How did the Black Death change society? It ended serfdom and slavery, improved worker conditions, brought a recession, harmed religion, increased antisemitism, improved medical practice, improved women’s rights, and changed the world of art and fashion. There were three major plagues, but let’s look at the middle one, the one that is most famous. It […]
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How did the Black Death spread? It was spread by people along trade routes. The Black Death is another name for bubonic plague, which is caused by a bacteria called Yersinia pestis. Y. pestis generally lives in fleas that feed on rats. When the flea bites the rat, the bacteria passes into the rat’s blood.
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How much blood can you lose? Well, obviously all of it. How much blood can you lose and still function? Depending on your body size, from between 15 to 30%. We have approximately 5 liters of blood in our bodies, but that varies by size. An average-sized female of 165 cm will have about 4.3
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Why is PM 2.5 dangerous? They are particles that are too small for our nose to catch. PM stands for Particle Matter and they are microscopic solid or liquid particles that are small enough and light enough to be suspended in the air. There are many sources of these particles. In some countries, one of
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How do fossils form? They form when the bones of an animal are turned to mineral. A fossil forms when an animal dies in water or falls into water. This water is more commonly an ocean or a lake because for a fossil to form, the sediment at the bottom of the water has to
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Why do we get hot when we exercise? Because heat is a byproduct of the process muscles use to make energy. Let’s look at how we get energy to our muscles. We are unable to make our own energy, we can only convert one energy source into another. We have to eat plants or animals
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Could penguins fly in the past? Yes, they could, but millions of years ago. There are many birds that could fly at some point but that have lost the ability. The Galapagos Cormorant is a good example. They are only found on two of the Galapagos islands. They are not originally from the island, so
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How do chemotherapy and radiotherapy work? Chemotherapy works by damaging the DNA inside the nucleus of the cancer cells and stopping them dividing. Radiotherapy works by targeting the cancer directly and damaging its DNA. How does cancer form? As our cells age, they die and new cells replace them. Some cells are replaced more quickly
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Why do dragonflies have four wings? So that they can hover and fly in any direction that they wish. Most insects have two pairs of wings but the second set in some of them have evolved to have a different purpose. Two examples of these are flies and beetles. (I know we are talking about
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How does crop rotation work? By alternating crops to give the soil a rest and to replace nutrients that are removed. People transitioned from a hunter-gatherer culture to an agricultural culture in about 12000 BC. First, they domesticated animals. This happened in different places on Earth within a few thousand years. In about 9500 BC,
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