Science chap 1

• Elements that make up living organisms

  • Carbon (18%)
  • Hydrogen (10%)
  • Oxygen (65%)
  • Nitrogen (3%)
  • Sulphur
  • Phosphorous
  • Sodium
  • Potassium
  • Calcium
  • Magnesium
  • Iron
  • Chlorine
• There are only about 25 elements in the living body out of the 92 elements present in nature
• Most common 4 elements in the living body

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
• Organic compounds


  Compounds which contain Carbon
• Inorganic compounds


  Compounds which do not contain Carbon ( carbon dioxide, carbon monoxide, bicarbonate, carbonates )
• Main types of biomolecules

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic acids
• Vitamins are also one of the organic compounds found in living matter
• Inorganic molecules essential for life

  • Water
  • Minerals
  • Gases
• Carbohydrates are the most abundant organic compound on earth which is produced during photosynthesis
• Carbohydrates


  Compounds composed of Carbon, Hydrogen and Oxygen with Hydrogen and Oxygen in a 2:1 ratio
• Types of carbohydrates


  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• Monosaccharides


  Structural units of carbohydrates, simple sugars that are crystal shaped, generally sweet and water soluble
• Monosaccharides


  • Glucose
  • Fructose
  • Galactose
• Disaccharides


  Two monosaccharides joined together with the release of a water molecule
• Disaccharides


  • Maltose
  • Sucrose
  • Lactose
• Polysaccharides


  Polymers of many monosaccharides, insoluble in normal water, not crystal shaped
• Polysaccharides


  • Cellulose
  • Starch
  • Glycogen
• Cellulose is not digested in the human digestive system, but it helps to avoid constipation
• The type of carbohydrate that stores in plants is starch, and the type that stores in animals is glycogen
• Carbohydrates are the main source of energy for organisms
• Carbohydrates also serve as storage compounds, structural components in plant cell walls, and constituents of nucleic acids and as an energy source .
• Tests to identify carbohydrates

  1. Starch test

  2. Glucose test

  3. Sucrose test
• Starch test


  1. Small amount of food is obtained and grind well with water

  2. A drop of Iodine solution is added to the above solution

  3. Purplish blue colour appears
• Types of monosaccharides


  • Glucose
  • Fructose
  • Galactose
• Glucose


  Present in ripen fruits, bee honey
• Adding water, the end product during hydrolysis of all starchy food is glucose, which is absorbed into blood
• Plants produce glucose during photosynthesis
• Energy is released during breakdown of glucose in cellular respiration
• Fructose


  Formed during ripening of fruits, known as "fruit sugar", the sweetest sugar
• Galactose


  Present in dairy products, no sweet taste
• Types of disaccharides


  • Maltose
  • Sucrose
  • Lactose
• Maltose


  Present in germinating seeds, an intermediate product of starch hydrolysis
• Sucrose


  Present in white and brown sugar, sugar cane and beet, some fruits, phloem sap in trees
• Lactose


  Present in dairy products, union of glucose and galactose, not as sweet as sucrose, 4-6% in cow's milk, 6-7% in human milk
• Types of polysaccharides


  • Cellulose
  • Starch
  • Glycogen
• Cellulose


  • Not digested in human digestive system, helps avoid constipation
• Starch


  The type of carbohydrate that stores in plants
• Glycogen


  The type of carbohydrate that stores in animal body
• Protein


  An essential constituent in all living cells, made up of polymerized amino acid molecules
• Elements present in proteins

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
  • Sulphur ( sometime )