3.5 Continued: Problems For C3 Plants And Adaptations

Question 1

What is photorespiration?

Answer 1

On very hot days, plants close their stomata to stop water loss

Question 2

Why is photorespiration bad for plants? (3)

Answer 2

• causes less CO2 to be present, and more O2
• then Rubisco will bind to O2 and use ATP
• this produces more CO2 but no sugar is produced
  (Rubisco binding to O2 is insufficient and wont build the carbs we need)

Question 3

How have plants that live in hot, dry climates evolved to have alternate mechanisms of carbon fixation? Like what type of plants do we have now?

Answer 3

• C4 plants

- CAM plants

Question 4

What do C4 plants do? (5)

Answer 4

• have spatial separation of steps :compartmentalization
  1. stomata partially close to conserve water
  2. Mesophyll cells fix CO2 into a 4-C molecule
  3. Transferred to bundle sheath cells
  4. Releases CO2 to be used in the Calvin Cycle

Question 5

What are examples of C4 plants?

Answer 5

• corn, grasses, sugar cane

Question 6

What do CAM plants do to their stomata?

Answer 6

• open stomata at night (cooler, less evaporation) and close during the day (hot, increase temp)

Question 7

What do CAM plants do to themselves? (2)

Answer 7

1. CO2 is incorporated into organic acids and stored in vacuoles ( in mesophyll)
2. During the day, light reactions occur and CO2 is released from the organic acids and incorporated into the Calvin Cycle

Question 8

What are examples of CAM plants?

Answer 8

Pineapple, cacti, succulents, jade