Leaf Structure Aquaponics
Leaf Structure-Dermal layers • Cuticle-The thin waxy covering on the outer surface of the leaf has a thin waxy covering This layer's primary function is to prevent water loss within the leaf. (Plants that live entirely within water do not have a cuticle). • Directly underneath the cuticle is a layer of cells called the epidermis(upper and lower)
Leaf Tissues • Mesophyll • Ground tissue between upper and lower epidermis • Two types: • Palisade parenchyma (mesophyll) cells • Lots of chloroplasts in these cells • Most photosynthesis occurs here • Spongy parenchyma (mesophyll) cells • Lots of air spaces where O2 and CO2 circulate • Near stomata (Think: sponges have lots of air spaces) • Veins • Xylem and phloem are continuous from roots through stem to leaves
Vascular Tissue • Transports materials in roots, stems, & leaves. • Xylem • Carry water & minerals up from roots • Tube-shaped dead cells • Their walls are used as water pipes • Phloem • Carry nutrients (food) throughout plant • SUGARS (sucrose), amino acids…. • Tube-shaped living cells
Stomata and Guard Cells • The underside portion of a leaf has stomata and is the site of transpiration (water movement) and gas exchange.
Stomata help regulate the rate of transpiration • Guard cells • 2 cells on either side of stomata (surrounds stomata) • regulate water loss • What conditions will promote closing of guard cells? • Hot, dry, windy conditions
Stoma Opening/Closing • http://academic.kellogg.edu/herbrandsonc/bio111/animations/0021.swf
Leaf cross section VeinH2O Mesophyll (leaf tissue) CO2 O2 Stomata Figure 10.3 Cross Section 30-40 chloroplasts CO2 O2 Stomata; Stoma (pl)