Biology b3 revision

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  • 1. Exchange of materials Transporting substances around the Body  Microbiology  
  • 2. Diffusion is the movement of a fluid across a concentration gradient from an area of high concentration to an area of low concentration. Osmosis is the movement of water across a partially permeable membrane from an area of high concentration to an area of low concentration.
  • 3.  In active transport, energy is needed.  The  energy comes from cellular respiration Happens in the cytoplasm and mitochondria Cell membrane cytoplasm Mitochondria nucleus    More respiration happening, more active transport can take place This is because the fluid can move from low to high concentrations. This is called moving against the gradient.
  • 4.  The uptake of mineral ions through the soil.  The ions are found in very dilute solutions.  The solution inside the plant is a lot stronger.  Ions taken in against the gradient.  Glucose is moved out of kidney into your blood.  It goes against the gradient.  Marine birds consume large amounts of salt when they drink water.  The kidneys cannot get rid of it all.  They have salt glands which use active transport.
  • 5.       When we breathe in, our ribcage moves up and out Our diaphragm flattens Air is pulled into the lungs When we breathe out, our ribcage moves down and in Our diaphragm inflates Air is forced out of the lungs DIAP H RAG M
  • 6.  Lungs are made up of clusters of alveoli  tiny air sacs with large surface areas  Have a rich blood supply  maintains a concentration gradient in both directions. Oxygen constantly being removed from the blood and carbon dioxide constantly entering the lungs gas exchange happens at the highest concentration gradients o make it rapid and effective.  
  • 7.   The food we eat is broken down in the gut. It forms simple sugars:  Glucose  amino acids  fatty acids  glycerol.    These products are of no use in the gut. Via active transport and diffusion, the molecules from food enter the bloodstream. food is broken down during the digestion process.
  • 8.  After being broken down, the food molecules are small enough to pass through the walls of the small intestine into the blood vessels.  They can move this way because there is a very high concentration of food molecules in the gut, and a very low concentration in the blood, so the process here is diffusion. They move along a very steep concentration gradient. 
  • 9.  The lining of the small intestine is folded into thousands of tiny villi.  They increase the uptake of digested food by diffusion.  the  villi increase the surface area dramatically. Diffusion is very rapid and efficient in the gut, because it has a rich blood supply  digested food molecules are carried away the second it diffuses.  a steep concentration gradient is constantly maintained.
  • 10.  Fish have protective scales all over their bodies  prevent water  They have gills  made    of very thin layers of tissue GILLLLLS! with a rich blood supply.  Very  them from directly taking in oxygen from the thin Less surface area for the gas to diffuse across. Fish do not need to worry about keeping the gills moist living in water. Gills do not work in air  “suffocate” out of water  if not kept moist constantly the gills stick together  and there isn’t enough surface area for the fish to get enough oxygen to survive.
  • 11.    All plants require carbon dioxide and water for photosynthesis. The carbon dioxide is obtained via diffusion through the leaves. The flattened shape of the leaves:  increases the surface area for diffusion to happen.  Ensures the photosynthesising cells are close to an edge.  A problem is that water is always being lost by evaporation.  allowing vapour. carbon dioxide in will also lose water
  • 12.  The plant does not need carbon dioxide all the time  At night there is no sunlight   They are adapted for effective exchange  have stomata (opening holes)    both gas-proof and waterproof. Roots have been adapted for uptake of water and mineral ions.   can open and close at specific times to allow carbon dioxide in and out. Have a waxy cuticle covering them   photosynthesis cannot take place. Water is vital for shaping cells and for photosynthesis. The roots themselves are thin and have a large surface area. The root hair cells have also adapted to increase surface area  increase efficiency of water uptake.   The cell membranes of root hair cells have microvilli  further increase surface area for diffusion and osmosis.  The distance between here and the xylem (transport tissue for the water) is small.
  • 13. 1  2  3 The loss of water vapour through the surface of the leaves is called transpiration. As water is lost through the opening in stomata, more water is pulled up through the xylem to take its place. 4 5 6 7   8 9  This constant movement of water around the plant is known as the transpiration stream. Anything affecting evaporation on a plant will also affect transpiration. Factors which increase evaporation will also increase transpiration.
