Question

Which one of the following helps in the upward movement of water and dissolved minerals from the roots to the leaves through the stem
(a) Translocation
(b) Transportation
(c) Transpiration
(d) Transaction

Answer 1

Hint: The stomatal apparatus release water and moisture to the surroundings. This causes the plant to absorb more water through roots and transport it upwards along with dissolved nutrients. So, the process of excretion of moisture and gases through stomata is the cause for upward movement of water and minerals.

Complete answer:
The process in which the moisture and gaseous wastes are excreted through the stomata present in the leaves and lenticels of the stem and fruits is termed as transpiration. Through this process, the water present in the plant body is excreted out into the atmosphere to keep the plant cool and allow the root to absorb more water and important nutrients from the soil. The rate of transpiration is affected by light, humidity, temperature and leaf surface.
- Transpiration Pull: It is the process in which a force of pulling is produced inside the xylem tissue. This force causes the upward movement of the water column in the xylem vessels. This occurs in all higher plants and trees. This theory is also called cohesion- tension theory.
- When the process of transpiration occurs, a suction pressure is created as water is lost to the atmosphere. Due to this suction force, the water molecules in the xylem adhere to each other through the mechanism of cohesion and form a water column. This water column is pulled upwards due to the suction pressure which results in the upward movement of water and dissolved minerals.
So, the answer is, “Transpiration”.

Note: Transpiration pull mechanism in plants results from the excretion or evaporation of water from the surface of cells in the leaves and stomatal openings on the stem. This process thus helps in the proper flow of water and minerals in the xylem while protecting the plant from embolisms.