More Science Lessons (KS3)
A series of free Science Lessons for 7th Grade and 8th Grade, KS3 and Checkpoint Science in preparation for GCSE and IGCSE Science.
Microbes and disease
Many living things are so small that they can only be seen through a microscope. These living things are called microorganisms or microbes. There are three main types of microbe: fungi, bacteria, viruses.
The body has natural barriers to stop harmful microbes getting inside the body. Some of them are:
1. Acid in the stomach kills many microbes.
2. Sticky mucus in the lungs traps microbes, and then cilia sweep it out of the lungs.
3. The skin stops microbes from getting into the body.
4. Scabs form on the skin if you get a cut, stopping microbes from getting into your body.
5. Tears contain substances that kill bacteria.
The body has an immune system that kills microbes if they get past the natural barriers. White blood cells are very important in the immune system. Some white blood cells can engulf microbes and kill them. Some white blood cells can make substances called antibodies that stick to microbes.
Pasteur's swan-necked flask experiment and pasteurisation.
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