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.