Plant gas exchange and water loss Flashcards
Do all plants photosynthesise?
Not all photosynthesize
those that do, don’t at night
How are plants gas exchange similar to insects?
no living cell is far from external air and source of o2 and co2 diffusion occurs in gas-phase, more rapid than in water
How is the plant adapted from gas exchange?
air spaces in the leaves large SA: VOL of living tissue
short fast diffusion pathway
stomata
How is the leaf adapted for gas exchange?
Stomata= short diffusion pathway, no cell far from stomata
mesophyll interconnecting air spaces= so gases can readily come in contact with mesophyll cells
large SA of mesophyll for rapid diffusion
Where is the stomata usually found?
stomata are usually found on the underside of the leaf
surrounded by guard cells
What is the role of the guard cell?
open and close the stomata to control the rate of gaseous exchange and water loss
It has a thicker inner wall
Name the parts of the leaf in their structural order
Upper epidermis
palisade mesophyll
spongy mesophyll
lower epidermis
How to plants reduce water loss?
waterproof covering
no small SA: VOL ( as photosynthesis requires large SA
ability to close stomata
Define Xerophytes
plants adapted to live where H20 is in short supply
Name and describe the 5 ways xerophytes are adapted to reduce water loss
Thick cuticle ( thicker =less loss)
Rolling leaves ( protect lower epidermis in layer of highly water-saturated air)
Hairy leaves (trap moist air)
Stomata in pits or grooves (trap moist air)
Reduced SA: VOL on the leaves ( slower rate of diffusion)
when answering a question on xerophytes adaptations what is the words you should use?
reduce water potential gradient
slower diffusion
less h2o lost from air spaces
hence less evaporation of water
Describe how insects reduce h2o loss
they cannot use body surface to diffuse gases so have an internal network of trachea
small SA: VOL minimises area over which h2o is lost
waterproof covering over the body
spiracles conflict with the need for oxygen
