“Answers: Ch 3 Tissues In Action Class 9 [Exploration] NCERT textbook is prepared solely based on the NCERT textbook for grade 9. We have not used any reference books to prepare the solutions.
We have also mentioned the exact page, paragraph, and line numbers from the chapter where each answer is taken from.
This way, you’ll know exactly where each question comes from.
There are 15 questions in total in the Revise, Reflect, Refine section. Some questions have subparts.
First, make sure to read the chapter thoroughly. Then, prepare the short notes for Chapter 3, “Tissues in Action.”
Finally, you should now try solving the end-of-chapter questions titled “Revise, Reflect, Refine.”
Click on the Table of Contents to go directly to the desired question.
Happy solving!
Revise, Reflect, Refine
Answers
Q1.
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 a large, prominent nucleus.
(iv) They are functionally differentiated cells.
Answer
(iii) They have thin walls, dense cytoplasm, and a large, prominent nucleus.
Source: Page 31, Section 3.2.3, paragraph 5 “The cells of the meristematic tissues are small, have thin cell walls, a large and prominent nucleus, and dense cytoplasm with many organelles. Vacuoles are generally absent, and the cells are tightly packed with little or no intercellular space. These characteristics of meristematic tissue allow them continuous and rapid cell division.”
Q2.
If a plant is unable to transport food from leaves to roots, which tissue
is malfunctioning?
(i) Xylem
(ii) Phloem
(iii) Epidermis
(iv) Sclerenchyma
Answers
(ii) Phloem
Source: Page 33, Section 3.2.4 (iii), paragraph 2 “Sieve tubes transport food from leaves to other parts of the plant.” Phloem contains sieve tubes, companion cells, phloem parenchyma and phloem fibres. It is the tissue that moves food from leaves to other parts of the plant.
Q3.
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.
Answers
(iii) To allow quick exchange of materials across them.
Source: Page 35, Table 3.2, Row 1 “Exchange: Helps in rapid diffusion of liquids and gases — Single layer of thin, flat cells — Lining of the tissue in the blood vessels and lungs.”
Being thin allows materials like gases and liquids to pass through quickly and easily.
Q4.
You can perform these two jumps (Fig. 3.21):
● Straight-leg jump — keep knees and ankles stiff.
● Normal jump — bend knees and ankles naturally.
● How did your ankle, knee, and hip positions differ between the two
jumps?
Answers
In the straight-leg jump, knees and ankles are kept stiff. There is no bending at these joints. The body lands with a jolt as there is no cushioning.
In the normal jump, knees and ankles bend naturally. This bending absorbs the impact of landing.
Source: Page 37, Section 3.3.2, Table 3.4 Cartilage “provides flexibility and cushions the ends of bones for shock absorption.”
Source: Page 37, Table 3.4. Bones give “strength, support, and protection.” Joints allow bending and movement. The hinge joints at the knees and ankles allow bending in one direction, helping in a smooth and safe landing.
Q5.
Which type of joint is involved when you bend your knees and ankles?
(i) Ball and socket
(ii) Hinge
(iii) Pivot
Answers
(ii) Hinge
Source: Page 40, Section 3.5.2 “The elbow bends and straightens in one direction only, like a door hinge. This type of joint is called a hinge joint. A similar hinge joint is present in the knee.”
The knee and ankle both work like hinges, bending in one direction only.
Q6.
In each of the following cases (A, B, C, and D), choose the correct option
as given below:
(i) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(ii) Both (A) and (R) are true, but (R) is not the correct explanation
of (A).
(iii) (A) is true, but (R) is false.
(iv) (A) is false, but (R) is 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.
Answers
A| Answer: (iii) (A) is true, but (R) is false.
Source: Page 35, Table 3.2, Row 1 Epithelium in the lungs is a “single layer of thin, flat cells” — NOT multiple layers of tall cells. A single thin layer allows rapid diffusion, not slow diffusion. So the assertion is correct, but the reason is wrong.
B| Answer: (i) Both (A) and (R) are true, and (R) is the correct explanation of (A).
