It is simply a binder or catalyst for the other ingredients.
Flour is the main ingredient in muffins.
Flour ( pasta ) is the main ingredient
Flour is an ingredient used in baking. It has no "opposite."
The flour ingredient would be altered, wholemeal flour contains bran and wheatgerm while white flour has these ingredients removed.
The protein content of the flour.
Oatmeal cookies can be made without the flour, however the oats will need to has a binder. The binder could be ground up oats, for example. Without the binder, the cookies will fall apart and never solidify into a handheld object.
flour
Flour!
Flour
It's flour
Flour is the ingredient with the greatest amount, but without the ginger and molasses, the cookies would not have their unique taste.