Tag: major activities of living organisms

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.