Active transport, this is the only transport method that can move species against their concentration gradient (from low to high concentration). Facilitated diffusion only moves species down their concentration gradient from high to low concentration.

Solution are or three types mainly Hypotonic, hypertonic, and Ringers solution a solution is said to be concentrated when solute or solvent are not in required amount .But in every cell there is a need for transport of substance and active transport is a moment of substance against the concentration gradient...

Movement of cell against concentration gradient is called active transport.

Active transport is the process by which cells move molecules or ions across a cell membrane against a concentration gradient. This means that the molecules or ions are being moved from an area of lower concentration to an area of higher concentration. Unlike passive transport, which does not require energy, active transport requires the cell to expend energy in the form of ATP (adenosine triphosphate).

Key points:
- Active transport is a vital process for cells because it allows them to maintain specific concentrations of molecules or ions inside the cell, even when the concentration is higher outside the cell.
- This process is crucial for various physiological functions, such as the uptake of nutrients, removal of waste products, and maintenance of ion gradients across cell membranes.
- Active transport proteins, also known as pumps, are embedded in the cell membrane and are responsible for moving molecules or ions against their concentration gradient.
- These pumps use ATP as an energy source to drive the transport process. ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate, releasing energy that is used to power the movement of molecules or ions.
- Examples of active transport include the sodium-potassium pump, which maintains the concentration gradients of sodium and potassium ions across cell membranes, and the calcium pump, which removes calcium ions from the cytoplasm to maintain low intracellular calcium levels.
- Active transport is a highly specific process, with different pumps dedicated to transporting specific molecules or ions.
- The process of active transport allows cells to control their internal environment, regulate cell volume, and perform specialized functions necessary for life.
- Without active transport, cells would not be able to maintain homeostasis and carry out essential functions required for their survival.

In conclusion, active transport is the movement of cells against a concentration gradient and is a fundamental process that allows cells to maintain specific concentrations of molecules or ions inside the cell.