Lesson 1 - The need for gas exchange surfaces

Question 1

state some adaptations for gas exchange occur in small organisms

Answer 1

• small diffusion distances
• large surface area, so large SA to V ratio
• low metabolic demands, as they don’t need to regulate their body temperature, don’t need lots of oxygen or produce lots of carbon dioxide

Question 2

why don’t small organisms need a specialised gas exchange system

Answer 2

diffusion is enough to supply their needs

Question 3

why do large organisms need a specialised gas exchange system

Answer 3

• the substances need to travel longer distances
• higher metabolic demand, as need to control body temperature and are very active
• higher oxygen demands

Question 4

state 3 factors which affect rate of diffusion

Answer 4

• surface area
• concentration gradient
• diffusion distance