Exchange systems

• How do Villi and Microvilli benefit organisms ?


  Through increased surface area which increases absorption of digested food.
• How do alveoli and Bronchioles benefit Humans?


  provide a large surface area for gas exchange
• How do spiracles and Tracheoles benefit insects?


  Provide a large surface area for gas exchange
• How do gill filaments and lamellae benefit fish?


  Provide a large surface area for gas exchange.
• How do thin wide leaves benefit plants?

  Provide a larger surface area for gas exchange
• How do capillaries benefit humans?


  provide a large surface area for gas exchange
• Why do insects have an exoskeleton made of hard fibrous material and a lipid layer?


  Exoskeleton is used at protection in insects.

  Lipid layer prevents water loss.
• What do insects have instead of lungs?


  A tracheal system
• What adaptations do insects have to limit water loss but increase evaporation?


  Insects have a small surface area to volume ratio where water can evaporate from.

  Insects have a waterproof exoskeleton so water cannot evaporate across the whole length of the body.

  Insects have spiracles where gases enter and water can evaporate from which can open and close to reduce water loss.
• What are the 3 parts of an insects tracheal system?

  Trachea, Tracheoles and spiracles
• What are spiracles and where do they belong?


  On the outside of insects.

  Spiracles are round, valve like openings running along the length of the abdomen. Oxygen and carbon dioxide enter and leave the spiracles.

  The trachea attach to these openings.
• What is the trachea and what organism is it found in?


  Insects

  The trachea is a network of internal tubes.

  The trachea tubes have rings within them to strengthen tubes and keep them open.
• What does the trachea branch into?


  Smaller tubes called tracheoles
• What do tracheoles do?


  These extend throughout all the tissues in the insect to deliver oxygen to all respiring cells.
• How do insects carry out gaseous exchange by simple diffusion?


  When the insects cells start to respire they use up oxygen and produce carbon dioxide, this creates a concentration gradient from the tracheoles to the atmosphere.
• How do insects carry out mass transport gas exchange?


  Insects contracts and relaxes their abdominal muscles to move gases on mass
• How do insects carry out gaseous exchange when in flight?


  When in flight the muscle cells start to respire anaerobically to produce lactate. This lowers the water potential of cells and therefore water moves from the tracheoles into the cells by osmosis. This decreases the volume in the tracheoles and as a result more air from the atmosphere is drawn in.
• How are insects adapted for efficient diffusion?

  Large number of fine tracheoles which provides a large surface area.

  Walls of the tracheoles are thin and short diffusion distance between the spiracles and tracheoles provides a short diffusion distance.

  The use of oxygen and production of carbon dioxide sets up a steep diffusion gradient.
• Why do gills require a gas exchange surface?


  They have a small surface area to volume ratio so require gills to exchange gas.
• Why do fishes have a specialised adaptation to maintain the concentration gradient?


  Fish obtain oxygen from water but there is 30 times less oxygen in water than air.
• Ficks law

  
• How many layers of gills are on both sides of the head of gills?


  4 layers
• What are gills made out of?


  Stacks of gill filaments
• What is each gill filaments covered in?

  Lamellae
• How are lamellae positioned on the gill filament?


  Positioned at right angles to the filament
• What do lamellae provide to the fish?


  A large surface area
• Where does the diffusion of gases in fish only happen in?

  Lamellae
• How in oxygen transported in water for fish?

  Water rushes in and over the gills and then out through a hole in the sides of head.
• What adaptations do fish have which provide a large surface area to volume ratio?


  Large surface to volume ratio created by many gill filaments covered in many gill lamellae.
• What adaptations do fish have to provide a short diffusion distance?


  Due to a capillary network in every lamellae and very thin gill lamellae.
• What adaptations do fish have at maintaining a concentration gradient?


  Countercurrent flow mechanism.
• Explain the countercurrent exchange principle.

  This is when water flows over the gills in the opposite direction to the flow of blood in the capillaries.
• How does the counter current exchange principle benefit a fish?


  Countercurrent flow ensures that equilibrium is not reached.

  This ensures that a diffusion gradient is maintained across the entire length of the gill lamellae.
• What 3 key layers of a leaf do u need to know for gas exchange?

  Palisade mesophyll

  Spongy mesophyll

  Stomata
• Where is the exact site of gas exchange in a leaf?

  Stomata
• Why does spongy mesophyll have lots of space?


  Space for gases to diffuse in.
• Where do gases diffuse to after the spongy mesophyll layer?


  To the palisade mesophyll, where most photosynthesis takes place because it is near the top of the cell.
• What is the vascular bundle?


  Where the xylem and phloem occur
• What gases are exchanged at the stomata?


  Oxygen diffuses out of the stomata.

  Carbon dioxide diffuses in through the stomata.
• How do plants reduce water loss?

  To reduce water loss by evaporation, stomata close at night when photosynthesis wouldnt be occuring