Extra 20 important long-answer questions from the chapter:6 "Tissues" for Class 9 CBSE Science:-

1. What is a tissue? Why is it necessary in multicellular organisms?

Answer:

A

tissue is a group of similar cells

that perform a specific function.

In

unicellular organisms

, a single cell performs all functions.

In

multicellular organisms

, different tissues perform different functions, leading to

division of

labour

.

It

increases efficiency

and allows organisms to grow larger and more complex.

Tissues help in

repair and regeneration

of body parts.

They provide

structural and functional support

to the body.

 

2. What are the differences between meristematic and permanent tissues?

Answer:

Feature	Meristematic Tissue	Permanent Tissue
Cell division	Actively dividing cells	Do not divide
Function	Growth of the plant	Support, transport, protection
Cell structure	Small, thin-walled cells	Larger, thick or thin-walled
Example	Apical meristem	Xylem, Phloem

Meristematic tissues help in

growth and development

.

Permanent tissues help in

transport, storage, and mechanical support

.

As a plant matures,

meristematic cells differentiate

into permanent cells.

 

3. Explain the functions of different types of meristematic tissues.

Answer:

Apical meristem

: Found at the

tips of roots and shoots

, helps in

growth in length

.

Lateral meristem

: Found along the

sides of stems and roots

, increases

thickness

.

Intercalary meristem

: Present

at nodes

of grasses and regenerates lost parts.

 

4. What are simple permanent tissues? Explain their types.

Answer:

Parenchyma

:

Living cells with thin walls.

Stores

starch and nutrients

.

Found in

leaves, roots, fruits

.

Helps in

photosynthesis (chlorenchyma)

and

buoyancy (aerenchyma)

.

Collenchyma

:

Living cells with

thickened cell walls

.

Provides

support and flexibility

.

Found in

leaf veins and stem edges

.

Sclerenchyma

:

Dead cells with

thick lignified walls

.

Provides

strength and rigidity

.

Found in

seeds, nuts, and coconut shells

.

 

5. Explain the structure and function of xylem.

Answer:

Xylem

transports

water and minerals

from roots to leaves.

It consists of:

Tracheid’s

: Tube-like, conduct water.

Vessels

: Long channels for water movement.

Xylem

fibres

: Provide support.

Xylem parenchyma

: Stores food.

Xylem cells are

mostly dead

except xylem parenchyma.

Water transport in xylem is

unidirectional (upward only)

.

Provides

mechanical support

to plants.

 

6. Explain the structure and function of phloem.

Answer:

Phloem

transports

food from leaves to other parts

.

It consists of:

Sieve tubes

: Conducts food.

Companion cells

: Helps sieve tubes function.

Phloem

fibres

: Provides support.

Phloem parenchyma

: Stores food.

Phloem is

living tissue

(except phloem

fibres

).

Transport in phloem is

bidirectional (upward and downward)

.

Plays a crucial role in

growth and storage

in plants.

 

7. Differentiate between xylem and phloem.

Answer:

Feature	Xylem	Phloem
Function	Transports water	Transports food
Direction	Upward only	Both directions
Cell type	Dead (except parenchyma)	Living (except fibres)

 

8. What are connective tissues? Explain their types.

Answer:

Blood

: Transports nutrients, oxygen, and waste.

Bone

: Hard structure for support and protection.

Cartilage

: Flexible tissue in nose, ear, joints.

Ligaments

: Connects bones to bones.

Tendons

: Connects muscles to bones.

Adipose tissue

: Stores fat and insulates the body.

 

9. Differentiate between ligaments and tendons.

Answer:

Feature	Ligament	Tendon
Connects	Bone to bone	Muscle to bone
Strength	More elastic	Less elastic
Function	Provides flexibility	Helps in movement

 

10. Explain the function of muscular tissue.

Answer:

Responsible for movement

in the body.

Skeletal muscles

– Voluntary movement.

Smooth muscles

– Involuntary movement.

Cardiac muscles

– Found in the heart, never tires.

Helps in

digestion, circulation, and locomotion

.

Contracts and relaxes to

generate force

.

 

11. What are the characteristics of meristematic tissue?

Answer:

Actively dividing cells

found in growing parts of plants.

