Gas Exchange in Single-Celled Organisms and Insects

sammi_taylor01
Flashcards by , created about 6 years ago

AS Biology2 (Exchange and Transport) Flashcards on Gas Exchange in Single-Celled Organisms and Insects, created by sammi_taylor01 on 05/29/2013.

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sammi_taylor01
Created by sammi_taylor01 about 6 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 :-)