Use the periodic table to help answer the following question Why does potassium (K) form a +1 cation, but calcium (Ca) forms a +2 cation ?

What have we learned from fossil evidence about evolution? a) it is an abrupt change. b)the process is observable. c) it takes place during one lifetime only. d)the most complex traits are always selected.

What are the formed elements (cell or parts of cell) in blood and what are their functions ?

Variety of living organisms; includes genetic, species, and ecological types.