Class 9 Science Chapter 3: Tissues in Action — Solutions

These Class 9 Science Exploration Chapter 3 solutions cover Tissues in Action from NCERT’s Exploration, first edition April 2026 (printed pages 28–47).

Class 9 Science Exploration Chapter 3 Solutions – Overview

Chapter 3 of Exploration, Tissues in Action, explains how groups of cells form tissues that share a common function. In plants it covers meristematic tissue (which keeps dividing) and permanent tissues — parenchyma, collenchyma, sclerenchyma, and the complex conducting tissues xylem and phloem — along with the protective epidermis. In animals it covers epithelial, connective, muscular and nervous tissues, and how each tissue’s structure suits its job. The 15 exercise questions and the activity and discussion prompts are explained below.

Key Concepts & Definitions

“Think It Over” — Answers

How is the study of tissues important for life processes and human welfare?

How are tissues in plants and animals different, and why?

What makes cells group together to form tissues, and why do some tissues grow throughout life while others do not?

How does division of labour relate to structure and function?

Activities and discussion answers

Activity 3.1: Onion-root growth

Record actual root lengths on days 1–7. Jar A is the intact-root comparison; cut tips in Jar B remove the apical meristem, so the cut roots are expected to stop normal elongation over the observation period. New roots may form from the bulb. Use the same onion variety, light, water and temperature, and compare several roots rather than inventing identical measurements.

Activities 3.2 and 3.3: Blood and connective tissues

Platelets and clotting factors help form a clot after a cut. White blood cells participate in defence; inflammation can cause redness and swelling. Exercise increases oxygen demand and blood flow. These are explanations of the textbook observations, not diagnoses.

At the elbow, hard bone gives support; the outer ear contains flexible cartilage; tendons transmit muscle pull to bones; ligaments stabilise joints by connecting bones. The permitted range of a joint also depends on its shape, capsule and other tissues.

Activity 3.4: Percentage estimates

Use age-appropriate reference data and treat the result as an estimate. A bathroom scale does not measure bone or muscle mass separately, and a skeleton percentage is not the same as the “bone mass” reading of a consumer body-composition scale.

$$m_{\mathrm{component}}=m_{\mathrm{body}}\times\frac{p}{100}$$

For an illustrative 50 kg body mass and an assumed 14% skeletal proportion:

$$m_{\mathrm{skeleton}}=50\,\mathrm{kg}\times\frac{14}{100}=7\,\mathrm{kg}$$

This is classroom arithmetic, not a personal measurement or health assessment. Real proportions vary with age, body composition and the measurement definition.

Activity 3.5: Joint movements — sample observations

Pause and Ponder: Answers 1–5

1. Coir versus coriander: coconut husk contains thick, lignified sclerenchyma fibres; a young coriander stalk has living, more flexible supporting tissues.
2. Cuticle: a thick waxy layer reduces water loss in desert plants. In a submerged plant, a strong barrier can impede exchange of gases and dissolved substances across the surface.
3. Dead xylem and living leaves: hollow conducting cells provide a low-resistance pathway. Evaporation from leaves creates tension; cohesion between water molecules helps transmit this pull down the water column. Xylem does not actively pump using its dead cells.
4. No stomata: gas exchange and control of transpiration would be severely affected in a typical land leaf, reducing carbon dioxide uptake and transpiration pull. This assumes a land plant normally dependent on stomata; some submerged leaves differ.
5. Dance poses — sample: raised arms use shoulder ball-and-socket joints; bent knees and elbows use mainly hinge action; head turning uses the upper-neck pivot, while hips also use ball-and-socket joints. Identify the visible posture rather than assigning one joint to the entire dance.

Think as a Scientist: Carrot-cell culture (Table 3.6)

(a) Some mature living carrot cells can regain division and regenerate a whole plant under suitable culture conditions: totipotency.

(b) The light + air + liquid nutrient treatment has the highest reported increase (20%). Both other treatments say only “reduced”; the table cannot identify which has the lowest biomass. Also, light, aeration and medium state are not varied independently, so the results do not isolate a single cause.

(c) The same medium and conditions will not generally regenerate a complete animal from an ordinary differentiated animal cell. Animal cloning or pluripotent-cell methods require additional specialised procedures.

(d) Sample applications: rapid multiplication of selected crops and production of disease-free planting material using appropriate tissue-culture methods. These are potential applications, not proof that any culture is automatically pathogen-free.

Journey Beyond: Sample response

Pruning changes shoot growth and can encourage axillary buds; grafting requires compatible tissue and vascular connection; irrigation supports water uptake but waterlogging harms roots. A leaf survey should record real observations and distinguish traditional claims from tested evidence. Animal-cell regeneration raises technical, welfare and ethical questions and should not be treated as equivalent to routine plant micropropagation.

