Exchange of materials

• What do animals need to exchange with their environment?

  Materials
• Why is material exchange in animals more complicated than in unicellular organisms?

  Because animals are multicellular organisms
• What substances do organisms exchange with their environment?

  • Substances needed from the environment
  • Waste products to be removed
• What do cells need for aerobic respiration?

  Oxygen
• What waste product is produced during aerobic respiration?

  Carbon dioxide
• How do gases move between cells and the environment?

  By diffusion
• How do cells take up water?

  By osmosis
• What do dissolved food molecules in animals include?

  Glucose and amino acids
• What is urea in animals?

  A waste product from proteins
• How is urea removed from the body?

  By diffusion into the blood plasma
• What organ removes urea from the blood?

  Kidneys
• What factors influence how easily an organism exchanges substances with its environment?

  Surface area to volume ratio
• How does a larger surface area to volume ratio affect material exchange?

  It facilitates easier exchange of substances
• How can surface area to volume ratios be compared among organisms?

  • Larger ratios indicate more efficient exchange
  • Smaller ratios indicate less efficient exchange
• If a hippopotamus has a surface area to volume ratio of 64:32, what is the simplified ratio?

  2:1
• What is the surface area of a block with dimensions 2 cm x 4 cm x 4 cm?

  64 cm²
• What is the volume of a block with dimensions 2 cm x 4 cm x 4 cm?

  32 cm³
• How can the surface area to volume ratio of a hippopotamus be calculated?

  By comparing surface area to volume
• What does a higher surface area to volume ratio indicate about an organism?

  It indicates more efficient material exchange
• What is the surface area of a cube with dimensions 1 cm x 1 cm x 1 cm?

  6 cm²
• What is the volume of a cube with dimensions 1 cm x 1 cm x 1 cm?

  1 cm³
• What is the relationship between surface area and volume in organisms?

  • Larger organisms have smaller ratios
  • Smaller organisms have larger ratios
• How can the hippopotamus be written in ratio form?

  6:4:3:2
• How do you get the ratio in the form n:1?

  Divide both sides of the ratio by volume
• What is the surface area to volume ratio of the hippopotamus?

  2:1
• How can an amouse be represented in dimensions?

  1 cm x 1 cm x 1 cm block
• What is the surface area of the amouse block?

  6 cm²
• What is the volume of the amouse block?

  1 cm³
• What is the surface area to volume ratio of the mouse?

  6:1
• How does the surface area of a cube compare to its volume?

  Surface area is six times its volume
• How does the surface area of a hippopotamus compare to its volume?

  Surface area is only twice its volume
• Why do multicellular organisms need exchange surfaces?

  To facilitate gas and substance exchange
• What are the characteristics of single-celled organisms regarding exchange surfaces?

  • Gases and dissolved substances diffuse directly into the cell
  • Large surface area compared to volume
  • Efficient exchange due to proximity to the cell membrane
• How do multicellular organisms differ in their exchange surfaces?

  They have smaller surface area compared to volume
• What challenge do multicellular organisms face regarding substance exchange?

  Difficulty in exchanging enough substances efficiently
• What do multicellular organisms need for efficient diffusion?

  Some sort of exchange surface
• What is the role of exchange surfaces in multicellular organisms?

  To supply the volume of the cell with substances
• What is the size of a red blood cell block representation?

  7 µm x 7 µm x 1 µm
• How do you calculate the surface area to volume ratio of the red blood cell?

  Calculate its surface area and volume ratio
• What is the importance of exchange surfaces in multicellular organisms?

  They allow for efficient substance exchange