  • 14.  Sunny and warm conditions increase rate of photosynthesis  more   carbon dioxide is needed Means stomata are opened  means water is lost these conditions also increase transpiration rate:  Hot  dry  windy.  Adaptation to help with the problem of water loss is  Waxy cuticle  plant can wilt  happens when more water is lost than gained  prevent much water loss by minimising the surface area
  • 15.  The blood circulation system we have is made up of three main components:  blood vessels  the heart  the blood One transports blood from the heart to the lungs and back again.  the other takes blood around the rest of the body.  With this system, we are constantly receiving oxygenated blood from the lungs. 
  • 16.  There are three main blood vessels in the system, which have all adapted to carry out specific functions.  The arteries carry blood away from the heart to the organs in the body.   This is usually oxygenated blood, explaining the red tubes. Is our pulse  The    veins carry blood towards the heart usually low in oxygen deep purple-red in colour. No pulse in veins  do contain valves which prevent the backflow of blood.  The capillaries are found in junctions between the arteries and veins.   These are found in huge networks. The walls are a single cell thick so diffusion is easy.
  • 17.     Our hearts are made of two pumps, for the double circulation. These together beat around seventy times a minute. The walls of the heart are made pretty much entirely from muscle which gets oxygen from the coronary blood vessels. Split into four chambers  Ventricle and Atrium for each circulatory system
  • 18.  The liquid part of our blood is called plasma.        It transports red blood cells, white blood cells and platelets. Blood plasma is a yellow liquid which transports all blood cells and other substances around the body. Carbon dioxide produced in the organs is carried in plasma back to the lungs. It is the red blood cells which give blood its red colour. Urea, a waste product formed in the liver is carried in the plasma to the kidneys. In the kidneys, urea is removed from the blood and changed into urine. All substances are transported in plasma.
  • 19.   The function of red blood cells is to pick up oxygen from the lungs and deliver it to cells and tissues where it is needed. Their adaptations to improve efficiency at their job include: being shaped like biconcave discs increases surface area:volume ratio over which diffusion takes place  packed full of haemoglobin - pigments which can carry oxygen  Have no nucleus, more room for haemoglobin and diffusion! WOO.   A haemoglobin is a large protein molecule folded around four iron atoms ( THAT LOOKS PRETTY MINT!) Oxygen + Haemoglobin ---> Oxyhaemoglobin  In an area of high oxygen concentration, haemoglobin can react with oxygen to form oxyhaemoglobin, which is bright red in colour, ergo blood being the colour it is.
  • 20.   Lone haemoglobin after is purple/deep red, which explains the colour of veins. Haemoglobin are made from iron a  diet lacking iron can results in anaemia makes you pale and have no energy.  This is because your body cannot make enough red blood cells  you cannot carry enough oxygen around the body for your needs.
  • 21.  Muscles in our bodies need a lot of energy.  They contain many mitochondria to supply  Muscles also contain glycogen stores   glycogen is a carbohydrate which can turn into glucose. Our body respires more during exercise so our muscles contract:   this energy. glucose + oxygen → carbon dioxide + water (+ energy) when exercising your muscles contract harder and faster  need more glucose and oxygen to supply their energy needs.  More carbon dioxide is obviously produced –  has to be removed to keep muscles working efficiently.
