Biology- Plant Transpiration?

Question

How do plants transport water? How does this relate to vascular tissue, cohhesion, adhesion, and stomata? What are the factors that affect this process?

Answer 1

What is transpiration?

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 includes a process called guttation, which is the loss of water in liquid form from the uninjured leaf or stem of the plant, principally through water stomata.

Studies have revealed that about 10 percent of the moisture found in the atmosphere is released by plants through transpiration. The remaining 90 percent is mainly supplied by evaporation from oceans, seas, and other bodies of water (lakes, rivers, streams).

Answer 2

Plants transport water passively, which means they do not use even 1 single ATP to shuffle water.

Water forms the strongest hydrogen bonds and these bonds give water the property of cohesion, and adhesion. Adhesion is used to hang on the the inner surface of the vascular, Cohesion is the hydrogen bond formed between molecules, together with the two, the water will form a "U" shape within the tube.

Stomata is the opening on the surface of leaf, and water is evaporated from the stomata. when the water molecule on the top becomes vapor, the cohesion and adhesion are the forces pull the water up a little more. So as the water leave from the top, adhesion to the inner surface of the tube pull the water up to replace the loss, and cohesion within the water keep the top high.

Many factors can affect this process. For example, temperature will effect the speed of vaporization; humidity, the more moist in the air, the less water vaporize; and of course, if you cut the tube, this process will be stopped, and the vascular tissues are located in the outer surface of the trunk, if we carve on the tree, or some animal come by and chew on it, the process will be interrupted.

Answer 3

TRANSPIRATION-COHESION-ADHESION THEORY:



a). water exits leaf through stomata.

b). this water loss is replaced by evaporation from mesophyll cells, lowering their water potential, causing them to take water from neighboring cells.

c). the process connects back to the tracheids causing water to be taken from the xylem.

d).Water travels from the tracheids to the air following a water potential gradient.

e). Waters cohesive and adhesive properties and the small diameter of xylem aid in its movement of up the tube.

f). This pull decreases water pressure in the xylem causing the roots to take water from the soil.



How Stomata Operate:



Turgid guard cells open the stomata, while flaccid ones close them.

The potassium (K+) ion is responsible for the stomatal action.

Uptake of K+ causes the cell to become turgid decreasing its water potential.

The stomata open at dawn caused by the light inducing the cells to take in K+. An internal clock (circadian rhythm) will make them open even if in they are kept in the dark.

Guard cells will close due to water deficiency and high temperatures.