Source: Page 38, Section 3.3.3 “Cardiac muscles work tirelessly and rhythmically, enabling the heart to beat throughout life without fatigue.”
C| Answer: (iv) (A) is false, but (R) is true.
The reason explains why — high mitochondria provide constant energy, and a rich blood supply delivers oxygen continuously, making non-stop contraction possible.
Source: Page 37, Table 3.4 “Tendons: Connects muscle to bone, and thus, brings about movement.”
Tendons connect muscle to bone — NOT bone to bone. Ligaments connect bone to bone. The reason is correct, but the assertion is wrong.
D| Answer: (iii) (A) is true, but (R) is false.
Source: Page 40, Section 3.5.2 “The elbow bends and straightens in one direction only like a door hinge.”
A hinge joint does move in only one plane — the assertion is correct. But the reason is false. Hinge joints do NOT allow sliding in all directions. That is why movement is limited to one direction.
Q7.
Plot a graph between the age of a tree (in years) on the x-axis and the
diameter of the tree (in cm) along with the number of annual rings
formed over time on the y-axis, using the data given in Table 3.7.
(i) Analyse the graph in terms of the diameter of the stem over time
and share the interpretation.
(ii) What is the relation between the diameter of the teak tree to the
Annual rings formed?
(iii) Which specialised tissue is responsible for the girth of the stem
And where is it located?
Answers
(i) Answer: As the age of the tree increases, the diameter of the stem also increases. The growth is not perfectly even — there is a sharper increase between years 10 and 20 (from 8 cm to 24 cm). After year 20, growth becomes more gradual. Overall, older trees have wider stems.
Source: Page 30, Section 3.2.2 “The stems of dicot plants not only grow in length but also increase in diameter or girth over time.”
(ii) Answer: The number of annual rings equals the age of the tree in years. As the diameter increases, the number of annual rings also increases. Each year, one new ring is added. So, more rings mean a greater diameter.
Source: Page 30, Section 3.2.2 “By counting these annual rings, scientists can estimate the age of a tree.”
(iii)Answer: The lateral meristem is responsible for the increase in girth of the stem.
Source: Page 31, Section 3.2.2 “The increase in girth occurs due to the presence of actively dividing cells arranged in a ring in the stem. These cells divide and produce new cells inside and outside in a concentric manner, leading to an increase in the diameter of the stem. This meristematic tissue is called the lateral meristem.”
It is located along the circumference (ring) of the stem.
Q8.
In a forest, it was observed that one of the trees was severely debarked by an elephant to meet its food requirements, as the bark is a rich source of nutrients (Fig. 3.22). Based on your learning, answer the following:
(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 to answer the questions above? How would the answer change if your assumptions are also changed?
Answers
(i) Answer: The bark contains the epidermis (protective tissue). Removing it hampers:
- Reduction of water loss
- Protection from mechanical injury
- Protection from harmful microorganisms
Source: Page 32, Section 3.2.4 (i) “The epidermis forms the outermost layer of the plant body… It protects all parts of the plants… The cuticle also protects against mechanical injury and invasion by parasites.”
(ii) Answer: Further damage would affect the lateral meristem, xylem, and phloem tissues lying below the bark.
Source: Page 31, Section 3.2.2 and Page 33, Section 3.2.4 (iii) The lateral meristem is located along the circumference of the stem. Xylem and phloem are the vascular (conducting) tissues found just beneath.
(iii) Answer: If the lateral meristem is damaged, the tree will stop growing in girth. If xylem is damaged, water and minerals cannot travel from roots to leaves. If phloem is damaged, food cannot travel from leaves to other parts.
Source: Page 33, Section 3.2.4 (iii) “Xylem is the tissue that transports water and minerals from the roots to other parts of the plant.” “Sieve tubes transport food from leaves to other parts of the plant.”
(iv) Answer:
Assumption 1: The bark contains only the epidermis and cork tissue. If the bark is thicker and includes phloem, then debarking would also disrupt food transport immediately.
Assumption 2: The inner vascular tissues (xylem and phloem) are undamaged after debarking. If they are also damaged, then both water transport and food transport would stop, and the tree may die.
