gas exchange in plants what are the two main gases that all organisms on earth need to exchange back...
TRANSCRIPT
Gas Exchange in Plants
What are the two main gases that all organisms on earth need to exchange back and forth between themselves and the environment?
OXYGEN AND CARBON DIOXIDE
Why do autotrophs and heterotrophs need to exchange these gases?
A. Autotrophs
SUCH AS . . .
1. Need CO2 for photosynthesis.
2. Use O2 for cellular respiration.
3. Get rid of excess O2 through . . . STAY TUNED!
Why do autotrophs and heterotrophs need to exchange these gases?
B. Heterotrophs
SUCH AS . . .
1. Use O2 for cellular respiration.
2. Get rid of CO2 as a waste gas.
How do flowering plants exchange these gases?
They use three vegetative structures:
1.Roots
2.Stems
3.Leaves
How do flowering plants exchange these gases?
1. Roots
a. CO2 dissolves in water in soil.
b. CO2 absorbed by root hairs; transported by xylem
c. Photosynthesis produces O2; transported by phloem.
How do flowering plants exchange these gases?
2. Stems
a. Lenticels – tiny openings in stems for gas exchange.
(white “spots” are the openings)
How do flowering plants exchange these gases?
3. Leaves
a. Review leaf’s cross-section structure.
CuticleUpper epidermis
Lower epidermis
Palisade layer
Spongy layer
Guard cells and stomata
How do flowering plants exchange these gases?
3. Leaves
b. O2 and CO2 AND H2O are exchanged at stomata formed by guard cells.
c. Guard cells are in OPEN position when filled with water and CLOSED when water is scarce. Guard cell Animation
How do flowering plants exchange these gases?
3. Leaves
d. What type of plant would be most likely found in the rainforest? One with lots of guard cells or one with few guard cells?
LOTS OF GUARD CELLS – WHY?
How do flowering plants exchange these gases?
3. Leaves
e. Gas exchange also happens at spongy layer and palisade layer.