Tag: long distance transport of water

Questions Related to long distance transport of water

Water drops present on leaf margins of Tropaeolum, balsam and grasses in early morning are due to

  1. Guttation

  2. Dew

  3. Osmosis

  4. Transpiration


Correct Option: A
Explanation:

Guttation is the loss of water in liquid form through hydathodes. Guttation is usually seen under environmental conditions when transpiration is low and soil is well watered. It occurs under the influence of positive root pressure. Water droplets present on leaf margins of some plants in the early morning is not due drops but the water that has oozed out from xylem tracheids. 

Guttation drops can be differentiated from dew drops

  1. By taste

  2. As dew drops will be seen

  3. As guttation drops will be restricted on the margins of the leaf

  4. All of the above


Correct Option: D
Explanation:

Guttation is the loss of water in liquid form through hydathodes. Guttation is usually seen under environmental conditions when transpiration is low and soil is well watered. It occurs under the influence of positive root pressure. Water droplets present on leaf margins of some plants in the early morning is not due drops but the water that has oozed out from xylem tracheids. Xylem tracheids contain dissolved minerals in the water. Hence water lost in guttation is not pure water but a solution of minerals and will not be tasteless as the pure water of dew drops.

Loss of water from tips of leaves is called as

  1. Bleeding

  2. Guttation

  3. Respiration

  4. Transpiration


Correct Option: B
Explanation:

Loss of water in vapour form through stomata is called as transpiration. Loss of water in solution form through vein endings in leaves is called as guttation. Transpiration occurs under the influence of vapour pressure gradient. Guttation is caused due to root pressure when soil is well watered and transpiration is low due to high atmospheric humidity.

Water lost in guttation is

  1. Pure water

  2. Impure water

  3. In vapour form

  4. None of the above


Correct Option: B
Explanation:

Guttation is the loss of water in solution form through hydathodes. It occurs under the influence of root pressure. When transpiration is low and plant absorbs water from well-watered soil under the influence of root pressure. The excess water oozes out as a dilute solution of minerals and other solutes from dead endings of veins. Thus, the correct answer is option B.

The hydathodes are related with

  1. Transpiration

  2. Guttation

  3. Bleeding

  4. All of the above


Correct Option: B
Explanation:

Guttation is defined as loss of water in liquid form through water stomata or hydathodes. The water is lost as a dilute solution of mineral salts. Guttation occurs under the influence of positive root pressure.

Guttation take place during night when

  1. Root pressure is positive

  2. Root pressure is negative

  3. Always take place

  4. It does not takes place at all


Correct Option: A
Explanation:

Guttation is the loss of water in liquid form as a dilute solution from uninjured 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. Thus, mostly guttation is observed during night time when transpiration is low, for example, due to high atmospheric humidity and sufficient water is present in soil. The most important force responsible for guttation is positive root pressure.

Guttation takes place through

  1. Lenticels

  2. Pneumatophores

  3. Stomata

  4. Hydathodes


Correct Option: D
Explanation:

Guttation is the loss of water in the form of the dilute solution which consists salts and minerals through stomata or hydathodes. Guttation occurs under the influence of root pressure when soil is well watered but humidity is high consequently transpiration is less.

The whitish powder around hydathode is due to 

  1. Guttation

  2. Salt depositon from air

  3. Salt formation over surface

  4. Bleeding


Correct Option: A
Explanation:

Loss of water as dilute solution of minerals and salts from hydathodes is called as guttation. It is prominently seen when transpiration is low but root pressure is high. When water evaporates, the mineral salts are left behind as whitish deposits.

Therefore, the correct answer is option A.

Which of the following is not a rhythmic phenomenon?

  1. Stomatal opening and closing

  2. Guttation

  3. Nyctinasty

  4. Photonastic movement


Correct Option: B
Explanation:

The movements showed by plants can be classified broadly as
(1) Hygroscopic- due to loss or gain of water and
(2) Vital- due to irritability of the cytoplasm. 
Nyctinasty or sleep movements are rhythmic movements, also called as sleep movements and are caused by relative changes in cell size on the opposite sides of the leaf base called as pulvinus. 

Photonasty is the nastic movement caused in response to light. 
Guttation is the loss of water in solution through hydathodes. This is not an example of rhythmic movement and depends on environmental conditions. Thus, the correct answer is option B.

Which condition favours guttation?

  1. High water absorption

  2. High transpiration

  3. Low transpiration

  4. Both A and C


Correct Option: D
Explanation:

Guttation is the loss of water through water stomata (hydathodes) in solution form as a dilute solution of mineral salts. This process occurs, when the absorption of water exceeds transpiration i.e., when plants are absorbing water actively. A positive root pressure is built up under the influence of which excess water simply oozes out through the dead ends of xylem tracheids and vessels. Thus, the correct answer is option D.