Gas Exchange In Plants Flashcards
What are the adaptions of a leaf for gas exchange and photosynthesis?
Large surface area
Thin
Transparent cuticle and upper epidermis
Air spaces
Stomata
Elongated palisade cells which are full of moving chloroplasts
What is the significance in a leaf of having a large surface area for gas exchange?
More diffusion due to more stomata
What is the significance in a leaf being thin for gas exchange?
Has a short diffusion pathway
What is the significance in a leaf in having air spaces for gas exchange?
Allow CO2 to travel through bottom of the leaf to palisade cells
What is the significance in a leaf in having stomata for gas exchange?
CO2 enters down the diffusion pathway (concentration gradient)
What is the significance in a leaf in having air spaces for photosynthesis?
Allows CO2 to enter down the concentration gradient
What is the significance in a leaf in having elongated palisade cells filled with chloroplasts for photosynthesis?
More light absorbed - site of photosynthesis
What is the significance in a leaf in having a transparent upper epidermis and cuticle for photosynthesis?
Allows more light to be absorbed as it passes through the top two layers
What is the significance in a leaf in being thin for photosynthesis?
Allows light through the whole leaf
What is the significance in a leaf in having a large surface area for photosynthesis?
More surface for sunlight to hit and therefore be absorbed
How do guard cells (stomata) open?
Chloroplasts in guard cells photosynthesize producing ATP
Allows K+ to actively transport into guard cells from surrounding epidermal cells
Starch converted to malate
K+ and starch are soluble and lower the water potential of guard cells
Water enters via osmosis
Thicker inner wall stretched less than the out wall
Creates a pore (stoma)
How do guard cells (stomata) close?
K+ in the guard cells diffuse passively out down the conc gradient
Water moves out the guard cell via osmosis
Cell is now flaccid and the stoma closes
Where would hydrophyte plants be found?
In areas with an abundance of water
Where would xerophyte plants be found?
In areas with very little water (desert)
Where would mesosphyte plants be found?
In areas where there is some water present
Which type of plant has many stomata in the upper adaxial surface (upper epidermis)?
Xerophytes
Which type of plant has very few stomata in the upper adaxial surface (upper epidermis)?
Mesophytes
Which type of plant has stomata only in the upper adaxial surface (upper epidermis)?
Hydrophytes
Which type of plant has no stomata in the lower abaxial surface (lower epidermis)?
Hydrophytes
Which type of plant has many stomata in the lower abaxial surface (lower epidermis)?
Mesophytes
Which type of plant has few stomata in the lower abaxial surface (lower epidermis)?
Xerophytes
Which type of plant has a cuticle on the lower abaxial surface (lower epidermis)?
Xerophyte - thick on rolled leaves
Which types of plant has no cuticle on the lower abaxial surface (lower epidermis)?
Hydrophytes and mesophytes
Which type of plant has little/no cuticle on the upper adaxial surface (upper epidermis)?
Hydrophytes
Which type of plant has a waxy cuticle on the upper adaxial surface (upper epidermis)?
Mesophytes
Xerophytes - thin on rolled leaves, thin on flat leaves
In which plants are air spaces used for buoyancy?
Hydrophytes
In which plants are there air spaces to allow diffusion of gases?
Mesophytes
Xerophytes
Why do xerophytes have hairs?
To trap water vapour and reduce the water potential gradient and prevent water from being lost
Why do xerophytes have rolled leaves?
Reduce the area where transpiration can occur
