Question

What is the passive transport of molecules?

Answer 1

Passive transport:

1. The transport of molecular entities across the semi-permeable plasma membrane, without any expenditure of energy (ATP), is known as passive transport.
2. Since the plasma membrane is uncharged, neutral molecules can pass passively through it.

Types of passive transport:

1. Simple diffusion: Type of passive transport in which assistance of any membrane protein is not required and the substances move from their higher concentration to lower concentration across the plasma membrane.
2. Facilitated diffusion: In this process, the substances pass through the plasma membrane via special protein channels. Charged particles can't directly pass through the phospholipid membrane so they use a facilitated transport system.
3. Filtration: In this process, solids are separated from liquids or gases. In a living system, selective absorption of nutrients is done by filtration e.g. ultrafiltration in the glomerulus.
4. Osmosis: The movement of water molecules from their higher concentration to their lower concentration across a semipermeable membrane is known as osmosis.