Assumption 3: The tree is a mature dicot with a well-developed lateral meristem. If it is a young plant, the extent of damage and regeneration capacity would differ.
Source: Page 31–33, Sections 3.2.2, 3.2.3, 3.2.4
Q9.
Aamrapali observed that a young mango sapling’s stem bends flexibly
during monsoon winds and does not break. Which tissue is responsible
for this flexibility? Predict and provide your explanation of the impact
if the existing tissue was replaced by sclerenchyma.
Answers
Answer: The tissue responsible for flexibility is collenchyma.
Source: Page 32–33, Section 3.2.4 (ii) “Collenchyma consists of living cells with unevenly thickened corners due to pectin (a chemical that gives flexibility like rubber) deposition. This tissue provides support and flexibility, allowing parts of the plant like stems and tendrils to bend without breaking.”
If collenchyma were replaced by sclerenchyma:
The stem would become hard and rigid. It would not bend during strong winds. Instead, it would snap or break easily.
Source: Page 33, Section 3.2.4 (ii) c “Sclerenchyma cells have thick walls due to deposition of lignin, making them hard and strong. Most of these cells are dead.”
Q10.
Sohan designed an experiment for the regeneration of sugarcane, where he
used cuttings to grow sugarcane. He used two types of cuttings, type ‘A’ and type ‘B’ (Fig. 3.23). After a few weeks, type ‘B’ cuttings sprouted and developed into sugarcane plants, whereas the type ‘A’ cuttings did not sprout.
(i) Why were the type ‘B’ cuttings able to grow as sugarcane but type ‘A’ could
not?
(ii) What difference was present in type ‘B’ compared to type ‘A’?
(iii) What observation or measurement was made to determine whether this change had an effect?
(iv) What parameters should be kept the same for both types of cuttings to ensure a fair comparison?
Answers
(i) Answer: Type B cuttings likely contained a node with intercalary meristem. This meristematic tissue has actively dividing cells that allow the plant to regenerate and sprout.
Type A cuttings probably had no node, so no meristematic tissue was present to allow growth.
Source: Page 31, Section 3.2.3 “The intercalary meristem is located at the base of the internode or just above the node… Grass also appears after some time being mowed and/or grazed by animals. This happens because of the presence of intercalary meristem at the nodes of its stem.”
(ii) Answer: Type B cuttings had a node (the point on the stem where branches or leaves arise), which contains the intercalary meristem. Type A cuttings had no node — only the internode (the part of the stem between two nodes).
Source: Page 31, Section 3.2.3 “The node is the point on the plant stem where branches or leaves arise. The part of stem between the two nodes is called an internode.”
(iii) Answer: The observation made was whether the cuttings sprouted and developed into new plants after a few weeks. Type B showed new shoots growing, while Type A showed no sprouting.
This observation proved that the presence of a node (with meristematic cells) is essential for regeneration.
(iv) Answer: The following should be kept the same for both:
- Same length of cuttings
- Same soil type and pot size
- The same amount of water is given
- Same sunlight and temperature conditions
- Same time period of observation
- Cuttings taken from the same sugarcane plant
This ensures that the only variable being tested is the presence or absence of a node.
Q11.
During the discussion in class, Rohan gives a statement that, “A tissue
is a group of similar cells performing similar functions”. But Rajiv
counter argues that, “this is true in case of simple tissues but little
different in case of complex tissues”. Provide your explanation in view
of the discussion in class.
Answers
Rohan is partially correct. His definition fits simple tissues well.
Simple tissues like parenchyma, collenchyma, and sclerenchyma are made of only one type of cell, all performing similar functions.
Source: Page 32, Section 3.2.4 “Permanent tissues can be simple (composed of only one type of cell)…”
Complex tissues like xylem and phloem are made of more than one type of cell, all working together for one function.
Source: Page 33, Section 3.2.4 (iii) “Plants have specialised conducting tissues called xylem and phloem, together known as complex permanent tissues, because they are made up of different types of cells working together.”
So Rajiv is correct — in complex tissues, different types of cells work together for a common function. The cells are not all similar, but the tissue as a whole still performs one job.
Q12.
