Tag: water transport

Questions Related to water transport

Rising column of water does not break its connection with xylem walls despite negative pressure or tension due to

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. Cohesion amongst water molecules

  2. Strong transpiration pull

  3. Adhesion

  4. Surface tension

Show answer
Correct Option: C
Explanation:
The attraction between the molecule of dissimilar substances is called adhesion. Walls of tracheid and vessels of xylem are made up of lignin and cellulose and due to adhesive force, they have a close affinity for water. Thus, a rising column of water does not break its connection with xylem walls despite negative pressure or tension. 
So the correct answer is 'Adhesion'.

Root pressure theory cannot explain the ascent of sap because it is not found in 

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. Bryophytes

  2. All plants and in all seasons

  3. Trees

  4. Spring

Show answer
Correct Option: B
Explanation:
Root pressure theory is proposed by Priestly. It is defined as the pressure which set up in the cortical cells of the roots due to the osmotic action under which water passes from the living cells of the root in the xylem and thus helps in the ascent of sap. The ascent of sap also occurs in plants without roots and root pressure. Thus this theory cannot explain the ascent of sap.
So the correct answer is 'All plants and in all season'.

Which of the following factor is responsible for the transpirational pull?

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. High water potential in the leaf

  2. Low water potential in the leaf

  3. High solute potential in leaf

  4. Both B and C

Show answer
Correct Option: D
Explanation:

Transpiration is the process of water movement from soil solution into the plants and then to the atmosphere. The direction and intensity of water movement are determined by the difference in the water potential gradient between the two regions. The water potential in the leaf is lower which allows the movement of water in the upward direction. When the water potential is low, the solute potential is high. 

Thus, the correct answer is option D. 

Guttation is caused due to

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. High water potential.

  2. High root pressure.

  3. Low transpiration.

  4. All of the above.

Show answer
Correct Option: D
Explanation:

Guttation is the loss of water in liquid form as a dilute solution from the leaf tips. The uninjured leaf tips have hydathodes or water stomata. Under conditions of low transpiration dilute solution of minerals oozes out through them under the influence of increased root pressure. Water potential depends on the number of water molecules in the system. More the number of water molecules, greater will be the water potential. Under the conditions, when there are more water molecules in the system, water potential is expected to be higher. There is more water molecules will be stuffed up inside leaf in the intercellular spaces giving rise to a positive water potential. There is low transpiration and guttation takes place.

Thus, the correct answer is option D. 

The cut end of a shoot is dipped in eosine solution. What will happen?

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. Ascent of sap does not occur.

  2. Ascent of sap does not occur but the leaves remain fresh.

  3. Leaves will but ascent of sap continues.

  4. Ascent of sap occurs and the tracheary elements get stained.

Show answer
Correct Option: D
Explanation:
Eosine solution is a $1%$% alcoholic staining solution, that can be used for the staining of plant elements.
When a cut end of the stem is dipped in eosine solution, then due to concentration gradient diffusion occurs and hence ascent of sap occurs. Since it is staining agent it stains the tracheary elements.
So the correct answer is 'Ascent of sap occurs and the tracheary elements get stained'.


Deficiency of oxygen increases the rate of salt absorption

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

A deficiency of 0xygen always causes a corresponding decrease in the rate of mineral absorption. It is probably due to the unavailability of ATP. The increased oxygen tension helps in increased uptake of salts. So the given statement is false.

Choose the correct answers from the alternatives given.
What role cohesion and adhesion play in xylem transport?

water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. Like transpiration, they create a tension

  2. Like root pressure, they create a positive pressure

  3. Like sugars, they cause water to enter xylem

  4. They create a continuous water column in xylem

Show answer
Correct Option: D
Explanation:

Cohesion is the mutual attraction between water molecules. Adhesion is the attraction of water molecules to polar surfaces (such as walls of xylem vessels). These both forces together helps in the formation of a thin, unbroken column of water which leads to the mass flow of water in apoplastic pathway.

Hence, the correct answer is 'They create a continuous water column in xylem'.