BIOLOGY - ADAPTATIONS FOR GAS EXCHANGE

Large surface area for large contact with air for diffusion/gas exchange. Thin for small diffusion distance, moist to allows gases to dissolve into solution before diffusion and permeable to allow gases to pass through

Proportionately less surface area in relation to its volume

Small single-celled organisms that live in aquatic environments, they have a large surface area compared to its volume. Diffusion across the cell surface membrane can meet the needs of the whole organism and the gas exchange surface is thin, resulting in short diffusion paths to the centre of its body

Aquatic animals with a flattened shape, it has a large surface area to volume ratio of the body surface for gas exchange. It also means that diffusion paths for respiratory gases are short

Terrestrial animals, they are more active than flatworms and so have a higher metabolic rate. They have an extended tubular shape which gives them a lower surface area to volume ratio than the flatworm

Evolved to have a circulatory system that transports oxygen to its cells more efficiently than diffusion. Blood capillaries lie directly below the skin surface - these maintain a diffusion gradient at the gas exchange surface. Earthworms also have a respiratory pigment in the blood to transport oxygen