2.2 Adaptations for gas exchange AMOEBA + FLATWORM + EARTHWORM

Question 1

How does an amoeba obtain sufficient volumes of oxygen to satisfy metabolic needs?

Answer 1

-Unicellular so oxygen requirement low
-Large surface area:volume ratio
-Diffusion across membrane sufficient to satisfy
-metabolic needs

Question 2

How does flatworm obtain sufficient volumes of oxygen to satisfy metabolic needs?

Answer 2

-Multicellular but slow moving so low oxygen requirements
-Flat shape ensures high surface area:volume ratio and shorter diffusion distance
-Diffusion across external membrane sufficient to satisfy metabolic needs

Question 3

How does an earthworm obtain sufficient volumes of oxygen to satisfy metabolic needs?

Answer 3

-Multicellular but slow moving so low oxygen requirements
-Smaller surface area:volume ratio
-Round shape increases diffusion distance, so have circulatory system with respiratory pigment close to surface to distribute oxygen to the tissues
-Circulatory system enables diffusion to still occur across external membrane