plant systems

Question 1

vascular plants

Answer 1

specialised cells so they can absorb and transport water to the rest of the leaves for photosynthesis

Question 2

translocation

Answer 2

phloem: water osmoses from xylem into phloem which forces sugars upwards ( not full response)

Question 3

transpiration

Answer 3

suction pressure which draws water up the xylem vessels from roots so for water to enter plant, some must be lost by transpiration

Question 4

how to set up a potometer

Answer 4

1. fill a sink with water; insert plant into rubber bung and smear with vaseline(to ensure airtight seal)
   2.remove water and attach to stand
2. use syringe to set water level at zero on scale
3. reservoir in syringe is to allow the air bubble to travel back to the start of the measuring scale for repeating the experiment
4. as water moves up through the plant, the air bubble moves along the scale giving a measure of water absorbed by the plant over time and hence transpiration rate

Question 5

excess transpiration –>

Answer 5

more water lost than what is coming in –> water imbalance –> plasmolysed cells –> not erect and plants wilt to conserve leftover water and reduce surface area for transpiration

Question 6

how does the stomata close?

Answer 6

1. stimulus: decrease in water –> abscisic acid (hormone) released
2. abscisic acid binds to specific guard cell receptors
3. Cl- and K+ ions pumped out of guard cells
4. water moves out of guard cell
5. guard cells = flaccid
6. stomata closes

Question 7

how does the stomata open?

Answer 7

1. light stimulus –> light receptor
   2 Cl- and K+ ions pumped into guard cells
2. water moves into guard cells
3. guard cells become turgid
4. stomata open