Match the letters in the image below with the the morphogen that is critical in patterning the rostro-caudal axis in the developing embryo.

Do Carbonate, Evaporite, or Silicate (crystalline) rocks contribute most to the dissolved constituents of rivers? And why? 

A compound that partially ionizes, producing H+ (H3O+) is called: 

What is the most abundant form of inorganic carbon in seawater at pH = 8?  

Fe has a residence time in the oceans of ~350 years. Do you expect it to be a conservative or nonconservative element? 

River chemistry is very similar between all major rivers worldwide

A water solution with very few dissolved ions can buffer pH changes 

Which rock dissolves the slowest in water? 

On a warm sunny day, do you expect the air temperature to get warmer or colder as you approach a lake? Explain how this is related to hydrogen bonds. 

What is a major concern when using hospitalized patients as controls?