Transpiration - class-IX

Amount of water not available to plants is called as echard. It includes hygroscopic water and chemically bound water. 

Plants on hills are exposed to higher wind speeds and lower atmospheric pressure, both of which increase the rate of evaporation and thus the rate of transpiration.

Amount of water not available to plants is called as echard. It includes hygroscopic water and chemically bound water. 

Physiologically dry soil means that water is present in the soil but is not available to the plants either because of high salt concentration, or lack of water in liquid form or poor aeration. These conditions respectively occur in saline marshes, cold deserts and water logged soil.

The accumulation of potassium ions (K+) in guard cells lowers their water potential, causing water to enter by osmosis, which leads to the opening of stomata.

Transpiration keeps plant cool.

If the temperature of soil drops down drastically then absorption of water is decreased. This happens because one water starts changing its physical state from liquid to solid, so that passive absorption is decreased and the process of respiration stops at extreme temperatures. If respiration stops ATP will not be available for active absorption.

Transpiration is the process by which plants throw out the extra water present in it. Since water is an essential ingredient in the survival of the plants, it is absorbed through the roots. However, only a small amount of water is taken up for the metabolic activity. The rest 90-95% water is thrown out through the process of transpiration. The stomata along with the guard cells present in the underside of the leaves help the plants to transpire.  The process of transpiration enables the mass flow of mineral and water from the roots to the shoots and thus maintains the osmotic pressure of the cells and cools the plants.

In the day-time, when photosynthesis occurs, the guard cells are turgid while in the evening, regardless of the availability of water, these guard cells lose turgidity. When they are turgid, stomata open, and carbon dioxide enters freely. When they are flaccid, carbon dioxide is largely excluded, but water loss is also retarded. hence, the daytime loss of water in the vapor form from stomata is a trade-off for intake of carbon dioxide.

In water-logged soil, air is displaced by water. Roots cannot respire aerobically, leading to a lack of energy for active water absorption, making the soil physiologically dry for the plant.

Increased rainfall will lead to washing away of mineral elements along water, hence, it will not make minerals more available to plants.

Transpiration is the process of loss of water through the aerial parts of the plant. It depends upon the amount of humidity level of the atmosphere.

Transpiration helps in the absorption of carbon dioxide gas from the atmosphere and its transportation.

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. The leaves contains tiny pores called stoma which helps in the gas exchange of oxygen and carbon dioxide. More the stoma (pores) on the leaves result in the increase in the transpiration via stomata. The leaf with the bigger surface area will transpire more when compared to the lower surface area. Each stomata is gaurded by guard cells which helps in the opening and closing of stomata. When stomata are open, transpiration rates increase; when they are closed, transpiration rates decrease.

In hot summer days when loss of water vapour occurs from foliar surface because these are the main site of water loss or transpiration and directly exposed to sunlight.

Transpiration is the evaporation of the water from the stomata of the plants. The water absorbed by the roots is transported up to the leaves where stomata are present. Stomata open during the daytime and increasing temperature results in loss of water in the form of vapours. This is similar to the sweating process that occurs in humans. It cools the plants during high temperature.

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

When a well-watered plant stem is cut near the base, xylem sap often exudes from the cut surface. This phenomenon is driven by positive hydrostatic pressure built up in the roots, known as root pressure.

Water is pulled upwards through the plants due to transpiration. Transpiration is the loss of water in the form of water vapour through stomata. The model that explains this translocation of water is called Cohesion-tension transpiration pull model of water transport. Less than one percent of water reaching the plant is used in photosynthesis and plant growth.

Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salination can be caused by natural processes, such as mineral weathering or the gradual withdrawal of an ocean. It can also be caused by artificial processes such as irrigation. The ions responsible for salination are: Na$^{+}$, K$^{+}$, Ca$^{2+}$, Mg$^{2+}$ and Cl$^{-}$. When excess irrigation is done, the negatively charged ions are leached or washed away and only positively charged ions remain in the soil as they are held up by clay particles in the soil. This creates salinity problem.

In Botany, the term exudate refers to the fluid emitted through pores in the plants and the process is called as exuding. Examples of plant exudates are saps, gums, resins, latex and nectar. Sticky exudates are released from the glandular trichomes of the leaves or branches when damaged or even flowers. These sticky exudations are tactile signals of the plants which either work as alarm signals to the aphids, traps insects or are signals for pollinators.
Therefore, the correct answer is option D.

Evaporation of water and uptake of minerals and water is a function of transpiration.

Stomata are the aperture which is mainly present at the dorsal surface of the leaf. It is meant for gaseous exchange but it also allows the loss of water through transpiration. Loss of water can lead to wilting, serious dessication and often the death of a plant if there is a shortage of water. 

Transpiration is influenced by pH, $CO _2$, hormones etc. It is largely dependent upon absorption of water from the soil.

Transpiration is the process of loss of water through the aerial parts of the plant. It depends upon the amount of humidity level of the atmosphere.

Water enters the soil through the pores by the means of capillary action and gravity. Microspores are soil pores with capillary water in it. They hold maximum water by capillary forces. These pores have high water holding capacity as water within these pores is immobile. However, water is readily available for plant.

Chresard is an available soil water to plants. Water enters the soil through the pores by the means of capillary action and gravity. Micropores hold maximum water by capillary forces. These pores have high water holding capacity as water within these pores is immobile. However, this water is available for plant. 

Infiltration is downward entry of water into the soil whereas percolation is the downward flow of water through soil. Percolated water reaches deep in the soil to water table. Percolation of water first occurs through macropores that are bigger than 50 micron. These are present between soil particles and microspores. Later, percolation occurs through microspores.

During night, the dried soil surface becomes wet. This is due to the water droplets that forms a thin layer due to condensation. This is called as night recovery. As the soil surface cools at night by radiating its heat, moisture present in the atmosphere condenses. This results in the formation of water droplets on the soil. At night as the air cools to the dew point, condensation occurs and soil becomes wet without rain.

During night, the dried soil surface becomes wet. This is due to the water droplets that forms a thin layer due to condensation. This is called as night recovery. As the soil surface cools at night by radiating its heat, water vapour present in the atmosphere condenses. This results in the formation of water droplets on the soil. At night as the air cools to the dew point, condensation occurs and soil becomes wet without rain.

Dry atmosphere means lack of moisture content in the air. Due to this, air has a lot of capacity to hold water and thus the rate of transpiration increases.

• Water loss from the leaves in the form of water vapour through the openings called stomata is called transpiration.
  
• Imbibition is a phenomenon that refers to the absorption of one substance by another, usually uptake of water by a plant or a seed.
  
• Guttation is excretion of xylem sap on the tips of some plants through pores called hydathodes.
  
• Translocation is the movement of the material from the source to sink inside the plant. Example, movement of starch from leaves to roots or other plant parts.