Dear Sir/Madam

Please explain me absorption of  minerals by root hair and also absorption of water separatrely




Asked by arti.aggarwal17 | 13th Feb, 2019, 08:01: AM

Expert Answer:

Mechanism of Transport of Water and Minerals

Root Pressure

  • Water enters the root hair through osmosis, and mineral ions enter the root cells by active transport.
  • Both water and minerals move upward from cell to cell through the cortex of the root by osmosis.
  • From the cortex, water and minerals are brought to the xylem.
  • The sap which contains water and dissolved minerals move upwards from the root cells through the xylem. The upward movement of sap is called the ascent of sap.
  • The xylem vessels of the roots are in continuation with the xylem vessels of the stem.

Transpiration Pull

  • Transpiration is the loss of water in the form of water vapour from the aerial parts of a plant.
  • It occurs through openings called stomata.
  • Water loss through evaporation lowers the concentration of water inside the mesophyll cells.
  • Due to this, water enters mesophyll cells from neighbouring xylem vessels through osmosis.
  • As water evaporates from the leaves, a suction force is created. This force helps to draw more water up through the stem which causes the roots to absorb more water from the soil.
  • Higher the rate of transpiration, greater the rate of absorption of water and solutes from the soil.
  • Transpiration also helps in maintaining the temperature of the plant body.

Mechanism of Transport of Food

  • Food synthesised during photosynthesis is loaded into sieve tubes by utilising ATP.
  • The presence of food inside the phloem develops the concentration gradient of water. Thus, water enters the phloem by osmosis.
  • Osmosis develops high pressure inside the phloem which transports the food from the phloem to plant parts where the concentration of food is less.
  • This process is called translocation.
  • In spring, the sugar stored in the root or stem tissues is transported to the buds. 

Answered by Sheetal Kolte | 13th Feb, 2019, 11:48: AM