How can substances be transported across a membrane against their concentration gradient?

To move substances against a concentration or electrochemical gradient, a cell must use energy.

Explanation:

This occurs because During active transport, substances move against the concentration gradient from an area of low concentration to an area of high concentration which is a  “active” progress which requires the use of energy (usually in the form of ATP). It is the opposite of passive transport.

the "power" of a lens is its resolution power, or its ability to distinguish between to closely located points. with the low power lens, it is likely you will see the rough form of the hay and maybe some movement of dots around the hay. however, when observed with the high power lens, the detailed features of the hay become visible and the microbes being grown are more clearly visible.

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