1. What’s the relationship between structure and function in a leaf?
What’s in a Leaf
What’s the relationship between structure and function in a leaf?

2. Model 1 – Leaf Sun-Catcher
Sun (energy), Water (liquid), Carbon Dioxide
Water (gas), Oxygen, Sugars
Water
Central Vein

3. Water has changed from a liquid to a gas.

4. Equation for Photosynthesis
Using above equation:
Reactants? Carbon Dioxide and Water
Reactants enter? Carbon Dioxide through stomata (underside of leaf), Water through roots to stem (xylem) and then central vein of leaf
Products? Sugars and Oxygen
Products exit? Oxygen through the stomata, Sugars through the veins

5. 7) Matter OR Energy ? Solar (light) Energy Chemical Energy
(C-C and C-H bonds)

6. Model 2 – Cross Section of a Leaf
Layers: Cuticle Upper epidermis (skin) Palisade mesophyll (middle) Spongy mesophyll (middle) Lower epidermis (skin) Cuticle
Vein position
Model 1 - Central vein in middle with other veins branching off
Model 2 – Between palisade and spongy mesophyll

7. Model 2 – Cross Section of a Leaf
Veins: get water to all parts of the plant … the leaf requires water to help make sugar
Sunlight enters Water enters (liquid) Carbon dioxide enters Sugar exits Oxygen exits Water (gas) exits
Xylem (liquid water)
Phloem (sugar)

8. Palisade mesophyll and guard cells have chloroplasts
Palisade and guard cells (chloroplasts conduct photosynthesis)
Chlorophyll (green pigment) are mostly in Palisade mesophyll
Light goes through cuticle and upper epidermis
Palisade mesophyll have lots of chloroplasts, arranged vertically, tightly packed, and larger.
More cells = More chloroplasts = More photosynthesis

9. Most light is absorbed before reaching the spongy mesophyll
If Upper epidermis had chloroplast it would decrease light reaching the Palisade layer
Epidermis functions like skin to protect what’s inside a leaf
The cuticle is “water-tight” to prevent water from escaping. Water must be used for the plant to photosynthesize.

10. Lower surface
Stoma is between guard cell
Stoma is an opening
Water can exit through the stoma when open … good or bad?
Guard cells regulate the opening and closing of the stoma just like “gates”
Stoma open = access to more air space
Air space = oxygen, carbon dioxide, water

11. Stomata are closed … what happens?
Water and Oxygen stay in the plant. Upside?
Carbon Dioxide cannot enter. Downside?
Cuticle and stomata work together. How so?
Water regulation!

12. 28 & 29
Use your sentences tracing the pathway or reactants entering the leaf and products exiting the leaf to draw a picture of the equation of photosynthesis.

13. Extension Questions
Plants with larger leaves … advantage or disadvantage?
Cacti … what structures give an advantage or disadvantage?
Aquatic plants … adaptations?
Knowledge of Plant Cells
Water storage?
Large Vacuole
Sugar destination?
Go to mitochondria (energy)
Cell wall function?
Structure and strength so leaf is lifted up toward the light