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Biology 3

Biology 3. AQA Science. Diffusion Revision.

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Biology 3

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  1. Biology 3 AQA Science

  2. Diffusion Revision Diffusion is when particles spread from an area of high concentration to an area of ___ concentration. The particles move along a “concentration _____” and this process takes no _____ (it’s a “passive” process”). Diffusion can be accelerated by increasing the _______ of the particles, which makes them move _______. Words – faster, low, gradient, temperature, energy

  3. Active Transport In diffusion substances moved along a concentration gradient. In active transport, substances move against this gradient: Outside cell Inside cell This process takes ______ and this comes from ___________. It enables cells to take in substances even though there are in very small __________. Root hair cells take in ______ using active transport. Words – concentration, energy, respiration, nutrients Cell membrane

  4. Diffusion in the Body Oxygen diffuses in Out goes waste CO2 Cells use diffusion to swap the oxygen they need for the carbon dioxide they no longer want: Other examples of where diffusion happens in humans: Alveoli in the lungs Villi in the intestines

  5. Diffusion in Villi In the intestine, large food molecules are broken down into smaller ones that then diffuse into the blood through villi in the intestine. Villi also have a very good blood supply and a large surface area. They have tiny folds in their cell membrane called microvilli, which increase the surface area.

  6. The Respiratory System

  7. O2 Diffusion in the lungs Oxygen diffuses in and carbon dioxide diffuses out of blood in the lungs: CO2 Alveoli have three things that help them to do this job: a massive surface area, a moist lining that is only one cell thick and a very good blood supply.

  8. Diffusion and Active Transport in plants Carbon dioxide diffuses into the leaf through holes in the bottom surface. Mineral Less concentrated More concentrated …while plant nutrients are taken in by root hair cells using active transport.

  9. Photosynthesis – the 4 things you need SUNLIGHT Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen WATER Travels up from the roots CARBON DIOXIDE Enters the leaf through small holes on the underneath

  10. Structure of the Leaf Large surface area Lots of chlorophyll Transparent Thin structure Packed with chloroplasts Network of veins Lots of air spaces Holes

  11. Transpiration 1) Water evaporates through the stomata 2) Water passes back into the leaf through xylem vessels by osmosis 3) Water is then pulled upwards through the xylem tissue 4) This is replaced by water entering from the root tissue 5) Water enters root hair cells by osmosis to eventually replace the water lost through respiration

  12. Factors affecting transpiration 1) High light intensity This causes the stomata to open thereby increasing the rate of water loss. 2) High temperatures This increases the speed of molecule movement and so speeds up transpiration. 3) Increased wind This will blow the molecules away and so speeds up transpiration. 4) High humidity This decreases the concentration gradient and so slows transpiration down.

  13. Water loss Water loss through the stomata is biggest on a hot, dry, windy day. Plants that live in these conditions often have a thicker waxy layer.

  14. Controlling water loss Water and carbon dioxide enter here No more water and carbon dioxide allowed in Carbon dioxide enters a leaf through the ________. These cells are also responsible for controlling the ______ content of the ____… The ______ cells control how wide the stomata opens (if at all). If too much water is being lost through the stomata then the guard cells will _____ to prevent further loss. Words – water, close, stomata, guard, leaf

  15. The Circulatory system The circulatory system is responsible for pumping ______ around the body. We need blood to be taken around the body because blood contains ________ and _______. These are needed so that all the ____ in our bodies can produce _____ through _________. The main organs in the circulatory system are the _____, the lungs and the kidneys. Words – energy, heart, blood, glucose, respiration, oxygen, cells

  16. “Double Circulation” 1) Blood gets pumped from the heart to the lungs and picks up oxygen. The haemoglobin in the cells becomes oxyhaemoglobin 2) The blood is then taken back to the heart… 3) The heart pumps the blood to the intestine (where oxygen and glucose are removed). The oxyhaemoglobin is split up into oxygen and haemoglobin… 5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again 4) … and to the rest of the body (where oxygen is also removed)

  17. Arteries, veins and capillaries Arteries carry high pressure blood away from the heart. They have smaller lumen and no valves. Capillaries have thin walls (one cell thick) to allow glucose and oxygen to pass through. Also used to connect arteries to veins. “Lumen” Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and have valves to prevent backflow of blood.

  18. The four parts of blood 1. RED BLOOD CELLS – contain haemoglobin and carry ______ around the body. They have no _______ and a large surface area. 2. PLATELETS – small bits of cells that lie around waiting for a cut to happen so that they can ____ (for a scab). 3. WHITE BLOOD CELLS – kill invading _______ by producing _________ or engulfing (“eating”) the microbe. These three are all carried around by the PLASMA (a straw-coloured liquid). Plasma transports CO2 and ______ as well as taking away waste products to the ______. Words – antibodies, clot, kidneys, oxygen, nucleus, glucose, microbes.

  19. (Aerobic) Respiration Every life process (e.g. growth) needs ENERGY. ___________ is the process our bodies use to produce this energy: Glucose + oxygen water + carbon dioxide + ENERGY The glucose we need comes from ______ and the oxygen from _________. Water and carbon dioxide are breathed out. The MAIN product of this equation is _________. Muscles also contain glycogen, which can be quickly converted into glucose. Words – breathing, energy, respiration, food

  20. The Effect of Exercise Heart rate/min Breathing rate/min 100 225 Rest Exercise Recovery 75 175 50 125 25 75 5 mins 10 mins 15 mins 20 mins During exercise the following things happen: heart rate increases, breathing increases and arteries supplying muscles dilate. These three things all help muscles to get the oxygen and glucose they need.

