Question

Passive absorption of water from the soil is mainly affected by
a. Tissue organisation of root
b. Sucking power of root hairs
c. Tension of cell sap due to transpiration
d. Osmotic concentration of cell sap

Answer 1

Passive absorption means movement along a concentration gradient and does not require energy. The term was first coined by Renner. Here only the roots act as an organ or part of assimilation. Therefore, it is also called "through root". Its rate is fast during the day in plants,

Complete answer:
Passive absorption means movement along a concentration gradient and does not require energy. The term was first coined by Renner.
Passive absorption depends on the following factors:
• Root system: The number and length of root hairs and the length of the root hair area determine how much water is absorbed by the soil. The root hairs regulate the surface area in contact with the water capillaries.
• Root Range and Depth: It has also been observed that the deeper parts of the root are less effective at absorbing water than the shallower parts.
• Root Metabolism Model: Since the lifespan of root hairs is short, the hair becomes dry and stops functioning. So, there is a need for new root hair creation. Thus, the constant formation and growth of root hairs promote water absorption. Root hair metabolism also affects water absorption.
• Availability of soil water: The amount of water in the soil influences the rate of water absorption
• The concentration of salts: If the soil water is rich in minerals this increases the osmotic potential of the soil. Such soils are termed physiologically dry.
• Soil hair: The amount of aeration of soil greatly influences the water absorption. A soil which is waterlogged or has low oxygen is also physiologically dry high percentage of CO2 is detrimental to the absorption of water. Poorly aerated soils show decreased root growth and the lesser surface is available for permeability.
• The air in soil: The degree of aeration of the soil has a large effect on moisture absorption. Even soils with a registered water content or low oxygen content are physiologically dry, and a high carbon dioxide content negatively affects water absorption. Poorly ventilated soil reduces root growth and root permeability.
• Transpiration: The absorption of moisture is also closely related to the rate of perspiration. Sweat is known to cause stress due to water loss. Consequently, high levels of perspiration increase moisture absorption.
• Soil temperature: maximum absorption rate at fifteen to twenty degree. Even cold soils are physiologically dry. Low temperatures affect root metabolism. In particular, it affects permeability and kidney function.

Hence, the correct answer is option (C).

Additional information:
Passive water intake usually occurs when transpiration rates are high. The rapid evaporation of water from the leaf during evaporation creates water pressure in the throat of the leaf. This tension is transferred through the xylem of the stem to the water in the root xylem the water rises to reach the transpiration surface water. This force for water penetration is created due to the rapid evaporation of the leaves, so the root cells remain passive in this process.

Note: Even without roots, passive water absorption can occur. Root cells do not play an active role in this type of water absorption. Transpiration creates tension in the neck. This water absorption takes place in the buds. This type of absorption takes all year round. Passive water recovery occurs in all types of plants. It uses radiation energy, and metabolic poisons have no direct effect on passive water absorption. Passive water recovery creates negative pressure in the throat canal. Appears in the form of perspiration.