The answer is; catalyst
These proteins are called enzymes. They work by lowering the activation energy of reactants and hence speed up the biochemical reaction. They are not affected in the process hence one enzyme molecule can catalyze many reactions. An example of such an enzyme is carbonic anhydrase that enables carbon dioxide to dissolve in blood plasma as carbonic acid.
Answer:
In this case, the scientist want to test the presence of the limonite in the yellow rocks, So, proposed hypothesis should include the color of rock they want to observe and the posssible outcome, which need to be tested. So, a proposed hypothesis can be: The rocks, which have yellow color are made up of mineral lime.
