Tag: absorption by roots - the processes involved

Questions Related to absorption by roots - the processes involved

If the stem of the plant is cut just above the root then

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Water will seep or exude out of the cut end for a considerable amount of time.

  2. Water will seep or exude out of the cut end continuously

  3. Both A and B

  4. None of these

Show answer
Correct Option: A
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 upwards 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.

Root pressure is a _______

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Pulling force

  2. Pushing force

  3. Both A and B

  4. None of these

Show answer
Correct Option: B
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.

Root pressure can be measured by

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Attaching a barometer to the cut end of the stem

  2. Attaching a manometer to the cut end of the stem

  3. Attaching a thermometer to the cut end of the stem

  4. Attaching a potometer to the cut end of the stem.

Show answer
Correct Option: B
Explanation:

The root pressure can be measured by attaching a suitable mercury manometer to the cut end of the stem. Root pressure provides a force which causes pushing of water in the 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.

Root pressure is maximum when

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Transpiration is high and absorption low

  2. Transpiration is very low and absorption is high

  3. Transpiration is very high and absorption is high

  4. Transpiration and absorption both are slow

Show answer
Correct Option: B
Explanation:

Root pressure is the positive pressure that develops in the roots of the plants by active absorption of nutrients from the soil. The active absorption depends on the active accumulation of solute in xylem sap. Root pressure in maximum when transpiration is very low and absorption is high because transpiration is the output of water from a plant, and absorption is the input of water into a plant. If the output is low and input is high, the pressure will be at its greatest. 

So, the correct answer is 'Transpiration is very low and absorption is high'.

Who defined the term root pressure? 

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Stephan Hales

  2. Mendel

  3. Griffith

  4. Godiewski

Show answer
Correct Option: A
Explanation:

Root pressure is defined as the osmotic pressure in the root cell through which the water is translocated into leaves from the stem. The term root pressure was given by Stephan Hales. Thus the correct answer is option A.

Root pressure is maximum when

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Transpiration is high and absorption is very low

  2. Transpiration is very low and absorption is high

  3. Transpiration is very high and absorption is also high

  4. Transpiration and absorption both are slow

Show answer
Correct Option: B
Explanation:

Stephentiales (1727) coined the term root pressure. Root pressure is developed when rate of water absorption is more than the rate of transpiration.

Which of the following statement is wrong in root-presure concept of ascent of sap ?

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Water can be raised to a height of 6'-7'.

  2. Water moves upward in the absence of shoot.

  3. Water moves by this force is slow.

  4. Root pressure operates in all the plants.

Show answer
Correct Option: D
Explanation:
Root pressure is not operated in lower plants and plants of small height and aquatic plants because they have several other mechanisms to conduct water. Root pressure 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 'Root pressure operates in all the plants'.

Root pressure may be caused by 

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Osmotic flow of water into xylem of absorbing part of root.

  2. Loss of water from xylem of the plant due to transpiration.

  3. Low water potential of leaves.

  4. High water potential of leaves.

Show answer
Correct Option: A
Explanation:

When there is no transpiration then due to lack of transpiration pull water does not move upwards. At this time through osmosis water is absorbed from the soil and it accumulates in xylem region of the root .The accumulation through osmosis causes root pressure and water moves upwards.
Thus, the correct option is (A).

Root pressure is due to  

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Active absorption/ transportation

  2. Passive absorption/ transport

  3. Increased transpiration

  4. Increased photosynthesis

Show answer
Correct Option: A
Explanation:
(A)Active absorption is the absorption of water by roots with the help of ATP.
Root pressure is due to active absorption and active distribution of mineral nutrients. It is measured by potometer.
(B)Passive adsorption is the energy independent process.
(C)Transpiration is the evaporation of water from the upper surface of the leaves.
(D)Photosynthesis is the process of making of glucose.
So, the correct answer is (A) 'Active absorption/ transportation'.

Exudation of xylem sap on cutting of a shoot is due to

biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

  1. Gutttation

  2. Root pressure

  3. Transpiration

  4. None of the above

Show answer
Correct Option: B
Explanation:
(A) Guttation is the secretion of droplets from the pores of the tree.
(B) When stem base is cut xylem sap releases and it is due to root pressure [It push the xylem sap upward so when we cut stem base the pulling force of root pressure works].
(C) Transpiration is the evaporation of water from the upper surface of the leaves.
So, the correct answer is 'Root pressure'.