  • 22.   So during exercise… heart rate increases and arteries dilate –  This increase the blood flow to exercising muscles    breathing rate increases, and you breathe deeper –   You breathe more often You draw more air into the lungs with each breath,     increases oxygen and glucose supply increases the rate of carbon dioxide removal Increases the amount of oxygen being brought into the body Increases the amount of oxygen picked up by red blood cells  This oxygen is carried to the exercising muscles Exercise is very beneficial to us when done regularly. Regular exercise… increases the size of the heart  Increases the size of the lungs    they develop a bigger blood supply They develop a more efficient blood supply
  • 23.     When you are doing extremely vigorous exercise over a long period of time, the muscles need so much oxygen that even an increase in breathing rate and heart rate does not supply enough. Respiration which does not involve oxygen must be done – anaerobic respiration. Muscles only switch to anaerobic respiration when they have been exercising for a long time and fatigue. Anaerobic respiration is not as efficient as aerobic respiration  the glucose molecules are not completely broken down   less energy is released. Anaerobic respiration:
  • 24.      After finishing a lot of exercise, you are out of breath for quite some time. Your body does this to get rid of the waste lactic acid which can cause problems The lactic acid has to be broken down into carbon dioxide and water which requires oxygen The amount of oxygen required to break down all of the lactic acid is called the oxygen debt. Oxygen debt repayment:
  • 25.    Your kidneys are vital in maintaining homeostasis. They filter out urea and remove it in urine because urea is poisonous. Water balance in the body must be maintained because too much water or too little water in cells can destroy them  the kidneys can remove excess water and release it from the body in urine.   The kidneys can remove excess salt from the body in the same way. The kidneys filter the blood and then reabsorb everything your body needs.
  • 26.  sugar (glucose), amino acids, mineral salts and urea all move out of the blood and into the kidneys along a concentration gradient.  The blood cells are too big to pass through the tubules and so are left behind. ALL of the sugar is reabsorbed back into the blood by active transport. The amount of water and the dissolved mineral ions which are reabsorbed vary. It depends on how much of each is needed by the body – this is selective reabsorption. Urine contains waste urea along with excess mineral ions and water not needed by the body. The quantities vary depending on how much you have taken in and given out.     
  • 27.       The human kidneys are not immune from damage. when they are damaged and stop functioning, toxins like urea stop being removed from the body, leading to death. The dialysis machine relies on a process called dialysis to clean the blood. A person’s blood leaves their body and flows into the machine, through partially permeable membranes. A dialysis fluid, which contains a certain concentration of substances ensures diffusion of unwanted substances from the blood into the fluid. However, glucose remains in the blood.
  • 28.       The dialysis machine prevents unwanted substances from building up and restores them to normal levels. However they build up again after a few days, which means regular dialysis must be done. Some dialysis machines can be fitted in homes It is essential the patient does not lose vital substances from the blood like glucose and important mineral ions. The fluid contains the normal content of mineral ions, so that any excess mineral ions are lost by diffusion, but no more. There is no urea in the dialysis fluid.
  • 29.  Advantages of these machines:  Constant medical attention  Saves lives  Much more readily available  than transplants Disadvantages of these machines:  repeated use at 8 hours per day  must follow a strict, healthy diet  after some years, the levels can be hard to maintain
  • 30.      The other solution to the problem of kidney failure is a kidney transplant. A replacement kidney must be healthy and donated by a donor. The majority of the time, it doesn’t just function quickly. The antigens on the kidney will be different from their own The problem with this is that the recipient’s immune system may reject the new kidney  Means  your body will destroy it. During a transplant, everything is done to prevent such a thing, but it is always a risk.
  • 31.  There are certain things that can be done to minimalize the risk of rejection:  Use a donor similar to the recipient with the same blood type.  This means they will share some of the same antigens.  Using immunosuppressant drugs. Given to recipients which suppress their immune system – for the rest of their lives.  means you are prone to disease  your body cannot deal well with any infection once caught. 
  • 32.  Advantages  Can continue life freely without dialysis.  Saves lives  Can eat what you like without worrying  Disadvantages A borrowed kidney will only last about 9 years before shutting down.  Rejection  Have to take your medicine everyday for the rest of your life in case it is ever rejected by the immune system.  Waiting lists for kidney recipients can go on for years.  Finding a suitable donor often proves hard.
  • 33. Yeast is probably the most important microorganisms for us.  Yeasts are single-celled organisms with a nucleus, cytoplasm and membrane surrounded by a cell wall.  They reproduce by asexual budding (splitting into two to form two new yeast cells).  Provided with a lot of oxygen, yeast cells will respire aerobically.  They break down sugar as an energy source, producing the waste products carbon dioxide and water.  When there is a lack of oxygen they respire anaerobically, which produces ethanol and carbon dioxide.  Ethanol is alcohol.  This process of anaerobic respiration in yeast cells is called fermentation. 
