Biology Unit 3a AQA Summary 5.0 / 5 based on 1 rating ? BiologyGCSEAQA Created by: Han2812Created on: 09-05-13 18:40 What is Osmosis? The movement of water molecules from an area (high to low concentration) 1 of 26 What is Diffusion? Where particles move from an area (high to low) 2 of 26 What 2 substances diffuse out of stomata? Water Vapour and Oxygen 3 of 26 What happens when you breath in? The rib cage expands, diaphram contracts and moves down, decreasing the pressure and drawing air in 4 of 26 What happens when you breath out? The diaphram relaxes, the rib cage decreases, increasing the pressure and pushing air out 5 of 26 Where are the alveoli? How do the maximise diffusion or CO2 and Oxygen? In the lungs. Gave a large surface area, moist lining, very thin walls, good blood supply 6 of 26 Where are the Villi? How do the maximise diffusion? In the small intestine. Increase the surface area of the intestine, single layer of cells, good blood supply 7 of 26 What is active transport? The movement of molecules against the concentration gradient (low to high), uses energy (different to diffusion) 8 of 26 What does the phloem do? Transports food substances, mainly dissolved sugars to growing regions and storage organs 9 of 26 What does the Xylem do? This transports water and minerals up by the transpiration stream 10 of 26 What causes transpiration? Evaporation and diffusion of water from inside the leaves 11 of 26 What are the four different arteries and veins in the heart? The pulmonary artery, vena cava (Right Side - deoxygenated blood), pulmonary vein and aorta (Left side - oxygenated blood) 12 of 26 Why do the arteries have strong, elastic walls? To cope with the blood being pumped from the heart at high speed - elastic fibres to allow them to stretch and spring back 13 of 26 How do capillaries increase the rate of diffusion? Really small, only allow one blood cell at a time, one cell thick wall - allows blood to have a short diffusion path to the cells 14 of 26 What is the job of the red blood cell? To carry oxygen from the lungs to the cells in the body 15 of 26 What is the job of the white blood cell? To defend against diseases, produce antibodies to neutralise any toxins produced by microorganisms 16 of 26 What helps the blood clot? Platelets 17 of 26 What are stents? they are tubes which are inserted into the artery, get opened up and keep the artery open 18 of 26 What is homeostasis? The maintenace of a constant internal environment? 19 of 26 What 6 main things does homeostasis control? Temperatur, water content, ion content, blood sugar levels, carbon dioxide, urea 20 of 26 What happens if you are too hot? Hairs lie flat, sweat is produced - evaporates cooling the skin down, blood vessels dilate to get rid of excess heat 21 of 26 What happens if you are too cold? Hairs rise up, no sweat produced, shiver and blood vessels close off near the skin to save heat 22 of 26 What are the three main roles of the kidney? To clean the blood of urea, adjust ions and adjust water content 23 of 26 What substances diffuse through the partically permamble membrane in renal dialysi? Urea, excess ions and water 24 of 26 What causes Type 1 diabetes? Lack of insulin - cant diffuse sugars from the blood effectively into cells 25 of 26 How can this be controlled? Insulin injectors, low carb diets, exercise 26 of 26
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