TRANSPORTATION IN PLANTS
INTRODUCTION
Plants lack regular transport system like animals in transportation in plants. We know that plants prepare their food with the help of carbon di oxide and water. The place of photosynthesis is green leaves. Beside it, plants need other minerals like nitrogen and phosphorus . these minerals plant collect directly from the soil. The conduction of some materials to short height of plants occurs through diffusion. But for materials to reach longer distance needs proper transportation system. There are two pathways developed in plants independently which comprises Xylem Tissue and Phloem Tissue.
Both xylem and phloem tissues carry substances from one part of plant body to another. Xylem transports water and minerals which are available in the soil. Phloem transports products of photosynthesis from leaves to other parts of plants.
TRANSPORT OF WATER AND MINERALS IN TRANSPORTATION IN PLANTS
Xylem tissue of plants has interconnected network of vessels and tracheids. We found these structure in roots, stem and leaves. They form continuous system of water conducting channels which reaches all parts of the plants. At the roots, cells in the contact with the soil actively take up ions, creating a difference in the concentration of these ions between the roots and soil.
MECHANISM IN TRASPORTATION OF WATER AND AMINO ACIDS IN PLANTS
The water that enters into roots from soil eliminates this difference. In this way concentration becomes equal. Hence. There is a steady movement of water into root xylem from the soil. It creates a column of water which pushes water upwards. Plants uses another strategy for movement of water in upward direction in xylem is transpiration. It is applicable in plants with more height.
Transpiration in transportation of food and amino acids plants
The loss of water in the form of vapors from the aerial parts of the plant we term it as Transpiration. It takes place mainly through the stomata. These are present at the lower surface of leaf. Some amount of water is lost through the stomata. This water is replaced by water from xylem. Evaporation of water molecules from leaf’s cell or guard cell creates a suction or transpiration pull. This suction force pulls water from the xylem cells of the root. This process has some advantages:
- Water and minerals are dissolved in the soil which is absorbed by root hairs also with amino acids. By this process water goes upward through xylem.
- This process regulates temperature of plant.
- It maintains a constant supply of ions to the leaves .
- This process removes excess water from the plants.
TRANSPORT OF FOOD AND OTHER SUBSTANCES LIKE AMINO ACIDS IN TRANSPORTATION IN PLANTS
The movement of soluble products like sugar from photosynthesis from leaves to other parts of plants we terms as translocation. It occurs in the part of vascular tissues called phloem. Besides the products of photosynthesis, phloem also transports amino acids and plant hormones. Plants deliver these substances to the storage organs of roots , fruits , seeds and growing organs.
Companion cells along with sieve tubes helps in translocation of substances including amino acids, both in upward and downward direction. Phloem uses energy to achieve this process. Vascular tissue phloem transfers the sucrose by utilizing energy from ATP. It increases the osmotic pressure of the tissue causing water and amino acids to move into it.
There is less pressure which makes the movement of food material like vitamins amino acids etc in the tissues of phloem. This allows phloem to move material according to the plant need. For example, in the spring, sugar is stored in the roots and stem tissues. This sugar would be transported to the buds which need more energy for growth and development.
QUESTIONS RELATED TO TRANSPORTATION IN PLANTS
Qs1: What pulls up water through the xylem vessels in a plant?
Ans1: The continuous loss of water through stomata which means transpiration pulls up water through the xylem vessels in a plant.
Qs2: What is the role of transpiration stream?
Ans2: The transpiration stream helps the plants to maintain adequate minerals , amino acids uptake. Generally many essential minerals occur in low concentration in the soil.
Qs3: What is the significance of root pressure?
Ans3: The pressure with which water is pushed into the xylem tubes of the root we term as root pressure. The water along with amino acids moving upward forms a continuous column. Root pressure maintains this column up to certain height.
Qs4: Give one adaptation of plants that helps them to prevent excess loss of water through stomata.
Ans4: Waxy leaf cuticle helps plants to prevent loss of water through stomata by transpiration.
Qs5: Why have plants low energy needs?
Ans5: Plants have low energy needs as they do not perform physical movement and have a large proportion of dead-cells in many tissues.
Qs6: Which mechanism plays an important role in transportation of water in plants: (i)During day time (ii) At night?
Ans6: (i) During day time, the transpiration pull plays an important role in transportation of water in plants along with amino acids.
(ii) At night, root pressure plays an important role in transportation of water along with amino acids in plants.
Qs7: Transport of food in plants requires living tissues and energy. Justify the statement.
Ans7: Sieve tube in phloem transport food with expense of energy ATP. As phloem is largely composed of living cells, so it shows that food transport along with amino acids requires living tissues and energy.
Qs8: How does the plant transport water and minerals.
Ans8: Xylem transports water and minerals in plants. The cells in roots which are in contact with soil actively, can take up ions. In this way there is a creation of difference in concentration of ions between cell sap and soil water.Amino acids help in building protein or peptide bond.
Water moves into the roots to eliminate this difference of concentration forming a steady movement of water in the root xylem. This creates a column of water that is steadily pushed upward. Loss of water from leaves creates a suction that pulls water from the xylem of the roots to the aerial parts of the body.
Qs9: How food is transported in plants?
Ans9: The transportation of food along with amino acids is carried by phloem in plants by utilizing energy (ATP). This helps in increasing the osmotic pressure of the tissue causing water to move into it.
Thus, the generated pressure allows the movement of materials from phloem to the tissue which have less pressure.
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