What process is responsible for moving chlorine ions into the cells of green algae against their concentration gradient?

• A. Osmosis
• B. Diffusion
• C. Active transport
• D. Facilitated diffusion

Answer: (C)

The movement of chlorine ions into the cells of green algae against their concentration gradient is achieved through active transport. This process requires energy, typically in the form of ATP, because it involves moving ions from an area of lower concentration (outside the cell) to an area of higher concentration (inside the cell).

Active transport is carried out by specific transport proteins or pumps in the cell membrane that utilize energy to transport substances against their gradient. In this case, since chlorine ions are being moved into the cells where they are already present in higher concentrations, it confirms that energy is necessary to achieve this movement.

Other processes, such as osmosis and diffusion, do not require energy and would not be able to transport ions against their concentration gradient. Osmosis specifically refers to the movement of water across a semipermeable membrane, while diffusion is the process of molecules moving from an area of high concentration to an area of low concentration. Facilitated diffusion involves the movement of substances across a cell membrane via transport proteins, but it still occurs along the concentration gradient, which is not applicable in this scenario.