AP BIOLOGY

Detailed explanation-1: -Passive transport does not require the cell to expend any energy and involves a substance diffusing down its concentration gradient across a membrane.

Detailed explanation-2: -area with lower concentration. The difference between the concentrations is called the “concentration gradient”. Diffusion goes down the gradient until an equilibrium is reached.

Detailed explanation-3: -Answer and Explanation: In the case of osmosis, the cell does not need to use cell energy. ATP is the form of energy that is meant by the term “cell energy", and no ATP would be required for osmosis.

Detailed explanation-4: -Passive transport requires no energy input, as compounds are able to move freely across the membrane based only on a favourable concentration gradient (Figure 1.11).

Detailed explanation-5: -Passive transport, most commonly by diffusion, occurs along a concentration gradient from high to low concentration. No energy is necessary for this mode of transport.