Class 7th
Tissues
What is Organization? (Quick Recap)
Organization is the proper arrangement of living parts where:
each part performs a specific function
all parts work together in coordination
In living organisms, simple units combine to form complex units.
Why Organization is Important?
Makes life processes efficient
Allows division of labour
Helps in growth, repair, and survival
Prevents confusion of functions
LEVELS OF ORGANIZATION
Cellular Level
What happens at this level?
Life begins at the cell
Cells perform basic life activities
Examples of specialized cells
Nerve cells (neurons)
→ Specialized to conduct messages throughout the body
Red blood cells (RBCs)
→ Specialized to transport oxygen from lungs to tissues
Muscle cells
→ Specialized to contract and cause movement
Root hair cells (plants)
,→ Specialized to absorb water and minerals
Thus , Each cell has a specific shape and function.
Tissue Level
What is a tissue?
A tissue is a group of similar cells
Cells work together to perform one function
Examples
Nervous tissue
→ Made of nerve cells
→ Conducts electrical messages
Blood tissue
→ RBCs transport oxygen
→ WBCs fight infection
→ Platelets help in clotting
Muscle tissue
→ Helps in movement of body parts
Xylem tissue (plants)
→ Transports water and minerals
Organ Level
What is an organ?
An organ is made of different tissues
All tissues work together to perform a specific task
Examples
Heart
→ Made of muscle tissue, connective tissue, nervous tissue
→ Pumps blood throughout the body
,Lungs
→ Help in exchange of gases
Leaf (plant organ)
→ Epidermis protects
→ Mesophyll performs photosynthesis
→ Vascular tissues transport materials
Organ System Level
What is an organ system?
A group of organs working together
Performs major life functions
Examples
Circulatory System
Organs involved:
Heart
Blood vessels
Blood
Function:
→ Transport oxygen, nutrients, hormones, and wastes
Nervous System
Organs involved:
Brain
Spinal cord
Nerves
Function:
→ Controls and coordinates body activities
Digestive System
, Organs involved:
Mouth, stomach, intestines
Function:
→ Digestion and absorption of food
Transport System in Plants
Tissues involved:
Xylem and phloem
Function:
→ Transport water and food
Organism Level
What is an organism?
A complete living individual
All organ systems work together
Examples
Human being
Tree
Bird
Failure of one system affects the whole organism.
Levels of Organization Higher Than Organism
Population – group of same species
Community – different populations
Ecosystem – community + environment
Biosphere – all ecosystems on Earth
Ecosystem & Food Chain (Simple Link)
Plants are producers
Animals are consumers
Tissues
What is Organization? (Quick Recap)
Organization is the proper arrangement of living parts where:
each part performs a specific function
all parts work together in coordination
In living organisms, simple units combine to form complex units.
Why Organization is Important?
Makes life processes efficient
Allows division of labour
Helps in growth, repair, and survival
Prevents confusion of functions
LEVELS OF ORGANIZATION
Cellular Level
What happens at this level?
Life begins at the cell
Cells perform basic life activities
Examples of specialized cells
Nerve cells (neurons)
→ Specialized to conduct messages throughout the body
Red blood cells (RBCs)
→ Specialized to transport oxygen from lungs to tissues
Muscle cells
→ Specialized to contract and cause movement
Root hair cells (plants)
,→ Specialized to absorb water and minerals
Thus , Each cell has a specific shape and function.
Tissue Level
What is a tissue?
A tissue is a group of similar cells
Cells work together to perform one function
Examples
Nervous tissue
→ Made of nerve cells
→ Conducts electrical messages
Blood tissue
→ RBCs transport oxygen
→ WBCs fight infection
→ Platelets help in clotting
Muscle tissue
→ Helps in movement of body parts
Xylem tissue (plants)
→ Transports water and minerals
Organ Level
What is an organ?
An organ is made of different tissues
All tissues work together to perform a specific task
Examples
Heart
→ Made of muscle tissue, connective tissue, nervous tissue
→ Pumps blood throughout the body
,Lungs
→ Help in exchange of gases
Leaf (plant organ)
→ Epidermis protects
→ Mesophyll performs photosynthesis
→ Vascular tissues transport materials
Organ System Level
What is an organ system?
A group of organs working together
Performs major life functions
Examples
Circulatory System
Organs involved:
Heart
Blood vessels
Blood
Function:
→ Transport oxygen, nutrients, hormones, and wastes
Nervous System
Organs involved:
Brain
Spinal cord
Nerves
Function:
→ Controls and coordinates body activities
Digestive System
, Organs involved:
Mouth, stomach, intestines
Function:
→ Digestion and absorption of food
Transport System in Plants
Tissues involved:
Xylem and phloem
Function:
→ Transport water and food
Organism Level
What is an organism?
A complete living individual
All organ systems work together
Examples
Human being
Tree
Bird
Failure of one system affects the whole organism.
Levels of Organization Higher Than Organism
Population – group of same species
Community – different populations
Ecosystem – community + environment
Biosphere – all ecosystems on Earth
Ecosystem & Food Chain (Simple Link)
Plants are producers
Animals are consumers
