Functions of Life

• Unicellular organisms are the smallest organisms capable of independent life
• All living things carry out 7 basic functions integral to survival
• What are the 7 basic functions of life?

  Metabolism, Reproduction, Sensitivity, Homeostasis, Excretion, Nutrition, Growth
• Metabolism – Living things undertake essential chemical reactions
• Reproduction – Living things produce offspring, either sexually or asexually
• Sensitivity – Living things are responsive to internal and external stimuli
• Homeostasis – Living things maintain a stable internal environment
• Excretion – Living things exhibit the removal of waste products
• Nutrition – Living things exchange materials and gases with the environment
• Growth – Living things can move and change shape or size
• 7 functions of life mnemonic?

  MR SHENG
• Unicellular organisms must be able to carry out all life functions
• Paramecium


  • Surrounded by small hairs called cilia which allow it to move
  • Engulf food via a specialised membranous feeding groove called a cytostome
  • Food particles are enclosed within small vacuoles that contain enzymes for digestion
  • Solid wastes are removed via an anal pore, while liquid wastes are pumped out via contractile vacuoles
  • Essential gases enter (e.g. O2) and exit (e.g. CO2) the cell via diffusion
  • Divide asexually (fission) although horizontal gene transfer can occur via conjugation
• Movementin Paramecium 


  Paramecia move using cilia
• Nutrition in Paramecium 


  Paramecia engulf food via a specialised membranous feeding groove called a cytostome
• Metabolism in Paramecium 


  Food particles are enclosed within small vacuoles that contain enzymes for digestion
• Excretion in Paramecium 


  Solid wastes are removed via an anal pore, while liquid wastes are pumped out via contractile vacuoles
• Homeostasis in Paramecium


  Essential gases enter (e.g. O2) and exit (e.g. CO2) the cell via diffusion
• Scenedesmus


  • Exchange gases and other essential materials via diffusion
  • Chlorophyll pigments allow organic molecules to be produced via photosynthesis
  • Daughter cells form as non-motile autospores via the internal asexual division of the parent cell
  • May exist as unicells or form colonies for protection