Small, thin-walled cells

with a dense cytoplasm.

No intercellular spaces

, making the tissue compact.

Large nuclei

for rapid cell division.

Found in

root tips, shoot tips, and nodes

.

Helps in

primary and secondary growth

.

Differentiates into

permanent tissue

after maturation.

 

12. How does collenchyma support the plant body?

Answer:

Elongated cells

with unevenly thickened walls.

Provides

mechanical support

to growing stems and leaves.

Contains cellulose and pectin

, making it flexible.

Allows

bending of stems and leaves without breaking

.

Found in

leaf veins, petioles, and herbaceous stems

.

Helps in

photosynthesis

(some contain chloroplasts).

Protects young plant parts from

wind and mechanical stress

.

 

13. Describe the structure and function of sclerenchyma fibres.

Answer:

Long, narrow, and thick-walled dead cells

.

Cell walls have lignin

, making them hard.

No cytoplasm, only

empty lumen inside

.

Provides

strength and rigidity

to plants.

Found in

bark, seed coats, coconut husk, and stems

.

Helps plants

stand upright and resist bending

.

Used in industries for

making ropes and textiles

.

 

14. How does epidermal tissue protect plants?

Answer:

Forms the

outermost protective layer

of the plant body.

Prevents water loss

through a waxy cuticle.

Protects from injury, pathogens, and mechanical damage

.

Some epidermal cells form

root hairs

, increasing water absorption.

Contains

stomata for gas exchange

and transpiration.

In desert plants, epidermis is

thick to reduce water loss

.

Trichomes (hair-like structures)

help reduce evaporation and protect from herbivores.

 

15. Explain the different types of animal connective tissue.

Answer:

Fluid connective tissue

– Blood and lymph, transports nutrients and fights infection.

Fibrous connective tissue

– Ligaments and tendons, connect bones and muscles.

Skeletal connective tissue

– Bone and cartilage, provides support.

Adipose tissue

– Stores fat, provides insulation.

Areolar tissue

– Fills spaces, provides cushioning and support.

Lymph

– Helps in immunity and maintaining fluid balance.

Connective tissues

bind, support, and protect the body

.

 

16. What is the role of cartilage in the human body?

Answer:

Smooth, flexible connective tissue

with no blood supply.

Provides

cushioning between bones

(in joints).

Found in

nose, ear, trachea, and larynx

.

Reduces friction

in joint movements.

Forms the framework of

embryonic skeleton

.

Protects bones from

wear and tear

.

Helps in the

formation of intervertebral discs

in the spine.

 

17. Describe the function of blood as a connective tissue.

Answer:

Transports oxygen

(via red blood cells).

Carries

nutrients and hormones

to different parts of the body.

Removes waste

like carbon dioxide and urea.

White blood cells

fight

infections

.

Platelets help in blood clotting

and wound healing.

Maintains

body temperature and pH balance

.

Helps in

immunity and disease resistance

.

 

18. Explain the importance of muscular tissue in the human body.

Answer:

Helps in

body movement and locomotion

.

Maintains posture and body balance

.

Cardiac muscles help in

pumping blood

.

Smooth muscles assist in

digestion and respiration

.

Generates

heat

during contraction.

Protects internal organs by

absorbing shocks

.

Facial muscles

allow expressions like smiling and frowning.

 

19. How does nervous tissue help in coordination and control?

Answer:

Composed of

neurons

(nerve cells).

Transmits

electrical signals

across the body.

Controls

voluntary and involuntary actions

.

Helps in

thinking, memory, and reflex actions

.

Found in the

brain, spinal cord, and nerves

.

Neurons communicate using

synapses and neurotransmitters

.

Plays a major role in

homeostasis and body regulation

.

 

20. Why are plant and animal tissues important for survival?

Answer:

Plant tissues

help in

photosynthesis, water transport, and support

.

Meristematic tissue

helps in

growth

.

Xylem and phloem

transport water and nutrients.

Animal tissues

help in

movement, protection, and communication

.

Muscle tissue

enables movement, while

nervous tissue

controls actions.

Connective tissues

provide

support and protection

.

Without tissues,

multicellular organisms could not function efficiently

.