6.4 - 6.5 - gas exchange in plant leaf & limiting water loss

Question 1

which process in plants takes in CO2 & releases O2?

Answer 1

photosynthesis

Question 2

which process in plants take in O2 & release CO2?

Answer 2

respiration

Question 3

describe the structure of a plant leaf and explain how it’s designed for effective gas exchange. (dtlm)

Answer 3

• diffusion by gas (short, fast diffusion pathway)
• thin (short, fast diffusion pathway)
• large air spaces in mesophyll (gases could come into contact with large SA)
• many stomata (short diffusion pathway)

Question 4

describe how the stomata works with guard cells.

Answer 4

guard cells surround the stomata and open/closes through stomatal pores -> controls rate of gaseous exchange

Question 5

describe 3 features of insects that limits the rate of water lost.

Answer 5

• small SA:V ratio - minimise area over where water is lost
• waterproof coverings
• spiracles - opening of tracheae which could be closed

Question 6

describe 3 features of plants that limit the rate of water loss.

Answer 6

• waterproof coverings over part of the plants
• stomata could open & close
• xerophytes which limit water loss through transpiration

Question 7

what are 5 modifications that limit water loss in plants?

Answer 7

• thick cuticles
• rolling leaves up (protects lower epidermis from outside & traps water vapour)
• hairy leaves (traps still, moist air)
• stomata in pits / grooves (traps still, moist air)
• lower SA:V ratio