Name Date Period. Orange juice, milk, onions, yogurt, spaghetti, papaya, spinach, pork chops, oatmeal, whole wheat bread and eggs

Transcription

1 Name Date Period Nutritionists tend to sort foods into groups, according to the main nutrients each food item contains. The USDA s new food guideline, My Plate, divide foods into five groups: fruits, vegetables, protein, dairy, and grains. Orange juice, milk, onions, yogurt, spaghetti, papaya, spinach, pork chops, oatmeal, whole wheat bread and eggs 1. Create a chart you can make it on the back and put the food to the group you think it belongs 2. When we are told to cut down on carbs, we usually avoid starchy foods (potatoes, rice, and bread) and sugary foods (cookies and soft drinks). But is that the whole story about carbs? Which foods in the chart that you made contain carbs? List them on the back: There are many types of carbohydrates. The one we re most familiar with is sugar, a simple carbohydrate. Sugary carbs sweeten fruits, soft drinks, and many snack foods and they give our bodies a quick burst of energy. Another type of carb is starch, a complex carbohydrate that packs a lot of energy in one bite! Starchy foods include potatoes, rice, and yucca. Different foods contain different proportions of sugar and starch. Which food do you think contains more sugar? Which food contains more starch? Drag and drop each food to the right category. 3. Create a T-chart - one side labeled High in Starch and the other side labeled High in Sugar then put the foods listed into their appropriate column: Raisins, Granola Bars, Apple Sauce, White Rice, Macaroni, Orange, Beets, Barley, Onions and Bagel. Think you know all there is to know about carbs? It gets more complicated! We ve looked at examples of two types of carbs: a simple carbohydrate called sugar and a complex carbohydrate called starch. There s another important carb that we eat every day. It s fiber. Fiber is a complex carbohydrate that we don t digest. Unlike sugars and starches, we don t use fiber for energy, but we need it to keep our bodies healthy. For example, celery is mostly made of water and fiber! 4. Make a list from the foods below that are good sources of fiber. Raspberries, Artichokes, Honey, Jello, Chicken, Lima Beans, Split Peas, eggs, Prune Juice. Let s take a closer look at the chemistry of carbohydrates.

2 We can break down the word carbohydrate into carbo for carbon and hydrate for water, which is a compound of hydrogen and oxygen. So carbohydrates are a compound of carbon, hydrogen, and oxygen. Scientists use symbols to represent chemical elements and compounds. These symbols are listed on the periodic table of elements. The simplest types of carbohydrates are sugars. All living things break down these simple sugars, such as glucose, for energy. You may have heard the term blood sugar. That s another name for glucose, which is delivered to our cells through the bloodstream. We get glucose from lots of different foods, especially fruits and vegetables. Like all carbohydrates, each glucose molecule is made up of a specific number of carbon, hydrogen, and oxygen atoms in a particular structure. Scientists use formulas, like a recipe, to write out the chemical ingredients in each molecule. The simplest types of carbohydrates are sugars. All living things break down these simple sugars, such as glucose, for energy. You may have heard the term blood sugar. That s another name for glucose, which is delivered to our cells through the bloodstream. We get glucose from lots of different foods, especially fruits and vegetables. Like all carbohydrates, each glucose molecule is made up of a specific number of carbon, hydrogen, and oxygen atoms in a particular structure. Scientists use formulas, like a recipe, to write out the chemical ingredients in each molecule. 5. Look at the diagram and count the atoms for each element. Write the chemical formula for glucose!

3 Another way to represent the glucose molecule is by its shape. The glucose molecule is often shown as a polygon, a geometrical shape with three or more sides. 6. What geometric shape would the glucose molecule be considered? Glucose is a building block for other more complex carbohydrates. A single molecule of glucose is called a monosaccharide. Mono- is the prefix for one (think of the word monologue, a speech by one actor). Saccharide is another word for carbohydrate. Link a molecule of glucose to another molecule of glucose and you get an entirely different sugar: maltose. Maltose is a disaccharide, made up of two units of glucose. Di- is a prefix meaning two (think of the word dialogue, conversation between two people). 7. Which diagram represents the disaccharide maltose? Pick One A. B. C. D. In addition to glucose, there are other monosaccharides. Fructose is a common monosaccharide found in fruit, vegetables, and in the high-fructose corn syrup that sweetens many soft drinks and snacks. In fact, fructose is the sweetest of all natural sugars.

