Multicellular Organisms - Transpiration

Question 1

Name and describe the roles of the 3 organs in plants

Answer 1

1. Roots - supplies the plant with water
2. Stems - holds the leaves in the correct position to absorb sunlight
3. Leaves - exchanges gases in the air for photosynthesis

Question 2

Describe the adaptation of the upper epidermis and its role

Answer 2

• Thin and transparent
• Lets light through to the palisade layer below.

Question 3

Describe the adaptation of the palisade mesophyll and its role

Answer 3

• Has long, thin palisade and mesophyll cells, packed closely together
• Contains lots of chloroplasts (its the main site of photosynthesis)

Question 4

Describe the adaptation of the spongy mesophyll and its role

Answer 4

• Consists of air spaces between them
• They have the air spaces to allow gases to circulate within the leaf.

Question 5

Describe the adaptation of the vein and its role

Answer 5

• contains xylem vessels and phloem
• They allow waters and sugars to be transported into or out of the leaves.

Question 6

Describe the adaptation of the lower epidermis and its role

Answer 6

• thin layer containing guard cells and stomata
• guard cells allow the regulation of gas exchange

Question 7

Describe the adaptation of the guard cells and its role

Answer 7

• they work in pairs
• control the opening and closing of the stomata

Question 8

Describe the adaptation of the stomata and its role

Answer 8

• tiny pores on the leaf surface
• Site for the exchange of gases (evapouration of water)

Question 9

Define transpiration

Answer 9

Process of water moving through a plant and its evapouration through the stomata on the underside of the leaves

Question 10

Explain the process of transpiration

Answer 10

• Water molecules move cell to cell by osmosis.
  1. Water enters root hairs, crosses the root cortex by osmosis.
  2. Water enters xylem then is drawn up the xylem in the transpiration stream
  3. Water moves along the xylem into the leaf, where it evapourates into airspaces between the spongy mesophyll cells, creating vapour
  4. Stomata open for the vapour to diffuse in the air.

water loss = transpiration