TOPIC 3: Mass Transport Systems

The larger the organism…

The smaller the SA:V ratio

The smaller the organism…

The larger the SA:V ratio

What does the SA:V ratio effect?

Diffusion

How will diffusion be if the SA:V ratio is large?

Fast

What is a unicellular organism?

Comprised of only one cell

What is a multicellular organism?

Comprised of more than one cell

Which organism will have a higher metabolic demand?

Multicellular

→ Requires more substances, e.g., glucose, to be transported

Can large organisms rely on diffusion to meet their metabolic demands?

No.

• They require mass transport systems & specialised exchange surfaces to get the substances they need.

→ As they have a small SA:V ratio= diffusion is slow

What is a specialised exchange surface?

Alveoli & villi

What is a mass transport system?

A system, which enables the bulk transport of materials in an organism.

e.g., circulatory system