6.2 Gas exchange in single-celled organisms and Insects

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GCSE (Organisms Exchange Substances with their Environment) Biology Fichas sobre 6.2 Gas exchange in single-celled organisms and Insects, creado por Sea Chel Pie el 04/02/2019.
Sea Chel Pie
Fichas por Sea Chel Pie, actualizado hace más de 1 año
Sea Chel Pie
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how are Single-celled organisms adapted ? ~ Small -> Large SA:V ratio ~ O₂ absorbed by DIffusion -> across body surface by cell-surface membrane ~ CO₂ from respiration diffuses out
how are Insects evolved for Gas Exchange ~ Tracheae, Internal Network of Tubes ~ Spiracle, pores on surface ~ Tracheae support by Chitin (Strengthened Rings) -> prevent Collapse ~ Tracheoles, tracheae divides into small deadend tubes -> extend throughout all body tissue
Structure inside Insect
how are these Structures helpful for gas exchange in Insects ~ Atmospheric air, with O₂ -> bought directly to Respiring tissue -> due to Short diffusion Pathway from tracheoles to any body cell
Respiratory gases move in and put of Tracheal system in 3 ways 1. Along a Diffusion Gradient 2. Mass Transport 3. Ends of the Tracheoles filled with Water
1. How does O₂ enter the cell ~ O₂ concentration decreases inside end of Tracheoles -> cuz, O₂ used up during Respiration ~ this creates Diffusion Gradient causing Gaseous O₂ to enter cells -> from atmospheric air -> through Tracheae & Tracheoles
1. how does CO₂ leave the cell ~ CO₂ concentration increases inside end of Tracheoles -> cuz CO₂ produced during Respration ~ this created conc. gradient in the other way causing Gaseous CO₂ to leave cells -> from Tracheoles to atmospheric air
2. what is Mass Transport ~ Contraction of muscles in insects can squeeze the Trachea -> enabling mass movement of air in and out ~ this further speeds up the exchange of respiratory gases
what happens when the Muscle cells around the Tracheoles respire Anaerobically? How does H₂O enter cells? ~ produce Lactate, during major Activity ~ Lactate is soluble -> Lowers the water potential of muscle cells ~ H₂O moves Into cell from Tracheoles by Osmosis
how does Air move into the Tracheoles? ~ H₂O in ends of Tracheoles decreases in volume ~ so Air is drawn into the Tracheoles
what is the Final diffusion pathway? downside? ~ in a Gas rather than Liquid phase -> increases the rate of air flow into Tracheoles ~ but also Greater Water Evaporation
what are Spiracles? ~ Gases enter and leave through tiny pores ~ on Body surface ~Opened and Closed by Valves
why don't Insects keep Spiracles open all the time? When do they open? ~ Water vapor can evaporate from spiracle ~ > closed to Prevent water Loss ~ periodically open to allow Gas exchange
Limitations of the Tracheal system 1. relies Mostly on Diffusion to exchange between environment and cells -> for effectiveness -> diffusion pathway must be short 2. Limits size of Insects -> due to length of pathway
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