Roots and leaves
The major driving force of water uptake in a large tree is transpiration.Transpiration is the process by which plants absorb water through the roots and release it as water vapor through the pores in their leaves. Once this water evaporates, a negative water vapor pressure is created or develops in the surrounding cells of the leaf. when this happens, water is pulled into the leaf from the vascular system, the xylem, to replace the water that has been transpired from the leaf.This pulling of water, or tension, that occurs in the leaf, will extend through the rest of the xylem column of the tree right into the xylem of the roots as result of the cohesive force holding the water molecules along the sides of the xylem tubing.The xylem is a continuous water column extending from the roots to the leaves.<span>Finally, the negative water pressure that occurs even to the roots will result in an increase of water uptake from the soil.</span>
He difference between acute stress and chronic stress is one of severity and time. Acute stress is short lived and may not have very severe effects on you. Chronic stress is when you are under stress<span> on an ongoing basis and can lead to physical disease, mental disorder and spiritual dark nights of the soul.</span>
Answer:
D.the movement of air currents by conversation cells
In the dark, an object is more clearly seen when viewed in peripheral vision than when viewed directly, this phenomenon occurs because the rods located in the retina are:<u> more </u><u>sensitive</u><u> in the dark than </u><u>cones</u>.
The retina extends through the posterior portion of the eyeball is the innermost layer and in it are the photoreceptors: cones and rods.
Rods and cones are the two types of photoreceptor cells in vertebrates that capture light energy (photons) and convert it into electrical signals.
- The rods are sensitive to changes in light, since their detection thresholds are low, so they only come into operation when the light intensity is low (scotopic vision or night vision).
- Scotopic vision has relatively low acuity, as the details of an object cannot be discerned or its color appreciated.
- On the contrary, cones have a much higher threshold for light, they are responsible for daytime vision (photopic vision) and their mission is to detect colors and shapes (details).
Therefore, we can conclude that in the dark, an object is more clearly seen when viewed in peripheral vision than when viewed directly, this phenomenon occurs because the rods located in the retina are: more sensitive in the dark.
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