Transport Systems- Plants 2.5

Protects the top of a leaf and prevents water loss. The Waxy Cuticle is a protective layer that helps in reducing water loss from the leaf surface.

The top side of a leaf. This layer is transparent allowing light to pass through. The Upper Epidermis is crucial for light penetration necessary for photosynthesis.

Contains lots of chloroplasts as most of photosynthesis happens here. The Palisade Mesophyll is typically located just beneath the upper epidermis and is densely packed with chloroplasts.

Gas exchange takes place within this layer. The Spongy Mesophyll has air spaces that facilitate the exchange of gases, such as carbon dioxide and oxygen.

Contains xylem and phloem. This is where water, minerals, and sugar pass through a leaf. Xylem transports water and minerals, while phloem carries sugars produced by photosynthesis.

The underside of a leaf. Contains many stomata. The Lower Epidermis plays a significant role in regulating gas exchange through the stomata.

Opens to allow carbon dioxide to enter and oxygen and water vapor to exit. Stomata are small openings that regulate gas exchange and transpiration in plants.

These surround each stoma. They open and close the stoma when it is required. Guard Cells are specialized cells that control the size of the stomatal opening, thus regulating gas exchange and water loss.

Transport of water and minerals Xylem consists of dead cells and has a thick cell wall made of lignin.

Transport of sugars Phloem has a thin cell wall made of cellulose and allows for two-way flow.

One-way flow

Two-way flow

• Thick cell wall made of lignin • Dead cells

False

False

-Wind Speed -Temperature -Humidity -Surface Area

Decreases The leaf is surrounded by moist air, so the water vapour will evaporate from the leaf slower

Increases More stomata present, so more loss of water vapour

Increases Water vapour moves faster, therefore evaporating out a faster rate

Increases Air movement increases the evaporation of water vapour out of the stomata