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Ask Professor Pansy Winter 2016/2017 Now that it’s winter, I’m starting to catch up on some of the wonderful questions you all asked earlier this year. As always, thank you so much for your curiosity! Alyssa, age 4 asks How do roots grow? Roots grow a lot like your hair grows. All living things are made up of parts called cells, which are usually too small for us to see. When our hair grows, our bodies add more cells from where our hair connects to our heads. When a plant’s roots grow, the plant adds more cells to the tips of the roots. Plants need roots for three main reasons. Fist, they connect plants to the soil and keep them upright. Second, they act like straws to slurp up water and nutrients (plant food) from the soil. Third, many plants use their roots to help store food that their leaves make. There are different kinds of roots. A carrot is a kind of tap root that humans can eat. Lettuce is an example of a plant that has hair-like fibrous roots instead. The roots of big trees can even be as long as a school bus! Gabby, age 8 asks When did people start to plant plants? People first started planting plants about 12,000 years ago. That is a very long time compared to one human life span, but it’s a very short time compared to how long humans have existed. We have only been planting plants for less than 5% of our history so far. The first people to plant plants lived in the Western Asia region, which is also called the Middle East or Near East. At first, they planted seeds from the best wild grain plants. Over time, they started farming. Some other early farmed plants were squash in what is now Mexico and potatoes in South America. By farming some of their food instead of only eating wild plants, people were able to have more control over their food supply. That led to a lot of other changes in the way people lived. The first cities grew up along with the first farmed grains. We have learned a lot about planting plants since 12,000 years ago. We are still learning how to grow and share food in a way that is fair for all people and the Earth. If we grow some of our own food, it can help us be thankful for the work that farmers do. We can also visit gardens and farms to learn more. People also plant plants for decoration, for shade, to provide habitat, and just for fun. James, age 9 asks Is a shovel better with jagged sides or not? The best kind of shovel depends on what a person wants to use it for. Shovels with jagged (also called serrated) sides can be very useful for cutting through a lot of roots or very hard soil. For usual digging in loose soil, smooth edges work just fine. There are also other kinds of shovels, such as ones with flat tips that are for scooping rather than digging. Each one has a specific purpose. The important thing is to use the right tool for the right job. Having the right tool can make it easier to get the job done. Moxie, age 8 asks How do trees produce oxygen? Oxygen and carbon dioxide are two important gases that exist in the air. They are part of an amazing relationship between animals and plants. Animals breathe in oxygen and breathe our carbon dioxide. Plants do just the opposite: they breathe in carbon dioxide and breathe out oxygen. Here’s a short version of the amazing chemical reactions plants and animals do: Plants (photosynthesis) Animals (combustion) Carbon dioxide + Water + Energy (from the sun) Sugar + Oxygen turns into Sugar + Oxygen turns into Carbon dioxide + Water + Energy (which powers our bodies) Plants don’t have lungs. Instead, they “breathe” using their leaves. Carbon dioxide is made out of two parts: carbon and oxygen. Water is also made out of two parts: hydrogen and oxygen. Plants use energy from sunlight to break carbon dioxide and water into their smaller parts – carbon, hydrogen, and oxygen – and then put the parts back together in new combinations. All of the carbon and hydrogen plus some of the oxygen get combined to make sugar. It’s not the white sugar you get in the store, but a simple carbohydrate. Sugar is the basic building block plants use to build their bodies. But there is some oxygen left over after all this happens. The plant “breathes out” that oxygen into the air. Trees “breathe” a lot because they are so big. They take in a lot of carbon dioxide and release a lot of oxygen. Your body does the opposite of what a plant does. You breathe in oxygen, and that oxygen combines with carbon and hydrogen from your food to make carbon dioxide and water. In the process, energy gets released so that your body can use it. Your body doesn’t need the carbon dioxide it made, so you breathe it out. Plants and animals both have amazing abilities, and we depend on each other to live.