What is active transport?

What is active transport?

• A. Movement across a membrane against their concentration gradient using energy (ATP).
• B. Movement across a membrane down their concentration gradient using energy (ATP).
• C. Movement of substances across a membrane against their concentration gradient using energy (ATP).
• D. Diffusion through membrane channels.

Answer: (C)

Active transport uses energy to move substances across a membrane from where they are less concentrated to where they are more concentrated. This energy, usually provided by ATP, powers transport proteins (pumps) that change shape to push the substance against its gradient. This capability is crucial for maintaining ion gradients and nutrient uptake that wouldn’t occur if the substances could only diffuse down their concentration gradient. In contrast, diffusion or facilitated diffusion moves substances down the gradient and does not require energy. So the best description is movement across a membrane against the concentration gradient using energy (ATP).

Active transport uses energy to move substances across a membrane from where they are less concentrated to where they are more concentrated. This energy, usually provided by ATP, powers transport proteins (pumps) that change shape to push the substance against its gradient. This capability is crucial for maintaining ion gradients and nutrient uptake that wouldn’t occur if the substances could only diffuse down their concentration gradient. In contrast, diffusion or facilitated diffusion moves substances down the gradient and does not require energy. So the best description is movement across a membrane against the concentration gradient using energy (ATP).