Gas exchange in plants Flashcards
(13 cards)
1
Q
Photosynthesis
A
- Provides O2 for aerobic respiration
- CO2 + H2O -> glucose + O2
2
Q
Spongy mesophyll layer
A
- Large surface area -> have irregular shapes, arranged with large air spaces between them
- Surfaces are moist
3
Q
Waxy cuticle
A
- Impermeable/waterproof
- Reduces water loss/evaporation
4
Q
Palisade layer
A
Tightly packed together to trap as much light as possible
5
Q
Upper epidermis
A
Transparent to allow maximum light through to cells with chloroplasts
6
Q
Leaves
A
- Large surface area
- Thin -> aids diffusion to the palisade layer
7
Q
What is the role of guard cells?
A
Can open and close (allow CO2 to diffuse into the leaf during the day and closes at night to prevent water loss)
8
Q
Opening of stomata
A
- Solutes (K+) moved into the guard cell by active transport
- Water moves into cell by osmosis
- Guard cell turgor pressure increases
- Stoma opens (due to uneven bending from cellulose in cell wall)
9
Q
Where are the stomata found?
A
Underside of the leaf
10
Q
What is the role of the stomata?
A
Allows gases to diffuse in and out of the leaf
11
Q
Closing of stomata
A
- Solutes (K+) move out of the guard cell by active transport
- Water moves out of the cell by osmosis
- Guard cell becomes flaccid (turgor pressure decreases)
- Stoma closes
12
Q
How are plants adapted to survive in dry sand?
A
- Curved leaves so stomata are on the inside of the leaf (which reduces the water potential gradient by trapping water vapour, results in less transpiration)
- Hairs reduce air movement
- Stomata in pits (less transpiration)
- Thick waxy cuticle reduces water loss
13
Q
What are lenticels?
A
Spongy areas with loosely packed cells that are the site of gas exchange in woody stems and roots
