1. BIOLOGY 3 LIFE PROCESSES & MICRO ORGANISMS

2. LIFE PROCESSES

3. Gas & Solute Exchange Diffusion, Osmosis and Active Transport life processes need gases or other dissolved substances before they can happen and waste substances also need to move out of the cells so that the organism can get rid off them, these substances move to where they need to be by diffusion, osmosis and active transport diffusion is where particles move from an area of high concentration to an area of low concentration osmosis is the movement of water particles across a partially permeable membrane from an area of high water concentration to and area of low concentration diffusion and osmosis involve stuff moving from an area where there’s a high concentration of it to an area where there’s lower concentration of it, sometimes substances need to move the other direction, this is active transport the exchange surface is where gases and dissolved substances move through, they have to allow enough of the necessary substances to pass through, they are adapted to maximise effectiveness Structure of Leaves carbon dioxide diffuses into the air spaces within the leaf then into the cells where photosynthesis happens, the leaf’s structure is adapted for this underneath of the leaf is an exchange surface, it’s covered in little holes called stomata which the carbon dioxide diffuses in through water vapour and oxygen also diffuse out through the stomata the size of the stomata are controlled by guard cells, these close the stomata if the plant is losing water faster than it is being replaced by the roots flattened shape of the leaf increases the area of this exchange surface making it more effective walls of the cells inside the leaf form another exchange surface, the air spaces inside the leaf increase the area of this surface so there’s more chance for carbon dioxide to get into the cells

4. Breathing System Lungs Are in the Thorax thorax: top part of the body lungs are separated from the lower part by the diaphragm and protected by the ribcage air you breathe in goes through the trachea (windpipe) and this splits into two tubes called bronchi, one going to each lung the bronchus splits into lots of smaller tubes called bronchioles bronchioles end at small bags called alveoli where the gas exchange takes place The lungs need oxygen from the air to get into your blood stream so that it can get to your cells for respiration and carbon dioxide needs to be dispose of. Breathing is how the air gets in and out of your lungs.

5. Breathing Breathing In (Inhaling) intercostal muscles contract pulling the ribcage and sternum up and out, expanding the ribcage diaphragm contracts, pulling downwards to increase the volume of the chest thorax volume increases, decreasing the pressure inside the chest so air is sucked into the lungs Breathing Out (Exhaling) intercostal muscles relax, dropping the ribcage and sternum down and in, contracting the ribcage diaphragm relaxes, moving back upwards to decrease the volume of the chest thorax volume decreases, increasing the pressure inside the chest so air is forced out intercostal muscles: muscles between ribs sternum: bone in the middle of the chest diaphragm: sheet of muscles below the lungs thorax: top part of body

6. Diffusion – Cell Membranes Gas Exchange Happens in the Lungs the lungs job is to transfer oxygen to the blood and remove waste carbon dioxide from it they contain millions of little air sacs called alveoli where gas exchange takes place alveoli are specialised to maximise the diffusion of oxygen and carbon dioxide: enormous surface area moist lining - dissolving gases very thin walls copious blood supply Villi Provide Really Big Surface Area inside of the small intestine is covered in millions of these tiny little villi they increase the surface area in a big way so that digested food is absorbed much more quickly into the blood they have single layer of surface cells and a very good blood supply to assist quick absorption

7. Active Transport Sometimes substances need to be absorbed against a concentration gradient, from a lower concentration to a higher one. This process is called Active Transport. As the particles move against the concentration gradient they require energy from the cell. Root Hairs the cells on the surface of plant roots grow into long hairs which stick out into the soil, giving it a big surface area for absorbing water and mineral ions from the soil concentration of the minerals is usually higher in the root hair cell than in the soil around it active transport allows the plant to absorb minerals against a concentration gradient, this is essential for growth but active transport needs energy from respiration to make it work We Need Active Transport to Stop Us Starving it is used in the gut when there is a low concentration of nutrients in the gut but a high concentration in the blood when there’s a higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood but sometimes there’s a lower concentration of nutrients in the gut than there is in the blood active transport allows nutrients to be takes into the blood even though the concentration gradient is the wrong way

8. Circulation System we have a double circulation system, one full circuit goes through the heart twice the heart is two pumps, the right side pumps deoxygenated blood to the lungs collecting oxygen and removing carbon dioxide and the left side pumps oxygenated blood around the body left side is muscular and thicker to give the blood a bigger push so it can get around the body normally arteries carry oxygenated blood and veins carry deoxygenated blood, but the pulmonary (connected to the lungs) artery and vein are big exceptions arteries carry the blood away from the heart at high pressure and veins bring back blood to the heart at low pressure the arteries eventually split off into thousands of tiny capillaries which take the blood to every cell in the body valves are only in veins to make sure the blood flow in the right direction, as the blood might flow backwards because it is in low pressure

