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15 Cards in this Set
- Front
- Back
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Surface area |
-The total number of cells in direct contact with the environment -Surface area affects the exchange of materials at exchange surfaces |
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Volume |
-The area occupied by metabolically active cells -Volume of metabolically active tissue influences demand for materials |
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SA Volume interaction |
SA determines the rate of supply of materials to metabolically active cells |
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Erythrocytes |
- Biconcave disc increases SA for transportation of oxygen - Lack of nucleus increases volume for carrying haemoglobin |
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Alveoli |
- Millions to increase SA -Course to blood to maintain diffusion gradient -1 cell thick walls allow for gas exchange |
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Root hair cell |
-Extended structure for increased SA -Semi permeable one cell thick -Transports water and nutrients |
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Leaf mesophyll |
-Air spaces to increase SA for for diffusion Co2 needed for photosynthesis -Air currents maintain diffusion gradient - Guard cells control when Co2 and O2 can leave the cell -One cell thick -Area for transpiration improved |
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Capillaries |
-1 cell thick semi permeable cell membrane -Large SA due to capillary network -Close proximity to the cells |
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Mass Transport (In plants) |
-Water movement in xylem -Translocation in phloem |
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Mass Transport (In Mammals) |
-circulation -ventilation |
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Ficks Law (Plants) |
Diffusion rate = surface area x difference in concentration /thickness of exchange surface |
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Gas Exchange in plants |
-O2 for respiration -CO2 for photosynthesis |
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Net Exchange |
Midday - Photosynthesis > respiration Midnight - Photosynthesis < respiration Compensation point Photosynthesis = respiration |
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Ficks Law (Mammals) |
Diffusion rate = SA of membrane x Difference in concentration across the membrane / thickness of membrane |
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Other features of gas exchange (mammals) |
-Layer of moisture in alveoli for gases to dissolve into -Surfactant in moisture layer a lipoprotein to reduce tension inside lungs to prevent collapse |
