Transcript File
What’s in your food? The major food groups: Carbohydrate (starch and glucose) Protein fat How to test each ingredient: 1.Test for Starch: - to a food add three or four drops of iodine, if starch is present the solution will change color to dark blue. 2. Test for Glucose: -take some food in a test tube and add some Benedict’s solution. - put the test tube in a beaker full of water and place it on a tripod with a bunsen underneath. - If solution changes color to pink-red then glucose is present. 3. Test for protein: - add some (1cm in a test tube) sodium hydroxide (solution A) followed by some copper sulfate (solution B) to food. A purple color indicates the presence of protein 4. Test for fat: - Gently shake 2mL of fat with some ethanol in a test tube and add some water to the food, if the solution turns cloudy if fat is present. Testing what’s in your food: We have provided different kinds of food. Do tests on EACH type of food to see if they contain glucose/starch/protein/fat. Open up a word document and make a table for you to collect data. Food Glucose starch protein fat egg - - + + apple + -/+ - - sultana + + - - weetbix -/+ + - - bread + + - - Quiz: You have just completely burnt about 2 grams worth of the brand ‘energetic’ chips and the heat produced raised 10grams of water a temperature of 17 oC. How much energy is in each gram of chips assuming that it take 4.2J of energy to raise 1 degree C on 1 gram of water (4.2J/gC). Bomb calorimeter Quiz • • • • Does sugar belong to carbohydrate, fat or protein? What type of energy does food contain? Fibre is a form of carbohydrate, fat or protein? What is protein broken down to (note they are the building blocks of cells)? • Which has got more energy, carbohydrate or fat? • Name five things that a healthy diet must have. Carbohydrate: (composed of carbon, hydrogen and oxygen) -Is the cheapest and most readily available source of energy. Usually made by plants through photosynthesis (using sunlight to turn carbon dioxide and water into glucose). -Includes sugar (sucrose), glucose, starch and many more. -Fibre (cellulose) is also a type of carbohydrate that humans cannot digest, but herbivores can (thanks to their bacterial friends). Proteins: -Both plants and meat have protein, beans and nuts have got lots of protein too. -Proteins are made of amino acids, and amino acid and these are the things that your body needs to build up the cells. -For example your muscle cells has got lots of protein. If your body is like a house, then protein is like the bricks. (carbohydrate and fats are like electricity or firewood). -When you eat meat, your body digest the protein into amino acids, and then absorb it and use it to build new proteins. -Proteins contain nitrogen, sulfur as well as hydrogen, oxygen and carbon. Fat: -animal fat are found in cheese, milk, butter etc. Plant fat are found in fruits and seeds etc. - Fat is used to build the cells as well as protein (especially cell membrane), but its major use is as an energy source. Fats can produce twice as much as energy as carbohydrate or proteins, and fats can be stored. What a healthy diet must have: 1. Sufficient energy: If you don’t consume enough energy, you may end up using your body protein to stay alive as your fat and carbohydrate run out. 2. Correct proportion of carbohydrate, fat and protein. Not enough protein may result in stunted growth. 3. We need mineral salts, we need iron in our blood, we need calcium for our bones, we need sodium and potassium. A lack of iron gives us anemia, a lack of iodine gives us goiter, a lack of calcium will likely to result in osteoporosis. 4. We need vitamins to live, there are a lot of vitamins, these are the chemicals that our body cannot build and need to get from elsewhere, i.e. our food. e.g. vitamin C from fruits, a lack of vitamin C gives us scurvies. 5. Water 6. Fiber : To avoid constipation and help move the ‘stuff’ through our gut. We humans cannot digest fiber to turn it into energy but herbivores can. Structure of tooth Quiz • What’s the name of the teeth that’s responsible for gripping and holding onto prey? (in humans it’s function is to bite into and cut a piece off the food) • What’s the name of the largest teeth (and pointy teeth) in carnivores? What’s its function? • What teeth are for grinding of the food • What’s name of the tube that connects mouth to stomach? • What does stomach contain? • What’s the general function of teeth? • Where do chemical energy come from? Where do we get chemical potential energy from? Where do we get chemical potential energy from? Quiz • Where is saliva produced in the human body? • Where do plants get their chemical potential energy from? • What’s the main function of saliva in your mouth? (think about the weetbix you chewed yesterday) • What do we need fibers for? • What substances are in your stomach? • Where in your body does most of the physical digestion happen? • Where in your body does most of the chemical digestion happen? • What do starch and protein break down to? Enzymes Enzymes are biological catalyst (normally protein) that speed up chemical reactions, enzymes involved in the digestive system is usually for breaking down the main food groups. Carbohydrate: Fat: Protein: Enzymes The names of enzymes usually have a suffix of –ase. E.g. the enzyme that breaks down protein is called protease. Carbohydrate: Fat: Protein: amylase lipase (lipid = fat) protease So in the duodenum the enzymes break down the food for absorption in the small intestine. Journey of food • Imagine you are a piece of food, use a poster/PPT/report to describe the journey of you going through the human digestive system. (However you can also choose to do other animals such as cows or tigers etc). • Do this in pairs or threes. • You may choose to include pictures in your presentation. • Each pair will have 5 minutes to present to the class of their adventure. Make sure you include the type of food that animal eats, the main parts of the digestive system of that animal and how that animal digest food. Food SWAT Chemical potential energy Acid and pepsin fibre Large intestine Canine Salivary gland liver lipase ingestion protein Chemical digestion saliva Fatty acid starch egestion 4.2 J/gC Quiz: • What enzyme breaks down starch? • Which organ in our body secretes most of our digestive enzymes? • Which organ in our body absorbs all of the digested food? • What’s the function of the large intestine? • What does bile do? • Where do most of the mechanical (physical digestion) take place in our body? • Is there digestion in the small intestine? • What’s the difference between physical and chemical digestion? bile Questions: What’s the function of bile? Why do we need bile to do such things? How does bile do it?