Transpiration & Translocation

Question 1

Purpose of Phloem cells

Answer 1

• Join together to make a phloem tube
• Have end caps with pores to allow the transport of water and food substances (usually dissolved sugars)
• Allow 2 way movement

Question 2

What do Phloem tubes transport

Answer 2

• Food subtances (mainly dissolved sugars)
• Made via photosynthesis transported to the rest of the leaf for storage or immediate use (growth)
• Translocation

Question 3

What is Transpiration

Answer 3

• Loss of water from the surface of the plant (usualy the leaf) due to diffusion or evaporation

Question 4

What is the Transpiration Stream

Answer 4

• Transport of water from the roots to the leaves via dead xylem cells
• As 1 water molecule is lost, another is drawn up via the root, creating a continuous transpiration stream

Question 5

Xylem cells

Answer 5

• Dead cells with no end caps
• Join to make a xylem tube which is strengthened by lignin
• Allow 1 way transport of water (roots to leaves)

Question 6

How does Ligh Intensity affect rate of transpiration

Answer 6

• More light intensity = more sunlight
• More sunlight = more photosynthesis
• More photosynthesis = more stomata open to let in CO2
• More stomata open = more water is lost due to diffusion / evaporation

Question 7

How does Temperature affect rate of transpiration

Answer 7

• Higher temperature = water particles have more energy
• More energy = more evaporation
• More evaporation = more loss of water (transpiration)

Question 8

How does Air Flow affect rate of transpiration

Answer 8

• Higher air flow = lost water is quickly blown away
• Blown away = concentration gradient remains high
• High conc grad = more diffusion takes place
• More diffusion = more loss of water (transpiration)

Question 9

How does Humidity affect transpiration

Answer 9

• Higher humidity = lower concentration gradient
• Lower conc grad = less loss of water (transpiration)