Gas exchange Flashcards
What is cellular respiration?
Cellular respiration is a process occurring in all living cells that releases energy in the form of ATP.
When is the energy released during cellular respiration?
Energy is released when substrate molecules such as glucose is oxidised.
What do organisms use cellular respiration (the energy released) for?
To perform important life functions such as nutrition and excretion.
What is needed for aerobic respiration and what does it produce?
-Needs oxygen.
-Produces carbon dioxide as a waste product.
What is gas exchange?
Gas exchange is the process by which oxygen and carbon dioxide are exchanged between living organisms and their environment.
What process absorbs carbon dioxide and releases oxygen?
Photosynthesis.
By what process does gas exchange take place by?
-Diffusion, which is the net movement of molecules from a region of high concentration to a region of low concentration.
What factors impact the rate of diffusion?
-Size of the respiratory surface
-Concentration gradient
-Diffusion distance
Why do the challenges of gas exchange become greater when an organism increases in size?
Because an increase in size results in a smaller surface area to volume ratio meaning there is a greater diffusion distance.
How does gas exchange occur in single celled organisms?
They can do it directly with the atmosphere.
-Oxygen diffuses in while carbon dioxide diffuses out.
Why is gas exchange so efficient in single celled organisms?
Small, unicellular organisms have a large surface area to volume ratio and a short diffusion distance from the centre to its exterior, allowing for efficient gas exchange.
Why do the cells of large and active organisms require more oxygen than smaller ones? What do they have for this?
They require more to meet their higher metabolic demands. They have specialised organs for gas exchange.
What are the properties of gas exchange surfaces?
-Permeability - for gases to move across the surface
-Thin tissue layer - to create a short diffusion distance for oxygen and CO2.
-Presence of moisture - that gases can dissolve.
-Large surface area - allows many gas molecules to diffuse across at the same time.
What does a steep concentration gradient ensure?
it ensures a high diffusion rate across a gas exchange surface.
-allows the diffusion of oxygen into the body and the diffusion of carbon dioxide out.
How is a steep concentration gradient maintained?
-Dense network of blood vessels to provide a large surface area for the diffusion of gases. This is because blood provides a good transport medium for both oxygen and carbon dioxide.
-A continuous blood flow in the blood vessels to ensure that oxygen is constantly transported away from the gas exchange surface and carbon dioxide towards them. This ensures that oxygen will always diffuse into the blood and carbon dioxide out of the blood in the lungs.
-Ventilation with air in lungs and water in gills to bring oxygen close to the gas exchange surface and to remove carbon dioxide.
