Question

Why does active transport take place in the small intestine during absorption of food molecules? I thought it was only diffusion that occurs ( high concentration to low )

Answer 1

Well if the small intestine needs to absorb the nutrients, then the nutrients kind of have to go somewhere right?
also, there is a transfer from high to low
inside the small intestine there are lots of nutrients that need to be absorbed to be made into energy
the cells would only have to take in more nutrients if it has run out, aka it's low on nutrients
thus the high concentration outside the cell and the low concentration inside leads to the active transport through the cell membrane