transpiration

Question 1

what is transpiration?

Answer 1

loss of water vapour from the leaves

Question 2

how does the water move through the leaves?

Answer 2

osmosis

Question 3

what covers the epidermis of the leaf?

Answer 3

-waxy cuticle- impermeable to water

Question 4

Most water passes out if the ______ as water vapour. Water leaves the cells of the ________ and evaporates into the air spaces between the ________ ________. The water vapour then diffuses out of the _______.

Answer 4

-stomata
-mesopyll
- spongy mesophyll
- stomata

Question 5

what happens when water is lost from the mesophyll cells?

Answer 5

• they have a low water potential sowater moves into them by osmosis from surrounding mesophyll cells
• water that leaves surrounding cells is replaced by water from the xylem

Question 6

what does transpiration do?

Answer 6

• causes water to be pulled up the xylem in the stream and roots in a continuous flow

Question 7

what is the transpiration stream

Answer 7

• the term for the continuous flow transpiration (water being pulled up the xylem in stem and roots)

Question 8

functions of transpiration stream

Answer 8

• carries mineral ions to the leaves- to synthesise amino acids and chlorophyll
  -keeps turgor pressure high in leaves, preventing wilting
  -evaporation cools the leaves
  -supplies the water for photosynthesis

Question 9

how does temperature effect transpiration

Answer 9

-increases transpiration
-because water evaporates faster due to more Kinetic energy of water molecules

Question 10

how does humidity effect transpiration

Answer 10

-high humidity decreases transpiration
-because air already has high water potential, and so evaporation decreases

Question 11

how does wind speed effect transpiration

Answer 11

-high wind speed increases transpiration l
- because water vapour is blown away from the leaf quickly as fast as it is diffused out

Question 12

how does light intensity effect transpiration

Answer 12

-not directly- but in daylight stomata open, and so high light intensity increases transpiration as it allows more water to diffuse out of the leaves

Question 13

how does water supply effect transpiration

Answer 13

-if water is in short supply, the plant will start to wilt, which will happen after guard cells become flaccid and the stomata start to close, reducing transpiration