CAPTURING SOLAR
ENERGY: LIGHT
DEPENDENT
REACTIONS
PLANT STRUCTURE
LEAVES: the photosynthetic organ of plants
-
Carry out photosynthesis
-
3 types of tissue
a) Epidermis (upper and lower)
b) Mesophyll
c) Vascular Bundles
PLANT STRUCTURE
LEAVES
PLANT STRUCTURE
a) EPIDERMIS
-
Single layer of cells at the upper and lower surfaces of
the leaf
-
Main function: protect inner layers from dessication,
bacterial invasion, and mechanical injury
-
Cells have thick walls made of cutin and lack
chloroplasts
PLANT STRUCTURE
a) EPIDERMIS
-
Contain stomates on underside of leaf
-
Function: passageway for oxygen, carbon dioxide and
water
-
Opening regulated by pair of guard cells
-
Movement of water controlled by active transport of K+
-
Guard cells actively take up K+
-
Open stomata: light stimulates K+ pump
-
Closed stomata: high CO2 within leaf and low water
PLANT STRUCTURE
a) EPIDERMIS
PLANT STRUCTURE
b) MESOPHYLL
-
Tissue between two epidermal layers
-
Composed of palisade cells and spongy cells
-
Packed with chloroplasts, site of photosynthesis
PLANT STRUCTURE
c) VASCULAR BUNDLES:
Xylem: transport water and dissolved minerals upwards into
mesophyll
- dead vessels and tracheids
Phloem: conduct dissolved food material (products of
photosynthesis) downwards to lower parts of plant
- live sieve tubes and companion cells
PLANT STRUCTURE
c) VASCULAR BUNDLES: