Biology - plant nutrition, leaf structure

What are some leaf adaptations?

Larger surface area, leaves are thin and branching veins

Why do leaves adapt to have a larger surface area?

To maxmise carbon dioxide and water absorption

Why do leaves adapt to have thin leaves?

Reduces diffusion distance for carbon dioxide

Why do leaves adapt to have branching veins?

To bring water to leaf cells and carry away products of photosynthesis (e.g sucrose)

Cuticle

Thin, waxy layer. Secreted by epidermal cells. Limits water loss to evaporation

Upper epidermis

Protects against water loss and physical damage. No chloroplasts, transparent to allow light to reach cells below, covered by cuticle

Lower epidermis

Lines the lower surface of the leaf. Contains stomata. Protects against diseases and parasites.

Stomata

Tiny openings in the epidermis - for the diffusion of gases. Capable of closing to reduce water loss. Surrounded by pair of guard cells.

Guard cells

Control opening and closing of stomata. Water moves in, cells become rigid, pore opens. Water moves out, cells become limp, pore closes.

Palisade mesophyll

Long colummar cells. Many chloroplasts in the cytoplasm. Most photosynthesis occurs here

Spong mespophyll

Fewer chloroplasts, less photosynthesis. Lossely packed cells, has air paces. Focused on moving gases through intercelluar speaces.

Air spaces

Carbon dioxide and oxgyen diffuses into or out of leaf cells. Water vapour evaporates into air spaces from mesophyll cells

Vascular bundles

Makes up the veins of a leaf. Consist of xylem and phloem

Xylem

Transports water and mineral ions to leaf cells

Phloem (food)

Transports sugars made in the leaf to other parts of the plant.