Concentration gradient and passive-active transport

Question

Explain the relationship between concentration gradient and passive and active transport?

Answer 1

The passive transport is a movement of substances across membranes in favor of their concentration gradient, that is, from a more concentrated area to a less concentrated area. Active transport, on other hand, is the transport of substances across membranes alongside their concentration gradient, from a less concentrated to a much concentrated area. In passive transport, since it is spontaneous, there is no energy spent; the active transport though needs energy (or work) to take place.

Active transport works to maintain or raise the concentration gradient of a substance among two areas while passive transport acts in a manner to decrease the concentration gradient.