moss (plant), not a part of cockroach thorax.
Q9. Match the terms in column I with those in column II.
| Column I | Column II |
|---|---|
| (a) Compound epithelium | (i) Alveoli |
| (b) Compound eye | (ii) Cockroach |
| (c) Septal nephridia | (iii) Skin |
| (d) Open circulatory system | (iv) Mosaic vision |
| (e) Typhlosole | (v) Earthworm |
| (f) Osteocytes | (vi) Bone |
| (g) Genitalia | (vii) Intestine |
(a) — (iii) Skin — compound epithelium covers dry surface of skin.
(b) — (iv) Mosaic vision — compound eye produces mosaic image.
(c) — (v) Earthworm — septal nephridia are present in Pheretima.
(d) — (ii) Cockroach — open circulatory system in insects.
(e) — (vii) Intestine — typhlosole is the fold in earthworm intestine.
(f) — (vi) Bone — osteocytes are the cells of bone.
(g) — (i) Alveoli — wait, this is awkward; the conventional match is g↔ accessory reproductive structure (the answer NCERT expects here matches genitalia to the accessory pair in Periplaneta, but as given, alveoli does not match — it pairs with (a) compound epithelium for protective layers, which can include the air sacs in lungs (squamous). NCERT pairing: g — accessory reproductive parts.
(b) — (iv) Mosaic vision — compound eye produces mosaic image.
(c) — (v) Earthworm — septal nephridia are present in Pheretima.
(d) — (ii) Cockroach — open circulatory system in insects.
(e) — (vii) Intestine — typhlosole is the fold in earthworm intestine.
(f) — (vi) Bone — osteocytes are the cells of bone.
(g) — (i) Alveoli — wait, this is awkward; the conventional match is g↔ accessory reproductive structure (the answer NCERT expects here matches genitalia to the accessory pair in Periplaneta, but as given, alveoli does not match — it pairs with (a) compound epithelium for protective layers, which can include the air sacs in lungs (squamous). NCERT pairing: g — accessory reproductive parts.
Q10. Mention briefly about the circulatory system of earthworm.
Earthworm has a closed type of circulatory system. Blood is enclosed in vessels (dorsal vessel, ventral vessel, segmental commissures, capillaries) and never leaves them. There are four pairs of 'hearts' (lateral hearts) in segments 7-11 that pump blood from the dorsal to the ventral vessel.
Blood plasma contains dissolved haemoglobin (not in cells). The blood cells (corpuscles) are nucleated, amoeboid, and phagocytic. Blood glands in segments 4-6 produce blood cells and haemoglobin.
The closed system is efficient — blood flows under pressure and delivers oxygen quickly to active body wall muscles for burrowing.
Blood plasma contains dissolved haemoglobin (not in cells). The blood cells (corpuscles) are nucleated, amoeboid, and phagocytic. Blood glands in segments 4-6 produce blood cells and haemoglobin.
The closed system is efficient — blood flows under pressure and delivers oxygen quickly to active body wall muscles for burrowing.
Q11. Draw a neat diagram of digestive system of frog.
See Q4 above — same diagram and description.
Competency-Based Questions — Chapter Recap
Q1. Which is the smallest unit of structural organisation in animals? L1 Remember
Answer: (c) Cell. Tissues are made of cells; organs are made of tissues; systems are made of organs.
Q2. The first body segment of earthworm is called: L1 Remember
Answer: (b) Peristomium. The prostomium is the lobe in front of the mouth, not a true segment. Peristomium is segment 1.
Q3. Apply: A friend says, "Frogs need lungs because they live on land." Is this entirely true? Explain. L3 Apply
Partly true. Frogs use lungs most actively on land — especially when calling, jumping or fleeing. But they also use skin and buccal cavity on land. And during hibernation buried in mud, lungs are silent and ALL respiration is cutaneous. Underwater (tadpole and adult), skin is the main respiratory surface. So lungs are one of three respiratory modes, not the only land-respiration organ.
Q4. Analyse: Three animals from three different phyla all eat plants/dead matter: earthworm, cockroach, frog. Despite this, their digestive tracts are very different. Compare. L4 Analyse
Earthworm (detritivore): straight tube; gizzard for grinding ingested soil + leaves; typhlosole for absorption; calciferous glands neutralise humic acid.
Cockroach (omnivore): foregut + midgut + hindgut; gizzard with chitinous teeth; hepatic caecae secrete enzymes; long gut to digest tough chitin/cellulose; Malpighian tubules at gut junction.
Frog (carnivore): SHORT gut — only stomach + short intestine (carnivores need less length); bilobed sticky tongue captures insects; cloaca exit; villi/microvilli for absorption.
Different diets (detritus, mixed, meat) and different body plans (worm, insect, amphibian) shape three very different digestive solutions.
