ScienceCBSE Class 9 · Tissues in Action

Animal Tissues: Epithelial, Connective, Muscular, Nervous and the Skeleton (Class 9)

Updated 17 October 2026 · Fact-checked

Animal tissues are of four kinds: epithelial (covers and lines, cells closely packed), connective (cells in a matrix: blood, bone, cartilage, tendon, ligament), muscular (skeletal, smooth, cardiac) and nervous (neurons that carry messages). Tendons join muscle to bone and ligaments join bone to bone; the musculoskeletal system of bones, muscles, joints, cartilage, tendons and ligaments works under the nervous system, and joints are ball and socket, hinge, pivot or fixed.

Notice that tendons join muscle to bone, while the ligament joins bone to bone, and cartilage cushions the joint ends.

Illustration drawn for QuestionBuddy.

Understand Animal Tissues and the Musculoskeletal System

Epithelial tissue covers the body (skin) and lines internal organs such as the mouth, lungs, blood vessels and intestine. Its cells are packed closely with little space between them, so it keeps out germs, reduces water loss and controls what is absorbed or released. Structure fits function: exchange (one layer of thin, flat cells, as in blood vessels and the air sacs of the lungs); protection (many layers, flat outer cells, as in skin and the mouth); secretion (cube-shaped or tall gland cells, as in salivary and sweat glands); sensing (receptor cells with hair-like cilia, as in the nose and inner ear); absorption (one layer of tall, pillar-like cells, often with tiny projections, as in the small intestine). The rule: thin where things must pass, thick where wear and tear is high.

Connective tissue joins and supports other tissues; its cells lie in a matrix. Blood has a fluid matrix, plasma (about 55% of blood volume); the formed elements (about 45%) are red blood cells (haemoglobin carries oxygen; life about 4 months or 120 days), white blood cells (fight infection) and platelets (help clotting). Bone has a hard matrix with calcium and phosphorus compounds for strength and support. Cartilage is soft, jelly-like but firm: flexibility, and cushions bone ends (ear, nose tip, joints). Tendon is tough, strong fibres joining muscle to bone and passing the muscle's pull to the bone. Ligament is tough, slightly stretchy fibres joining bone to bone, keeping joints stable. Bone marrow contains stem cells that make new blood cells.

Muscular tissue contracts and relaxes to cause movement. Skeletal (striated): voluntary, long cylindrical unbranched fibres, many nuclei per fibre, clear stripes, attached to bones; quick, strong, tires. Smooth: involuntary, spindle-shaped, one nucleus, no stripes, in stomach, intestine and blood vessels; slow, steady. Cardiac: involuntary, cylindrical and branched, one nucleus, faint stripes, only in the heart; rhythmic and never tires.

Nervous tissue has neurons that receive, process and pass on messages. The cell body contains the nucleus; dendrites are short branches that receive signals; the axon is one long fibre that carries the message away, ending in axon terminals that pass it to the next cell. The brain is the control centre; muscles do not act on their own, nerves tell them when to contract.

Musculoskeletal system. Bones, muscles, joints, cartilage, tendons and ligaments work together under the nervous system for standing, moving, posture and protection of soft organs. The skeleton is about 12 to 15% of an adult's body weight. Muscles can only pull: when a muscle contracts, its tendon pulls on a bone and the bone moves at a joint. Joints: ball and socket (all directions; shoulder, hip), hinge (one plane; elbow, knee), pivot (turning; skull on the backbone), fixed (no movement; skull bones). The backbone is a chain of vertebrae with cartilage discs that cushion and allow bending and protect the spinal cord; the rib cage has 12 pairs of ribs joined to the backbone and breastbone through flexible cartilage, guarding the heart and lungs; the skull has flat bones fused by fixed joints.

Care. Fracture: a break in a bone (keep still, splint, X-ray). Sprain: ligament stretched or torn. Strain: muscle or tendon over-stretched. Dislocation: bone pushed out of its joint. First aid for sprains and strains: rest, cold pack, bandage support, keep raised. Care: good posture, calcium, phosphorus and vitamin D for bones, protein for muscles, and regular exercise such as running, skipping, yoga and Surya Namaskar.

