Gas Exchange in Plants

What is the function of leaf structure in gas exchange

To maximise diffusion of carbon dioxide into the leaf and oxygen out of the leaf while limiting water loss

What is the role of air spaces in leaves

They allow rapid diffusion of gases through the leaf to mesophyll cells

What is the function of palisade mesophyll cells

They contain many chloroplasts and carry out most photosynthesis

What is the function of spongy mesophyll cells

They provide surface area for gas exchange and contain air spaces

What is the role of stomata

They allow gas exchange and water vapour loss and are controlled by guard cells

What is the function of the waxy cuticle

To reduce water loss by evaporation from the leaf surface

Why are stomata mainly on the lower epidermis

To reduce water loss by avoiding direct sunlight and wind exposure

How do guard cells control water loss

They open and close stomata depending on conditions

What are xerophytes

Plants adapted to survive in dry environments with limited water availability

Why do xerophytes need adaptations

To reduce water loss and prevent desiccation

What is a thick waxy cuticle in xerophytes

An adaptation that reduces evaporation from leaf surfaces

How do rolled leaves reduce water loss

They trap moist air and reduce air movement around stomata

How do leaf hairs reduce water loss

They trap a layer of moist air reducing the diffusion gradient

What are sunken stomata

Stomata located in pits that reduce air flow and water loss

Why do xerophytes have small leaves

To reduce surface area and limit water loss

What is the trade off in leaf structure

Large surface area for photosynthesis increases water loss risk

How do plants limit water loss

By closing stomata having a waxy cuticle and structural adaptations

What is the role of vascular tissue in leaves

To transport water minerals and sugars through xylem and phloem