Class 9 Science Exploration Chapter 3 Solutions — Revise, Reflect, Refine

1. Meristematic tissues divide repeatedly. What property of their cells allows them to do this? (i) They have thick walls for protection. (ii) They contain large vacuoles that store nutrients. (iii) They have thin walls, dense cytoplasm and large prominent nucleus. (iv) They are functionally differentiated cells.

2. If a plant is unable to transport food from leaves to roots, which tissue is malfunctioning? (i) Xylem (ii) Phloem (iii) Epidermis (iv) Sclerenchyma

3. Why are the epithelial tissues that line an animal’s internal organs usually only one or a few cells thick? (i) To store food efficiently. (ii) To provide maximum strength. (iii) To allow quick exchange of materials across them. (iv) To reduce friction.

4. You can perform two jumps: a straight-leg jump (knees and ankles stiff) and a normal jump (knees and ankles bent naturally). How did your ankle, knee and hip positions differ between the two jumps?

5. Which type of joint is involved when you bend your knees and ankles? (i) Ball and socket (ii) Hinge (iii) Pivot

6. In each case (A–D), choose: (i) Both A and R true and R is the correct explanation of A; (ii) Both true but R is not the correct explanation; (iii) A true, R false; (iv) A false, R true. A. Assertion: Epithelium is well-suited for gas exchange in the lungs. Reason: It consists of multiple layers of tall cells that slow down diffusion. B. Assertion: Cardiac muscle can contract continuously without fatigue. Reason: Cardiac muscle cells have a high number of mitochondria and an abundant blood supply. C. Assertion: Tendons connect bone to bone and allow joint movement. Reason: Tendons are made of tough connective tissue that transmits force from muscle to bone. D. Assertion: In a hinge joint, movement occurs primarily in one plane. Reason: The bone ends are shaped to allow sliding in all directions.

7. Using the data in Table 3.7 (age of a teak tree vs diameter and number of annual rings), plot a graph and answer: (i) Analyse the graph in terms of the diameter of the stem over time. (ii) What is the relation between the diameter of the teak tree and the annual rings formed? (iii) Which specialised tissue is responsible for the girth of the stem and where is it located?

8. A tree was severely debarked by an elephant (the bark is rich in nutrients). (i) Which function(s) of the tree is/are hampered by debarking? (ii) Which plant tissue would be affected by further damage to the tree trunk even after debarking? (iii) Which function of the tree would be hampered if the tissues beneath the bark were severely damaged? (iv) What assumptions are you making, and how would the answer change if the assumptions changed?

9. A young mango sapling’s stem bends flexibly in monsoon winds and does not break. Which tissue is responsible for this flexibility? Predict the impact if it were replaced by sclerenchyma.

10. Sohan grew sugarcane from two types of cuttings; type ‘B’ sprouted but type ‘A’ did not. (i) Why could type B grow but type A could not? (ii) What difference was present in type B compared to type A? (iii) What observation determined whether the change had an effect? (iv) What parameters should be kept the same for a fair comparison?

11. Rohan says, “A tissue is a group of similar cells performing similar functions”, but Rajiv argues this is true for simple tissues but different for complex tissues. Explain.

12. Coconut husk fibres used for mats are tough and fibrous. Which tissue provides this strength? Why could living parenchyma not serve the same purpose?

13. Vibha claims, “Meristematic cells are located only at the root and shoot apices.” What do you think, and what question could Neha ask to help correct the statement?

14. A plant cell and an animal cell are of the same size. (i) Which cell will have a larger vacuole? Give reasons. (ii) What assumptions are you making?

15. A textbook states, “Each plant tissue performs only one specific function.” What questions would you ask to critically examine this, and which tissues would you use as examples?

Common Misconceptions to Avoid

Extra Practice Questions

Very Short Answer Type Questions

Q1. Which tissue connects a muscle to a bone?

Q2. Name the tissue that transports water in a plant.

Q3. Which muscle works continuously throughout life without tiring?

Short Answer Type Questions

Q1. Differentiate between parenchyma, collenchyma and sclerenchyma.

Q2. Why is xylem called a complex tissue?

Long Answer Type Question

Q1. Name the four types of animal tissues and state one function of each.

MCQs & Assertion–Reason

For each Assertion–Reason question, choose: (A) Both true and the Reason correctly explains the Assertion; (B) Both true but the Reason is not the correct explanation; (C) Assertion true, Reason false; (D) Assertion false, Reason true.

Quick Revision Summary

Real-life Applications

Frequently Asked Questions