Photosynthesis (leaf structure)

Leaf Structures To understand photosynthesis it is important to understand the leaf structures and functions. Leaves are the plants “food supply factory.” In higher plants the leaf structures is adapted to maximize light absorption and carbon dioxide diffusion.

Leaf structures Veins (xylem and phloem) Mesophyll Palisade layer (parenchyma cells) Spongy Layer Cuticle Upper and Lower epidermis Stomates Guard cells

Veins (xylem and phloem) This is a network that acts like a plumbing system that supplies water and minerals to the leaf and that carries the products of photosynthesis away to other parts of the plant. Xylem: carries water and dissolved minerals from the roots to the leaves Phloem: carries the food made in the leaves to the rest of the plant

Mesophyll The green leaf cells between the upper and lower epidermis of a leaf which is loaded with chloroplasts. The mesophyll consists of 2 layers: Palisade layer (parenchyma cells) Spongy Layer

Palisade layer (parenchyma cells) This layer is found right below the upper epidermis, which is made of parenchyma cells. Most photosynthesis in plants takes place in the palisade layer of the leaves

Spongy Layer This layer is found below the palisade layer and above the lower epidermis, which contains many air spaces. The spongy layer is involved in gas exchange.

Cuticle This is a thin non-living waxy substance that covers leaves. The cuticle helps reduce water loss and protection from most bacteria, fungi, and insects.

Upper and Lower epidermis This is a single layer of cells, which covers the upper and lower surfaces of leaves. The epidermis also provides protection to the leaves from most bacteria, fungi, and insects.

Stomates Are minute pores found in the epidermis of leaves, which allows diffusion of gases in and out. During the day, stomata absorb carbon dioxide from the air and release oxygen and water. Evaporation of water from the leaf is referred to as transpiration, is the major source of water loss in leaves.

Guard cells Are two bean-shaped cells that surround the stomata. The guard cells control the size of the stomata. When the guard cells swell, the stomata open. When the guard cells shrink, the stomata close.

Chloroplast Chloroplast- a organelle in plant cells and algae that contain the chlorophyll pigments and the enzyme systems for photosynthesis.

Diagram of A Chloroplast

Chlorophyll Chlorophyll a light absorbing pigment that gives plants their green color and converts the energy of sunlight to food in the process known as photosynthesis.

Plant leaf pigments