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• What do concentration gradients not affect?

  The rate of active transport
• What is the role of exchanging substances in multicellular organisms?

  It is trickier in multicellular organisms
• What does an organism need to supply its cells with?

  • Substances like glucose
  • Oxygen
  • Water
• Why does an organism need to live?

  To perform processes like respiration and photosynthesis
• What must an organism do with waste products?

  Get rid of waste products
• How are proteins stored in the body?

  Excess amino acids are converted into fats
• What is produced as a waste product from reactions?

  Urea
• How is urea filtered out of the body?

  It is filtered out by the kidneys
• What is the process of removing urea from the body called?

  Excretion
• How do single-celled organisms exchange substances?

  • They exchange substances directly with the environment
  • They have a large surface area to volume ratio
• How do multicellular organisms exchange substances?

  • They have specialized systems for exchange
  • They face challenges due to smaller surface area to volume ratio
• Why is diffusion quicker in single-celled organisms?

  They have a shorter distance to travel
• What is a key difference in substance exchange between single-celled and multicellular organisms?

  Single-celled organisms exchange directly, multicellular do not
• What are the challenges faced by multicellular organisms in substance exchange?

  • Smaller surface area to volume ratio
  • Need for specialized systems for efficient exchange
• What do organisms have in relation to their surface area?

  Relatively large surface area to volume ratio
• Why is a large surface area to volume ratio beneficial for organisms?

  It allows for efficient exchange of substances
• How does the difficulty of substance exchange differ in multicellular organisms?

  It is more difficult to exchange substances
• What is a reason for slow diffusion across the outer membrane in multicellular organisms?

  Some cells are deep inside the organism
• What do larger organisms have that affects substance exchange?

  Lower surface area to volume ratio
• What is the implication of a lower surface area to volume ratio for larger organisms?

  It is difficult to exchange enough substances
• What do multicellular organisms need for effective substance exchange?

  • Specialized exchange organs
  • Each with a specialized exchange surface
  • Adapted for efficient substance transfer
• What do multicellular organisms require to transport materials?

  Transport systems
• What is the role of transport systems in multicellular organisms?

  To carry materials from exchange organs
• What is the transport system in animals called?

  Circulatory system
• What is the transport system in plants called?

  Xylem and phloem
• What do xylem and phloem do in plants?

  Transport water and nutrients
• What do specialized exchange surfaces in multicellular organisms do?

  Facilitate efficient substance exchange
• Why do multicellular organisms need specialized exchange surfaces?

  To meet higher metabolic demands
• How do specialized exchange surfaces enhance efficiency?

  By increasing surface area for exchange
• What are the characteristics of effective exchange surfaces?

  • Large surface area
  • Thin barrier for diffusion
  • Moist environment
  • Good blood supply (in animals)