Gcse Biology Unit 3 Summary

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[pic] AQA GCSE Biology New Unit 3 Summary Notes Unit 3 Summary We need to understand how biological and environmental systems operate when they are working well in order to be able to intervene when things go wrong. Modern developments in biomedical and technological research allow us to do so. B3.1 Movement of molecules in and out of cells Summary The cells, tissues and organs in plants and animals are adapted to take up and get rid of dissolved substances. Different conditions can affect the rate of transfer. Sometimes energy is needed for transfer to take place. Dissolved substances Dissolved substances move by diffusion and by active transport. Diffusion (covered in more detail in unit 2): • The movement…show more content…
• Breathing out (exhalation): o The ribcage moves down and in. o The diaphragm moves upwards into a domed shape. o This reduces the volume inside the thorax. o This increases the pressure inside the thorax. o Air leaves the lungs. [pic] Artificial ventilators • Artificial ventilation may be used when someone is unable breathe themselves. • There are many possible risks with this process, including collapsed lungs, airway injury, damage to the airsacs (alveoli), and pneumonia. • Therefore, care must be taken to do it properly. • Manual ventilators: o Often used for first aid to help someone breathe. o A mask attached to a bag is placed over the mouth and nose. o The bag can be squeezed, pushing air into the lungs. • Mechanical ventilators: o Machines can be used that enable air to move into and out of the lungs: o Negative pressure machines. ▪ Often referred to as iron lungs. ▪ These are used in cases of paralysis, for example, due to polio. ▪ The patient’s thorax is contained inside a metal box that can create a very low pressure outside the…show more content…
o Wind moves the water vapour away from the leaf, maintaining the concentration gradient. • Most of the water lost by transpiration leaves through the stomata. • Stomata close when it is dark, when carbon dioxide is not required. • This reduces the amount of water lost by the plant at a time when it is not needed for photosynthesis. • If plants lose water faster than it is replaced by the roots, the stomata can close to prevent wilting. B3.2 Transport systems in plants and animals Summary Substances are transported around the body by the circulatory system (the heart, the blood vessels and the blood). They are transported from where they are taken into the body to the cells, or from the cells to where they are removed from the body. Modern developments in biomedical and technological research enable us to help when the circulatory system is not working well. Plants have separate transport systems for water and nutrients. The blood system • The circulatory system transports substances around the body. [pic] • The heart is an organ that pumps blood around the body. • Much of the wall of the heart is made from muscle

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