Special surfaces of gas exchange

Organisms need to obtain resources from their _______________.

environment

How much they require depends upon their:

Volume (Bulk)

Activity levels

Metabolic rate of diffusion

Surface area

How does an organism’s size relate to it’s surface area to volume ratio?

The larger the organism, the lower the surface area to volume ratio.

How does surface area to volume ratio affect transport of molecules>

The lower the SA/V ratio, the further distance molecules must travel to reach all parts of the organism.

Why do larger organisms require mass transport and specialised gas exchange surfaces.

Small SA/V ratio

Diffusion insufficient to provide all cells with the required oxygen and remove all carbon dioxide

Large organisms are more active than smaller organisms

Four features of an efficient gas exchange surface.

Large surface area

Thin Barrier

Fresh supply of molecules

Ventilation mechanism

Why is a large surface area important for efficient gas exchange?

More space for molecules to pass through

Why is a thin barrier important for efficient gas exchange?

Short diffusion distances

Why is a fresh supply of molecules important for efficient gas exchange?

Maintains a steep diffusion gradient

Why is a ventilation mechanism important for efficient gas exchange?

maintains a steep diffusion gradient

Other features and why they’re important?

Moist — allows gases to dissolve

What type of organism is an amoeba?

Unicellular

Single cells have a very ________ surface area to volume ratio?

large

The cell membrane is _______ so diffusion into the cell is rapid

thin

A single cell is thin so ____________ _______________ inside the cell are short.

diffusion distance

Therefore _________ ______________ across the cell membrane is sufficient to meet the demands of the respiratory processes.

simple diffusion

What type of organisms are earthworms>

Multicellular organisms

What size is the SA/V ratio of an flatworm?

relatively small

However ____ structures provide a large ____________ _____ and reduces the diffusion distance

flat

surface area

__________ _______________ is sufficient to meet the demands of respiratory processes

Simple diffusion

What type of organisms are earthworms?

Cylindrical, multicellular organisms

How large is the SA/V ratio of earthworms?

relatively small

Earthworms are _____ _______________ and have a low ____________ _____ therefore require little oxygen

slow moving

metabolic rate

Earthworms rely on ___________ ______________ for gas exchange

external surface

Earthworms require a ________________ _________ to transport oxygen to the tissues and remove carbon dioxide in order to ___________ a steep diffusion gradient

circulatory system

maintain