Notes of Class 8

Above diagram is the T.S. (tranasverse section) of leaf in which conducting tissues are visible. Let's label the parts in the diagram.

(a)Cuticle (b)Palisade tissue (c)Xylem (d)Sub stomatal space (e)Phloem (f)Lower epidermis 

Above diagram represents the parts of phloem. (a)Sieve tube (b) Phloem parenchyma (c)Companion cell (d) Sieve plate.

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For better understanding of transportation of mineral and water by root let us understand following terms :-

Semipermeable membrane :- The membrane which allows only solvent to pass through it not the solute is called semipermeable membrane.

Cell sap :- Cell sap is the watery liquid contained in the vacuole of root hair cells. Concentration of cell sap is more than concentration of soil water.

Diffusion :- Movement of material from its higher concentration to the lower concentration.

Osmosis :- Movement of solvent from its higher concentration ( Low conc. of solution ) to its lower concentration ( High conc. of solution ) through a semipermeable membrane is called osmosis.

In our next session we will discuss the structure of root. Your assignment is to draw the labeled diagram given above and learn the notes. Bye...... take care.