Need for gas exchange surface

Question 2

Gas exchange in large organisms

Answer 2

Substance need to travel long distances from the outside to reach the cytoplasm of all the cell
Eventually the substances are going to reach the cells by simple diffusion but not fast enough to keep the organism alive
The metabolic rate of larger organisms tend to be higher than that in smaller animals
The demands of each individual cell for 02 & nutrients & the amount of C02 & other waste produced is much higher in each individual mammal cell than in unicellular organisms
Evolved specialised system such as
Lungs in human
Gills in fish
Tracheal system in insects
Stomata in plants

Question 4

Properties of gas exchange surfaces

Answer 4

The respiratory gases are exchanged by simple diffusion
The rate of diffusion is controlled by several factors:
1. Surface area
2. The concentration against membrane
3. Thickness of the exchange surfaces

Question 5

Surface area

Answer 5

The rate of diffusion is directly proportional to surface area of the membrane. The larger the surface area the greater the diffusion (more particles can be exchanged at the same time)

Question 6

Concentration gradient across membrane

Answer 6

Rate of diffusion directly proportional to the concept gradient. The larger the concentration gradient the greater the rate of diffusion

Question 7

Thickness of membrane

Answer 7

Rate of diffusion is inversely proportional to the thickness of the membrane or the diffusion distance. Since the cell membranes are extremely thin the rate of diffusion will be high

Question 8

Fick’s law

Answer 8

The relationship between the factors & the rate of diffusion
Rate of diffusion