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| What are microbes? | Living things are so small that they can only be seen through a microscope. |
| What is another name for microbes? | Micro-organisms. |
| What are the three main types of microbes? | Fungi, bacteria, viruses. |
| Which fungi are microbes? | Very small fungi that can only be seen under the microscope. Mushrooms and toadstools are fungi, but these are made of lots of cells, so they are not microbes. Yeasts are single-celled fungi, so they are microbes. |
| What are the characteristics of fungi? | They are usually the largest type of microbe. They have a Cell membrane, a hard Cell wall and a nucleus. |
| What are the characteristics of bacteria? | Bacteria are usually smaller than fungi. Bacteria have many different shapes. Some have 'tails' (called flagella) that let them swim. They have a Cell membrane, a soft Cell wall but no nucleus. |
| What are the characteristics of viruses? | Viruses are the smallest type of microbe. A virus can only reproduce inside a cell, so some people are not convinced that viruses are really living things. They don’t have a Cell membrane, a Cell wall or a nucleus. Instead of a cell wall they have a protein coat. |
| Which microbes are useful? | Yeast cells are useful to bakers and brewers. Yeast cells can change sugar into carbon dioxide and alcohol. This is useful to bakers because the gas helps the bread rise, and it is useful to brewers because it adds the alcohol needed for their drinks. Bacteria are also useful to us. For example, certain bacteria cause the changes needed in milk to make yogurt and cheese out of it. |
| Give examples of harmful microbes. | Fungi can cause athlete's foot and thrush. Bacteria can cause Tuberculosis, TB (affects the lungs). Salmonella (causes food poisoning), whooping cough (affects the lungs). Viruses can cause chicken pox, common cold, influenza (flu), measles, mumps (affects salivary glands), rubella (german measles). |
| How do microbes cause disease? | They reproduce in the body and produce harmful substances called toxins, and damage tissues and organs. |
| What do you call someone who has harmful disease-causing microbes in them? | They are infected. |
| What do you call a disease caused by microbes that can pass from one person to another? | An infectious disease. |
| How do harmful microbes spread from one person to another? | In air, in water, through touch¸ through contaminated food, through contact with animals. |
| How do harmful microbes spread via the air? | Droplets containing microbes fly into the air when people sneeze or cough. The microbes they contain get into other people if breathed in. |
| Which harmful microbes spread via the air? | Chicken pox, colds, flu, measles and tuberculosis are spread via the air. |
| How do harmful microbes spread via contact with animals? | The microbes can get into a person who is scratched or bitten by such an animal. Malaria is a tropical disease spread by a tiny fly called a mosquito. |
| How do harmful microbes spread via food? | Food can have harmful microbes in and on it. The microbes get into the body when the food is eaten, causing food poisoning. Thorough cooking kills most microbes, but they can survive under-cooking and careless handling of food. |
| How do harmful microbes spread via touch? | Microbes can be passed from one person to another when people touch each other, or when they touch something an infected person has handled, such as a towel. Athlete's food is spread like this. Bacteria on the skin can be killed by antiseptics, and bacteria on surfaces can be killed by disinfectants. Washing your hands reduces the chance of spreading microbes. |
| How do harmful microbes spread via water? | Water can have harmful microbes in it. The microbes get into the body when the water is swallowed. Cholera is a disease caused by a bacterium that spreads like this. Thorough boiling or adding chlorine to the water can reduce the chance of spreading microbes in this way. |
| How does the body defend us against microbes? | With natural barriers and the immune system. |
| Give examples of the body’s natural barriers. | Acid in the stomach kills many microbes, sticky mucus in the lungs traps microbes, and then cilia sweep it out of the lungs, the skin stops microbes from getting into the body, scabs form on the skin if you get a cut, stopping microbes from getting into your body, tears contain substances that kill bacteria. |
| How does the body’s immune system defend us against microbes? | Through the white blood cells. Some white cells can engulf (swallow) microbes and kill them. Other white blood cells can make substances called antibodies that stick to microbes and kill them. |
| How do antibodies attack microbes? | The white blood cells develop antibodies to the antigens in the microbes. Different microbes have different antigens, so only white blood cells with the right antibodies can stick to them. |
| How can we protect ourselves against microbes? | With antibiotics and immunisation. |
| What are antibiotics? | Antibiotics are substances used by doctors when harmful microbes have infected you. They are substances that harm bacteria by stopping the bacteria reproducing and others kill the bacteria, such as tuberculosis and food poisoning. |
| What microbes can’t be treated with antibiotics? | They only harm a few viruses, so antibiotics cannot treat diseases such as colds and flu, which are caused by common viruses. |
| What does it mean to be immune to an infection? | After you have been infected by a microbe, your white blood cells produce antibodies. it takes time for your body to start fighting the infection by making enough white blood cells with the correct antibody. After a second infection by the same microbe, your body makes the correct antibodies much faster because the white blood cells remember the infection. The microbe doesn't get a chance to make you ill this time, and we say that you are immune to the microbe and the disease it causes. |
| What is immunisation? | Immunisation is a process that doctors use to make people immune from certain illnesses, even before they have been infected. It involves you receiving an injection containing a vaccine. Vaccines contain a dead or weak form of the disease-causing microbe, or some of its antigens. In response to the vaccine your immune system produces white blood cells with the correct antibody to kill the microbe, so you become immune without falling ill. |
| What microbes are we usually immunised against? | Diphtheria, whooping cough, polio, tetanus, meningitis, measles, mumps and tuberculosis. Girls are also immunised against rubella. |