9. Blood Capillaries use diffusion to deliver food and oxygen direct to body tissues and take carbon dioxide and other waste materials away their walls are usually only one cell thick to make it easy for stuff to pass in and out of them they are too small to see without a microscope Red Blood Cells its job is to carry oxygen from the lungs to all the cells in the body concave shape to give a large surface area for absorbing oxygen no nucleus, allowing more room for oxygen contain haemoglobin the special pigment that gives blood the red colour, which combines with oxygen to become oxyhaemoglobin this makes the blood oxygenated in body tissues the reverse happens to release oxygen to the cells Plasma it is the pale straw coloured liquid which carries just about everything: platelets, red and white blood cells nutrients like glucose and amino acids are soluble products of digestion which are absorbed from the gut and taken to the body cells carbon dioxide from the organs to the lungs urea from the liver to the kidneys a as a waste product of digestion antibodies and antitoxins produced by white blood cells protecting us from poisons and disease hormones are chemicals that control some of our body functions Made Up Of 4 Main Parts white blood cells: part of the immune system red blood cells: carry oxygen plasma: liquid that carries everything in the blood platelets: small fragments of cells that help blood to clot at a wound

10. Exercise Exercise Increases the Heart Rate muscles are made of muscle cells, these use oxygen to release energy from glucose (respiration) which is used to contract muscles an increase in muscle activity means more glucose and oxygen are needed to be supplied to the muscle cells and extra carbon dioxide needs to be removed, for this to happen the blood flow has to be faster this is why physical activity: increases your breathing rate and makes you breathe more deeply increases the speed at which the heart pumps dilates (makes wider) the arteries which supply blood to the muscles Glycogen is Used During Exercise some glucose from food is stored as glycogen glycogen’s mainly stored in the liver, but each muscle also has its own store in vigorous exercise muscles use glucose rapidly and take their glycogen stores to provide more energy if the glycogen store runs out, the muscles don’t get the energy needed to keep contracting and they get tired Anaerobic Respiration anaerobic means without oxygen, it is the incomplete breakdown of glucose which produces lactic acid glucose → energy + lactic acid not the best way to convert glucose into energy as lactic acid build up in the muscles which is painful and causes the muscles to get tired it doesn’t release as much energy as aerobic reparation but it’s useful in emergencies anaerobic respiration lead to oxygen debt after exercising you have to repay the oxygen you didn’t get to your muscles in time as your body couldn’t keep up meaning you have to keep breathing hard for a while after you stop, to get oxygen into you muscles to oxidise the lactic acid into carbon dioxide and water while high levels of carbon dioxide and lactic acid are detected in the blood the pulse and breathing rate stay high and try to solve the situation

11. Kidneys Nephrons - Filtration Units in the Kidneys Ultra Filtration high pressure is build up which squeezes water, urea, ions and sugar out of the blood and into the Bowman’s capsule membranes between the blood vessels and Bowman’s capsule act like filters, so big molecules like proteins and blood cells are not squeezed out Re absorption as the liquid flows along the nephron useful substances are reabsorbed back into the blood all the sugar is reabsorbed, this involves the process of active transport sufficient ions are reabsorbed, excess ions are not and active transport is needed sufficient water is reabsorbed Release of Wastes remaining substances including urea continue out of the nephron into the ureter down the bladder and out the urethra as urine

12. Kidney Failure Waste Substances if kidneys don’t work properly waste substances build up in the blood and you lose the ability to control levels of ions and water in your blood, eventually resulting in death people with kidney failure can be kept alive by having dialysis treatment (machines do the job of the kidney) or having a kidney transplant Dialysis Machines Filter the Blood it has to be done regularly to keep the concentrations of dissolved substances in the blood at normal levels and remove waste substances in a machine the person’s blood flows alongside a selectively permeable barrier surrounded by dialysis fluid, they act like the membranes in the kidney dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood so that useful dissolved ions and glucose won’t be lost waste substance (urea) and excess ions and water diffuse across the barrier dialysis sessions have to be performed 3 times a week and each session take 3-4 hours Transplanted Organs Can Be Rejected the only cure for kidney disease is to have a kidney transplant, they are usually from people who have died suddenly or from people who are still alive as we all have 2 of them it can be rejected by the body as their immune system treat it as an invading body and attack it, to prevent this precautions are take: donor with a tissue type that closely matches, they are based on the antigens patient’s bone marrow is zapped with radiation to stop white blood cells being produced patient takes drugs that suppress the immune system

