Title 11 Transport in plants ppt - part 5.pdf ✅

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• It is the long-distance movement of organic substances (food, primarily sucrose) from a source (region of synthesis the food i.e., the leaf) to a sink (region of storage or utilization of food) through the phloem. • The source and sink may be reversed depending on the season, or the plant’s needs. E.g. In early spring, the sugar stored in roots is moved to the tree buds for growth and development of photosynthetic apparatus. Thus root becomes the source and buds the sink. bankofbiology.com
• Direction of movement in the phloem can be upwards or downwards (bi-directional). • In xylem, the movement is always upwards (unidirectional). Hence, food in phloem sap can be transported in any direction. • Phloem sap is mainly water and sucrose, but other sugars, hormones and amino acids are also translocated. bankofbiology.com