Tag: absorption by roots - the processes involved

Questions Related to absorption by roots - the processes involved

The cause of guttation is mainly due to

  1. Root pressure

  2. Osmosis

  3. Transpiration pull

  4. Cohesive force


Correct Option: A
Explanation:

Guttation is a loss of water from plants in liquid form through hydathodes. The force responsible for guttation is positive root pressure. Guttation is easily observed when transpiration rate is low and soil is well watered.

So, the correct answer is option A.

The pressure exerted on the fluid contents of the cortical cells of root by turgidity, which forces the water into xylem vessels and upward into stem for a certain height is

  1. Imbibition

  2. Root pressure

  3. Capillarity

  4. None of the above


Correct Option: B
Explanation:

Root pressure helps to pull the cell sap through a plant stem to the leaves. It occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the day.

So, the correct answer is option B.

Root pressure in maximum, when

  1. Transpiration is high and absorption is very low.

  2. Transpiration is very low and absorption is high.

  3. Absorption is very high and transpiration is also very high.

  4. Absorption is very low and transpiration is also low.


Correct Option: B
Explanation:

When transpiration is low and soil is generally well watered, a positive root pressure develops. Under the influence of positive root, pressure water oozes out from ends of xylary elements in plants. The main reason for the development of positive root pressure is the active absorption of minerals and water by roots.

So, the correct answer is option B.

Which apparatus is used in the measurement of root pressure ______________.

  1. Potometer

  2. Manometer

  3. Auxenometer

  4. Barometer


Correct Option: B

Guttation is dependent on

  1. Root pressure

  2. Active absorption

  3. Flaccidity of root cortical cells

  4. High rate of transpiration


Correct Option: A
Explanation:

Transpiration is defined as loss of water as gas or vapors from aerial parts, like leaves through the stomatal pore. If there is less of transpiration as due to high atmospheric humidity and the soil is well watered; there will be an increase in root pressure. The increased root pressure leads to oozing out of a solution of minerals from hydathodes (called as guttation) and other openings (called as bleeding). 

So, the correct answer is option A.

Pressure caused by water entering the root from soil is known as

  1. Imbibition 

  2. Root pressure

  3. Turgor pressure

  4. Wall pressure


Correct Option: B
Explanation:

Root pressure can be defined as the pressure exerted by the cortical cells of the root upon the sap in the xylem vessels which pushes the sap upward if the stem of the plant is cut just above the root water seeps or exudes out of the cut end of the stem for a considerable period of time. This indicates that there is a force pushing water up the stem from the roots.

1 atm pressure can raise water to a height of more than _____

  1. $10$ feet

  2. $20$ feet

  3. $100$ feet

  4. $32$ feet


Correct Option: D
Explanation:

One atmospheric pressure can raise water to a height of more than $32$ feet. so a pressure of about $13$ atmospheres would be required to raise water at the top of a $416$ feet high tree. The tension developed in the xylem sap of trees that are actively transpiring can be measured only indirectly and has been found to be high as $-77$ bars.

How much pressure would be required to raise water to the top of a $416$ ft. high tree ?

  1. $1$ atm

  2. $13$ atm

  3. $-77$ bars

  4. All of the above


Correct Option: B
Explanation:

One atmospheric pressure can raise water to a height of more than $32$ feet. So a pressure of about $13$ atmospheres would be required to raise water at the top of a $416$ feet high tree. The tension developed in the xylem sap of trees that are actively transpiring can be measured only indirectly and has been found to be high as $-77$ bars.

Root pressure helps in


i Continuous flow of water in plants
ii Pulling force
iii Replacement of lost water

  1. i, ii

  2. ii, iii

  3. i, iii

  4. All of the above


Correct Option: C
Explanation:

Root pressure provides a force which causes pushing of water in a stem. A continuous flow of water is maintained in the plants because the leaves transpire water through stomata and to replace the lost water the water drawn by the roots moves up.