You measure the concentration of a polar molecule inside and outside of a cell. You find that the concentration is high outside but gradually increasing inside the cell. You also measure the ATP concentration inside the cell and find that it remains constant. Your best hypothesis for the process that is occurring would be: a. active transport b. passive transport c. facilitated diffusion d. simple diffusion e. endocytosis

The correct answer is passive transport

Explanation:

Passive transport is the transport in which the molecules move inside the cell along the concentration gradient without the use of energy.

So here there is a concentration gradient and the polar molecule is moving from its high concentration to its lower concentration which results in increment of that polar molecule inside the cell and it is also given that no energy is used in this case as ATP concentration is constant which shows that the transport is passive transport. In active transport ATP is used to transport molecules across cell membrane.