Adaptations For Gaesous Exchange Flashcards
Define the term diffusion.
The movement of molecules from a region of high concentration to a region of low concentration down a concentration gradient.
State, in words, the quantitive relationship between the length and the surface area/volume ratio.
The size of the ratio is inversely proportional to the length.
For an amoeba and a planaria, explain why simple diffusion provides an adequate gaseous exchange between the organism and the environment.
Amoeba-being unicellular it has a large surface area to volume ratio/gases have a short diffusion path.
Planaria-although multicellular, these are flat and so have a large surface area to volume ratio.
Name the respiratory exchange surface in mammals.
Alveoli.
Name the muscles which operate the ventilation mechanism in mammals.
Diaphragm and intercostal muscles.
Explain the importance of the alveoli exchange surface in a mammal.
As the mammal is large it has a small SA:volume ratio, therefore diffusion paths are slow.
Alveoli are needed to increase SA.
Describe four properties that the respiratory surfaces of fish and mammals have in common.
Large SA. Thin/short diffusion path. Permeable. Good blood supply. Moist.
Give two advantages to a mammal having internal lungs.
Infolding reduces heat/water loss.
Protection by ribs.
Explain the function of cartilage for the respiratory system.
To provide flexible support to the trachea/prevents collapse of air passage.
Explain the function of the diaphragm in the respiratory system.
Contracts and flattens to increase volume and decrease pressure of the thorax.
State the respiratory surface used in the tracheal system in insects.
Where the trachiole touches the muscle.
State two advantages of using the tracheal system for gas exchange.
Oxygen is supplied directly to the tissues so no transport system or pigment is required.
This makes for a much faster system.
Describe and explain the process of inspiration in mammals.
Intercostal muscles contract, ribs move up and out.
Diaphragm contracts and flattens.
Volume increases and pressure decreases.
Air rushes in as atmospheric pressure is higher.
State the difficulties aquatic organisms face, compared to terrestrial organisms in obtaining oxygen from water.
Water contains less oxygen than air.
Diffusion rates are much slower.
Water is a dense medium making it more difficult to pump.
Explain what is meant by the terms ‘parallel flow’ and ‘counter-current flow’ and state why the counter-current system is more efficient.
Parallel flow-water and blood in gills flow in the same direction.
Counter-current-water and blood flow in the opposite direction.
Concentration gradient is maintained over the entire gill surface, making it more efficient.
State the roles of the cuticle, palisade mesophyll layer, air spaces and stomata in the plant.
Cuticle-reduces water loss.
Palisade mesophyll layer-main site of photosynthesis.
Air spaces-for diffusion of gases.
Stomata-for exchange of gases.
Give two functions of stomata in leaves.
Allow gas exchange of O2 and CO2.
Control water loss.
Explain how the flow of water into the guard cells leads to the opening of stomatal pores.
Potassium ions are actively pumped into the guard cells.
The water potential is lowered.
Water flows in by osmosis.
Guard cells become turgid.
Inner wall of guard cell is thicker than outer wall so guard cells curve away from each other.
When guard cells are treated with cyanide the stomatal pores fail to open. Explain why cyanide has this effect on these cells.
Cyanide inhibits respiration/ATP synthesis.
Stops active transport of potassium ions into guard cells.
