gas exchange

• what is the definition of gas exchange


  the process by which oxygen reaches cells and carbon dioxide is removed from them
• what is a picture of a amoeba

  
• what are the characteristics of an unicellular organism such as an amoeba


  extremely large sa:v ratio , gas exchange occurs across whole surface, permeable membrane ,doesn't require specialises gas exchange organs
• what is an example of a unicellular orgainsm


  amoeba
• what is an examples of simple multi cellular organisms


  flat worms and earthworms
• what are the characteristics / advantages of a flatworms strucutre


  an evolved flattened shape ,a high sa:v ratio and a permeable membrane
• what advantages does a permeable membrane give to simple organism such as amoebas and flatworms


  it allow the easy diffusion of gasses
• what advantages does the flatworms flattened shape give


  it increases the surface area to volume ratio
• What does a flatworm look like?

  
• why is a short diffusion pathway an advantage


  there is no need for specialises gas exchange organs
• what are the characteristics of multi-cellular organisms


  small sa:v ratio, specialised gas exchanges mechanism and more metabolically active
• what does an earth worm look like

  
• what shape has a earth worm developed over time


  a tubular elongated shape
• what do earthworms secrete and why


  mucus to keep the cells of their body surface moist
• what does the earthworms tubular shape mean for its habitats


  it is restricted to damp environments
• how does the earthworms elongated shape act as an advantage


  it gives the earth worm a large surface area to volume ratio
• how do earthworms respire


  through their skin
• what does the circulation of blood in a earth worm do


  it maintains a concentration gradient so that oxygen can diffuse through
• what is a respiratory pigment give an example


  a pigment that carries oxygen ,haemoglobin