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GlossaryBacteriamicro-organisms that can cause decay and disease- Non-harmful bacteria are used in food industryDecay to go bad or rot awayDougha soft mixture of flour and water used to make breadFungusa micro-organism such as yeast- A mushroom is also a fungusGerma micro-organism that causes diseasesMicrobe another word for micro-organismMicroorganisman organism that is too small to see, such as viruses, bacteria and fungiMould a greenish micro-organism that can grow on old food or on cold wet places such as damp wallsVaccinateto protect someone against a disease by giving them a mild form of the diseaseVirus a micro-organism that can cause infectious diseasesYeast a fungus used to make breadYoghurta food made with milk and non-harmful bacteriaMy TargetsI can ...____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________MicrobesMicro-organism is the term given to anything that is too small to see without the use of a microscope. Often when the term micro-organism or microbe is used we think mainly of bacteria and viruses- in other words, germs.Microbes can cause diseases in human s which can then spread quickly from one person to another. When you have a cold, cover your mouth when you cough to help to make sure that the germs do not spread.Microbes can reproduce very quickly in the right conditions. Many like warm and damp conditions.Harmful micro-organismsWhat diseases are caused by micro-organisms?Many diseases are caused by micro-organisms but some are not. For example, scurvy is a disease caused by a lack of vitamin C in your dietThere are three main types of micro-organisms: viruses, bacteria and fungi.4314825118110VirusesViruses cause diseases like colds, flu and chicken pox. You can easily catch diseases like these from other people when they sneeze in the air. You should always try to sneeze into a handkerchief to avoid spreading diseases.Bacteria-6667567945 Bacteria cause diseases like food poisoning and diphtheria. They also cause conditions like boils and tooth decay.Bacteria in your mouth feed on sugar in your food. They make substances called acids that can make holes in your teeth (tooth decay). The bacteria can also damage your gums and cause gum disease, which can make your teeth fall out. You need to brush your teeth twice a day to remove the bacteria from your teeth.310515039370FungiOnly some fungi are micro-organisms. These can cause conditions like athlete’s foot. VaccinationsWhat are vaccinations?People often have injections, called vaccinations, to stop them from getting diseases. When you are vaccinated you are injected with a vaccine. A vaccine contains dead or weak forms of the microorganism that causes a disease. The vaccine will not give you the disease, but your body makes chemicals called antibodies to destroy the micro-organisms in the vaccine. These antibodies then stay in your body, often for the rest of your life. If the real microorganism gets inside you, the antibodies are ready to destroy them.You need a different type of antibody to destroy each type of micro-organism, which is why you need to have different vaccines for different diseases.AgeVaccine given2- 4 months Diphtheria, whooping cough, polio, tetanus1- 2 years Measles, mumps, rubella3- 5 yearsDiphtheria, tetanus, polio10- 14 yearsRubella (given to girls if they have not already had the vaccine)13 yearsTuberculosis331597052070You only get some diseases once because of antibodies. For example if you are ill with measles, your body makes antibodies to destroy the measles viruses. After a few days you start to get better because the antibodies have now been made. If measles viruses get into you again, the antibodies are ready there to destroy them.However, diseases like colds are caused by many different viruses so you will always get these diseases!DecayHow does decay occur?3724275-2540This food has gone mouldy! Mould is a micro-organism but there is so much of it here that you can see it.As well as mould, there are many other micro-organisms that you cannot see, growing and reproducing on the food.The micro-organisms feed on the food and turn it into other things, and this is called decay. This happens fastest when it is warm and damp. The micro-organisms can make you very ill with food poisoning.Bacteria can float around in the air and land on food that is uncovered.There are many ways in which we can preserve food to stop it going bad4266565685801. Heat the food well to kill the bacteria. Then put it on a clean sealed container to stop any other bacteria landing on it. 2. Keep the food very cold. The cold does not kill the bacteria but it stops them from reproducing.3. Dry the food out so that there is no water for the bacteria to live on.4. Make any food that is going to be kept for a while very sugary, because bacteria cannot survive very strong sugar solutions.Useful decayHow can decay be useful?Dead things, like leaves, don’t pile up in nature but disappear because micro- organisms feed on them. This is useful because the dead things contain substances called nutrients, which plants need to grow. When the dead things decay, the nutrients go into the soil.-34290055880Compost heapsGardeners often put vegetable peelings, leaves and grass clippings on a compost heap. Eventually the dead things decay to make compost, which gardeners put on the soil. 294259092710 Landfill sitesMany manufactured things, like plastic and glass, don’t decay and can litter the environment. When we throw them away, they are dumped in huge landfill sites.Helpful microbesSome microbes are very helpful. We use some of them to help make food.Yeast is a helpful microbe. It produces a gas that helps bread to rise. When making bread, the dough is left to rise until it has doubled in size.Some animals, such as cows, have helpful bacteria inside their stomachs which help them digest plants.Microbes can also be found in yoghurt- they help to give it that special taste.Some people also like eating microbes which have been specially grown in cheese. This cheese is not mouldy, just tasty!Bread and cheeseBread341947592710Yeast is a type of fungus that is used to make most types of bread. It feeds on sugar in the bread mixture (called dough) and makes bubbles of gas called carbon dioxide. These bubbles make the bread dough rise and it is then baked. -466725117475CheeseBacteria are used to make cheese. Milk is first heated to about 70 ?C for 16 seconds. This kills most of the bacteria in it, including any dangerous ones. Special bacteria are then added, which feed on the milk and turn it into a lumpy substance, a bit like watery cottage cheese.The liquid (whey) is removed, leaving only the solid bits (curds). The curds are mixed with more bacteria and the cheese is pressed into shape. The cheeses are then left for a time to allow the bacteria to feed on the cheese and give it its flavour. Sometimes a special mould is added to make blue cheese.1. Which of the following are diseases? Underline the answers.German measles tooth ache mumpsCold chickenpox broken ankle2. What is the name of the way of preventing diseases like smallpox?..............................................................................................................3. Ali and Omar investigated bread. They placed it in a clear plastic bag and left it for 10 days. They observed it frequently and recorded what they saw.Day 1Day 4Day 7Day 10No mould Some very small bits of mouldMore mouldyVery mouldy4. What did the mould feed on? .......................................................................................................... 