If the inner lining of the air sacs neither thin nor highly vascularized, then it can be inferred that AIR SACS ARE CANNOT BE THE SITES OF GASEOUS EXCHANGE BETWEEN AIR AND BLOOD. Air sacs are generally lined with mucus and surrounded with blood capillaries.
In case of birds, air sacs play an important role in respiratory system.
A is the answer. It’s like addition.
Jet streams are fast moving air currents much like how a river is a fast moving water current so the answer is jet streams.
The answer is A
Explanation: don’t mind the volume, look at the surface area-to-volume ratios because they affect the efficiently of a cell to obtain nutrients and eliminate waste.
Hope that helps! :)
