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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...