13. MICRO ORGANISMS

14. Theory Of Biogenesis The theory of biogenesis is that living things are created from other living organisms. Before people use to think that life could spontaneously generate and appear from non living material. But then evidence showed that this couldn’t be the case. in 1859 Louis Pasteur heated broth in two flasks, both of which were left open to the air however one of the flasks had a curved neck so that bacteria in the air would settle in the loop and not get through to the broth the broth in the flask with the curved neck stayed fresh proving that it was the microbes and not the air causing it to go off before 1765 it was believed that substances in food were changed into microbes which caused the food to go off Lazzaro Spallanzani boiled two sets of broth to kill the microbes then sealed one flask and the other open, only the open one went off this showed that microbes got into the food from the air, but people thought this meant air from outside the flask was necessary to start the change the theory that fresh air caused substances in food to change into microbes was disproved by Theodor Shwann in 1837, he showed that meat would not go off in air provided the air was heated first to kill micro organisms

15. Food & Drink Organisms such as bacteria causes changes in food, often the changes are bad but sometimes they’re useful and mean we can have food that we wouldn’t have otherwise. Most Cheese is made using bacteria a culture of bacteria is added to milk the bacteria produce solid curds in the milk the curds are separated from the liquid whey more bacteria are sometimes added to the curds and the whole thing is left to ripen moulds are added to give blue cheese its colour and taste Yoghurt is made using bacteria as well milk is heat treated first to kill off any bacteria that may be in it, then cooled a starter culture of bacteria is added, the bacteria ferment the lactose sugar (found in milk) to lactic acid the acid causes the milk to clot and solidify into yoghurt sterilised flavours are sometimes then added

16. Using Yeast Yeast is a Single Celled Fungus it is a microorganism it can respire with or without oxygen anaerobic respiration (without oxygen) of glucose by yeast is called fermentation: glucose → ethanol + carbon dioxide + energy it can also respire aerobically (with oxygen), this produces more energy and is needed to grow and reproduce: glucose + oxygen → carbon dioxide + water + energy Yeast Is Used To Make Bread it is used in dough to produce light bread it converts sugars to carbon dioxide and some ethanol, it’s the carbon dioxide that makes the bread rise as the carbon dioxide expands, it gets trapped in the dough as bubbles creating the little holes in bread, making it lighter Alcoholic Drinks beer is made from grains, usually barley barley grains are allowed to germinate (the seed starts to grow into a new plant) for a few days, this is when the starch in the grains is broken down into sugar by enzymes the grains are dried in a kiln this is called malting the malted grain is mashed up and water is added to produce a sugary solution with lots of bits in it, this is sieved to remove the bits hops are added to the mixture to give it its bitter flavour the sugary solution is then fermented by yeast turning the sugar into alcohol

17. Microorganism in Industry Microorganisms are Grown in Fermenters on a Large Scale a fermenter is a big container full of liquid culture medium which microorganisms can grow and reproduce in, it needs to give the conditions they need to grow and produce their useful product food is provided in the liquid culture medium and more can be pumped in if needed air is piped in to supply oxygen to the microorganisms they need to be kept at the right temperature, they produce heat by respiration so the fermenters must be cooled down usually with water in a water cooled jacket right pH is needed for microorganisms to thrive sterile conditions are needed to prevent contamination from other microorganisms micro organisms need to be kept from sinking to the bottom so a motorised stirrer keeps them moving around and maintains an even temperature

18. Microorganism in Industry Mycroprotein it means protein from fungi, it’s a type of single celled protein it’s used to make meat substitutes for vegetarian meals, the main source is Fusarium the fungus is grown in fermenters using glucose syrup such as food, it is obtained by digesting maize starch with enzymes the fungus respires aerobically, so oxygen is supplied with nitrogen and other minerals it’s important to prevent other microorganisms growing in the fermenter so it’s sterilised using steam, nutrients are heat sterililsed and the air supply is filtered Penicillin it’s an antibiotic made by growing the mould in a fermenter the mould is grown in a liquid culture medium containing sugar and other nutrients the sugar is used up as the mould grows the mould only starts to make penicillin after using up most of the nutrients for growth Alexander Fleming discovered Penicillin accidently in 1928. A culture a bacteria became contaminated with mould, which wiped out areas of bacteria. No one took notice of this until the Second World War, when the huge number of injuries made it important to find something that would heal infected wounds.

