Exchange of Substances

• What is the main factor that affects the ease of substance exchange in organisms?

  Surface area to volume ratio
• Why do cells need to exchange substances with their environment?

  To take in oxygen and nutrients, and excrete waste
• What waste products do cells need to excrete?

  Carbon dioxide and urea
• How does surface area to volume ratio affect substance exchange?

  Smaller organisms have higher ratios, facilitating exchange
• Which animal has a higher surface area to volume ratio, a mouse or a hippo?

  Mouse
• Why do multicellular organisms need specialized exchange organs?

  To efficiently supply cells with substances and remove waste
• What is the role of mass transport systems in multicellular organisms?

  To carry substances to and from cells
• What does mass transport in mammals typically refer to?

  The circulatory system
• What do plants use for mass transport?

  Xylem and phloem
• How does body size affect heat exchange in organisms?

  Smaller organisms lose heat more easily
• Why do smaller organisms require a higher metabolic rate?

  To generate enough heat to stay warm
• How does the shape of an animal affect its heat loss?

  Compact shapes minimize heat loss
• What adaptation does the Arctic fox have to reduce heat loss?

  Small ears and a round head
• How do desert mammals adapt to reduce water loss?

  Kidney structures produce less urine
• What do small mammals in cold regions need to eat to support their metabolic rates?

  High energy foods like seeds and nuts
• How do elephants adapt to keep cool in hot regions?

  They have large flat ears to increase surface area
• What is the main gas exchange surface in plants?

  Surface of the mesophyll cells
• How do stomata function in gas exchange for plants?

  They open for gas exchange and close to retain water
• What adaptations do xerophytes have to minimize water loss?

  Sunken stomata and waxy cuticles
• How do insects minimize water loss during gas exchange?

  By closing spiracles and having a waxy cuticle
• What is the role of guard cells in plants?

  They control the opening and closing of stomata
• What is the primary function of gas exchange surfaces?

  To facilitate diffusion of gases
• Where does gas exchange occur in humans?

  In the lungs
• What happens to air as it enters the trachea in humans?

  It travels to the lungs for gas exchange
• Why is a large surface area important for gas exchange surfaces?

  It increases the rate of diffusion
• How do single-celled organisms exchange gases?

  By diffusion through their outer surface
• What is the counter-current system in fish gills?

  Blood flows opposite to water flow
• What is the purpose of lamellae in fish gills?

  To increase surface area for gas exchange
• How do tracheae in insects facilitate gas exchange?

  They allow direct diffusion to cells
• What is the role of spiracles in insects?

  They allow air to enter the tracheae
• What do mesophyll cells in plants do?

  Facilitate gas exchange for photosynthesis
• How do guard cells respond to dehydration in plants?

  They lose water and close the stomata
• What adaptations do xerophytes have to survive in dry habitats?

  Reduced stomata and waxy cuticles
• Why do plants need CO₂ for photosynthesis?

  It is a reactant in the photosynthesis process
• What is the waste gas produced during respiration?

  Carbon dioxide
• How do stomata help plants during photosynthesis?

  They allow CO₂ to enter for photosynthesis
• How do adaptations in gas exchange surfaces improve efficiency?

  By increasing surface area and reducing diffusion distance
• What is the relationship between gas exchange and water loss in organisms?

  Gas exchange can lead to water loss
• What is the primary function of gas exchange surfaces in organisms?

  To facilitate the exchange of gases
• How do adaptations in the lungs facilitate gas exchange in humans?

  They provide a large surface area and thin walls