Animal Tissues and the Musculoskeletal System: formulas and key facts

Four animal tissues: $E p i t h e l ia l ∣ co nn ec t i v e ∣ m u sc u l a r ∣ n er v o u s$
Blood composition: Plasma about 55% | formed elements about 45% (RBC, WBC, platelets)
Tendon and ligament: Tendon: muscle to bone | ligament: bone to bone
Muscle types: Skeletal voluntary, striated, many nuclei
smooth involuntary, spindle, one nucleus
cardiac involuntary, branched, heart only
Joints: Ball and socket
hinge
pivot
fixed
Rate and count: $N u mb er o f b e a t s = r a t e p er min u t e \times min u t es$

Skeletal	voluntary, striated, many nuclei
smooth	involuntary, spindle, one nucleus
cardiac	involuntary, branched, heart only

How to solve Animal Tissues and the Musculoskeletal System questions

Use this method for tissue identification and data questions.

1Read the clues (where it is, cell shape, voluntary or involuntary, what it connects) and match them with the tissue or structure.
2For epithelial tissue relate the number of layers and shape of cells to the job.
3For connective tissue, name the matrix and the job (fluid, hard, firm, tough fibres).
4For muscle, state control, shape, number of nuclei and stripes.
5For joints, name the type from the range of movement and give an example.
6For numbers (blood volume, heart beats, skeleton weight), write the percentage or rate and multiply by the amount or time.

Animal Tissues and the Musculoskeletal System in real life

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Counting heartbeats

Suppose a student measures her pulse as 72 beats per minute when resting.

Find the number of heartbeats in an hour, in a day and in a year of 365 days, and say why cardiac muscle suits this job.

Try it first, then show the solutionSolution

Per hour: 72 × 60 = 4320 beats.
Per day: 4320 × 24 = 103 680 beats.
Per year: 103 680 × 365 = 37 843 200 beats, about 3.8 crore.
Cardiac muscle contracts rhythmically and never tires, and it works involuntarily without our control.

Answer: 4320; 103 680; 37 843 200; cardiac muscle never tires.

Memory hook: Heart muscle: involuntary and tireless.

Which joint is it?

Suppose a teacher asks students to shake their heads to say 'no', swing an arm in a circle, and bend an elbow, and to name the joint used each time.

Name each joint and one more example of it.

Try it first, then show the solutionSolution

Shaking the head 'no' turns the skull on the top of the backbone: a pivot joint.
Swinging the arm in a circle uses the shoulder: a ball and socket joint (the hip is another).
Bending the elbow moves the forearm in one plane: a hinge joint (the knee is another).

Answer: Pivot, ball and socket, hinge.

Memory hook: Circle: ball. Door: hinge. Turn: pivot.

Tricks to remember Animal Tissues and the Musculoskeletal System

Short memory aids. Say each one aloud once, then use it on a question the same day.

TM and LB
Tendon joins Muscle to bone; Ligament joins Bone to bone.
Use it when: Tendon versus ligament.
Thin where things pass, thick where it wears
One thin layer for exchange in lungs and vessels; many layers for skin.
Use it when: Epithelial tissue structure-function questions.
Voluntary means striped and many nuclei
Skeletal muscle: you choose it, stripes show, many nuclei. Smooth and cardiac are involuntary.
Use it when: Muscle comparison.
Dendrites receive, axon sends
Dendrites bring messages to the body; the axon carries them away.
Use it when: Neuron diagram.

Animal Tissues and the Musculoskeletal System: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Structure and function of epithelial tissue · 3 marks · Short answerBoard level

Explain why (a) the lining of blood vessels is made of a single layer of flat cells, (b) the skin has many layers of cells, and (c) the small intestine has tall pillar-shaped cells with tiny projections.

Try it first, then show the solutionSolution

(a) A single thin layer lets substances pass quickly by diffusion. (1)
(b) Many layers with flat outer cells protect against wear and germs. (1)
(c) Tall cells with projections give a large surface for absorbing digested food. (1)

Answer: (a) quick exchange; (b) protection; (c) absorption.

Example 2: Tendon, ligament and cartilage · 3 marks · Short answerBoard level

Distinguish tendon from ligament, and state the role of cartilage with two places where it is found.

Try it first, then show the solutionSolution

A tendon is tough, strong fibre that joins muscle to bone and passes the pull of the muscle to the bone. (1)
A ligament is tough, slightly stretchy fibre that joins bone to bone, keeping joints stable. (1)
Cartilage is soft, firm and jelly-like; it gives flexibility and cushions bone ends, as in the ear, the tip of the nose and joints. (1)

Answer: Tendon: muscle to bone; ligament: bone to bone; cartilage: flexible cushion in ear, nose and joints.

