What is the difference between active and passive transport across a membrane?

• A. Both active and passive transport move substances down their concentration gradients.
• B. Active transport is ATP dependent. Passive transport does not require energy.
• C. Active transport requires cell to cell communication. Passive transport does not require cell communication.
• D. Active transport can be performed without transport proteins while passive transport cannot.

Answer: (B)

Verified step by step guidance

1. Understand the basic definitions: Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, using energy in the form of ATP. Passive transport is the movement of molecules across a cell membrane from a region of higher concentration to a region of lower concentration, without the use of energy.
2. Identify the energy requirement: Active transport requires energy, typically in the form of ATP, because it moves substances against their concentration gradient. In contrast, passive transport does not require energy as it moves substances down their concentration gradient.
3. Consider the role of transport proteins: Active transport often involves specific transport proteins, such as pumps, that facilitate the movement of substances against their concentration gradient. Passive transport can occur through simple diffusion or facilitated diffusion, which may involve channel or carrier proteins but does not require energy.
4. Examine the direction of movement: In active transport, substances are moved from areas of low concentration to high concentration, which is against the natural flow and requires energy. In passive transport, substances move from areas of high concentration to low concentration, following the natural flow and not requiring energy.
5. Clarify the involvement of cell communication: Active transport may involve signaling pathways and cell communication to regulate the transport process, whereas passive transport generally does not require such communication as it relies on the natural diffusion process.