IGCSE BIOLOGY section 2.6: NUTRITION

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  • NUTRITION
    • The taking in of nutrients which are organic substances and mineral ions, containg raw materials or energy for growth and tissue repair, absorbing and assimilating them.
    • The elements which make up the following groups - carbohydrates, fats and proteins - are: Carbon, Hydrogen Oxygen, Nitrogen and Sulfur.
    • Simple sugars - starch and glycogen. A basic glucose molecule (simple sugar? / monosacharide) can come together with other glucose molecules to form Polysacharides such as glycogen and starch be removing water from the molecules.
    • Amino acids - proteins: proteins are long chains of amino acids which have been combined by the removal of water from their chemical make-up. The order of the amino acids determines the shape of the protein they have combined to form and our genes determine which amino acids are present in different proteins.
    • Fatty acids and Glycerol - fats and oils: 3 molecules of fatty acid & 1 molecule of glycerol are condensed (water removed) and form fats and oils, both of which are excellent stores of energy and form form barriers between watery environments such as that between a cell and its surroundings.
    • Test for Starch: A few drops of IODINE SOLUTION added to 2cm3 of unknown solution, mixture shaken gently. Positive result = DEEP BLUE / BLACK colour.
    • Test for Protein: A few drops of BIURET REAGENT added to 2cm3 of unknown solution, mixture gently shaken. Positive result = MAUVE / PURPLE colour.
    • Test for Reducing Sugars: 2cm3 BENEDICT'S SOLUTION added to 2cm3 unknown solution, mixture heated in boiling water bath (2 - 3 mins). Positive result = ORANGE / BRICK RED colour.
    • Test for Fats: add 5cm3 ETHANOL to small pieces of food, shake and leave, pour into DISTILLED water. Positive result = CLOUDY EMMULSION.
    • CARBO - HYDRATES: Are our main source of energy and can be found in foods such as pasta, potatoes, rice and bread...
      • Vitamins C and D: Are used for chemical processes (making enzymes). Can be found in fruit and veg, dairy products, fatty fish and we can make our own when exposed to the sun...
        • Calcium and Iron: calcium strengthens our teeth and bones and helps blood clotting, iron is needed to make Haemoglobin and transports oxygen. Can be found in milk, and red meat...
          • Water: is important to keep hydrated. Is found in water, drinks and liquid foods...
    • Fats: Are used for insulation, a source of energy, form cell membranes, waterproofing. They can be found in foods such as red meats and many dairy products...
    • Proteins: Are used for the growth and repair of muscle and body tissues. Proteins can be found in foods such as meat, eggs, fish, peas, nuts...
    • Vitamin D deficiency: can cause Rickets. symptoms - softening of bones causing bending and bulging joints.
    • Vitamin C deficiency: can cause Scurvy. Symptoms - skin covered with bruises and ulsers, soft bleedign gums, teeth falling out.
    • Calicuim deficiency: symptoms - weak bones and teeth, slow blood clotting.
    • Iron deficiency: can cause anaemia. Symptoms - lower levels of haemoglobin, less oxygen transported around the body. can take iron supplements (pills)

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