8.2,8.3,8.4 Transpiration, Translocation

Define transpiration.

loss of water vapour from plant leaves via evaporation of water at mesophyll cell surfaces, followed by diffusion of water thru the stomata

Transpiration Process
1. s__ hits leaf, heats water & evaporates
2. water vapour d__ out of the s__
> less water p__ inside leaf cells
3. water moves from x__ → leaf cells, __ the water potential gradient
4. leaves behind -ve pressure = sucks up water from stem
> water comes __ from roots
5. as less water pot. in roots, more water enters roots via o__

sunlight, diffuses, stomata, potential, xylem, down, up, osmosis

Define cohesion

result of attractive forces between water molecules

How is water pulled up by the xylem?

cohesive forces

Wilting
> water e__ faster than movement of water from s__ to roots
> s__ closes to lower t__
> plant doesn’t get enough w__, it loses water & turns f__
>> becomes soft, droopy, but isn’t d__
>> the plant is only p__ itself from sun r__ until it gets water
> when it gets water, = turgid & recovers

evaporates, soil, stomata, transpiration, water, flaccid, dead, protecting, rays

Factors affecting transpiration
T__
> ↑T = ↑__ = ↑rate of d__

temp, Ek, diffusion

Factors affecting transpiration
H__
> ↓H = ↓conc. of __ molecules outside = steeper __ gradient

humidity, water, conc

Factors affecting transpiration
W__ s__
> ↑WS = H₂O molecules b__ away = steeper __ gradient

wind speed, blown, conc

Factors affecting transpiration
L__ i__
> in daylight, s__ opens for __ = ↑H₂O vapour diffusing out

light intensity, stomata, photosynthesis

What is used to measure transpiration?

potometer

Why can potometers be sometimes inaccurate?

some water used for photosynthesis

Define translocation.

Movement of sucrose & amino acids in phloem from regions of production to regions of storage OR respiration/growth, via active transport

Source or sink?
parts of plant that release sucrose or amino acids

source

Source or sink?
parts of plant that use/store sucrose or amino acids

sink

What is an example of a plant that is a source and sink at diff times?

beetroot

Rate of translocation is higher on s__ days bc leaves p__ more = more sugar

sunny, photosynthesise