Tag: botany

Questions Related to botany

A sufficient atmospheric pressure required to push the water upto the top of tall plants must be

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. 2 atm

  2. 6 atm

  3. 20 atm

  4. All of the above

Show answer
Correct Option: C
Explanation:

Taller plants like Eucalyptus need higher pressure to raise the water up. While the value of root pressure ranges from 2.5 atmospheres. A pressure of about 20 atm. is required to raise the water to tops of tall trees.

Which of the following statement is/are  not true :-
A.In CAM plants stomata open during dark and remain closed during the day
B.Role of $Na^{+}$ in stomatal opening is now universally accepted
C.The water potential of root cells is higher than the water potential of soil
D.Capillary theory is the most accepted theory of water movement through plants
E.The walls of xylem vessels made up of ligno-cellulose have strong affinity for water molecules.

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. B ,C and E only

  2. B ,C and D only

  3. A ,B and C only

  4. B and C only

  5. A and E only

Show answer
Correct Option: B

Force for passive water absorption develops in

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Xylem

  2. Aerial parts

  3. Root

  4. Root hairs

Show answer
Correct Option: B
Explanation:

The force for passive water absorption originates in the aerial parts of the plant due to loss of water in transpiration. This creates a tension or low water potential of several atmospheres in the xylem channels. 

Thus, the correct answer is option (B). 

The phenomenon which forces water upwards into tracheary elements of xylem in the root region is

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Transpiration

  2. Root pressure

  3. Turgor pressure

  4. Imbibition pressure

Show answer
Correct Option: B
Explanation:

Root pressure is the force in root region that helps to drive water or sap upwards into tracheary elements of xylem. Water is absorbed through the root hairs from the soil. During low transpiration there is no transpiration pull that time root pressure increases and water moves upwards in xylem elements

Force for active water absorption is present in

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Xylem

  2. Aerial parts

  3. Root

  4. Root hairs

Show answer
Correct Option: C
Explanation:

Active water absorption is the absorption of water due to forces present in the root. Living cells in active metabolic condition are essential for this. Auxins are known to enhance water absorption (even from hypertonic solution) while respiratory inhibitors reduce the same.

Thus, the correct answer is option (C). 

Cohesive force of water molecules is of the magnitude of 

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. 1 - 10 atm

  2. 10 - 15 atm

  3. 45 - 200 atm

  4. 15 - 45 atm

Show answer
Correct Option: C
Explanation:
Cohesive force is called as the tensile strength of water. It is the force which acts between the water molecules. The cohesive strength of 47-207 atm. in xylem sap is sufficient to meet the stress of transpiration pull so that water column does not break.
Thus, the correct answer is option (C). 

Rate of water absorption is slow near freezing point because 

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Water absorption is a metabolic process

  2. Cell growth stops

  3. Transpiration is reduced

  4. Cell membrane become more viscous

Show answer
Correct Option: D
Explanation:

Rate of water absorption is slow near a freezing temperature because decreased temperature results in the decreased root growth. Also, freezing temperature makes the cell membrane more viscous. There is resistance in water absorption as permeability of cell membrane decrease and viscosity increases.  

Thus, the correct answer is option D.

Prolonged water-logging kills plants due to

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Stoppage of root respiration

  2. Dilution of soil nutrients

  3. Dilution of plant cell sap

  4. Leaching of nutrients

Show answer
Correct Option: A
Explanation:
Waterlogging is the saturation of soil with water which excludes air from the groundwater. If waterlogging will be prolonged then air cannot reach up to groundwater and root and it will result in the stoppage of root respiration.
So, the correct answer is 'Stoppage of root respiration'.

Which of the following is not an important factor in the regulation of transpiration?

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Light

  2. Temperature

  3. Humidity

  4. Nitrogen content in the soil

Show answer
Correct Option: D
Explanation:

Transpiration is the evaporation of the water molecule from the upper surface of leaves.

(A) The intensity of light is directly proportional to the amount of transpiration.
(B) With the temperature increase, the transpiration also increases.
(C) Humidity also affects the rate of transpiration.
(D) The nitrogen content in the soil does not affect the regulation of transpiration.
So, the correct answer is 'Nitrogen content in the soil'.

The principle by which blotting paper absorbs water is 

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Capillary action

  2. Transpiration pull

  3. Root pressure

  4. Absorptive capacity

Show answer
Correct Option: A
Explanation:
(A)Capillary action is the name of force by which water or any sap is pulled upwards direct through fine fibres or tubes. Blotting paper absorbs the water through capillary action only as thin threads like structure are present in blotting paper.
(B)Transpiration pull is also the process of upward movement of sap but it occurs during the process of transpiration.
(C)Root pressure is the transverse osmotic force causing sap rise in plants.
(D)Absorptive capacity is the capacity of absorption.
So, the correct answer is 'Capillary action'.