Chapter 6 – Tissues

(b) Sclerenchyma

(c) Apical and intercalary meristems are permanent tissues

(b) lateral meristem

(b) Companion cells

(b) Columnar epithelium

(c) Ligament break

(d) Skeletal muscles contract and pull the tendon to move the bones

(b) (ii) and (iii)

(c) localised and dividing cells

(c) Conduction of water

(c) Tendons are non-fibrous tissue and fragile

(c) kidney

(b) adipose tissue

(b) calcium and phosphorus

(c) muscles

(b) limbs

(c) tendons

(c) tendons

(c) Areolar

(b) cardiac muscle

(d) Chondrocytes

(b) phloem fibres

(a) Companion cells

(a) cuticle

(d) xylem vessels

(d) intercalary meristem TISSUES 43 16-04-2018

(c) remain at the same position

(a) relatively unspecified and thin walled

(a) collenchyma

(c) suberin

(b) conducting tissue

(c) Epithelial tissues have intercellular spaces between them

(c) tracheids

Hint— Fat acts as subcutaneous insulation of body for thermoregulation

(i) Subcutaneous layer (b) Filling of space inside the organs

(ii) Cartilage (c) Striated muscle

(iv) Areolar tissue (e) Surface of joints (v) Blood (f) Stratified squamous epithelium (vi) Skin

(iii) Skeletal muscle (d) Adipose tissue

(i) Thin walled, packing cells (b) Photosynthesis

(ii) Carbon fixation (c) Aerenchyma

(iii) Localized thickenings (d) Collenchyma

(iv) Buoyancy (e) Permanent tissue (v) Sclerenchyma

Hint— Because of transpiration

Hint—Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres. Nucleus Cytoplasm Xylem parenchyma

Hint—Sieve tubes, companion cells, phloem fibres and phloem parenchyma. Sieve plate Sieve tube Phloem parenchyma Section of phloem Companion cell

(a) Epithelial tissue is protective tissue in animal body.

(b) The lining of blood vessels, lung alveoli and kidney tubules are all made up of epithelial tissue.

(c) Epithelial cells have a lot of intercellular spaces.

(d) Epithelial layer is permeable layer. (e) Epithelial layer does not allow regulation of materials between body and external environment.

Voluntary muscles can be moved by conscious will when we want them to move. For example, muscles of limbs or skeletal muscles. Involuntary muscles function on their own. We cannot start or stop them from working by our desire. examples are cardiac muscles and smooth muscles.

(a) Jumping of frog

(b) Pumping of the heart

(c) Writing with hand

(d) Movement of chocolate in your intestine

(a) Lining of blood vessels is made up of———.

(b) Lining of small intestine is made up of ———.

(c) Lining of kidney tubules is made up of———.

(d) Epithelial cells with cilia are found in———of our body.

Hint— Due to aerenchyma present in the swollen petiole.

Hint- Epidermis having thick cuticle and waxy substances to prevent the invasion of parasites.

(a) Cork cells possesses———on their walls that makes it impervious to gases and water.

(b) ——— have tubular cells with perforated walls and are living in nature.

(c) Bone possesses a hard matrix composed of———and ———.

Hint—Epidermis is important for plants due to the following reasons (i) it gives protection (ii) helps in gaseous exchange (iii) checks water loss (iv) root hairs arising from epidermis helps in absorption of water and minerals.

(a) ———are forms of complex tissue.

(b) ———have guard cells.

(c) Cells of cork contain a chemical called———

(d) Husk of coconut is made of ———tissue. (e) ———gives flexibility in plants. (f) ———and———are both conducting tissues. (g) Xylem transports———and———from soil. (h) Phloem transport———from———to other parts of the plant.

