3.1.1 MODULE 3 EXCHANGE AND BREATHING

Why do single celled organisms not need specialised exchange surfaces?

Metabolic activity is low, so O2 and CO2 production of cell are low. The organism has a large SA:V.

1 of 5

What happens to the SA:V ratio as an organism gets bigger? What does this mean?

As an organism gets bigger, the the SA:V ratio gets smaller. So gases can’t be exchanged fast enough or in large amounts enough to survive.

2 of 5

What do all effective exchange surfaces have?

Increased SA, thin diffusion barriers, good blood supply and ventilation to maintain a diffusion gradient.

3 of 5

Why does ventilation create an efficient exchange surface?

Ventilation helps to maintain a steep concentration gradient, which means more efficient diffusion of gases and other substances.

4 of 5

Why does a good blood supply create an efficient exchange surface?

The steeper the conc gradient, the more diffusion takes place, having a

5 of 5

Other cards in this set

What happens to the SA:V ratio as an organism gets bigger? What does this mean?

As an organism gets bigger, the the SA:V ratio gets smaller. So gases can’t be exchanged fast enough or in large amounts enough to survive.

What do all effective exchange surfaces have?

Why does ventilation create an efficient exchange surface?

Why does a good blood supply create an efficient exchange surface?

Get Revising