| Adaptations for gas exchange | - Large surface area
- Thin - shorter diffusion path
- Maintaining steep concentration gradient |
| How single-celled organisms exchange gases across their body surface | - Absorb + release gases by diffusion through outer surface
- Relatively LSA, thin surface
- Oxygen can take part in biochemical reactions as soon as it diffuses into cell
- So there's no need for a gas exchange system |
| Gas exchange in insects | - Have internal network of tubes, tracheae
- Supported by strengthened rings, prevents from collapsing
- Divides into smaller tubes called tracheoles |
| Tracheoles | - In all tissues of insect
- Oxygen diffuses directly into tissues, as it has shorter diffusion path |
| Using tracheae in gas exchange in insects | - Air moves into tracheae through pores,spiracles
- Oxygen travels down concen. gradi. into cells
- Insects circulatory system doesn't transport O2
- CO2, from cells, diffuses down concen.grad. to spiracles, to be released
- Insects use rhythmic abdominal movements |
