Question

Write the function of xylem and phloem cells.

Answer 1

There is a need for transport system in plants to move water, minerals and food around. Such systems utilize continuous tubes called xylem and phloem. Xylem parenchyma, xylem vessels, xylem fibres and tracheids are the components of xylem. Sieve tube elements, phloem fibres, phloem parenchyma and companion cells together constitute phloem.

Complete answer
Xylem transports water and minerals from root to the whole body of the plant. Its basic function is to move water from roots to leaves and shoots.
Phloem transports food materials to the whole plant body. Its basic function is transport of food from source tissues.
Xylem is a specialized cell of vascular plants. It provides mechanical support and storage. It provides strength to organs and tissues, maintaining architecture of plants and resisting bending. Xylem is the wood, which is the world’s most valuable and abundant raw material. Genetic engineering has great scope to develop xylem with desired qualities for specific functions. The morphology, distribution and frequency of xylem cell types determine its physical, chemical and biological properties and the wood’s resulting properties. Vessel elements conduct water and tracheids transport xylem sap and provide structural support Except xylem parenchyma, all elements of xylem are dead, so it is a non-living entity.
Phloem is responsible for the transport of sugars from source tissues (leaf cells performing photosynthesis) to sink tissues (developing flowers and non-photosynthetic root cells). Proteins and mRNAs are transported throughout the plant through phloem.
Sieve tubes are primarily cell walls. Phloem fibres are dead cells possessing lignified cell walls. Phloem parenchyma located the termination of sieve tubes has the function of storage and translocation of food. Companion cells provide energy to sieve tubes for the transport of food.

Note:
Phloem often pairs with xylem and carries out function. Pressure in xylem is lesser than the atmospheric pressure. But, the pressure in phloem is greater than the atmospheric pressure. Xylem does the function of transport in only one direction. But, phloem performs transport functions in different directions. Xylem is mostly non-living structure, whereas phloem is living structure with long and thin cells perforated by tiny pores.