transpiration + translocation

Question 1

def root pressure

Answer 1

pressure resulting from the constant entry of water into roots

Question 2

def capillary action

Answer 2

tendency of water to move up inside very narrow tubes (cohesion + adhesion)

Question 3

def transpiration

Answer 3

loss of water from the aerial parts of a plant

Question 4

def transpiration pull

Answer 4

suction force caused by transpiration

Question 5

def transpiration stream

Answer 5

stream of water that moves up in a plant

Question 6

factors affecting: air humidity

Answer 6

relative air humidity decr, water vapour conc outside leaf decr

steep conc gradient btw intercellular air spaces and surroundings

rate of diffusion incr, transpiration incr

Question 7

factors affecting: wind speed

Answer 7

wind speed incr, water vapour conc outside leaf decr

steep conc gradient btw intercellular air spaces and surroundings

rate of diffusion incr, transpiration incr

Question 8

factors affecting: light intensity

Answer 8

light intensity incr, size of stomata incr

rate of diffusion incr, transpiration incr

Question 9

factors affecting: temperature

Answer 9

temp incr, rate of evaporation from thin film of water in intercellular air spaces incr, water vapour conc incr

steep conc gradient btw intercellular air spaces

rate of diffusion incr, transpiration incr

Question 10

importance of transpiration: trans pull

Answer 10

major suction force moves water and mineral salts up the xylem

Question 11

importance of transpiration: turgidity of cells

Answer 11

cells remain turgid as h2o lost is replaced

Question 12

importance of transpiration: water

Answer 12

leaves require water for photosynthesis

Question 13

importance of transpiration: cooling

Answer 13

evaporation of water cools plant by removing latent heat from vapourisation

Question 14

def translocation

Answer 14

transport of manufactured food substances (sucrose + amino acids)

Question 15

loading of sucrose

Answer 15

1. input of sucrose into sieve tube elements near the source (site of sugar production) lowers water potential of sieve tube elements.
2. water moves from xylem into sieve tube elements by osmosis  higher hydrostatic pressure
3. sucrose used up in respiration or converted to starch for storage
4. sieve tube elements have a low sucrose content, higher wp
5. water moves from sieve tube elements to xylem by osmosis  lower hydrostatic pressure in sieve tube elements
6. hydrostatic pressure created causes a mass flow of sucrose along the phloem

Question 16

unloading of sucrose

Answer 16

leaves by diffusion down conc gradient into cells that are sucrose-hungry

Question 17

effect of the unloading of sucrose on water potential of phloem?

Answer 17

pressure is reduced at the ‘sink’ and further promotes mass flow of sucrose solution from source