1. Plants: Leaves

2. Leaves
Play role in photosynthesis, gas exchange, storage, and protection from predators.
Leaf cells absorb energy from sunlight in a chloroplast which contains photopigments.
Photopigments are chemicals that absorb particular wavelengths of red and blue light and reflect green light.

3. Leaf Structure
Leaves make sugar and supply all living organisms with food and oxygen
They are designed so they can capture the most amount of sunlight.
Leaves are covered with a waxy cuticle that is produced by the epidermis. Both cuticle and epidermis provide protection.
Stomata are little passages on the underside of leaves that allow for gas and water vapour exchange. Woody plants have no stomata on the upperside, herbaceous plants do have stomata on the upperside.
Stomata are open during the day and closed at night

4. Carbon dioxide is used by chloroplasts to perform photosynthesis
Carbon dioxide is brought into the plant through the stoma, while oxygen and water are released into the atmosphere.
Photosynthesis cannot happen at night, so the stomata are closed.
Each stoma is surrounded by two guard cells that are kidney-shaped, specialized epidermal cells with chloroplasts
Water moves into the guard cells during the day because of all the ions that move into the cells.
The inside is thicker, so the outside can expand more, creating a hole between the two cells.

5. Cells within the leaf are the mesophyll cells that have a lot of chloroplasts and have two layers:
Palisade layer that are densely packed and have more chloroplasts
Spongy layer that are loosely spaced so air can come in contact with the cells.
Water loss from the leaves through evaporation is called transpiration
The xylem and phloem continue from the stems into the leaves in special vascular bundles called veins.
Monocot veins run parallel to each other
Dicot veins run in a branching network

7. Leaf Specializations
Dry climate: thicker cuticle, stomata on underside.
Cactus leaves are modified into spines
Aquatic plants have stomata on the upperside for gas exchange.
Onion bulb: stores water and carbs

8. Leaf Uses
Provide important nutrients and food energy in the diets of humans.
Use them for herbs and spices
Teas
They are nutritious (calcium, potassium, iron, magnesium, vitamins B, C, E, K)
Use waxy cuticle for polishes, cosmetics, candies.