Example 3: A spun blood sample and red blood cell turnover · 5 marks · Long answerHarder board level

A 20 mL blood sample is spun in a centrifuge and separates into a straw-coloured layer of 11 mL (plasma) above a darker layer of 9 mL (formed elements).
(a) Find the percentage of each layer in the sample. (1)
(b) For a person with 5 L of blood, what volume would be plasma? (1)
(c) Red blood cells live for about 120 days. If an equal share is replaced each day, what percentage is replaced daily and in 30 days? (2)
(d) Where are new blood cells made, and what are the three formed elements? (1)

Try it first, then show the solutionSolution

(a) Plasma = 11 ÷ 20 × 100 = 55%; formed elements = 9 ÷ 20 × 100 = 45%. (1)
(b) Plasma = 0.55 × 5 = 2.75 L. (1)
(c) 1 ÷ 120 = 0.83% per day; in 30 days 30 ÷ 120 = 25%. (2)
(d) New blood cells are made in the bone marrow, which contains stem cells. The formed elements are red blood cells, white blood cells and platelets. (1)

Answer: (a) 55% and 45%; (b) 2.75 L; (c) 0.83% per day and 25% in 30 days; (d) bone marrow; RBCs, WBCs, platelets.

Example 4: The tireless cardiac muscle · 5 marks · Long answerHarder board level

A resting heart beats 72 times a minute.
(a) How many beats occur in one hour and in one day? (2)
(b) How many beats occur in a 365-day year? (1)
(c) Compare cardiac muscle with skeletal muscle in control, shape and fatigue. (1)
(d) Where is smooth muscle found, and what does it do? (1)

Try it first, then show the solutionSolution

(a) Per hour: 72 × 60 = 4320; per day: 4320 × 24 = 103 680. (2)
(b) 103 680 × 365 = 37 843 200 beats per year. (1)
(c) Cardiac muscle is involuntary, cylindrical and branched, with rhythmic action that never tires; skeletal muscle is voluntary, long, unbranched, striated and tires. (1)
(d) Smooth muscle is found in the stomach, intestine and blood vessels, where it works slowly and steadily to move food or blood. (1)

Answer: (a) 4320 and 103 680; (b) 37 843 200; (c) involuntary, branched and tireless versus voluntary, unbranched and tiring; (d) stomach, intestine, blood vessels.

Example 5: A twisted ankle at football · 4 marks · Case-basedHOTS / competency

A 60 kg footballer twists his ankle badly during a match.
(a) Which tissue is most likely to be torn in a sprain, and which in a strain? (1)
(b) What is the range of the weight of his skeleton, at 12 to 15% of body weight? (1)
(c) The doctor suspects a fracture. What is a fracture, and how is it first treated? (1)
(d) Name the type of joint at his knee and at his hip, and say what movement each allows. (1)

Try it first, then show the solutionSolution

(a) A sprain is a ligament stretched or torn; a strain is a muscle or tendon over-stretched. (1)
(b) 12% of 60 = 7.2 kg and 15% of 60 = 9 kg, so 7.2 to 9 kg. (1)
(c) A fracture is a crack or break in a bone; keep the part still with a splint and get an X-ray. (1)
(d) The knee is a hinge joint (back and forth in one plane); the hip is a ball and socket joint (movement in all directions, including circles). (1)

Answer: (a) ligament; muscle or tendon; (b) 7.2 to 9 kg; (c) break in a bone, splint and X-ray; (d) hinge and ball and socket.

Where students lose marks in Animal Tissues and the Musculoskeletal System

The slips examiners see most often, and what to write instead.

Mistake: Swapping tendon and ligament.
Both are tough connective tissues.
Wrong working
Tendons join bone to bone.
Right working
Tendons join muscle to bone; ligaments join bone to bone.
Do this: TM and LB.
Usually costs: 1 mark.
Mistake: Saying smooth muscle is voluntary.
The names 'smooth' and 'striated' are not linked to control.
Wrong working
Smooth muscle in the intestine is under our control.
Right working
Smooth and cardiac muscles are involuntary; only skeletal muscle is voluntary.
Do this: Only the muscles attached to bones are voluntary.
Usually costs: 1 mark.
Mistake: Writing that blood is a muscle or epithelial tissue.
Blood is fluid, so it does not look like connective tissue.
Wrong working
Blood is epithelial tissue.
Right working
Blood is a connective tissue with a fluid matrix, plasma.
Do this: Connective means a matrix.
Usually costs: 1 mark.
Mistake: Using 55% for the cells and 45% for plasma.
The two percentages are reversed.
Wrong working
Plasma is 45% of blood.
Right working
Plasma is about 55% and the formed elements about 45%.
Do this: Fluid is the larger part.
Usually costs: 1 mark.
Mistake: Naming the knee a ball and socket joint.
The hip and knee are both large joints.
Wrong working
Knee is a ball and socket joint.
Right working
The knee is a hinge joint; the hip is a ball and socket joint.
Do this: Hinge allows one plane only.
Usually costs: 1 mark.

