factors affecting the rate of transpiration

Question 1

how does temperature affect the rate of reaction

Answer 1

more kinetic energy,more evaporation from mesophyll cells,more diffusion of water vapour through stomata.A higher air temperature can hold more moisture so it has a lower water potential making the gradient steeper.

Question 2

how does humidity affect rate of reaction

Answer 2

air inside leaf is saturated, whereas external air has lower water potential.

Increases in external humidity would lower the gradient

Question 3

how doe air movement affect rate of reaction

Answer 3

wind removes layer of saturated air just outside the stomata which reduces the water potential so the water potential gradient is steeper,therefore transpiration increases

Question 4

how does light intensity affect rate of transpiration

Answer 4

light opens the stomata so transpiration increases

Question 5

what is a potometre

Answer 5

a device used to measure water uptake by roots

Question 6

how does a potometre measure transpiration

Answer 6

transpiration is near impossible to measure so as water uptake is proportional to transpiration,this is used to indicate the rate of transpiration

Question 7

what is water uptake proportional to

Answer 7

transpiration

Question 8

what is transpiration

Answer 8

Transpiration is a process that involves loss of water vapour through the stomata of plants. The loss of water vapour from the plant cools the plant down when the weather is very hot, and water from the stem and roots moves upwards or is ‘pulled’ into the leaves.

Question 9

what is the first step in using a potometre

Answer 9

a sample of plant musr be cut from a plant underwater,this is to prevent any air from entering the xylem and breaking the water column

Question 10

what is the second step to using a potometre

Answer 10

the potometre is then filled with b water and all air bubbles are removed

Question 11

what is the third step to using a potometre

Answer 11

the cut leafy plant is then attached to the potometre , using rubber seals and petroleum jelly to make the equipment air tight

Question 12

what is the last step (fourth) to using a potometre

Answer 12

one air bubble is then introduced into the equipment and the distance that this air bubble has moved towards the plant is recorded

Question 13

how do you convert distamce of bubble movement into an estimate of transpiration

Answer 13

rate the distamce the bubble moved can be used to work out the volume of water in the tube that evaporated

Question 14

how is the volume of water in the tube evaporated recorded

Answer 14

this volume is divided by the time it took to loose that volume of water to get a rate

Question 15

this apparatus can be reset with different conditions applied to see if the rate changes ,what are some examples

Answer 15

a lamp could replicate sunlight

a fan may be applied to replicate wind

or a plastic bag over the plant to increase humidity

Question 16

why must the apparatus be set up and the plant shoot be cut under water

Answer 16

due to the cohesion tension theory,creating a negative pressure in the xylem,this would break the continuous flow of water and water column and prevent transpiration,cutting underwater means only water is drawn to the xylem

Question 17

in which part of the potometre do you find a bubble?

Answer 17

the capillary tube

Question 18

what do you use to measure the distance the air bubble moves

Answer 18

a ruler

Question 19

if you increase the temperature the rate of transpiration will_______

Answer 19

increase

Question 20

if the air bubble moves further there is?

Answer 20

an increased rate of transpiration