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CBSE | Class 9 | science
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Summary Note
Key concept recap
A tissue is a group of similar cells that perform a specific function in an organism.
Multicellular organisms like plants and animals have well-organized tissues to carry out specialized functions efficiently.
Division of labour among tissues leads to increased efficiency, as each tissue performs a specific task.
Examples of tissues include blood, muscle, and phloem.
Summary Note
Key concept recap
Plants are mostly stationary and require supportive tissues made up of dead cells, while animals move actively and contain living tissues.
Plant growth is localized in certain regions with meristematic tissue, whereas animal growth is more uniform.
Animals have more complex tissue and organ systems due to their active lifestyles.
Summary Note
Key concept recap
Meristematic tissues are responsible for plant growth and are found in specific regions.
They are classified into apical (tip growth), lateral (girth growth), and intercalary (node growth) meristems.
Meristematic cells are living, thin-walled, have dense cytoplasm and lack vacuoles.
Summary Note
Key concept recap
Permanent tissues are formed when meristematic cells differentiate and lose their ability to divide.
They are categorized as simple (one type of cell) and complex (more than one cell type).
Simple permanent tissues include parenchyma (storage), collenchyma (flexibility), and sclerenchyma (strength).
Summary Note
Key concept recap
Epidermis forms the protective outer layer in plants, often covered with waxy cutin and containing stomata.
Cork replaces epidermis in old stems, made of dead cells with suberin in walls.
Complex permanent tissues like xylem and phloem conduct water and food respectively and are composed of various cell types.
Summary Note
Key concept recap
Epithelial tissue forms coverings and linings in the body and protects internal structures.
Types include: squamous (flat), cuboidal (cube-shaped), columnar (tall), ciliated (with cilia), and glandular (secretion).
These tissues regulate exchange of materials and act as barriers.
Summary Note
Key concept recap
Connective tissues have cells spaced within an intercellular matrix.
Types include blood (fluid matrix), bone (hard matrix), ligament (connects bones), tendon (connects muscles to bones), cartilage (smooth joints), areolar (filler tissue), and adipose (fat storage).
They provide support, connection, and transport functions.
Summary Note
Key concept recap
Muscle tissues consist of elongated fibers and enable body movement.
Striated muscles are voluntary and attached to bones.
Smooth muscles are involuntary and found in internal organs.
Cardiac muscles are involuntary, branched, and found in the heart.
Summary Note
Key concept recap
Nervous tissue comprises neurons that transmit impulses across the body.
Each neuron has a cell body, axon, and dendrites.
They coordinate body functions and enable responses to stimuli by transmitting nerve impulses quickly.
Summary Note
Key concept recap
Tissue – A group of similar cells performing a specific function.
Meristematic Tissue – Actively dividing cells in plants.
Parenchyma – Simple tissue for storage.
Collenchyma – Provides flexibility to plants.
Sclerenchyma – Provides strength using lignin-thickened dead cells.
Epidermis – Protective outer layer of plant.
Xylem – Conducts water and minerals.
Phloem – Transports food in plants.
Neuron – Nerve cell that conducts impulses.
Striated Muscle – Voluntary, multi-nucleated muscle attached to bones.
