Nutrients

Name: __________________ Topic: Nutrients Concepts Summary Notes Nan Hua High School Biology 1 LO: State the roles of water in living organisms In animals: ● Medium in which chemical reactions occur. ● Transport dissolved substances around the body eg. digested products, metabolic waste products, hormones. ● Key component of protoplasm, lubricants, digestive juices, blood and tissue fluid. ● Needed in hydrolysis reactions. ● A component of sweat to be evaporated to remove latent heat of vaporisation to cool the body down. In flowering plants: ● Raw material for photosynthesis. ● Needed for turgor pressure to maintain cell structure. ● Transport of mineral salts and sucrose in xylem vessels and phloem vessels. Types of chemical reactions: ● Condensation reaction: a chemical reaction in which two smaller, simple molecules are joined together to form a larger and complex molecule with the removal of one molecule of water. ● Hydrolysis/ Hydrolytic reaction: a reaction in which a water molecule is needed to break down a larger, complex molecule into smaller, simple molecules. LO: List the chemical elements which make up ● carbohydrates ● fats ● proteins State that large molecules are synthesised from smaller basic units. ● glycogen from glucose ● polypeptides and proteins from amino acids lipids such as fats from glycerol and fatty acids Carbohydrates: 1. Carbohydrates are organic molecules made up of: • carbon • hydrogen • oxygen 2. Ratio of hydrogen to oxygen atoms in carbohydrates: 2:1.

Name: __________________ Topic: Nutrients Concepts Summary Notes Nan Hua High School Biology 2 Examples of carbohydrates Monosaccharides (cannot be further digested into smaller molecules) C6H12O6 Disaccharides (made up of 2 molecules of monosaccharides bonded together) C12H22O11 Polysaccharides (made up of many monosaccharide molecules bonded together) glucose Maltose (glucose + glucose) Starch fructose Sucrose (glucose + fructose) Cellulose galactose Lactose (glucose + galactose) Glycogen *All monosaccharides and disaccharides (except sucrose) are reducing sugars. Types of complex carbohydrates (made of glucose molecules bonded differently) Structure Function Occurrence Starch linear Storage (large molecules, insoluble in water, compact shapes, easily hydrolysed) Storage organs in plants Cellulose linear Protection from mechanical damage Cell walls of plants Glycogen branched Storage (large molecules, insoluble in water, compact shapes, easily hydrolysed) Stored in the liver and muscles of mammals 3. Functions of carbohydrates: • Substrate for respiration to release energy for cell activities • Form supporting structures such as cell walls in plants • Converted into other organic compounds such as amino acids and fats • Form part of nucleic acids such as DNA • Used to synthesise lubricants such as mucus • Used to synthesise nectar in flowers

Name: __________________ Topic: Nutrients Concepts Summary Notes Nan Hua High School Biology 3 Fats 1. Fats are organic molecules made up of: • carbon • hydrogen • oxygen 2. Fats contain much less oxygen in proportion to hydrogen and the proportions of the elements in fats are not fixed. 3. Fats can be broken down into simpler compounds by hydrolysis and it produces fatty acids and glycerol. 4. Functions of fats: • a source and store of energy • act as an insulating layer to prevent excessive heat loss • a solvent for fat soluble vitamins and some hormones • form the main part of protoplasm such as cell membrane • reduce water loss from the skin surface

Name: __________________ Topic: Nutrients Concepts Summary Notes Nan Hua High School Biology 4 Proteins 1. Proteins are organic molecules made up of: • carbon • hydrogen • oxygen • nitrogen • sulfur (may or may not be present) 2. Each protein molecule is made up of smaller basic units called amino acids. 3. Amino acids are made up of: • amino group • acid group • side chain 4. Peptide bonds link up amino acids to form a polypeptide. 5. One or more polypeptide chains fold to form a three dimensional structure held by hydrogen bonds called proteins. 6. Function of proteins: • Synthesis of new protoplasm for growth and repair of worn out body cells • Synthesis of enzymes and some hormones • Synthesis of antibodies

Name: __________________ Topic: Nutrients Concepts Summary Notes Nan Hua High School Biology 5 LO: Describe and carry out tests for ● starch (iodine in potassium iodide solution) ● reducing sugars (Benedict’s solution) ● protein (biuret test) ● fats (ethanol emulsion) Nutrient Test and reagent Observation and conclusion Starch • Iodine test • Add a few drops of iodine solution Positive: Blue-black colouration observed Negative: Solution remains brown Reducing Sugars • Benedict’s test • Add equal volume of Benedict’s solution to sample solution. • Leave test tube in boiling water bath for 5 minutes Positive: • green precipitate – trace amount • yellow / orange precipitate – moderate amount • orange red precipitate – large amount Negative: Solution remains blue Proteins • Biuret test • Add 1 cm3 sodium hydroxide solution to 2 cm3 of sample solution. • Add 1% copper sulfate solution drop by drop, shaking after every drop. Positive: Violet colouration observed Negative: Solution remains blue Fats • Ethanol-Emulsion test • Add 2 cm3 of ethanol to sample and shake thoroughly. • Decant ethanol into another test tube with 2 cm3 of water. Positive: Cloudy white emulsion observed Negative: Solution remains clear and colourless