Gas Exchange in Animals and Plants

Gas exchange

is the biological process where organisms obtain oxygen (O₂) and release carbon dioxide (CO₂) or vice versa, depending on their metabolic needs

External Gas Exchange

Occurs between an organism and the environment (e.g., lungs and air).

Internal Gas Exchange

Occurs between cells and internal transport systems (e.g., blood and tissues).

Respiratory System

What is responsible for gas exchange?

Diffusion

Movement of gases from an area of high concentration to an area of low concentration. It is a passive process that does not require energy and is the primary mechanism for gas exchange in both animals and plants.

Diffusion

Examples in Animals: Oxygen _____ from alveoli into blood. Carbon dioxide ______ from blood into alveoli.

Diffusion

Examples in Plants: Oxygen ____ out of stomata during photosynthesis. Carbon dioxide _____ into leaves for photosynthesis.

Convection (Bulk Flow)

Movement of gases through a medium (air or liquid) driven by pressure differences. It enhances diffusion by rapidly transporting gases across large distances within an organism.

Convection (Bulk Flow)

Examples in Animals: Breathing: Air moves into lungs via pressure changes. Circulatory system: Blood carries oxygen and carbon dioxide throughout the body.

Convection (Bulk Flow)

Examples in Plants: Air currents aid in gas diffusion through stomata. Movement of gases through intercellular spaces in leaves.

Active Transport

Energy-dependent movement of gases across membranes. While gas exchange primarily relies on diffusion and convection, some specialized cells use this to regulate oxygen levels in specific conditions.

Active Transport

Examples in Animals: Some specialized cells use this to regulate oxygen and carbon dioxide levels.

Examples in Plants: Root cells use it to absorb oxygen from soil.

Animals

Primary Function: Oxygen intake for respiration.

Plants

Primary Function: CO₂ intake for photosynthesis.

Plants

Gas Exchange Site: Stomata, lenticels

Plants

Gas Taken In: Carbon dioxide

Plants

Gas Released: Oxygen

Plants

Mechanism: Passive diffusion

Animals

Mechanism: Active breathing

Animals

Gas Exchange: Site Lungs, gills, tracheae