digestion

• Organisms are adapted to their environment based on the type and availability of food material as well as how it is obtained
• The form of nutrition differs depending on whether the food source is stationary (e.g. grass) or mobile (e.g. a deer)
• Differences in accessing food and nutritive apparatus used by a cow and a lion are influenced by the type of food source
• There are different strategies for taking in and using food by organisms
• Some organisms break down food material outside the body and then absorb it (e.g. fungi like bread moulds, yeast, mushrooms)
• Others take in whole material and break it down inside their bodies
• Nutrition depends on body design and functioning
• Some organisms derive nutrition from plants or animals without killing them through parasitic strategies (e.g. cuscuta, lice, leeches, tape-worms)
• Observations that help determine if a chemical reaction has occurred:

  • Change in state
  • Change in colour
  • Evolution of a gas
  • Change in temperature
• Variety of chemical reactions take place around us
• Types of chemical reactions and their symbolic representation will be studied in this chapter
• Magnesium ribbon burnt in oxygen converts to magnesium oxide
• Word-equation for the reaction: Magnesium + Oxygen → Magnesium oxide
• Reactants in the reaction (1.1): magnesium and oxygen
• Product formed during the reaction: magnesium oxide
• Word-equation format:

  • Reactants on the left-hand side (LHS) with a plus sign (+) between them
  • Products on the right-hand side (RHS) with a plus sign (+) between them
  • Arrow points towards the products, indicating the direction of the reaction