(c) process of transpirtaion and environemnt factors

What is tranpsiration a consequence of

Gas exchange

What is the purpos of transportation

Delivers water and mineral ions in water to cell

What is the overall process of the gas exchange

Co2 and o2 move through stomata (controlled by guard cells)

Open = exchange of gases + water vapour moves out

Closes = mainly in night but still need o2 for respiration so some still open slightly

Where does water move to and from

Water moves from roots to leaves

Where do water molecules evaporate from and where do they go?

Water molecules evaporate from mesophyll cells into stomata of leaf by diffusion

What happens when water enters stomata

Loss of water from mesophyll tissue = decreases W.P

Water move into cells from adjacent cells = osmosis along apoplst and symplast pathway

When does the osmosis stop and where does water move next

Until xylem is reached

Water move out of xylem into cells

What does water molecules do

Form hydrogen bonds with carbohydrates in xylem walls (adhesion)

H.B with each other = cohesion

What is the cohesion- tension theory

Water goes against gravity

Continuous stream through xylem to replace evaporated water

= transpiration pull - creates tension - moves water from soil to roots

How can a tree be an example of transpiration n

Diameter of tree increases when tension decreases (at night)

Diameter of tree DECREASEA when tension INCREAES (day time)

How does the xylem being cut be an example of transpiration

Xylem is cut - water is lost and no movement of water = continuous stream cut