Ans: A tissue is a group of cells that are similar in structure and work together to perform a specific function.

Ans: Histology is the study of tissues.

Ans: Apical meristem, Lateral meristem (cambium), and Intercalary meristem.

Ans: Lateral meristem (cambium) is responsible for increasing the girth of the stem and root.

Ans: Chlorenchyma is parenchyma tissue found in leaves that contains chlorophyll and performs photosynthesis.

Ans: Blood is the fluid connective tissue in the body.

Ans: Meristematic tissue: cells actively divide, thin walls, no vacuoles, found in growing regions. Permanent tissue: cells have stopped dividing, have definite shape and size, may be living or dead, derived from meristematic tissue.

Ans: Xylem: conducts water and minerals upward from roots; components include tracheids, vessels (dead cells), xylem parenchyma and fibres. Phloem: conducts food (sugars) from leaves to all parts; components include sieve tubes (living, no nucleus), companion cells, phloem parenchyma and fibres.

Ans: Striated: voluntary, skeletal, multinucleated, shows striations, fatigues quickly. Unstriated/Smooth: involuntary, found in gut and blood vessels, spindle-shaped, single nucleus. Cardiac: involuntary, only in heart, striated, never fatigues, connected by intercalated discs.

Ans: Simple permanent tissues are: (1) Parenchyma – living, thin-walled, loosely packed cells; store food and water; in leaves called chlorenchyma for photosynthesis; in aquatic plants called aerenchyma for buoyancy. (2) Collenchyma – living, with irregularly thickened corners; provides flexibility and mechanical support; found in leaf stalks. (3) Sclerenchyma – dead, heavily lignified thick walls; provides hardness and stiffness to the plant body; found in coconut husk, jute, and seed coats.

Ans: Epithelial tissue covers body surfaces and lines cavities. Types: (1) Simple squamous – flat cells, lines alveoli and blood vessels, allows diffusion. (2) Cuboidal – cube-shaped, found in kidney tubules and salivary glands, involved in secretion and absorption. (3) Columnar – column-shaped, lines intestine, helps in absorption. (4) Ciliated columnar – has cilia that move mucus, lines respiratory tract. (5) Glandular epithelium – forms glands and secretes hormones or enzymes.

Ans: Connective tissue connects and supports other tissues. Its cells are scattered in a matrix. Types: (1) Areolar – loose connective tissue, fills spaces between organs, contains collagen and elastin fibres. (2) Adipose – stores fat, insulates and cushions organs. (3) Dense fibrous – forms tendons (connecting bone to muscle) and ligaments (connecting bone to bone). (4) Cartilage – solid but flexible matrix (chondrin), found in nose, ear, trachea, and between joints. (5) Bone – hard matrix of calcium phosphate, provides framework and protection. (6) Blood – fluid matrix (plasma) with RBCs, WBCs and platelets; transports materials throughout the body.

Ans: Meristematic tissue is responsible for the growth of plants. Its cells actively divide by mitosis, adding new cells that eventually differentiate into permanent tissues, thus increasing the length and girth of the plant.

Ans: Blood is considered a connective tissue because it connects and integrates different parts of the body by transporting materials. Like other connective tissues, it has cells (RBCs, WBCs, platelets) scattered in a non-living fluid matrix called plasma.

Ans: Squamous epithelium forms the outer covering of the skin of the human body.

Ans: Xylem: (1) Conducts water and minerals upward from roots to leaves. (2) Mostly dead cells (except xylem parenchyma). (3) Consists of tracheids, vessels, xylem parenchyma and fibres. (4) Unidirectional transport. Phloem: (1) Conducts prepared food from leaves to all parts of the plant. (2) Mostly living cells (except phloem fibres). (3) Consists of sieve tubes, companion cells, phloem parenchyma and fibres. (4) Bidirectional transport possible.

Ans: Striated muscle: (1) Shows alternate light and dark bands (striations). (2) Multinucleated, cylindrical fibres. (3) Attached to bones — under voluntary control. (4) Fast but fatigues quickly. Smooth muscle: (1) No striations — uniform appearance. (2) Uninucleated, spindle-shaped fibres. (3) Found in walls of hollow organs — involuntary control. (4) Slow contractions but can sustain longer.

Ans: (1) Apical meristem — located at root and shoot tips; responsible for increase in length of the plant (primary growth). (2) Lateral meristem (cambium) — located on sides of stem and root; responsible for increase in girth/width of the plant (secondary growth; forms wood and bark). (3) Intercalary meristem — located at internodes and leaf bases; responsible for regeneration of damaged parts and elongation of internodes.

Ans: A neuron has three parts: (1) Cell body (cyton/soma) — irregular mass containing the nucleus, cytoplasm, and organelles (including Nissl bodies which are rough ER). (2) Dendrites — short, branched projections from the cell body that receive nerve impulses from other neurons. (3) Axon — a single long projection that carries nerve impulses away from the cell body toward the next neuron or effector organ. The axon is covered by a myelin sheath (formed by Schwann cells) which provides insulation and speeds up impulse conduction. The end of the axon has synaptic knobs that release chemical messengers called neurotransmitters at the synapse. Function: Neurons transmit electrical nerve impulses rapidly across the nervous system, enabling the body to sense, process and respond to stimuli.

Ans: Simple permanent tissues are made of one type of cell: (1) Parenchyma — living, thin-walled cells with large intercellular spaces; perform storage, photosynthesis (chlorenchyma) and secretion. Most abundant tissue in plants. (2) Collenchyma — living cells with thickened corners due to deposition of cellulose and pectin; provide mechanical support with flexibility; found in petioles and young stems. (3) Sclerenchyma — dead cells with uniformly thick lignified walls; no intercellular spaces; provide maximum rigidity and strength to plant; found in seed coats, husk, around vascular bundles. Exists as fibres (long) and sclereids (stone cells — short).

Ans: Animal tissues are of four main types: (1) Epithelial tissue — forms covering and lining; closely packed cells on basement membrane; types include squamous (skin), cuboidal (kidney tubules), columnar (intestine), ciliated (respiratory tract) and glandular epithelium. Functions: protection, secretion, absorption. (2) Connective tissue — supports and connects; cells in large matrix; types include areolar (fills spaces), adipose (fat storage), bone (support), cartilage (flexible support) and blood (transport). (3) Muscular tissue — enables movement by contraction; types: striated/skeletal (voluntary, attached to bones), smooth (involuntary, in organ walls), cardiac (involuntary, in heart — never fatigues). (4) Nervous tissue — transmits electrical impulses; basic unit is neuron with cell body, dendrites (receive) and axon (transmit). Found in brain, spinal cord and nerves.