B3.1 gas exachange Flashcards
What is gas exchange?
All organisms absorb one gas from the environment and release another one.
Which gas do redwood trees absorb and release?
Absorb carbon dioxide and release oxygen.
Which gas do humans absorb and release?
Absorb oxygen and release carbon dioxide.
What is the relationship between surface area and volume in gas exchange?
Unicellular and small organisms have a large surface area-to-volume ratio, allowing gas exchange through their outer surface.
What is an example of a unicellular organism that uses its outer surface for gas exchange?
Amoeba.
Where does gas exchange occur in terrestrial organisms?
At surfaces exposed to air, such as lungs.
Where does gas exchange occur in aquatic organisms?
At surfaces exposed to water, such as gills.
What is required for gas exchange in larger organisms?
A specialized gas exchange surface that is much larger than the outer surface.
What are examples of specialized gas exchange surfaces?
- Alveoli in lungs
- Spongy mesophyll in leaves.
How do gases exchange across surfaces?
By diffusion.
What properties must gas exchange surfaces have?
- Permeable
- Large surface area relative to volume
- Moist
- Thin.
What is the importance of concentration gradients at exchange surfaces?
Gases diffuse if there is a concentration gradient.
How is blood related to gas exchange in multicellular animals?
Blood is pumped through dense capillary networks close to the gas exchange surface.
What happens to concentration gradients during diffusion?
Diffusion tends to reduce concentration gradients.
What must be maintained for gases to continue to diffuse across exchange surfaces?
Concentration gradients.
How do small aerobically respiring organisms maintain concentration gradients?
Cell respiration maintains the gradients.
How do mammals maintain high concentrations of oxygen in their lungs?
By pumping air in and out of their lungs.
How do fish maintain concentration gradients for gas exchange?
By pumping fresh water over their gills.
What is the significance of the one-way flow of water in fish?
It ensures that oxygen concentration remains high and carbon dioxide concentration remains low.
What do the symbols [CO2] and [O2] represent?
[CO2] = concentration of carbon dioxide, [O2] = concentration of oxygen.
