Stomata and transpiration - class-XI

The loss of water in the vapour form from the exposed parts of a plant is called transpiration. The loss of water due to transpiration is quite high. It is 22 litre per day in sunflower, 36−4536−45 litres in apple and upto 11 tonne per day in elm tree.

Stomata has 3 major functions:

A.Cohesive force – force of attraction present between the water molecules is called cohesive force. Due to this, water column maintains tensile strength.

B.Pressure force – force developed to accumulation of pressure.

C.Suction force – force exists in the sucking of water.

D.Adhesive force – force of attraction exists between the water molecules and walls of the vessels is called adhesive force. Due to this, capillarity exists in the water column.

So, the correct option is ‘cohesive force’.

Transpiration is the loss of water by the stomatal openings of the aerial parts of the plant. This helps in the upward movement of water and minerals from the roots to the leaves by a cohesion-adhesion mechanism. 

Atmometer is a device used to measure the rate of water evaporation from a wet surface to the atmosphere and can be used to measure the rate of evapotranspiration. 

Transpiration is a process of loss of water from a plant in vapour form. One of the benefits of transpiration is that it causes surface cooling because evaporation of water requires energy. Consumption of energy leads to a cooling effect on the leaf surface. Also because of more water vapour content in shade, a tree shade is cooler than area exposed to sunlight. 

Antitranspirants are substances that are applied to the leaves to reduce transpiration. They are used on trees, cut flowers and shrubs. They reduces transpiration in fruit plants like apples, pears, orange, crop plants like cotton, tea, roses, tuber crops like potato, carrot and vegetable plants like chillies, tomato, cabbage. These are also used to protect plants from drying out too quickly. Various antitranspirants include abscisic acid (ABA), aspirin, silicon emulsions, plastics, waxes.

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Transpiration also cools plants, changes osmotic pressure of cells and enables mass flow of mineral nutrients and water from roots to shoots.

According to the transpiration pull theory, loss of water from aerial parts due to transpiration is a physical process and the loss of water generates the pulling force. Water is present as a continuous column in vascular tissues due to cohesive and adhesive forces. The loss of water due to transpiration is equal to the amount of water absorbed from the soil. More the transpiration loss of water, more the absorption of water from the soil and vice versa.

Transpiration generates tension in plants. This tension is the main pulling force, which pulls water to great heights in vascular plants. Thus, transpiration leads to the ascent of sap. Without transpiration, water and minerals will not rise from roots to aerial parts of plants and trees. 

Hydrophytes are plants growing in water. They may be submerged or floating. Floating hydrophytes have stomata on floating parts, for example, floating leaves of lotus have stomata on the upper surface. 

Transpiration is a loss of water in vapour form stomata. The rate of transpiration depends on a number of factors, like carbon dioxide concentration, temperature, light, humidity etc. The most important factor which governs the rate of transpiration is the vapour pressure gradient, which exists between leaf mesophyll and atmosphere. It has been estimated that almost 99 percent of water absorbed by plants is lost in transpiration. As transpiration generates the tension, which is the most important force responsible for water absorption.

Curtis famously described transpiration as an unavoidable evil because it is a necessary process for water transport and cooling, yet it results in significant water loss for the plant.

Plants produce carbon dioxide and water as respiratory waste products. Plants get rid of excess water by transpiration and guttation. Transpiration is evaporation of water from plant leaves by stomata.

Transpiration is the biological process where water is lost from the aerial parts of plants, primarily through stomata in leaves, in the form of water vapor.

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. 

Water moves from the soil into plant roots, up through the sapwood into the leaves. The water, warmed by the sun, turns into vapor (evaporates) and passes out through thousands of tiny pores (stomata) mostly on the underside of the leaf surface. This process is transpiration. It has two main functions: cooling the plant and pumping water and minerals to the leaves for photosynthesis. Photosynthesis, respiration and translocation can not keep the plant cool. Therefore, the correct answer is option B.

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Translocation is not involved in food translocation and growth and curvature of plants.

Transpiration is the process by which moisture or water is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Transfusion and translocation do not involve the loss of water. 

Submerged hydrophytes do not show transpiration, because they are submerged in water. Fungi do not come under plants. Algae do not have leaves and stomatal pores. So, they also do not show transpiration.

Transpiration is loss of water in vapor form, from living plant cells thus it is a physiological process while evaporation is loss of water from any free surface in vapor form, thus it is a physical process. 

Transpiration results in loss of water in vapour form. Water vapours are a prominent green house gas, responsible for maintenance of temperature on earth.

Water is essential for plants, it absorbs water from the soil through roots. However, plants absorbs much water, but only a small amount of water is used for their growth and metabolism. Persisting 97 - 99.5% of absorbed water is lost by transpiration. Transpiration is the process of elimination water in the form of water vapour from the aerial parts such as leaves, flowers and stem.

Water is transient in plants. Less than 1 per cent of the water reaching the leaves is used in photosynthesis and plant growth. Most of it is lost through the stomata in the leaves. This water loss in vapour form is known as transpiration.

Anti-transpirants are compounds applied to the leaves of plants to reduce transpiration. They are used to preserve and protect plants from drying out too quickly. They are also used to protect leaves from the salt burn and fungal diseases. Anti-transpirants reduce the stomatal opening and increase the leaf resistance to water vapour diffusion without affecting carbon dioxide uptake.

Transpiration is a process by which the moisture is carried through plants from the roots to the stomata where it is converted into vapour and is released out to the atmosphere that is the evaporation of water from plant leaves. Transpiration along with evaporation of moisture from land produced two-third of atmospheric moisture.

The continuous evaporation of water (or transpiration) from the cells of a leaf crates a kind of suction which pulls up water through the xylem vessles. Thus, transpiration helps in the upward movement of water and dissolved minerals from the roots to the leaves through the stem.