Class 9 Biology – Tissues

A set of vocabulary flashcards summarizing the essential terms and definitions from the Class 9 lecture on plant and animal tissues.

Tissue

A group of similar cells that work together to perform a specific function.

Meristematic Tissue

Plant tissue whose cells retain the ability to divide and are responsible for growth.

Permanent Tissue

Plant tissue composed of cells that have lost the ability to divide and are specialized for specific functions.

Apical Meristem

Meristem located at the tips of roots and shoots; causes primary (lengthwise) growth.

Intercalary Meristem

Meristem found at the base of leaves or internodes; aids in lengthening of those regions.

Lateral Meristem

Meristem situated along the sides of stems and roots; produces secondary (girth) growth.

Primary Growth

Increase in plant length originating from apical and intercalary meristems.

Secondary Growth

Increase in thickness of stems or roots due to lateral meristems.

Differentiation

Process by which cells take on permanent shape, size, and function.

Simple Permanent Tissue

Permanent plant tissue made of one cell type; includes parenchyma, collenchyma, and sclerenchyma.

Parenchyma

Living, thin-walled packing tissue that stores food and provides support.

Chlorenchyma

Parenchyma containing chlorophyll; performs photosynthesis.

Aerenchyma

Parenchyma with large air spaces; provides buoyancy in aquatic plants.

Collenchyma

Living plant tissue with thickened corners that imparts flexibility to stems and leaf stalks.

Sclerenchyma

Dead, thick-walled plant tissue providing hardness and mechanical support (e.g., coconut husk).

Complex Permanent Tissue

Plant tissue composed of more than one cell type; mainly xylem and phloem.

Xylem

Complex tissue that conducts water and minerals upward and gives mechanical strength; largely dead cells.

Tracheids

Elongated, dead xylem cells that conduct water in gymnosperms.

Vessels

Cylindrical tubes of dead xylem cells aligned end-to-end for efficient water transport in angiosperms.

Xylem Parenchyma

Living xylem cells that store starch and other substances.

Xylem Fibre (Xylem Sclerenchyma)

Dead, thick-walled fibres in xylem providing mechanical support.

Annual Rings

Concentric xylem layers in tree trunks used to determine a tree’s age.

Phloem

Complex tissue that transports organic food (sugars) throughout the plant.

Sieve Tubes

Living, tube-like phloem elements with perforated end walls (sieve plates) for translocation of food.

Companion Cells

Living phloem cells that regulate and support adjoining sieve tubes; originate from the same mother cell.

Phloem Parenchyma

Living phloem cells that store food and aid in lateral transport.

Phloem Fibre

Sclerenchymatous phloem cells providing mechanical strength.

Protective Tissue

Plant tissue forming outer coverings, mainly epidermis and cork.

Epidermis

Outer single-cell layer that protects plants, reduces water loss, and allows gas exchange.

Cork

Dead, multi-layered protective tissue forming part of bark; contains suberin to prevent water loss.

Epithelial Tissue

Animal tissue forming protective coverings and linings; cells rest on a basement membrane.

Squamous Epithelium

Single layer of flat cells lining blood vessels, alveoli, and mouth cavity.

Stratified Squamous Epithelium

Multiple layers of flat cells forming the outer skin; protects against abrasion.

Cuboidal Epithelium

Cube-shaped cells lining kidney tubules and salivary glands; involved in secretion and absorption.

Columnar Epithelium

Tall, pillar-like cells lining the small intestine; specialized for absorption.

Ciliated Epithelium

Columnar or cuboidal cells with cilia, found in respiratory tract and fallopian tubes; move mucus or ova.

Muscular Tissue

Animal tissue composed of contractile fibres responsible for movement.

Striated Muscle (Skeletal Muscle)

Voluntary, multinucleated, striped fibres attached to bones; fatigue easily.

Smooth Muscle (Non-Striated)

Involuntary, spindle-shaped fibres in walls of organs like stomach and intestine; enable peristalsis.

Cardiac Muscle

Involuntary, branched, uninucleated fibres with intercalated discs; form heart walls and contract rhythmically.

Connective Tissue

Animal tissue that binds, supports, and protects body structures; includes blood, bone, and cartilage.

Blood

Fluid connective tissue that transports gases, nutrients, hormones, and wastes; provides immunity.

Plasma

Liquid component of blood (~55%); 90% water plus proteins, salts, and other solutes.

Red Blood Cells (Erythrocytes)

Disc-shaped cells containing haemoglobin for oxygen transport.

White Blood Cells (Leukocytes)

Amoeboid cells that defend the body; include neutrophils, lymphocytes, monocytes, eosinophils, basophils.

Platelets (Thrombocytes)

Spindle-shaped blood fragments essential for clotting.

Tendon

Tough, non-elastic connective tissue attaching muscle to bone; whitish due to poor blood supply.

Ligament

Strong, elastic connective tissue connecting bone to bone; yellowish from elastin, stabilises joints.

Bone

Hard, porous connective tissue with mineralised matrix and blood vessels; provides structural framework.

Cartilage

Flexible connective tissue with a protein matrix and no blood vessels; forms ear pinna, nose tip, joints.

Areolar Tissue

Loose connective tissue filling spaces between organs, attaching skin to muscles, and supporting nerves and vessels.

Adipose Tissue

Fat-storage connective tissue beneath skin and around organs; insulates and cushions.

Nervous Tissue

Specialised animal tissue that senses stimuli and transmits nerve impulses.

Neuron

Structural and functional unit of nervous tissue; longest cell in the body.

Dendrite

Branched projection of a neuron that receives signals and conveys them to the cell body.

Cell Body (Cyton)

Main part of a neuron containing the nucleus and organelles.

Axon

Long, tubular extension of a neuron that conducts impulses away from the cell body.

Nerve Ending

Terminal part of an axon where signals are passed to another neuron or effector cell.