  • 34.     Yeast is used to produce bread and alcoholic drinks. In bread production, the yeast grows and respires – producing carbon dioxide which causes the bread to rise. The gas bubbles expand when baked due to the high temperatures, giving the bread its light, texture. All yeast cells are killed by the heat in the cooking process.
  • 35.       We can make beers and wines using yeast. Making beer relies on the process of malting, where barley grains are soaked in water to keep them warm. Germination begins and enzymes break down the starch in the grains into a sugary solution. This solution is extracted and used as an energy source for the yeast. The yeast and sugar mixture is fermented to produce alcohol, when hops are often added to give the drink its flavour. The beer is then left to settle, clear and develop fully its flavour.
  • 36.     Making wines uses the natural sugars found in grapes for the yeast’s energy source. The grapes would be pressed for their juice, which is mixed with yeast and water. The yeast is then left to respire anaerobically until all of the sugar is used up. The wine is later filtered to remove the yeast, and stored in bottles, where it is left for some time to mature.
  • 37.   Yoghurt is formed by the bacteria action on the lactose (milk sugar). You can make yoghurt by: adding a culture of the right type of bacteria to warm milk  keeping the mixture warm so the bacteria grow, reproduce and ferment  as the bacteria break down the lactose, lactic acid is produced       this process is lactic fermentation the lactic acid causes the milk to clot and solidify to form a yoghurt further bacterial action gives the yoghurt its creamy texture The same bacteria used to make yoghurt will also keep it from going Colourings, flavourings and other additives can be added to the yoghurt to improve its taste, appearance and texture.
  • 38.  We need microbes in large quantities for production of drugs, like antibiotics, and food.  To grow microbes on an industrial scale, large vessels called fermenters are used.  These have been developed to prevent occurrences which stop bacterial growth.  They react to changes, to try and maintain a stable environment  Industrial fermenters usually have:  An oxygen supply so the microorganisms can respire  A stirrer to keep the microbes in suspension  this maintains a constant temperature and makes sure that the oxygen and food are evenly spread out throughout the culture  A water-cooled jacket which removes excess heat produced from the respiration  Measuring devices for pH and temperature so changes can be made if necessary
  • 39.        A flammable mixture of gases forms when bacteria break down waste material of dead animals or plants in anaerobic conditions. The main component is methane, although the contents varies. The methane content tends to be around 50 to 80 per cent of the gas, the rest is made of carbon dioxide, water, hydrogen and hydrogen sulphide. Animal waste, dead animal and plant material and garden waste all contain carbohydrates which make them good energy sources for biogas generators. They tend to work best at around 30°C so are usually in hot countries. On average, every 10kg of dry dung can produce 3 cubic metres of biogas which is about 3 hours. Another advantage of these generators is that the waste, can be used as a fertiliser.
  • 40.   A type of food based on fungi is called mycoprotein. It is produced using the fungus Fusarium,      It requires aerobic conditions to grow. Its mass doubles every 5 hours this biomass is harvested, purified and dried to leave mycoprotein. It is pale yellow in colour and tastes faintly of mushrooms    grows and reproduces very rapidly based on a cheap energy supplyin a large fermenter. a range of colours and flavours can be added to it to enhance it. Mycoprotein serves as a high-protein, low-fat meat substitute. This means it is good for dieters and vegetarians.
  • 41.           Spontaneous generation is the belief that all living things come from a non-living thing. Biogenesis is the idea that living things created other living things. Louis Pasteur's broth Louis broiled broth for 15 min. He then let it sit for some time in a swan neck flask. He noticed that some dust had accumulated in the top part of the flask. He took a sample from the broth inside the flask. He noticed that nothing was growing in it. So he then preceded to shake the broth in the flask in such a way, that it would touch the dust at the top. He then took a sample from that and it was highly bacteria ridden.