Differences between Active Transport and Passive Transport
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Active Transport vs. Passive Transport[edit]
Active and passive transport are the two primary biological processes for moving substances across a cell membrane.[1] The fundamental difference between them is that active transport requires cellular energy to move substances against their concentration gradient, while passive transport does not require energy as substances move along the concentration gradient.[2] Both are crucial for supplying cells with nutrients, removing waste products, and maintaining cellular homeostasis.[3]
Comparison Table[edit]
| Category | Active Transport | Passive Transport |
|---|---|---|
| Energy Requirement | Requires cellular energy, typically in the form of ATP.[4] | Does not require cellular energy.[3] |
| Concentration Gradient | Moves substances against the concentration gradient (from a region of lower concentration to a region of higher concentration).[5] | Moves substances down the concentration gradient (from a region of higher concentration to a region of lower concentration). |
| Carrier Proteins | Requires the use of carrier proteins or pumps.[2] | May or may not involve carrier proteins (in the case of facilitated diffusion). |
| Speed of Process | Generally a rapid process.[3] | A comparatively slow process.[3] |
| Examples | Sodium-potassium pump, uptake of glucose in the intestines, uptake of mineral ions by plant roots. | Diffusion, osmosis, and facilitated diffusion. |
Active Transport[edit]
Active transport is the process of moving molecules or ions across a biological membrane from a region of lower concentration to one of higher concentration. Because this movement is against the concentration gradient, it requires the cell to expend energy. There are two main types of active transport: primary and secondary.
Primary active transport directly uses energy, typically from the hydrolysis of adenosine triphosphate (ATP), to transport substances. A key example of this is the sodium-potassium pump, which moves sodium ions out of the cell and potassium ions into the cell. Other examples include proton pumps and calcium pumps.
Secondary active transport, also known as coupled transport or cotransport, does not directly use ATP. Instead, it uses the electrochemical gradient created by primary active transport to move another substance against its own concentration gradient. This can occur in two ways: symport, where two substances are moved in the same direction, and antiport, where they are moved in opposite directions.
Passive Transport[edit]
Passive transport is the movement of substances across a cell membrane without the use of cellular energy.[3] This process relies on the natural kinetic energy and entropy of molecules moving down their concentration gradient. There are four main types of passive transport:
Simple diffusion is the movement of small, nonpolar molecules directly through the lipid bilayer of the membrane. Examples include the movement of oxygen and carbon dioxide.
Facilitated diffusion is the transport of larger or polar molecules across the membrane with the help of transmembrane proteins, such as channel proteins or carrier proteins.
Osmosis is the specific movement of water molecules across a selectively permeable membrane from an area of high water potential to an area of low water potential.
Filtration allows water and small solutes to pass through a membrane due to hydrostatic pressure.[1]
References[edit]
- ↑ 1.0 1.1 "thoughtco.com". Retrieved November 27, 2025.
- ↑ 2.0 2.1 "vedantu.com". Retrieved November 27, 2025.
- ↑ 3.0 3.1 3.2 3.3 3.4 "byjus.com". Retrieved November 27, 2025.
- ↑ "quicktakes.io". Retrieved November 27, 2025.
- ↑ "byjus.com". Retrieved November 27, 2025.