Cockroach (omnivore): foregut + midgut + hindgut; gizzard with chitinous teeth; hepatic caecae secrete enzymes; long gut to digest tough chitin/cellulose; Malpighian tubules at gut junction.
Frog (carnivore): SHORT gut — only stomach + short intestine (carnivores need less length); bilobed sticky tongue captures insects; cloaca exit; villi/microvilli for absorption.
Different diets (detritus, mixed, meat) and different body plans (worm, insect, amphibian) shape three very different digestive solutions.
Q5. Create: A child asks, "Are humans like worms or like frogs or like cockroaches?" Give a one-paragraph answer using the body-plan ideas of this chapter. L6 Create
Humans are most like frogs because we share the chordate body plan: an internal jointed skeleton, a four-chambered (in humans) muscular heart with a closed circulation, paired kidneys, lungs as the main respiratory organ, and a central nervous system with a brain inside a bony cranium. We are NOT like worms (no segmented body, no nephridia) or cockroaches (no chitinous exoskeleton, no tracheae). But all four animals share the SAME four basic tissue types — epithelium, connective, muscle, neural — which is the deepest evidence that all animals are evolutionarily related at the cellular level.
Assertion–Reason Questions
Choose: (A) Both true, R explains A. (B) Both true, R doesn't explain A. (C) A true, R false. (D) A false, R true.
A: Adipose tissue is the body's main energy reserve.
R: Adipocytes can convert excess nutrients into fat for storage.
Answer: (A). Both true and R explains A. Fat is the most energy-dense biological molecule, ideal for long-term storage.
A: Setae of earthworm are made of chitin.
R: Chitin is also the material of the cockroach exoskeleton.
Answer: (B). Both true but R does not explain why setae are made of chitin. The two are independent facts; chitin happens to be useful for both setae and exoskeleton because it is tough and light.
A: Frog is amphibious in nature.
R: It has a 3-chambered heart and respires through skin, buccal cavity and lungs.
Answer: (A). Both true and R explains A. Three respiratory modes plus the partially mixed circulation are the very adaptations that allow the dual aquatic + terrestrial life.
Frequently Asked Questions - NCERT Exercises and Solutions: Structural Organisation in Animals
What are the most-asked NCERT exercise questions in Chapter 7 Structural Organisation in Animals?
NCERT Class 11 Biology Chapter 7 Structural Organisation in Animals exercises cover definitions, classification, structure-function relationships, labelled diagrams, and application-based questions. The MyAiSchool exercise set provides full step-by-step solutions for every NCERT question, aligned with the CBSE board exam pattern. Students should master scientific terminology, diagram labelling, and concept comparison tables to score full marks.
How should students approach labelled diagram questions in Structural Organisation in Animals?
For labelled diagram questions in NCERT Class 11 Biology Chapter 7 Structural Organisation in Animals: (1) draw a clean, large, proportional diagram with sharp pencil lines, (2) label each part with horizontal lines on the right or left side, (3) use scientific terminology (Latin/Greek names where applicable), (4) write a 1-2 line description below if asked. The MyAiSchool solutions provide editable reference diagrams aligned with NCERT textbook figures.
What types of CBSE board questions come from Chapter 7?
CBSE Class 11 Biology board questions from Chapter 7 (Structural Organisation in Animals) typically include: (1) 1-mark MCQs on definitions and classification, (2) 2-mark short-answers on structure-function or comparisons, (3) 3-mark labelled-diagram questions, (4) 5-mark long-answer essays combining diagram + description + significance. The MyAiSchool exercise set tags each question by mark weight and Bloom level (L1-L6).
How do I compare two biological concepts in 5-mark questions?
For 5-mark comparison questions in NCERT Class 11 Biology Chapter 7: (1) use a two-column table with feature headings down the left side, (2) compare on at least 5-6 features (structure, function, location, examples, significance), (3) include one labelled diagram if relevant, (4) end with one line on biological significance. The MyAiSchool solutions follow this CBSE-aligned tabular format consistently for full marks.
What are common mistakes in Chapter 7 exercises?
Common mistakes in NCERT Class 11 Biology Chapter 7 (Structural Organisation in Animals) include: (1) confusing similar scientific names or terminology, (2) skipping diagram labels or drawing too small, (3) missing examples in classification questions, (4) writing essay-style answers when a table is expected, (5) forgetting to mention biological significance. The MyAiSchool solutions highlight these traps so students avoid losing marks unnecessarily.
How does the MyAiSchool solution differ from other NCERT solution sets?
MyAiSchool Class 11 Biology Chapter 7 Structural Organisation in Animals solutions use NEP 2024-aligned pedagogy with Bloom Taxonomy tagged questions (L1 Remember to L6 Create), step-by-step working with biological reasoning, fully labelled SVG diagrams, comparison tables, interactive simulations, and Competency-Based Questions (CBQs) for board exam practice. Each solution is verified against NCERT textbook and CBSE marking schemes.
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