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PROTOXYLEM:  The first formed primary xylem is called protoxylem METAXYLEM: The later formed primary xylem is considered as metaxylem. EXARCH: If protoxylem lies towards centre that is towards pith and metaxylem lies towards periphery then type of primary xylem is called exarch. ENDARCH: If protoxylem is towards periphery and metaxylem is towards centre(pith) then such arrangement of primary xylem is called as endarch.

PROTOPHLOEM: The phloem containing narrow sieve tubes. such first formed primary phloem is considered as protophloem. METAPHLOEM: Phloem containing larger sieve tubes. such later formed phloem is called metaphloem.

ARRANGEMENTS IN VASCULAR BUNDLES RADIAL: When xylem and phloem in a vascular bundles are arranged in alternate manner on different radii then such arrangement is called Radial arrangement. CONJOINT: Xylem and Phloem when arranged on same radii in the vascular bundles is considered as Conjoint. OPEN: When xylem and phloem are seperated by vascular cambium. Such arrangement with cambium is considerd as Open vascular bundles as in Dicots. CLOSED:  Vascular cambium is absent in between the xylem and phloem such arrangement of vascular bundles with no cambium is called Closed vascular bundles as in Monocots.

 TWO MAIN DIFFERENCES BETWEEN C3 AND C4 PLANTS: There are two main differences which exhibits in C3 and C4 plants internally. They are: 1. Kranz anatomy in C4 plants and absent in C3 plants. 2. Photorespiration in C3 plants and absent in C4 plants. Now this explanation will help you to understand the differences. In C4 plants, internal strucutre of leaf has bundle sheath cells around the vascular bundlles. Such anatomy of leaves are considered as Kranz anatomy . The cells contain chloroplast and it is impervious to gases exchange and no intercellular spaces in it. In C3 plants photorespiration process takes place. It is stated that photorespiration is a wasteful process because it does not yield ATP and NADPH but rather it utilises ATP to release CO2. In C4 plants it lacks because they have a mechanism that increase CO2 concentration and has a capacity to minimise the oxygenase activity. so in  C4 plants productivity and yield is better th...

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...