Differences between parenchyma and sclerenchyma. Parenchyma Sclerenchyma (1) Cells are thin walled and (1) Cells are thick walled and unspecialised lignified (2) These are living cells (2) Tissues are made up of dead cells (3) Cells are usually loosely packed (3) No intercellular spaces between with large intercellular space the cells are found (4) Stores nutrient and water in stem (4) Provides strength to the plant and roots parts (5) Some cells contain chlorophyll (5) The cells are long and narrow, called chlorenchyma and make the plant hard and stiff. perform photosynthesis. Other The tissue is present in the stem cells have large air cavities called around vascular bundles, in aerenchyma which provide veines of leaves and hard buoyancy to the hydrophytic covering of seeds and nuts. plants Cytoplasm Intercellular spaces Nucleus Middle lamella Chloroplast Vacuole Intercellular space T.S. Parenchyma Primary cell wall L.S. Parenchyma Simple pit pair Narrow lumen Lignified thick wall T.S. Sclerenchyma L.S. Sclerenchyma

Epithelial tissues are the covering or protective tissues in the animal body. Epithelium covers most organs and cavities within the body and keep different body systems separate. The skin, the lining of the mouth, the lining of blood vessels, lung alveoli and kidney tubules are all made of epithelial tissue. Epithelial tissue cells are tightly packed and form a continuous sheet. They have only a small amount of cementing material between them and almost no intercellular spaces. The permeability of the cells of various epithelia play an important role in regulating the exchange of materials between the body and the external environment and also between different parts of the body. Regardless of the type, all epithelia are usually separated from the underlying tissue by an extracellular fibrous basement membrane. Epithelial tissues are of following types— (1) Simple squamous epithelium (2) Stratified squamous epithelium (3) Columnar epithelium, and (4) Cubodial epithelium. These tissues differ in structure that correlate with their unique functions. For example, in cells lining blood vessels or lung alveoli, where transportation of substances occurs through a selectively permeable surface, there is a simple flat kind of epithelium. This is called the simple squamous epithelium. Simple squamous epithelial cells are extremely thin and flat and form a delicate lining. The skin, oesophagus and the lining of the mouth are also covered with squamous epithelium. Skin epithelial cells are arranged in many layers to prevent wear and tear. Since, they are arranged in a pattern of layers, the epithelium is called stratified squamous epithelium. Where absorption and secretion occur, as in the inner lining of the intestine, tall epithelial cells are present. This columnar epithelium facilitates movement across the epithelial barrier. In the respiratory tract, the columnar epithelial tissue also has cilia, which are hair-like projections on the outer surfaces of epithelial cells. These cilia can move, and their movement pushes the mucus forward to clear it. This type of epithelium is thus ciliated columnar epithelium. Cuboidal epithelium forms the lining of kidney tubules and ducts of salivary glands, where it provides mechanical support. Epithelial cells often acquire additional specialisation as gland cells, which can secrete substances at the epithelial surface. Sometimes a portion of the epithelial tissue folds inward, and a multicellular gland is formed. This is glandular epithelium. (a) Squamous (b) Cuboidal (c) Columnar (Ciliated) (d) Stratified squamous Different types of epithelial tissues ANSWERS 121

Nuclei Striations Striations (a) Striated muscle Nuclei Spindle shaped muscle cell Nucleus (c) Cardiac muscle (b) Smooth muscles

Hint— (a) No need of storage. (b) Because they are lignified. (c) Presence of stone cells (sclerenchyma) (d) Presence of Collenchyma. (e) Sclerenchyma.

Characteristics a) = Cells of cork are dead at maturity = These cells are compactly arranged = Cells do not possess intercellular spaces. = Cells possess a chemical substances suberin in their walls = They are several layers thick. b) As plants grow older, a strip of secondary meristem replaces the epidermis of the stem. Cells cut on the outer side by this meristem are called cork. c) They are protective in function for older stem/twigs/branches. They are impervious to gases and water.

Both xylem and phloem consist of more than one type of cells, which coordinate to perform a common function. Xylem Phloem Consists of tracheids, vessels, xylem, Consist of sieve tubes, companion cell, parenchyma and xylem fibres phloem parenchyma and phloem fibres. They transport water and minerals They transport food from leaves to other vertically from soil to aerial parts of parts of the plant. the plant. Most of the cells except xylem Most of the cells except phloem fibres are parenchyma are dead cells living cells.

(b) Define the process of differentiation

(a) Differentiate between meristematic and permanent tissues in plants

(c) Name any two simple and two complex permanent tissues in plants. TISSUES 47 16-04-2018