Coconut husk fibres are used for mats which are tough and fibrous.
Which tissue has structural features suitable for providing this
strength? Explain why living parenchyma couldn’t serve the same
purpose
Answers
Sclerenchyma is the tissue responsible for the toughness of coconut husk fibres.
Source: Page 33, Section 3.2.4 (ii) c “Sclerenchyma cells have thick walls due to deposition of lignin, making them hard and strong. Most of these cells are dead. This tissue is found in stems, leaf veins, and hard coverings of seeds and nuts, such as coconut husk and walnut shell.”
Why parenchyma cannot serve the same purpose: Parenchyma cells have thin walls and are loosely packed with intercellular spaces. They are living, soft, and used mainly for food storage — not for structural strength.
Source: Page 32, Section 3.2.4 (ii) a “Parenchyma consists of living cells with thin walls. These cells are loosely packed with intercellular spaces.”
Thin-walled, soft parenchyma cells cannot provide the rigidity and toughness needed for making mats.
Q13.
Vibha claims to her friend Neha that, “Meristematic cells are located
only at the root and shoot apices”. What do you think about this
statement? What question can Neha ask Vibha to help her understand
further if the statement is incorrect?
Answers
Vibha’s statement is incorrect. Meristematic cells are found in THREE locations, not just at the tips.
Source: Page 31, Section 3.2.3 “Thus, plants have three types of meristematic tissues — apical, lateral, and intercalary.”
- Apical meristem — at root and shoot tips (what Vibha mentioned)
- Lateral meristem — along the circumference of stems (increases girth)
- Intercalary meristem — at the base of internodes or just above nodes
Question: Neha can ask Vibha: “If meristematic cells are only at the tips, how does the stem of a dicot plant increase in thickness (girth) over time? And how does grass grow back after it is mowed?”
This would lead Vibha to discover the lateral meristem and the intercalary meristem.
Q14.
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 to answer the question above?
Answers
(i)The plant cell will have a larger vacuole.
Source: Page 31, Section 3.2.3, paragraph 4 Meristematic cells of plants “lack vacuoles.” However, once plant cells become permanent (mature), they develop large vacuoles for storage.
Source: Page 32, Section 3.2.4 (ii) a Parenchyma — mature plant cells — are loosely packed and store food materials.
Plant cells generally have large, central vacuoles that store water, food, and waste materials. Animal cells either have very small vacuoles or none at all.
(ii)
- If the plant cell were meristematic, it would not have a larger vacuole than an animal cell.
- We are assuming both cells are mature (not dividing/meristematic) cells. Meristematic plant cells do not have vacuoles.
- We are assuming the plant cell is a typical permanent tissue cell (like parenchyma), not a specialised cell.
- We are assuming “same size” means total cell size, not cytoplasm size.
Q15.
A textbook states, “Each plant tissue performs only one specific
function”. What questions would you ask to critically examine the
correctness of this statement? What examples of tissues would you
take to find out the answers to these questions?
Answers
This statement is not fully accurate. Some plant tissues perform more than one function.
Critical questions to ask:
- Does parenchyma only store food, or does it also perform photosynthesis?
- Does the epidermis only protect, or does it also help in gaseous exchange and transpiration?
- Does xylem only transport water, or does it also provide structural strength?
- Can sclerenchyma serve as both a supporting and a protective tissue?
Examples to test the statement:
Parenchyma — stores food AND performs photosynthesis in green parts AND in aquatic plants forms air spaces to help float.
Source: Page 32 “Parenchyma mainly stores food but also performs photosynthesis in the green parts of the plants. In aquatic plants, specialised parenchyma forms air spaces, which help them float.”
Epidermis — protects the plant AND helps in gaseous exchange through stomata AND assists in transpiration AND root hairs absorb water.
Source: Page 32 “In leaves, the epidermis contains pores called stomata, which apart from gaseous exchange helps in transpiration.”
Xylem — transports water AND minerals AND provides strength to the plant.
Source: Page 33 “Xylem is the tissue that transports water and minerals from the roots to other parts of the plant. It also provides strength to the plant.”
Therfore, Many tissues perform more than one function.
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