The key difference between ascent of sap and translocation is that ascent of sap is the transportation of water and minerals from the root to aerial parts of the plant through the xylem, while translocation is the transportation of foods/carbohydrates from leaves to other parts of the plant through the phloem.
What is the ascent of sap?
The ascent of sap is the movement of water and dissolved minerals through xylem tissue in vascular plants. Plant roots absorb water and dissolved minerals from the soil and hand them over to the xylem tissue in the roots.
What causes the ascent of sap in plants?
According to this theory, atmospheric pressure is responsible for the ascent of sap. Due to active transpiration, a vacuum is created in the xylem vessels, and to fill this vacuum, and water moves upward from below so as to equalise the pressure.
Does root pressure play a part in the ascent of sap?
Especially during the spring season root pressure does play a part in the ascent of sap in some plants. If the leafy top of a plant is cut off, the stump frequently bleeds. The exudation is sap. The pressure which causes exudation originates from osmotic forces in the roots and hence is called root pressure.
What are the three forces that cause ascent of sap?
Ans: Ascent of sap is caused due to the three kinds of forces. They are cohesive forces between the water molecules, the adhesive force between the water molecule and the walls of xylem vessels, and the transpiration pull. Q.3. What are the functions of the ascent of sap?
What are the Similarities Between Ascent of Sap and Translocation?
The ascent of sap and translocation occur through the vascular tissues of vascular plants.
What is Ascent of Sap?
The ascent of sap is the movement of water and dissolved minerals through xylem tissue in vascular plants. Plant roots absorb water and dissolved minerals from the soil and hand them over to the xylem tissue in the roots. Then xylem tracheids and vessels transport water and minerals from roots to aerial parts of the plant. The movement of the ascent of sap is upward.
What is the process of transporting water and minerals from the root to the aerial parts of the plant?
Thus, this process is called translocation.
How does sap work?
The ascent of sap takes place due to the passive forces created by several processes such as transpiration, root pressure and capillary forces, etc. Most importantly, when transpiration occurs in the leaves, it creates a transpiration pull or the suction pressure in leaves. The transpiration pull of one atmospheric pressure can pull the water up to 15-20 feet in height according to the estimations. Root pressure also pushes water upwards through the xylem. Water enters root hair cells due to low water potential inside the cell than the soil. When water accumulates inside the roots, a hydrostatic pressure develops in the root system, pushing the water upwards. Likewise, as a result of several passive forces, water moves from roots to upper parts of the plant.
Where does translocation take place?
Translocation takes place from sources to sink. Plant leaves are the primary source of translocation since they are the main sites of photosynthesis in plants. Sinks can be roots, flowers, fruits, stems, and developing leaves. Phloem translocation is a multidirectional process.
Does sucrose travel through the phloem?
Moreover, it utilizes energy during phloem loading and phloem unloading. Food travels along the phloem as sucrose. At the source, sucrose actively loads into the phloem tissue. In contrast, at the sink, sucrose actively unloads into the sink from the phloem tissue.
Where does the ascent of sap occur?
Ascent of Sap is defined as the translocation of water, usually upwards from the roots towards the top of the plant through the stem, i.e., to the leaves and growing points or apical meristems and other aerial plant parts.
When does root pressure appear to be absent?
Root pressure seems to be absent in summer when the water requirement is high. It is generally observed at night when evapotranspiration is low. 3. Physical Force Theory. As per this theory, the ascent of sap takes place through the dead xylem vessels.
What is the ascent of sap?
Meaning of Ascent of Sap: The upward movement of water from the root to the top of the plant is called as ascent of sap. Plants absorb water through the roots and transpire through leaves. The water moves from the root to the tip portion of the plant body against the force of gravity. The mechanisms involved in the transport ...
Why does sap rise?
According to him, the ascent of sap is due to the pulsatory activity of the inner-most layer of the cortex, just outside the endodermis.
Where does sap take place?
The ascent of sap takes place in the lumen of vessels and tracheids situated between the parenchyma root hair and cortex of the root below, and the mesophyll tissue of the leaf above. A number of theories have been put forward from time to time to account for the ascent of sap.
Who put forward the relay pump theory to explain the ascent of sap?
Godlewski (1884) put forward his relay pump theory to explain the ascent of sap. He thought that the upward movement of water was due to the pumping activity of the cells of wood parenchyma and medullary rays brought about by the periodic changes in their osmotic pressure.
Do plants exude xylem sap?
Under certain conditions, plants exhibit exudation of the xylem sap from the stump of a freshly cut stem.
When is the ascent of sap low?
ADVERTISEMENTS: (1) Root pressure is absent in woody plants, as secondary growth occurs is wood plant roots. (2) When root pressure is high, during night, then ascent of sap is low. Especially during the spring season root pressure does play a part in the ascent of sap in some plants.
Where are the forces required for ascent of sap generated?
According to these theories the forces required for ascent of sap are generated in living cells of plants.
Why does sap rise?
According to Godlewski (1884) ascent of sap takes place due to rhythmic change in the osmotic pressure of living cells of xylem parenchyma and medullary ray. These are responsible for bringing about pumping action of water in upward direction.
What is root pressure?
ADVERTISEMENTS: (i) Root pressure is the water pressure developed in the xylem of the roots when the rate of active absorption of water is greater than the rate of transpiration. (ii) In root cells, the xylem sap is hypertonic to the cell saps of other root cells. This is because, the salt ions absorbed by the roots from ...
Which theory of imbibition is responsible for ascent of sap?
A. Sachs imbibition theory: (i) According to this theory imbibition by thick walls of xylem vessels is responsible for ascent of sap. (ii) Sachs considered hydrophilic colloidal substances present in cell wall of vessels to be responsible for this process.
How does root pressure work?
3.2). Attach fine glass tube to the stump of actively growing plant. As water is forced up through the stem, the water column in glass tube rises, indicating that root pressure is operating.
What is the process by which water and minerals translocate from base to apex of the plant?
The process by which water and minerals translocate from base to apex of the plant is known as ascent of sap. It takes place through complex tissue xylem.