CLASS 9 · SCIENCE · CHAPTER 3

Tissues in Action

Simple answers to chapter questions and activities, all fifteen end questions, and all seven projects.

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Chapter Investigations

Textbook pages 39–65

Question Think It Over 1

How does studying cells and tissues help us understand life and support human welfare?

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It explains body functions, healing, disease, and medical treatments.

Answer

It explains body functions, healing, disease, and medical treatments.

Question Think It Over 2

How are plant and animal tissues different, and why?

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Plant tissues support and transport; animal tissues also enable movement and coordination.

Answer

Plant tissues support and transport; animal tissues also enable movement and coordination.

Question Think It Over 3

How does division of labour relate to tissue structure and function?

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Specialised structures make tissues, organs, and systems work efficiently.

Answer

Specialised structures make tissues, organs, and systems work efficiently.

Question Activity 3.1

What does the onion-root experiment show when one bulb’s root tips are cut?

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Root tips contain apical meristem that increases root length.

Answer

Root tips contain apical meristem that increases root length.

Question Meristem types

Which meristems help a plant grow longer, thicker, and regrow after cutting?

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Apical: length; lateral: girth; intercalary: regrowth.

Answer

Apical: length; lateral: girth; intercalary: regrowth.

Question Meristem cells

Why do meristematic cells usually have small or no vacuoles?

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Small vacuoles leave room for rapid cell division.

Answer

Small vacuoles leave room for rapid cell division.

Question Permanent tissue

What is the difference between simple and complex permanent tissues?

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Simple: one cell type; complex: several cell types working together.

Answer

Simple: one cell type; complex: several cell types working together.

Question Activity 3.2

What explains blood loss, clotting, redness during exercise, and swelling at an infected area?

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RBCs carry oxygen, platelets clot blood, and WBCs help fight infection.

Answer

RBCs carry oxygen, platelets clot blood, and WBCs help fight infection.

Question Activity 3.3

Match bone, cartilage, tendon, and ligament with their jobs.

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Bone supports; cartilage cushions; tendon joins muscle to bone; ligament joins bone to bone.

Answer

Bone supports; cartilage cushions; tendon joins muscle to bone; ligament joins bone to bone.

Question Activity 3.4

How can a student estimate the mass of bones and muscles?

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Multiply body mass by the relevant percentage.

Answer

Multiply body mass by the relevant percentage.

Question Activity 3.5

Why can some body parts move in many directions while others move only one way?

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Different joint structures allow different ranges of movement.

Answer

Different joint structures allow different ranges of movement.

Question Pause and Ponder 1

Why are coconut husk fibres hard and brittle while coriander leaf stalks are soft and flexible?

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Sclerenchyma strengthens coconut husk; softer tissues keep coriander flexible.

Answer

Sclerenchyma strengthens coconut husk; softer tissues keep coriander flexible.

Question Pause and Ponder 2

Why is a thick cuticle useful in a desert but less useful underwater?

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It conserves water in deserts but can hinder exchange underwater.

Answer

It conserves water in deserts but can hinder exchange underwater.

Question Pause and Ponder 3

How can dead xylem cells help water move upward with living leaves?

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Hollow xylem tubes conduct water; transpiration pull helps draw it upward.

Answer

Hollow xylem tubes conduct water; transpiration pull helps draw it upward.

Question Pause and Ponder 4

What might happen if stems and leaves had no stomata?

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Gas exchange and transpiration would be disrupted.

Answer

Gas exchange and transpiration would be disrupted.

Question Pause and Ponder 5

Which joints might be used in dance poses, and what movements do they allow?

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Identify the joint by its movement: rotate, hinge, or pivot.

Answer

Identify the joint by its movement: rotate, hinge, or pivot.

Question Table 3.6

What do the carrot-cell culture results suggest about light, air, and nutrients?

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Carrot cells grew best in the tested condition with air and liquid nutrients.

Answer

Carrot cells grew best in the tested condition with air and liquid nutrients.

Question Table 3.6

Which tested combination gave the highest and lowest biomass, and why?

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Highest: light + air + liquid nutrients; lowest conditions showed reduced mass.

Answer

Highest: light + air + liquid nutrients; lowest conditions showed reduced mass.

Question Table 3.6

Would animal cells necessarily show the same results as carrot cells?

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No; animal cells have different culture needs and cannot photosynthesise.

Answer

No; animal cells have different culture needs and cannot photosynthesise.

Revise, Reflect, Refine

Textbook pages 65–69

Question 1

Which feature helps meristematic cells divide repeatedly?

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Option (iii).

Answer

Option (iii).

Question 2

Which tissue transports food from leaves to roots?

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Phloem; option (ii).

Answer

Phloem; option (ii).

Question 3

Why are lung epithelial layers thin?

Steps only

Option (iii).

Answer

Option (iii).

Question 4

How do the knees and ankles differ in a straight-leg jump and a normal jump?