Exam tips

Use a table for muscle types: control, shape, nuclei, stripes, location, work.
Label a neuron with dendrites, cell body, nucleus, axon and axon terminals.
Always state the matrix when describing a connective tissue.
In percentage questions (blood, skeleton) write the percentage × total first, then check that the parts add up.
Learn the first-aid sequence: rest, cold pack, bandage support, raise.

Practice questions on Animal Tissues and the Musculoskeletal System

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 2 marks · Very short answerBoard level
Describe how a message passes through a neuron, naming the parts it uses in order.
Hint
Receive, process, send.
Answer
The dendrites receive the signal and pass it to the cell body, which contains the nucleus and controls the cell (1 mark). The axon, a long fibre, carries the message away and its axon terminals pass it to the next cell (1 mark).
Q2 · 3 marks · Short answerHarder board level
A girl has 4.8 L of blood with plasma making up 55%. (a) Find the volume of plasma and the volume of formed elements. (b) What are platelets for? (c) Why do red blood cells contain haemoglobin?
Hint
Formed elements are the remaining 45%.
Answer
(a) Plasma = 0.55 × 4.8 = 2.64 L; formed elements = 4.8 − 2.64 = 2.16 L (1 mark). (b) Platelets help blood clot at a cut (1 mark). (c) Haemoglobin, an iron-rich protein, carries oxygen (1 mark).
Q3 · 2 marks · Assertion-reasonBoard level
Assertion (A): Skeletal muscle is called voluntary muscle. Reason (R): Its contraction is under our conscious control. Choose: (a) A and R both true, R explains A; (b) A and R both true, R does not explain A; (c) A true, R false; (d) A false, R true.
Hint
What does voluntary mean?
Answer
(a). Voluntary means that we decide when to move it, and skeletal muscles attached to bones move when we choose.
Q4 · 3 marks · Short answerHarder board level
Name the type of joint at (i) the elbow, (ii) the shoulder, (iii) the junction of the skull and backbone allowing the head to turn, and (iv) the bones of the skull. State the movement each allows.
Hint
Think of a door, a ball in a cup, a pin and a seam.
Answer
(i) Hinge: back and forth in one plane (1 mark). (ii) Ball and socket: movement in all directions, including circles (1 mark). (iii) Pivot: turning side to side; (iv) fixed joints in the skull allow no movement (1 mark for both).
Q5 · 4 marks · Case-basedHOTS / competency
A growing student of mass 50 kg wants strong bones and muscles. (a) Find the likely mass of her skeleton using 12 to 15% of body weight. (b) Name two nutrients for bones and one for muscles with a source of each. (c) Explain the role of the cartilage discs between the vertebrae. (d) Give two habits that protect the musculoskeletal system.
Hint
12% of 50 and 15% of 50.
Answer
(a) 12% of 50 = 6 kg and 15% of 50 = 7.5 kg, so 6 to 7.5 kg (1 mark). (b) Calcium and phosphorus (milk, curd, ragi, green leafy vegetables) and vitamin D (sunlight) for bones; protein (pulses, eggs) for muscles (1 mark). (c) The discs cushion the vertebrae and allow the backbone to bend (1 mark). (d) Good posture such as a straight back and carrying the school bag on both shoulders, and regular exercise such as skipping or yoga (1 mark).

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Which tissue lines the small intestine and absorbs food?Show answer
Epithelial tissue made of tall, pillar-like cells.
2.What do red blood cells contain?Show answer
Haemoglobin.
3.Which muscle is found only in the heart?Show answer
Cardiac muscle.
4.How many pairs of ribs form the rib cage?Show answer
Twelve pairs.
5.Name the long fibre of a neuron that carries messages away.Show answer
The axon.
6.What is the matrix of blood called?Show answer
Plasma.

Animal Tissues and the Musculoskeletal System: frequently asked questions

Why can't muscles push?

Muscles can only contract and pull. A pair of muscles working in opposite ways, with tendons and bones, produces movement in both directions.

What is the difference between a sprain and a strain?

A sprain is damage to a ligament; a strain is damage to a muscle or tendon.

Why do the walls of the lung air sacs have a single thin layer?

A single thin layer of epithelial cells allows gases to diffuse quickly.

Are bones living tissue?

Yes. Bone is connective tissue with a hard matrix, and the bone marrow inside makes new blood cells.

Which part of a neuron is the control centre?

The cell body, which contains the nucleus.