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: -Passive mechanisms like diffusion use no energy, while active transport requires energy to get done.

Detailed explanation-3: -Passive transport: This does not require any energy expenditure as it occurs along the concentration gradient of the molecule being translocated. Examples include simple diffusion, facilitated diffusion, and osmosis.

Detailed explanation-4: -Passive transport occurs when substances cross the plasma membrane without any input of energy from the cell. No energy is needed because the substances are moving from an area where they have a higher concentration to an area where they have a lower concentration.

Detailed explanation-5: -Gases, hydrophobic molecules, and small polar uncharged molecules can diffuse through phospholipid bilayers. Larger polar molecules and charged molecules cannot.