Exchange of materials
- Created by: olivia_viney
- Created on: 04-02-16 19:10
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- Exchange of materials
- Osmosis
- Movement of water
- Movement of molecules is random and requires no energy from cells
- High concentration (dilute) to a low concentration
- Cell membrane partially permable
- Active transport
- Cells use active transport to absorb substances across partially permeable membranes against the concentration gradient.
- Requires the use of energy released in respiration
- Cells are able to absorb ions from dilute solutions.
- Glucose can be reabsorbed in the kidney tubules by active transport
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- Exchanging materials- the lungs
- Large organisms have exchange surfaces to obtain the food and oxygen they need
- Soluble food absorbed by the interstine
- The lungs contain the gaseous exchange surface
- Surface are is increased by alveoli (air sacs)
- Alveoli have thin walls and large surface area
- Surface are is increased by alveoli (air sacs)
- Lungs ventilated to maintain steep diffusion gradient
- Ventilating the lungs
- Lungs are situated in the throax, inside the rib cage and above the diaphragm
- When we breathe in
- The intercostal muscles contract
- The ribcage moves up and out and the diaphragm flattens
- Volume of throax increases
- When we breathe out
- Intercostal muscles of the ribcage and diaphragm relax
- Ribcage moves down and in and the diaphragm becomes domed
- Volume of throax decreases
- Exchange in plants
- Gases diffuse in and out leaves by the stomata
- Plants lose water vapour through stomata due to evaporation in the leaves
- Water and mineral ions are taken up by the roots
- Root hair cells in crease the surface area of roots for the absorption of water and mineral irons
- Transpiration
- The movement of the water through the plant is called transpiration steam
- The plant could dehydrate if the rate of evaporation in the leaves is greater than the water uptake by the roots
- The guard cells can close to prevent excessive water loss
- Wilting can protect the leaf from excessive water loss
- Osmosis
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