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23 Cards in this Set
- Front
- Back
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What make a good exchange surface? |
1) Large surface area 2) Large conc. gradient 3) Thin exchange surface |
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How does SA affect exchange of heat? |
- SA decreases, as the organism gets larger - Larger organism loses heat more slowly across it surface than a smaller organism |
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How do insects limit water loss? |
1) Waterproof covering 2) Smaller surface area to volume ratio |
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What are spiracles? |
Gas enters and leaves the insect through these tiny pores. |
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How do spiracles prevent water loss? |
They open and close |
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What are tracheoles? |
Small tubes which extend throughout the body tissues |
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What are tracheae? |
Network of tubes supported by strengthened rings |
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Why is the diffusion pathway always short? |
Every cell of an insect is only a very short distance from one of the tracheae or tracheoles |
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How does oxygen diffuse through an insect? |
1) Tissues respire using oxygen which reduces the oxygen conc. 2) Oxygen moves from an area of high conc. to low conc. from the tracheae to the tissue 3) This lowers the oxygen conc. in the tracheae so oxygen can move from the outside via spiracles |
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How does CO2 diffuse out of an insect? |
1) Respiration produces CO2, increasing the conc. at the tissue 2) CO2 moves from a high conc. at the tissue to low conc. in the tracheae 3) CO2 moves from high conc. in the tracheae to low conc. outside the insect via spiracles |
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How does muscle movement affect gas exchange in insects? |
Movement of muscle creates mass movement of air in an out the trachea, speeding up the gaseous exchange. |
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What organ helps fish to exchange gas? |
The gills |
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How is flow of water maintained in a fish? |
1) Fish opens mouth and the floor lowers to decrease the pressure and increase volume 2) Fish closes mouth and the floor is raised to decrease volume and increase pressure 3) Water is forced out of the gills |
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Describe the structure of gills. |
- Gill filaments - Each filament has lamellae - Lamellae are positioned at right angles to filaments - Lamellae contain capillaries - Thin epithelium |
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What features does the fish gas exchange have? |
- short diffusion path - large SA - maintains conc. gradient |
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How does a fish have a large surface area? |
Gill filament have many lamellae |
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Describe the system of counterflow. |
1) Water enters the mouth with oxygen 2) The water passes over the gill filaments 3) The position of the filaments and lamellae means that blood and water flow occur in opposite directions |
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How does counterflow aid the fish? |
Increases the fish's ability to absorb oxygen from the water as a diffusion gradient is always maintained. |
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What adaptations does a leaf have for gas exchange? |
1) Flat- gives a large surface area 2) Stomata- pores allow air to move in and out of the leaf 3) Air spaces in the leaf so short distance between mesophyll cells and air |
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How do leaves exchange CO2? |
1) Mesophyll cells photosynthesis and reduces CO2 conc. in cells 2) CO2 diffuses from the air spaces into the cells 3) This reduces the CO2 conc. in the air spaces causing CO2 to diffuse from the air outside through the stomata |
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How does oxygen diffuse out of leaves? |
1) Mesophyll cells produce O2 as a result of photosynthesis 2) O2 diffuses into the air spaces 3) This increases the conc. of O2 in the airspaces causing O2 to move from the air spaces to outside the leaf via the stomata |
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What adaptations do leaves have to reduce water loss? |
1) Waxy cuticle is waterproof 2) Air spaces are saturated in water vapour from the xylem ad water diffuse out of the stomata and evaporates 3) At night the guard cells close the stomata to prevent water loss |
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What adaptations do xerophytic plants have? |
1) Reduced number of stomata - less SA 2) Stomata in pits - reduces conc. gradient 3) Hairs to trap water - reduced conc.gradient 4) Rolled leaves - reduced conc. gradient 5) Spines - less SA 6) Thick waxy cuticle - increased diffusion pathway |