4 Fructose has the same chemical formula as glucose, but the atoms are arranged differently. The fructose molecule is often represented as a pentagon. 8. Which shape represents a fructose molecule? Pick One A. B. C. D. Let s review: Glucose is a sweet monosaccharide that we use for energy. It s also known as blood sugar. Fructose, another monosaccharide, is the sweetest of all natural sugars. What happens when you link one glucose molecule to one fructose molecule? You get a disaccharide called sucrose. Have you heard of it? Chances are you have sucrose in your pantry. 9. Which diagram represents sucrose? Pick One

5 A. B. C. D. So far we ve learned that a monosaccharide is the simplest form of sugar (like glucose and fructose). And a disaccharide is a sugar made of two monosaccharides bonded together (like maltose and sucrose). But there are more complex carbohydrates than these simple sugars such as starch. Starch is made of thousands of glucose molecules linked in a long chain. Starch is a type of polysaccharide, or complex carbohydrate. The prefix poly- means many, and saccharide is another word for carbohydrate. Even though starch is made up of many glucose molecules, starch is not sweet like glucose. Compare a spoonful of cornstarch to a spoonful of sugar! This is because starch molecules are too big to activate the sweetness receptors on our tongues. 10. Which statement best describes a starch molecule? A starch molecule is made up of 2 units of glucose. A starch molecule is a long chain of fructose molecules. A starch molecule is a chain of thousands of glucose molecules. A starch molecule is made up of hundreds of glucose molecules. There s another very important carbohydrate in our diet. It s a polysaccharide called fiber. If there are vegetables on your dinner plate, one type of fiber you ll eat is cellulose. Cellulose is a tough carbohydrate that we can t digest, but it gives the roughage that keeps the digestive system working smoothly. A cellulose molecule is a net made of thousands of glucose molecules.

6 11. What s the difference between a starch molecule and a cellulose molecule? Select your answer from the statements below: Starch is made from glucose; cellulose is made from fructose. Starch is a single chain of glucose; cellulose is a sheet of glucose. We can digest cellulose but we can t digest starch. Cellulose tastes sweeter compared to starch. Hungry for more about carbs? We get most of our energy from eating carbs, and the carbs we eat mostly come from plants. For example, the wheat plant is an important source of carbs. The wheat is ground into flour, and flour is made into bread, pasta, and other foods. Now where do the carbs in wheat come from? The answer is photosynthesis! Plants make carbs specifically, glucose by capturing the light energy from the sun to transform water (H₂O) and carbon dioxide (CO₂) into oxygen (O₂), and glucose (C₆H₁₂O₆), a monosaccharide. This process is called photosynthesis. The plants then break down, or digest, that glucose for energy to survive. Plants also use these glucose molecules to build more complex carbohydrates such as starch and fiber. Plants use starch to store energy, and the tough fiber provides structural support for the roots, stems, and leaves. Fill in the blank. 12. Carbon, oxygen, and are three chemical ingredients in photosynthesis. 13. Through photosynthesis, plants make a simple carbohydrate. Plants make their own food: glucose. This simple sugar is delivered to every cell in the plant for energy. Humans also use glucose for energy. That s why we eat plants (like apples and potatoes) and foods made from plants (like bread and pasta). Our digestive system extracts glucose and other nutrients from the food, and our bloodstream delivers these nutrients to all our cells. The veins in a leaf and the blood vessels in our brain do the same job: delivering nutrients such as glucose to the cells. 14. Another name for glucose is sugar because the bloodstream delivers it to all our cells.

7 The foods we eat contain nutrients, but we need to break down the foods first to get to those nutrients. Sometimes we need to break down the nutrients even further so they can be easily transported to all our cells. This is what the digestive system is for. The digestion of sugars and starches starts in the mouth, the moment we start salivating and chewing. We break down the carbs further in the stomach. Finally, the nutrients travel through the small intestine where they pass into the bloodstream and are absorbed by our cells. 15. Individual glucose molecules are small enough to pass from the into the bloodstream. What happens when we eat starches? These large chains of glucose need to be broken down into individual glucose molecules before they can be transported through the bloodstream. 16. Starch, a polysaccharide, is broken down into glucose, a saccharide, during digestion. What do raspberries, split peas, spinach, and whole grain bread all have in common? They all have dietary fiber! (You ll see it listed on food labels.) Dietary fiber, like the cellulose that gives structure to plants, passes through our system undigested. Humans can t break down the net-like structure of fiber, but we need those large fiber molecules to add bulk to our waste and make our bowel movements regular. 17. We can get, or roughage, in our diet by eating plants and plant-based foods. Fiber also keeps our blood sugar levels steady by slowing down the absorption of other sugars into the bloodstream. That s why eating food with lots of fiber makes you feel full for longer. 18. Foods high in and low in, like a candy bar, cause spikes in blood sugar levels.

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