Types of nutrition

Autotrophic Nutrition -
Heterotrophic Nutrition" Holozoic-Parasites-Saprophytes -

In green plants autotrophic nutrition includes two important processes that are

Absorption of water& salts -
Photosynthesis -

The processes of absorption of water @ salts




Adaptation of the root hairs to their function

a- They are thin walled to allow the passage of salts & water

b- They are large in number to increase the area of absorption

c- The cell sap with high conic. solution to help the water to pass from the soil to the hair

d- They produce viscous substance to move easily between the soil particles. & to stick to the soil




Diffusion is the movement of molecules or ions from high concentrated medium to low concentrated, medium due o the continues free motion of molecules. as a drop of ink in water

Permeability

Different walls have different permeability , They can he classified into
Permeable walls, Example, cellulose cell wall
. Impermeable walls Example: lignin. subrin & cutin
. Simi-permeable walls Example cellophane sheet & plasma membranes

Osmosis: is the passage of water molecules from a high concentrated medium of water to a low concentrated medium of water, through a Simi permeable membrane.
Osmotic pressure is the pressure that causes osmosis

Imbibition:: is the ability of the colloidal substances to absorb water, swell& increase in volume. Cellulose in cell walls, pectin & proteins of the protoplasm are all colloidal substances

Water move across the cortex till it reaches xylem vessels by three ways,




From cell sap of one cell to another, by osmosis -

From the cytoplasm of one cell to another through plasmodesmata -

Water move through cell walls & the intercellular spaces by imbibition -

Water move through cell walls & the intercellular spaces by imbibition -
How is water directed to the xylem vessels & not to the phloem vessels

The endodermal cell that face the phloem vessels are completely thickened with impermeable -
subrin (Casparian strip) so water never go toward phloem

Water moves through (the passage cells) by osmosis -





absorption of mineral salts -

Types of nutrients

Essential nutrients ------------ Macro nutrients -------- Micro nutrients

( C , O , H )----------------------- (K,P,Ca,S,Mg,Fe,N)--------- (Al,Zn,Mn,Mo,Bo,Cl,I,Cu)

The plants micro nutrients need them in small amounts to activate enzymes-

Deficiency of Macro and Micro-nutrients would lead to

Disturbances in plant growth -

May stop plant growth completely -

May cause no production of flowers or fruits -

The mechanism of absorption of mineral salts

Diffusion -

Exchange ions -

Active transport -

It is the passage of any substance through the cell membrane against concentration gradient by the help of some chemical energy that released during aerobic respiration

An experiment on Nitella algae to prove active transport -

An experiment to prove that active transport Need energy -

How the Ions directed toward xylem -

When the ions reach the cytoplasm of the epidermal cells they diffuse freely & move from the cytoplasm of one cell to another through plasmodesma

By diffusion, by active transport (partially), through intercellular spaces of the cortex cells. Ions may be accumulated in the endoderm cells. Ions move from the endoderin cells to the xylem vessels by active transport

Photosynthesis in green plants

The importance s of photosynthesis are