What do alkali metals and alkaline earth metals have in common? how are they different?

Alkali metals and alkaline earth metals both have chemical reactivity to air and water.  

Alkali are in group 1 of the periodic table. Alkaline earth metals are in  in group 2 of the periodic table. The main difference between alkaline and alkali is that alkali metals have one valence electron, when alkaline earth metals have two valence electrons.

Explanation:

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;