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Normal jump: knees and ankles bend; stiff-leg jump: little bending.

Answer

Normal jump: knees and ankles bend; stiff-leg jump: little bending.

Question 5

Which joint type is mainly involved when bending the knee and ankle?

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Hinge joint; option (ii).

Answer

Hinge joint; option (ii).

Question 6.1

Assertion: lung epithelium is suited to gas exchange. Reason: it has many layers of tall cells that slow diffusion. Which option is correct?

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Option (iii): assertion true, reason false.

Answer

Option (iii): assertion true, reason false.

Question 6.2

Assertion: cardiac muscle contracts continuously. Reason: it has many mitochondria and a rich blood supply. Which option is correct?

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Option (i): both true, and the reason explains the assertion.

Answer

Option (i): both true, and the reason explains the assertion.

Question 6.3

Assertion: tendons connect bone to bone. Reason: tendons transfer force from muscle to bone. Which option is correct?

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Option (iv): assertion false, reason true.

Answer

Option (iv): assertion false, reason true.

Question 6.4

Assertion: a hinge joint mainly moves in one plane. Reason: its bone ends slide freely in all directions. Which option is correct?

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Option (iii): assertion true, reason false.

Answer

Option (iii): assertion true, reason false.

Question 7

Plot the teak-tree age against both stem diameter and annual rings. What trends do the graph show, which tissue increases girth, and what assumptions are needed?

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Plot both series: diameter rises with age, and annual rings match the listed age. Cambium increases girth; this assumes one correctly counted ring forms each year.

Answer

Plot both series: diameter rises with age, and annual rings match the listed age. Cambium increases girth; this assumes one correctly counted ring forms each year.

Question 8

What functions are affected by debarking, and what assumptions are involved?

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Bark protects; phloem carries food; xylem carries water. The depth of damage matters.

Answer

Bark protects; phloem carries food; xylem carries water. The depth of damage matters.

Question 9

What tissue lets a young mango stem bend in monsoon winds? What if it were replaced by sclerenchyma?

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Collenchyma provides flexible support; sclerenchyma would make it stiffer.

Answer

Collenchyma provides flexible support; sclerenchyma would make it stiffer.

Question 10

Why might one sugarcane cutting sprout while another does not, and how can the test be fair?

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The successful cutting had a viable node/bud; keep growing conditions equal.

Answer

The successful cutting had a viable node/bud; keep growing conditions equal.

Question 11

Is a tissue always made of similar cells doing the same function?

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Simple tissues use similar cells; complex tissues use different cells working together.

Answer

Simple tissues use similar cells; complex tissues use different cells working together.

Question 12

Which tissue makes coconut husk strong, and why is parenchyma less suitable?

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Sclerenchyma; thick walls make it tough.

Answer

Sclerenchyma; thick walls make it tough.

Question 13

Are meristems found only at root and shoot tips? What could Neha ask?

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No; lateral and intercalary meristems also occur.

Answer

No; lateral and intercalary meristems also occur.

Question 14

Which same-sized cell usually has a larger vacuole, and what assumption is being made?

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A mature plant cell; the comparison assumes typical mature cells.

Answer

A mature plant cell; the comparison assumes typical mature cells.

Question 15

How can we test the claim that each plant tissue has only one function?

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Question the claim with examples such as epidermis, parenchyma, and xylem.

Answer

Question the claim with examples such as epidermis, parenchyma, and xylem.

The Journey Beyond

Textbook pages 69–71

Question Project 1

How can people reduce the risk of bone, ligament, and cartilage injuries?

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Use safe technique, gradual exercise, rest, and balanced nutrition.

Answer

Use safe technique, gradual exercise, rest, and balanced nutrition.

Question Project 2

What can you observe when you point and flex your toes while touching above the heel?

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The Achilles tendon tightens to transfer calf-muscle force to the heel.

Answer

The Achilles tendon tightens to transfer calf-muscle force to the heel.

Question Project 3

How can yoga or another physical practice support bones and muscles?

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Safe regular activity supports strength, flexibility, balance, and posture.

Answer

Safe regular activity supports strength, flexibility, balance, and posture.

Question Project 4

How do pruning, grafting, irrigation, and crop rotation support plant tissues?

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Each practice supports growth or resource balance in a different way.

Answer

Each practice supports growth or resource balance in a different way.

Question Project 5

How can a nature walk become a research project about leaves?

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Record leaf features and uses respectfully without damaging plants.

Answer

Record leaf features and uses respectfully without damaging plants.

Question Project 6

How can dance movements show different joint types?

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Observe which joints rotate, bend, or turn during each movement.

Answer

Observe which joints rotate, bend, or turn during each movement.

Question Project 7

Could a complete animal be made from an animal cell? What are possible benefits and challenges?

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It may be possible in limited research, but development, safety, welfare, and ethics are major challenges.

Answer

It may be possible in limited research, but development, safety, welfare, and ethics are major challenges.