2: D 3: A 4: B 5:A 6:C PLEASE MARK BRAINLIEST!!
Alveolar walls are thin to enable the quick passage of oxygen in and out of the lungs. The lungs works hand-in-hand with the heart and also is responsible in converting blood that's de-oxygenated into an oxygenated blood that is usable by the organ systems of the body. The alveolar walls are also designed to have thin membranes so that it can expand and constrict quickly allowing us to breather properly.
I don’t know dear keep trying
<span>John can use Cladistic
Analysis as an approach to trace the classifications of the lion and cat
because he can trace a common ancestor for them due to the cat and the lion
having the same characteristics and traits. They are considered to be closely
related because they share a common ancestor which means that they are closely
connected. The earliest discovery of using this method was by Peter Chalmers
Mitchell in 1901 as he was studying how different types of birds belong to the
same ancestry.</span>
