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PIGMENTS: Pigments are the substances that have an ability to absorb the light at different wavelengths. There are four types of pigments in plant. They are: 1.Chlorophyll a- (bright or blue-green) 2.Chlorophyll b-(yellow green) 3.Xanthophylls-(yellow) 4.Carotenoids-(yellow to yellow-orange)  * Chlorophyll a is the most abundant pigment responsible for trapping light. Other pigments are accessory pigments which protect chlorophyll a from photo-oxidation .

   In plants, growth starts from the germination of seeds. Then it develops internally and externally forming various parts. Plants undergoes primary and secondary growth which differs from each other in many ways. Primary growth in plants exhibits in plants within 1 year then plant undergoes secondary growth. PRIMARY GROWTH IN PLANTS: Primary growth in plants takes place inside the stem. Both dicotyledenous and monocotyledenous plants undergoes primary growth, and of course they show some variations. IN DICOTYLEDENOUS PLANTS: Stem consist of three zones . They are: 1.EPIDERMIS 2.GROUND TISSUE 3. STELE 1.EPIDERMIS: It is the outermost layer covered by cuticle. Epidermis protects the inner parts of the stem. Cuticle covers the epidermis and helps in transpiration. It may have trichomes and stomata. 2. GROUND TISSUE: The tissues other than vascular bundles and epidermis is considered as ground tissue. It is again divided in...

STOMATA: Stomata are the structures which is present on the epidermis of leaf mainly but in some plants it is also present in stems. *In Monocots stomata is dum-bell in shape *Whereas in Dicots it is bean shaped. Stomata consist of two types of cells. They are: 1. Guard cells 2. Subsidiary cells. 1. Guard cells: In Dicots the guard cells are bean shaped whereas in monocots guard cells are dum-bell shape. There are two guard cells in each stomata. As the stomata is bean shaped, the curved walls of stomata are thin and it has elasticity which means it has microfibrils through which water gets absorbed by the cell. A stomatal pore is present between the two guard cells. Inside the guard cells cytoplasm, organelles and chloroplast is present. Chloroplast helps in photosynthesis. When the cell absorbs the sunlight, chloroplast gets activated and forms sugars inside the cell. as a result the concentration inside the cells gets...

TRANSLOCATION OF MINERAL IONS: Different ions when reached to the xylem through active or passive transport, then further transport takes place through transpiration. The mineral elements sink at the growing regions of the plant such as the apical and lateral meristems, young leaves, developing flowers, fruits, seeds, and the storage organ. When the old parts gets dies or leaves fall off before dying the minerals get remobilised to the younger parts of the plant. Older leaves exports the minerals to the younger leaves. the elements which gets mobilised are Phosphorous, Sulphur, Nitrogen and Potassium. But the Calcium will not get mobilised. Much of the elements are carried in the form as Amino acids and related compounds. Phosphorous and Sulphur carried as organic compounds and Nitrogen is carried out as Inorganic compound. Hence, it is not that xylem transports only inorganic substances and phloem carries organic substances as it is traditionally believed. They both c...

Transpiration pull: In higher plants water is transported through xylem. This movement is accomplished by 'pulling' of water to the leaves of the plant. This is referred to as cohesion-tension-transpiration pull model  of water transport. This takes place in the higher plants . Transpiration  Less than 1 percent of water is utilized in the process of photosynthesis. Water is lost from the plants through stomata in the form of vapour on the surface of leaves. This process of removing water through stomata of leaves in the form of vapour is called as Transpiration.

DORSIVENTRAL LEAF: The dorsiventral leaves are found in dicots. In the vertical section of dicot leaf there are mainly divided into three parts. They are. Epidermis Mesophyll Vascular Bundles Epidermis: The upper and lower epidermis of leaf is covered by cuticle. The Adaxial(lower) surface has more number of Stomata than upper surface.Sometimes the upper surface lacks Stomata. Mesophyll: The layer present between the upper and lower epidermis is called as mesophyll. It possess chloroplast and carry out photosynthesis. it contains parenchymatous cells. Mesophyll is two types of parenchymatous cells.     -Palisade parenchyma     -Spongy parechyma Polisade parenchyma is an elongated cell,arranged vertically and parallel to each other. present on upper side of mesophyll Spongy parenchyma are oval or round loosely arranged situated below the palisade parenchyma extending to the lower epidermis. it contai...

ISOBILATERAL LEAF (MONOCOTYLEDENOUS): General features: Isobilateral leaves are found in Monocot leaves. Stomata is equally distributed on lower(abaxial) and upper(adaxial) surface of the leaf. Cuticle covers both upper and lower surface of the leaf. Leaf  is distinguished into three parts. Theyare              -Epidermis              -Mesophyll              -Vascular bundles Epidermis has stomata and cuticle.  In monocots Mesophyll is not defferentiated into polisade and spongy parenchyma unlike in Dicots.  Vascular bundles are seen in the mid-ribs and veins of the leaf. The size of the vascular bundle is depend on the size of the veins. Parellel venation is present in monocot leaves. In grasses ,certain upper epidermal cells along the veins modify themselves into large empty colourless cells.these are called Bulliform...