How much can a bladder hold? Approximately 500 ml in women and 500 ml in men. The bladder is an expandable muscular sac. It has an inner lining of cells, three layers of muscle, a layer of fat, and then another layer of cells. It is connected to the urethra at the bottom and has […]
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Why does bread need yeast? Bread doesn’t have to have yeast and there are many breads made without it. However, if you want the bread to rise, then it needs yeast. Yeast is a single-celled organism called Saccharomyces cerevisiae. It is a fungus, which means they make their energy by decomposing other things. There are
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Why can a peregrine falcon fly so fast? Because of their wings, their feathers, their breastbone, their heart, their lungs, and a few other things. Peregrine falcons are one of 40 species of falcon. They are about the same size as a crow and they are birds of prey. They eat medium sized birds, such
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How can an eagle see so far? Eagles can see about eight times farther than humans because the cones in their eyes are very small and tightly grouped together. There are 68 different species of eagle spread across the world. They are birds of prey that hunt by swooping down on their prey from high
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When did oxygen appear on Earth? Oxygen appeared on Earth between 2.4 and 2.2 billion years ago. The air we breathe is not made up mostly of oxygen. It is 78.084% nitrogen, 20.934% oxygen, 0.934% argon, 0.035% carbon dioxide, and then a lot of other trace elements. Our bodies need the oxygen and the carbon
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Why do crabs walk sideways? They walk sideways so they don’t trip over their legs. However, some crabs do walk forwards. There are many different species of crab and they can live in saltwater and in freshwater. The smallest crab is the pea crab, which is only a few millimeters across and is a parasite
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How can we catch a ball without looking at it? It is a combination of proprioception and the brain’s ability to predict. What is proprioception? It is the ability to sense your own body position. It is often called the sixth sense. All of our muscles, joints, and tendons have sensory receptors in them. When
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Why do we lose our voice when we are sick? We lose our voice because our vocal cords become inflamed. Let’s look at how the voice works to start with. We all have vocal cords inside our larynx, more commonly known as a voice box. The larynx is at the top of the trachea, the
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How big and how small can a mammal be? The Etruscan shrew is the smallest mammal and is 40 mm long and weighs 2 g. The blue whale is the largest mammal and is 29.9 m long and weighs 199 tons. The African elephant is the largest land animal and is about 4 m tall
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How does a joint replacement work? By replacing parts of the joint, or by replacing the whole joint. Joint replacement surgery is called arthroplasty. It is made from the Greek word “arthro”, which means joint and “plasty”, which means to mold or form. It is carried out when a joint is no longer usable or
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