1. Putting it all together
Gas exchange
Putting it all together

2. For achieved Write an introduction presenting the discussion.
What are the three groups of animals?
Why do they need to carry out gas exchange?
What are the requirements of all gas exchange systems?
Describe how each group does gas exchange
Describe two adaptations for each group of animals that help with gas exchange
How does one adaptation for each group help it to survive in its habitat?
Include labelled and annotated diagrams as support.

3. For merit All that you did for achieved, and…..
For at least two of the groups:
Explain how or why two adaptations for gas exchange enables them to live successfully in their way of life, consider its role, function and or purpose.

4. For excellence
All of that for merit, but the explanation needs more detail and you need all three groups explained.
You need to link several biological ideas in a comparison between gas exchange across the three animal groups:
How the gas exchange is linked to the success of each group

5. What are some of the environmental challenges
What are some of the environmental challenges? What adaptations have evolved to increase efficiency of gas exchange?
Oxygen content of medium
Air is dry
Air and water may contain dirt
High metabolic needs
Density of water vs air
Challenges of ventilation

6. Oxygen content Which groups extract from the same medium?
What adaptations do the animals have that allow them to get as much oxygen as possible out of the water?

7. Air is dry – compare and contrast
What groups is this a problem for? Why?
Explain how their adaptations help with this issue?
For each group you need to compare and contrast – which groups have a similar issue and how do they deal with it? Which ones is it not a problem for? Why? How is this an advantage?

8. Dirty medium? This can be a problem for all the groups.
What similarities and differences are there in the way that the animals are adapted to help them to remove the dirt from the air and water.
What would happen if they did not have these adaptations.

9. Metabolic needs What is oxygen needed for?
Is it the same for each group?
Are the demands for oxygen the same in each group?
How do the adaptations for gas exchange relate to the metabolic needs of each group?

10. Density of media Do the medium have the same density?
How can the densities affect gas exchange?
What adaptations do the animals have to help them to cope with the density of the media?
How do they ensure a constant supply of media containing oxygen to their gas exchange membranes?

11. Ventilation
Due to all the challenges listed above, adaptation enable efficient ventilation of gas exchange surfaces.
Discuss the adaptations each group has and how they increase efficiency in relation to the challenges of their environment.
What do they have? What do they do to lesson the challenge?