114105
Description
Flashcards by sammi_taylor01, updated more than 1 year ago
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Created by sammi_taylor01
over 11 years ago
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| Question | Answer |
| Give an example of a single-celled organism. | amoeba |
| How is oxygen absorbed in single-celled organisms? | Across their body surface via diffusion, as they have a large surface area to volume ratio. |
| What is a single-celled organisms body surface covered by? | A cell-surface membrane |
| Single-celled organisms have no barriers to the diffusion of gases, why? | They have a completely permeable cell wall. |
| What two features do insects have to reduce the amount of water lost? | -Waterproof coverings -Small surface area to volume ratio |
| Why is it hard for an insect to reduce water loss? | It has spiracles that are needed for the diffusion of gases, however these open and create water loss. This needs to be controlled in order to prevent the insect becoming dehydrated. |
| What is the pathway for diffusing gases out of an insect? | Trachea --> Tracheoles --> spiracles |
| How is the trachea given strength in insects? | They are supported by rings to stop the trachea collapsing. |
| Where do the tracheoles extend through in an insect? | The tracheoles extend through all the body tissues of the insect. In this way atmospheric air, containing the oxygen, is brought directly to respiring tissues. |
| In which two ways do respiratory gases move in and out of an insects tracheal system? | -Ventilation -Along a diffusion gradient |
| How can ventilation speed up respiratory rate in insects? | The movement of muscles create mass movements of air in and out of the trachea. |
| How do gases move in and out of insects? | Spiracles |
| How do the spiracles open and close? | A valve controls the motion of them |
| What are the limitations of an insects tracheal system? | -Relies mostly on diffusion to exchange gases -Diffusion pathway needs to be short therefore limiting the size and insect can be |
| FUN FACT | Insects are one of the most successful groups of organisms on Earth :-) |
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