Unit 2: Human nutrition Flashcards
Name 3 biological molecules
- Carbohydrates
- Lipids
- Proteins
Properties of carbohydrates
- They contain the elements carbon, hydrogen and oxygen in the ration 1:2:1
- Starch and glycogen are large, complex carbohydrates, which are made up of smaller units (eg. glucose or maltose molecules) joined together in a long chain
Properties of proteins
- Proteins are made up of long chains of amino acids
- They all contain carbon, nitrogen, hydrogen and oxygen atoms
Properties of proteins
- Proteins are made up of long chains of amino acids
- They all contain carbon, nitrogen, hydrogen and oxygen atoms
Properties of lipids
- Lipids are built from three fatty acids and one glycerol
- Lipids contain carbon, hydrogen and oxygen
Explain the test for glucose
- Use the benedicts test
- Prepare a food sample and transfer 5cm^3 to a test tube
- Prepare a water bath and set it to 75C
- Add some benedicts solution to the test tube (about 10 drops) using a pippette.
- Place the test tube in the water bath using a test tube holder and leave it for 5 minutes.
- If the food sample contains glucose, the solution will turn blue.
- It will turn green or yellow if there is low concentration of glucose.
- It will turn brick red for high concentrations of glucose
Make sure the tube is pointing away from you
Explain the test for starch
- Use iodine solution
- Make a food sample and transfer 5cm^3 of food into the test tube
- Add a few drops of iodine solution and gently shake the tube to mix the contents. If the sample contains starch, the colour of the solution will turn black or blue black
- If there is no starch, the solution stays browny-orange
Explain the test for proteins
- Use the biuret test
- Prepare a sample of food and transfer 2cm^3 of food to a test tube
- Add 2cm^3 of Biuret solution to the sample and mix the contents by gently shaking it
- If protein is present the solution will change from blue to pink or purple
- If no protein is present the solution stays blue
Explain the test for lipids
- Use the Sudan III test for lipids
- Prepare a sample of food tested(no need to filter it)
- Add 3 drops of Sudan III solution to the test tube
- If the solution contains lipids the solution will split into two layers, the top layer will be bright red
What 3 factors affect energy requirement
- Activity level: The more active a person is the more energy needed
- Age: Teenagers and children often need more energy than adults to grow and develope
- Pregnancy: Pregnant women often need more energy than other women
Write the order of the digestive system
Mouth, Oesophagos, Stomach, Liver, Gall bladder, Pancrease, Small intestine, Large intestine, Rectum
What is the function of the mouth in the digestive system
- Salivary glands in the moth produce amylase enzymes in the saliva
- Teeth break down food using mechanical digestion
What is the function of the oesophagos in the digestive system
The muscular tube that connects the mouth and stomach, allowing food to enter the stomach by peristalsis
What is the function of the stomach in the digestive system
- Pummels food with its muscle walls
- It produces the protease enzyme pepsin
- It produces HCl for two reasons: To kill bacteria, to give the optimal pH for protease enzymes to work(2pH-acids)
What is the function of the liver in the digestive system
Produces bile, this neutralises the stomach acids and emulsifies fat as it enters the small intestine