  21. Anaerobic respiration Glucose lactic acid + a bit of energy Unlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________: This happens when the body can’t provide oxygen quick enough for __________ respiration to take place. Anaerobic respiration produces energy much _______ than aerobic respiration but only produces 1/20th as much. Lactic acid is also produced, and this can build up in muscles causing ______ and an oxygen ______. This “debt” then needs to be “repaid” by deep breathing to ________ the lactic acid. Words – debt, oxygen, fatigue, oxidise, aerobic, quicker

  22. Kidneys Blood in Blood out Ureter (tube that takes urine down to bladder) Kidneys are responsible for controlling ion, urea and water content. Kidneys are made up of two important tissues – BLOOD VESSELS and TUBULES.

  23. Kidneys 1. ULTRAFILTRATION - Lots of water and products of digestion are squeezed out of the blood and into tubules under pressure. 2. SELECTIVE REABSORPTION – the blood takes back the things it wants (e.g. glucose and ions) even though this means going against a concentration gradient. 3. WASTE – excess water, excess ions and any urea are now removed through the ureter Kidneys work in 3 stages: Blood vessel Tubule

  24. Dialysis Partially permeable membranes Dialysis fluid Blood Dialysis fluid Sometimes kidneys can fail due to infections, toxic substances or genetic reasons. One possible answer is to use a dialysis machine: Urea Sugar Sugar Urea Urea and salt diffuse out of the blood into the dialysis fluid. Also, the dialysis fluid contains the same concentration of sugar and minerals as the blood so these don’t diffuse.

  25. Kidney transplants Instead of dialysis a kidney could be transplanted into the patient. This option is cheaper than dialysis but it requires a _______ (a normal person can still function with one kidney). This donor must have a similar ______ type to the patient. Also, the new kidney might be rejected by the body’s ______ system which will try to destroy the new organ. To work around this problem the patient can take “immunosuppresant ___” which suppress the immune system. Transplanted kidneys only work for around nine years and then the patient has to return to _______. Words – dialysis, donor, immune, tissue, drugs

  26. Micro organisms Cell wall Sugar Alcohol + carbon dioxide Sugar Water + carbon dioxide Nucleus Cytoplasm Aerobic respiration: Anaerobic respiration (fermentation): Micro organisms are tiny living organisms such as bacteria, viruses and fungi. Bacteria is used for making yoghurts and cheese. Yeast is a single-celled organism used in making alcoholic drinks and bread. The difference between these two processes is whether the yeast respires aerobically or anaerobically:

  27. Using micro organisms to make food To make alcoholic drinks _____ is needed. In wine, this sugar comes from the natural sugars in the _____. In beer, the sugar is provided by carbohydrates which are digested by _______ (a process called “______”). The sugars are then extracted and fermented and hops are added to give the beer its ________. In yoghurt production bacteria is added to warm ____. The bacteria ferments the sugar in the milk (lactose) to produce ______ ____. The lactic acid causes the milk to clot and turn into yoghurt. Words – lactic acid, malting, sugar, enzymes, grapes, milk, flavour

  28. Louis Pasteur Pasteur, 1822 - 1895 I did a lot of work on germs in the 1850s. The process of “pasteurising milk” is named after me. Research task: Find out what Pasteur did and the experiments he performed with their conclusions. Extension task: Find out about the work of earlier scientists Lazzaro Spallanzani and Theodor Schwann and how their work proved that the traditional idea of “spontaneous generation” was wrong.

  29. Fermenters Micro organisms A fermenter is a controlled environment (i.e. a large device) that provides ideal conditions for micro organisms to grow and feed. Temperature sensor Water cooled jacket pH sensor Sterile air supply Outlet tap

  30. Penicillin Today, penicillin is grown in ________ which use sugar and other ________ (sources of nitrogen). The penicillium fungus only starts producing penicillin when the food runs out. Alexander Fleming, 1881-1955 Another fungus used on a large scale is fusarium, which is used to make mycoprotein (a _______-rich food suitable for _________). The fungus is grown on starch under ________ conditions and the biomass is harvested and purified. Words – aerobic, nutrients, fermenters, protein, vegetarian I (accidentally) discovered penicillin in 1928

  31. Biofuels Biofuels are fuels that are “made” biologically. For example: • Manure or other waste that can be used to release _______ (biogas) • Corn or sugar cane that can undergo anaerobic respiration in a fermenter and then distilled to produce ______ like bio-ethanol. Biofuels have two main advantages over traditional fuels – they are ______ and ________. Words – alcohols, cleaner, burnt, renewable, methane

  32. Biogas Task: Find a diagram of a biogas generator and explain how it works. To do this you should include answers to the following questions: • What is the main part of biogas? • What process goes on inside the generator? • What raw materials go inside the generator and where do they come from? • What does the generator produce and what do you use these products for? Extension – find out how different types of biogas generator are used in different conditions and why.

  33. Growing micro organisms 1) Sterilise the inoculating loop 2) Dip the loop in the bacteria and spread it across the agar 3) Secure (but don’t seal) the lid with tape Method: • Questions: • Why are you sterilising the loop? • What does the agar do? • Why is the lid not sealed all the way around? • Why would you not want to culture your bacteria at 37OC?

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