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EDUCATORS & STUDENTS |
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| Sugar Science
Exploring Food Chains and Photosynthesis Food Chains Food chains are the sequence of feeding relationships through which plants and animals depend on each other for food. Food provides the nutrients plants and animals need to build and repair their body parts, and the energy they need to grow and function. There are countless food chains involving different plant and animal species in a variety of habitats all around the world. Every plant and animal belongs to at least one food chain, and these chains can be simple or very complex. At the base of the food chain lie the producers. Producers are mainly green plants and certain bacteria, which convert sunlight into food energy. Above the producers are the consumers who ingest live plants or other animals. Decomposers, such as, bacteria, molds, and fungi make use of energy stored in already dead plant and animal tissues. Energy from the Sun  The sun is the primary source of energy for all life. Even living organisms that seem to flourish in darkness feed on plants, insects, animals, or microorganisms that depend on sunlight for their survival. The sun provides energy that plants can use to make their own food. This is the first step in every food chain. Natural Food Factories All green plants can do something truly amazing and unique that no other living organism on earth can do. They can make their own food energy using sunlight, air, and water. This process by which plants produce food energy is called photosynthesis. The word photosynthesis comes from two Greek words. Photo means light and synthesis means putting things together to make something new. Photosynthesis in Action Green plants have a special chemical in their leaves called chlorophyll which is the substance that makes leaves green. The chlorophyll is found in little compartments of green leaves, called the chloroplasts, and allows the leaves to act like miniature solar panels capturing and storing the sun’s energy far more efficiently than anything ever devised by humans. Green plants use the energy from sunlight shining on their leaves to produce their own food. Carbon dioxide gas from the air enters through pores in the leaves, and water is absorbed through its roots. Carbon dioxide and water are combined with the energy from the sun to create food energy. Natural Food Energy The foods that plants make using the process of photosynthesis are sugars. These include glucose and fructose, which are converted by the plant into sucrose for storage. Sucrose, glucose, and fructose are found naturally in all plants, and are the basis for all food energy. The sugars that plants produce are stored in the root, leaf, seed, or fruit of the plant. Plants that produce sucrose in the largest quantities are sugar cane and sugar beets and thus are harvested to produce the sugar for commercial and industrial use. The reaction of photosynthesis can be written as the following
chemical equation when sucrose is being made:
Sugar, starches, and fibre are three types of carbohydrates we eat as food and are found mostly in grain products, vegetables, and fruits. The family of sugars is made up of many substances. The term sugar refers to 'sucrose', the main product of photosynthesis. The term 'sugars', however, can also refer to sucrose, in addition to a variety of other sugars found in nature such as glucose, fructose and lactose.  Carbohydrates contain carbon plus hydrogen and oxygen in the same ratio, and the general formula is CnH2nOn. Sugars are the basic building blocks of carbohydrates, which are often classified according to the number of sugar units they contain. Monosaccharides, for example, contain a single sugar unit, whereas disaccharides contain two. Glucose, fructose, and galactose are all examples of monosaccharides. When two monosaccharides are joined together chemically, a disaccharide is created. Sucrose, C12H22O11, is a disaccharide, made up of glucose and fructose.
Polysaccharides are another type of carbohydrate which are large molecules consisting of many sugar units (>9) in long chains of many repeating units. Starches and fibre are among this class of carbohydrates, with starch being the most abundant in our diet. Thousands of glucose units are strung together to comprise a single starch molecule. 
We are connected to the world around us through our five senses. One of their primary jobs is to help us tell if our environment is safe or not. Taste, for example, can help to detect if a food is fresh and good to eat or spoiled and dangerous to our health. A natural liking for foods rich in carbohydrates (starches and sugars) was inherited from our ancestors. These foods not only taste great, they are also full of energy. Primitive people needed a lot of energy to survive in cold weather, on long walks and to get away from animals. Our ancestors were more careful with foods with a bitter or sour taste, like some poisonous plants.  Discovering different flavours in foods is part of what makes eating fun. The tongue contains many bumps, and around the base of these bumps are taste buds. We have about 10,000 taste buds and inside them are special cells that sense taste. There are different kinds of taste buds, each designed to help taste different sensations. These taste sensations include sweet, salty, bitter, and sour. Some areas of the tongue may be better than other areas in detecting each of these tastes. Taste buds are only activated when food molecules fit the shape of receptors on its surface, much like a key fits into a lock. The taste bud then sends messages to the brain where they are decoded and registered as a 'taste'. Sweet and salty taste buds are the least sensitive, while bitter ones are most sensitive. With regards to taste, sugars are mostly described in terms of their sweetness. Fructose, one of the sugars found in fruit, is the sweetest. Sucrose or table sugar is less sweet than fructose but sweeter than lactose, a sugar found in milk. Common sugars are listed below in order of sweetness. Keep in mind that sweetness can also vary depending on the form of the sugar (solid or in solution), concentration, temperature, presence of other ingredients, and the taste differences between individuals.
As discussed above in Sugars and Carbohydrates, polysaccharides are longer chains of sugar units. However, starchy foods such as potatoes, pasta, breads and beans, do not taste sweet. This is due to the large structure of the polysaccharides, which do not fit on the tongue’s taste bud receptors, thus resulting in a perceived lack of sweetness. Starchy foods, however, can be broken down into smaller sugar units that can taste as sweet. For example, place a cracker in your mouth for a while. As the digestive process in your mouth begins to break down the starch molecules, you will begin to notice a sweet taste as they become smaller sugar units. For more information on Taste buds, visit www.kidshealth.org/kid
Before the body can make use of the food that is eaten, it must
be ‘digested’, meaning it must be broken down into its
basic parts. The digestive system works like a giant food processor.
This system is made up of a group of body parts called organs that
work to break food down both mechanically and chemically. This breaks
down food into nutrients, which are building blocks that the cells
can use for growth, repair, and energy. These simple units can then
easily cross from the intestine into the blood stream by a process
called absorption. From here they can be distributed all around
the body. Here is how we track the digestion of carbohydrates through
the human body.  Mouth
Stomach
Liver
Large Intestine
For more detail on the digestive system, visit the Human Anatomy Online. For more games, recipes and experiments related to the human body, click here |
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Canadian Sugar Institute
10 Bay Street, Suite 620 - Toronto, Ontario, M5J 2R8
Tel: 416-368-8091 - Fax: 416-368-6426 | info@sugar.ca
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