4 is the correct answer hope you get it right!!!
Differentiation occurs numerous times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types.
Because electrons are “pulled” towards the oxygen.
Except. Bones because it’s abs estructure that’s neuro chemicals can’t affect
"Different substances sometimes have the same chemical formula, such as glucose and fructose, but they have different components so they act differently."