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| 297146315 | How is an amoeba adapted for gaseous exchange? | Entire surface of the body Large surface area to volume ratio for example 6:1 They live in water so the skin can be kept moist Efficient blood supply to keep diffusion gradient Very thin membrane | |
| 297146316 | Where gaseous exchange can happen ? | In external gills In highly vascularized internal gills In highly vascularized lungs In terminal ends of fine tracheal tubes ( penetrate into all the tissue) | |
| 297146317 | Rate of diffusion = | (Surface area *Difference in concentration ) / Thickness of membrane | |
| 297146318 | How are fish adapted for gaseous exchange ? | They have four pairs of gills that lie in the pharynx Each gill is supported by a gill arch and has two stacks of lamellae which lie on top of each other. Unless kept apart by water they stick togethger. They lie in a cavity protected by the operculum. | |
| 297146319 | fish cont. | Each lamella has projections called gill plates. Blood flows from the afferent vessel in each gill arch down the inner side of each lamella, across the gill plate and back to an efferent vessel. Water flows in a counter current direction to the blood so the concentration of oxygen will never reach equilibrium. | |
| 297146320 | How are vertebrates adapted to gaseous exchange? | They have adapted through developing the lung for gaseous exchange with air. | |
| 297146321 | Amphibians ? | They tend to live in moist habitats as they require water for fertilisation. Tadpoles go through metamorphosis from using gills to using their skin and lungs for respiration. | |
| 297146322 | Reptiles? | Pairs of ribs project from the vertebrae. Ribs provide support and protection to the organs in the body cavity. The ribs are also used for the ventilation of the lungs. The lungs have a complex internal structure with in-growth of tissues increasing the surface area for gas exchange. | |
| 297146323 | Birds? | Ventilation of the lungs is far more efficient than in other vertebrates. They have a sytem of air sacs connected to the lungs. When the bird breaths in air the air left from the previos inhilation is sucked into the sacs. Ventilation of the lungs is brought about by the movement of the ribs. | |
| 297146324 | How do insects achieve effcient gas exchange ? | They have an extensive system of branching tracheoles, they also withdraw fluid in the tracheoles during exercise. The use of oxygen by cells in respiration keeps the concentration low in cells and some insects have a ventilation system which increases the concentration gradient. A short diffusion is achieved by thin tracheole walls, a lack of chitin, increasing permeability and withdrawal of fluid enabling air to reach closer to more cells, so reducing diffusion distance. |
