Cuticle

• Cuticle: A waxy, waterproof layer on the leaf surface that reduces water loss.

Guard Cells

• Guard Cells: Specialized cells that surround stomata and control their opening and closing, regulating gas exchange and water loss.

Stomata:

• Stomata: Pores on the leaf surface that allow for gas exchange.

Upper and Lower Epidermis:

• Upper and Lower Epidermis: Protective layers on the top and bottom of the leaf. Upper is a transparent layer that allows light to reach the palisade mesophyll. The lower epidermis is a single layer of cells on the underside of a leaf, containing stomata and guard cells. It plays a crucial role in regulating gas exchange and water loss through transpiration.

Palisade Mesophyll

• Palisade Mesophyll: A layer of tightly packed, elongated cells rich in chloroplasts, located near the top of the leaf to maximise light absorption.

Spongy Mesophyll

• Spongy Mesophyll: A layer of loosely arranged cells with air spaces that facilitate gas exchange.

Air Spaces

• Air Spaces: Gaps between spongy mesophyll cells that allow for the diffusion of carbon dioxide and oxygen.

(a) heart, limited to: vena cava, aorta, pulmonary artery and pulmonary vein

(b) lungs, limited to: pulmonary artery and pulmonary vein

(c) kidney, limited to: renal artery and renal vein

(d) liver : hepatic artery, hepatic veins and hepatic portal vein