Question

Active transport is
A. Formation of ATP
B. Against the gradient using ATP
C. Along gradient without using ATP
D. Against the gradient without using ATP

Answer 1

Active transport in cellular biology is the transfer of molecules from a region of lower concentration to a region of higher concentration. This occurs against the concentration gradient through a cell membrane. To accomplish this movement, active transportation requires cellular energy.

Complete answer: A cell has to use energy to transfer substances toward a concentration or electrochemical gradient. In order to maintain the right concentrations of ions and molecules in living cells, active transport mechanisms do exactly this, expending energy (often in the form of ATP). In reality, to keep their active transport processes going, cells expend most of the energy they gain in the metabolism. For example, much of the energy of a red blood cell is used to maintain levels of internal sodium and potassium that vary from those of the environment around it. Active transport is transport which requires chemical energy against a concentration gradient. Via the use of an integral membrane protein, active transport pushes ions or molecules in a particular direction. For example, going from a lower-concentration area to a higher-concentration area. You can classify active transport mechanisms into two groups. Explicitly, primary active transport uses a chemical energy source (e.g., ATP) to move molecules across a membrane toward their gradient. On the other hand, secondary active transport (cotransport) uses the electrochemical gradient produced by active transport as an energy source to move molecules to their gradient, so that no chemical energy source, such as ATP, is required directly.
Hence, option B is the correct answer.

Note: Simple gradients of concentration are differential concentrations of materials through space or membrane, but gradients are more complex in living systems. The electrochemical gradient is the combined gradient of concentration and electrical charge that affects an ion.