5. What day did the bread have the least mould? .........................................................................................................6. Why? .........................................................................................................7. What happened by day 10? .........................................................................................................8. How could Ali and Omar have slowed down the growth of the mould?.....................................................................................................................................................................................................................................................................................................................................1. Underline the foods that are made using micro-organismsYoghurt cake breadChocolate bars orange juice cheese2. Make a list of foods that you eat and drink that have been preserved by these different methodsFreezingDryingCanningPickling3. Maya and Lulwa divided a ball of bread dough made with yeast into three equal sizes (by weight) and placed the dough balls in containers of the same shape and size. The height of the dough was the same in each container at the start. A piece was placed in:A warm window sillcool corridorA cold fridgeThey measured in millimetres how much the dough had risen in each container in 60 minutes.Was this a fair test? ....................................................................................................................................... Why? ...................................................................................................................................................................................................................................................................................................................................4. Look at the table of their results. Draw a bar chart of their results on the given graph. Give your graph a title and label the axes.PlaceHow much the dough raised in 60 minutes (mm)Warm window sill30Cool corridor20Cold fridge6933450596905. Which dough raised the most? ...............................................................................6. How much higher was the dough on the window sill than the one in the cold fridge after 60 minutes?............................................................................... 7. Where should a baker leave dough to rise quickly? ................................................................................ 1. Micro-organisms can be harmful and cause disease. Which of these complaints are caused by microorganisms? For each complaint, put a tick if it is caused by a microorganism, and put a cross if it is not caused by micro-plaintTick or crossA coldA broken legA bruiseChickenpoxToothacheA nose bleedA graze2. Micro-organisms can also be useful, for example when they break down materials.Which of these objects can be broken down by micro-organisms?ObjectTick or crossPile of leavesGlass bottleVegetable peelingsPlastic bag Grass cuttingsDead birdcoins1. These pictures show the process of making yoghurt but they are in the wrong order. Rearrange them into the correct order.Choose the correct answer:1. Micro-organisms cannot be seen without a a. Microscopeb. Periscopec. Telescope2. Which of these is not true about micro-organisms?a. They are all harmful b. They feed and grow c. They reproduce3. What is yeast used for?a. To cure chickenpox b. To make bread rise c. To make yoghurt4. Why should cooked and uncooked foods be stored separately?a. Because bacteria only like cooked foodb. Because bacteria only like uncooked foodc. To stop bacteria spreading from one to the other5. Bacteria and viruses are both small types of micro-organisms. Which is smaller?a. Bacteria b. Virusesc. They are both the same sizeThere are a number of a different ways to preserve food. Read the explanations of the main methods of preserving food. Connect each explanation to its correct food picture.MethodHow it worksExampleCANNINGA. To stop the micro-organism from breeding, all water is removed from the food. When it is time to eat the food, water is added, making it swell up 347980-6985SALTINGB. The liquid is heated enough to kill the microbes but not enough to change the taste.24892089852545847038100DRYINGC. The food is cooled very quickly and stored at temperatures below 0°C. Micro-organisms will not multiply.PASTEURIZATIOND. Acid is added to the food. This kills the micro-organisms and the food can be kept for a long time.35369567945PICKLINGE. Adding a lot of salt to some foods also kills microbes. The salt draws water from them and they die.363220-10795FREEZINGF. The food is placed in a can and heated to kill the microbes. The cans are sealed so that no more micro-organisms can get inside.372745-23495Year 6 students are doing an experiment about yeast. That’s what they did: Step 1.They used 4 clean glass bottles.Step 2.In the 1st bottle they added a teaspoon of sugar.Step 3.In the 2nd bottle they added a teaspoon of yeast.Step 4.In the 3rd bottle they added a teaspoon of sugar and a teaspoon of yeast. Step 5.In the 4th bottle they added a teaspoon of yeast and 3 teaspoons of sugar. Step 6.They added a cup of water to each of the bottles and gently shaked them.Step 7.Afterwards, they immediately attached balloons to the tops of the bottles.Step 8.They waited for 30 minutes.1. What happened? Draw the balloons after 30 minutes. Yeast Sugar Yeast + Sugar Yeast + 3 Sugar483870032385318135032385161925032385123825323852. Which bottles are the “control” bottles?.................................................................................................. 3. Do you think this experiment was a fair test? Explain why.....................................................................................................................................................................................................................................................................................................................................4. Why do you think yeast is used to make bread?.................................................................................................................................................................. ................
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