Life science

• Cells


  Monomers of living organisms
• Cell parts


  • Membranes
  • Cytoplasm
• Molecules

  Made of elements and compounds
• Types of compounds


  • Inorganic
  • Organic
• Inorganic compounds

  • Do not contain carbon
  • Form simple small compounds
  • Not combustible
  • Found in environment as gases and mineral salts
  • Formed in environment and living organisms
• Water


  • Made up of 2H and 1O
  • Not a nutrient, but most important inorganic compound for living organisms
• Roles of water in living organisms

  • Solvent-substances dissolve in it
  • Medium in which metabolic reactions occur
  • Reactant
  • Transport agent
  • Regulate body temperature
  • Give rigidity and shape
  • Lubricant to aid movement
  • Excretion of waste
• Roles of water in the environment

  • Habitat for aquatic organisms
  • Medium in which external fertilization can occur
• Role of water in nutrition

  1. Food eaten

  2. Swallowed

  3. Reacts chemically

  4. Digested food dissolved

  5. Digested food softened

  6. Absorbed

  7. Transported to body cells
• Minerals


  Simple chemical substances needed by both plants and animals for growth and development and to keep the cells functioning
• Minerals


  • NaCl
• Minerals

  Formed by two or more elements bonded together
• Minerals


  Come from rocks and soil, absorbed from soil by plant roots, obtained by animals from eating food and drinking water
• Nutrients


  Chemical compounds and vitamins needed by the body obtained from food eaten
• Macronutrients


  Nutrients needed in relatively large quantities
• Micronutrients


  Nutrients needed in smaller quantities
• Micro-elements


  Needed in relatively small quantities (trace elements)
• Deficiency diseases occur when an organism has not enough of these nutrients in the body
• Table of minerals needed by animals

  • Na
  • K
  • Ca
  • P
• Na


  • Osmoregulation
  • Transmission of nerve impulses
• K


  • Osmoregulation
  • Transmission of nerve impulses
• Ca


  • Strengthens bones and teeth
  • Keeps muscles working
• P


  • Strengthens bones and teeth
  • Rides in DNA
• Deficiency of Na


  • Muscle cramps
  • Confusion and so on
• Deficiency of K

  • Muscle cramps
  • Fatigue
  • Irregular heartbeat
• Deficiency of Ca


  • Rickets in children
  • Osteoporosis
  • Muscle spasms
• Deficiency of P


  • Osteoporosis
  • Muscle and nerve dysfunction
• Table of the main macro-elements needed by plants

  • N (nitrates NO3-)
  • P (phosphates PO4-)
• N (nitrates NO3-)


  • Production of proteins, nucleic acids and chlorophyll
• Deficiency of N


  Stunted growth due to poor root growth
• P (phosphates PO4-)


  • Forms cell membranes, nucleic acids and ATP
• Deficiency of P


  • Chlorosis
  • Stunted growth due to poor root growth
• Plants can use N only in the form of nitrates and P in the form of phosphates
• Eutrophication


  An important environmental process which has a negative impact on water quality
• Eutrophication


  1. Over use of fertilizers in farming crops drains into dams and rivers

  2. Discharge of untreated sewage into dams and rivers

  3. Water becomes polluted and undrinkable
• Soils where crops are grown year after year

  • Mineral salts, especially nitrates and phosphates, become depleted
  • Pressure due to increased yields and quality of food produced by agriculture
  • Leads to widespread use of chemical fertilizers
• Too much or use of chemical fertilizers for too long

  Can lead to accumulation of nutrients in the soil reaching toxic levels, root chemical burns, soil fertility problems and eutrophication
• Eutrophication


  1. Nitrates and phosphates are soluble in water and get washed into water bodies by surface-runoff or leaching

  2. Nutrients enrich the water stimulating excessive algal growth (algal bloom)

  3. Algae cover the surface of the water blocking sunlight from submerged plants

  4. Plants deprived of sunlight can't produce energy which causes them to die

  5. Saprophytic bacteria and fungi reproduce rapidly and use up the oxygen supply in the water

  6. Other organisms in the water such as fish then die from a lack of oxygen
• Leaching


  The process by which soluble nutrients are washed out of the soil
• There are better farming practices and alternative fertilizers that farmers can apply to prevent the negative effects of using chemical fertilizers to grow food