The minerals absorbed are transported up the stem, to all parts of plant through the transpiration stream. The chief sinks for the mineral elements are the growing region of the plant, such as the apical and lateral meristems, young leaves, developing flowers, fruits, seeds and the storage organs. Unloading of the mineral ions occurs via fine vein endings through diffusion and active uptake by the cells. In plants, xylem are involved in transport of inorganic nutrients where phloem transport only organic materials.

Mineral ions are frequently remobilised from older parts of plant like leaves to the younger regions. Elements most readily mobilisal are phosphorus, sulphur, nitrogen, potassium, and some elements that forms the structurel component are not remobilised e.g., calcium.

The plant exudate (plant sap) is a mixture of the organic/inorganic compounds and ions, minerals, sugars and amino acids. If we chemically analyse these we can get to know which mineral nutrient is transported in which form in the plants. e.g., nitrogen is absorbed and transported a is $\mathrm{NO}_2$ and $\mathrm{NO}_3$ and sulphur in sulphate ion forms etc.

The life of cut plant in a vase can be increased by placing them in water immediately as air will rapidly move into the water conducting tissue and plug the cell. Also, providi nutrients and elements in a varied concentration can increase the life span of plants.

One phytohormone called cytokine can also be sprayed or plants can be dipped in the solution, as it delays the senescence of plant.

The rate of transpiration depends on number of factors. If the two species are related and have similar morphology then only external factors will determine the rate of transpiration like wind velocity, humidity temperature, light intensity etc.

Properties of water that make it useful for all biological processes on the earth are

(i) Water is the major solvent through which mineral nutrients enter a plant from the soil solution.

(ii) It is an ideal solvent with neutral pH .

(iii) Water is the major constituent of protoplasm. It constitute approximately $90 \%$ of the protoplasm.

(iv) Water act as a medium for translocation of nutritive substances. Mineral nutrients are absorbed by the roots. Carbohydrates that are formed during photosynthesis are transported by water from cell to cell, tissue to tissue and organ to organ.

(v) In plants, water is involved in photosynthesis by incorporating hydrogen atom into carbohydrate and oxygen atoms are further released as $\mathrm{O}_2$.

(vi) Water act as agent for temperature control. The specific heat of water helps plant in aintaining a relative stable internal temperature.

(vii) In some plants water is necessary for pollination. Like in bryophytes and pteridophytes, they essentially require water for the fertilisation process.