19. Fuel from Microorganisms Fuels Can Be Made By Fermentation fermentation of natural products will produce waste products which often can be used fermentation is when bacteria or yeast break sugars down by anaerobic respiration Ethanol is Made by Anaerobic Fermentation of Sugar yeast makes ethanol when they break down glucose by anaerobic respiration glucose → ethanol + carbon dioxide + energy sugar canes can be used or glucose can be derives from maize starch ethanol is distilled to separate it from the yeast and remaining glucose a mixture of ethanol and petrol (gasohol) can be used in cars Biogas is Made by Anaerobic Fermentation of Waste Material biogas is about 70% methane and 30% carbon dioxide lots of different micro organisms are used to produce biogas, they ferment plant and animal waste which contains carbon dioxide and sludge waste is used to make biogas in a larger scale generators need to be kept at a constant temperature to keep the micro organisms respiring there are two types of biogas generators: batch generator and continuous generator biogas cannot be stored as a liquid (it needs too high a pressure) so it has to be used straight away for heating, cooking, lighting, powering a turbine by products are used to fertilise crops and gardens

20. Fuel from Microorganisms Biogas Generator batch generators make biogas in small batches, they’re manually loaded up with waste which is left to digest and the by products are cleared away at the end of each session continuous generators make biogas all the time, waste is continuously fed in and biogas is produced in a steady rate, they are more suited to large scale biogas projects biogas generators all need to have: an inlet for waste material to be put in, an outlet for the digested material to be removed through, an outlet so that the biogas can be piped where it is needed When Designing a Generator cost: continuous generators are more expensive that batch ones as waste has to be mechanically pumped in and digested material mechanically removed all the time convenience: batch generators are less convenient as they have to be continually loaded, emptied and pumped in efficiency: gas is produced most quickly at 35°c if temperature drops the gas production will be slower, some areas will need to be insulated or kept warm, it shouldn’t have leaks or gas will be lost position: waste will smell during delivery, so they should be situated away from homes and it will be best located close to the waste source Economic & Environmental Effects carbon dioxide released into the atmosphere was taken in by plants when it was alive, so they’re carbon neutral doesn’t produce a lot of sulphur dioxide which causes acid rain methane is a greenhouse gas which is given off from untreated waste, so burning it as a biogas means it’s not released raw material is cheap and readily available digested material is a better fertiliser biogas generators act as a waste disposal system

21. Safety Micro organisms are Grown on Agar Jelly in a Petri Dish they are grown (cultured) in a culture medium carbohydrates are needed as and energy source also mineral ions and sometimes supplementary proteins and vitamins, these nutrients are sometimes added to the agar jelly agar jelly can be poured when hot and sets when cold, it’s poured into shallow round plastic dishes called petri dishes Equipment is Sterilised to Prevent Contamination if equipment is not sterilised, unwanted micro organisms in the growth medium will grow and contaminate the end product unwanted micro organisms might make harmful substances or cause disease petri dishes and the growth medium must be sterilised before use inoculation loops (used for transferring micro organisms to the growth medium) are sterilised by passing them through a flame the petri dish must have a lid to stop any micro organisms in the air contaminating the culture, the lid should be taped on however not all the way around as no oxygen will be able to get in which will cause anaerobic respiration Temperature in the lab at school cultures of micro organisms are kept at about 25°c harmful pathogens (micro organisms which cause disease) aren’t likely to grow at this temperature in industrial conditions, cultures are incubated at higher temperatures so they can grow a lot faster

22. Culture Bacteria To Culture Bacteria 1) sterilise the inoculating loop which is used to transfer micro organisms to the agar, by heating it to red hot in a flame and then leaving it to cool 2) dip the sterilised loop in a suspension of bacteria you want to grow 3) use it to make a zig zag streak across the surface of the agar 4) put the lid on quickly 5) secure the lid of the petri dish with short pieces of tape, but not sealing all the way around the edge 6) incubate the culture at no more than 25°c for several days 7) observe the number and type of colonies that appear Aseptic Technique agar and equipment sterilised inoculating loop is sterilised inoculating loop is allowed to cool lid is not left down lid is secured lid is not fully sealed incubated at no more than 25°c agar jelly: containing carbohydrates minerals proteins and sterilised at about 120°c incubator: right temperature oxygen: from air colony: identical bacteria all from the same cell, different bacteria have different colony morphology (appearance and colour) to grow bacteria need: warmth, food, space, oxygen, right pH, moisture