2.3B Transpiration + cohesion tension theory Flashcards
where in a plant does photosynthesis occur
the leaf
where in. a leaf does photosynthesis occur
palisade mesophyll
how does a leaf get carbon dioxide
it passes into the leaf via diffusion
how does the oxygen produced via photosynthesis leave the leaf
via diffusion
why do internal leaf spaces contain a high conc of water vapour
the surface of cells in leaves are covered with thin layer of water, which evaporates into water vapour
why does water vapor diffuse into external air
level of water vapor in external air is low(via stomata) This is transpiration
what happens to keep water continuous during transpiration
water is continuously being pulled out of xylem vessels “TENSION”
what is the attraction called when water molecules hydrogen bond with eachother
cohesion
cohesion tension theory:
transpiration pull + cohesion + adhesion = water drawn into roots, moves into stem and passes out leaves
what evidence supports cohesion-tension?
- if a plant stem is cut, air is sucked into xylem
- measuring diameter of a tree truck reduces when transpiration is at its maximum
what is used to measure the rate of water uptake into a plant
bubble potometer
why is an air bubble placed in the capillary tube of a potometer
the movement of the bubble indicates the volume of water taken up by the shoot
what 4 environmental factors affect the rate of transpiration
- light
- temperature
- humidity
- air movements
why does light affect transpiration
light stimulates stomata to open and close (allowing gas exchange for photosynthesis)
how does temperature effect transpiration
more temp = more transpiration
