Tissues Test - 26

Chondrocytes are the cells present in the cartilaginous tissue. These cells produce and maintain the cartilaginous matrix.

Phloem fibres are represented by the dead sclerenchyma fibres that are found in between the sieve tubes.

Cuticle works as a protective layer to minimize the effect of heat. Thus, cuticle helps in reducing water loss in desert plants.

Intercalary meristem facilities the longitudinal growth of internode and thus a sugarcane plant keeps on growing even in the absence of apical meristem.

The nail will remain at the same position after 3 years, but will appear to have sunk into the tree. This is because of the secondary growth of the tree which increases the girth of a tree. The increase in height of the plant will occur due to primary growth which occurs only in the regions of the apical meristems i.e. at the tips of the main stem or branches. As increase in height of the tree takes place from top only, therefore the nail will remain at the same position as it is inserted near the ground level.

Parenchyma is the simplest among simple tissues. Hence, cells are thin-walled and relatively unspecified.

Collenchyma is a living, simple permanent tissue which is present below the epidermis in petiole, leaves and stems of herbaceous dicots e.g. sunflower, tomato etc. Collenchyma provides flexibility to the plant parts and allows their easy bending without breaking. Cells of this tissue are elongated, irregularly thickened at the comers with very little intercellular spaces.

The cork cells are dead and lack inter cellular spaces. Its cells, whose walls are impregnated with suberin, are arranged in radial rows and fit closely together except where the cork is interrupted by lenticles.

Xylem and phloem are the complex permanent tissues which constitute a vascular bundle. Vascular or conducting tissue is a distinctive feature of higher plants, which has made their survival possible in terrestrial environment as .they make it possible for plants to survive without being surrounded with water.

Epithelial tissues do not have intercellular spaces between them, rather cells are tightly fit together to make a continuous sheet.

Xylem tissue of gymnosperms lacks the vessels and comprises of tracheids, fibres and parenchyma. Thus, the main water conducting tissue of gymnosperms is xylem tracheid. Sieve tubes translocate food material.

Sedentary existence contributes to the organ system design in animals.

Parenchyma is a type of simple tissue.

Companion cells are narrow, elongated, thin walled, living cells. They have dense cytoplasm and a prominent nucleus. Red blood cells of mammals, vessels (xylem elements) and sieve tube cells (phloem elements) lose their nuclei at maturity.

Xylem (a complex permanent tissue) is the chief conducting tissue of vascular plants responsible for conduction of water and inorganic solutes. The tissue is composed of four kinds of cell: tracheids, vessels (or tracheae), xylem parenchyma and xylem fibres. Vessels and tracheids help in long distance vertical conduction of water and minerals from the roots to different parts of the shoot system. The main stem along with all of its branches are all supplied with water and mineral by mean by xylem vessels and tracheids. Radial conduction i.e., sideways conduction of water occurs by xylem parenchyma.