Question

How would you compare and contrast diffusion and active transport?

Answer 1

Hint: The movement of molecules in the plants takes place by the process of diffusion and active transport. The movement of molecules takes place either along the concentration gradient as in diffusion or against the concentration gradient by active transport.

Complete answer:
The molecules move naturally along the concentration gradient that is from the region of higher concentration to the region of lower concentration. This movement does not need energy. The molecules that are small and do not have any charge move freely across the membrane either by diffusion or if they move against the concentration gradient by active transport. The difference between active transport and diffusion are-

Diffusion	Active Transport
The movement of molecules or ions along the concentration gradient i.e. from the region of higher concentration to the region of lower concentration.	The movement of molecules or ions against the concentration gradient i.e. from the region of lower concentration to the region of higher concentration.
The molecules move freely without any expenditure of energy.	The molecules move at the cost of energy in the form of ATP.
It is a slow process and occurs freely in all directions.	It is a rapid process and is unidirectional.
The molecules do not require any carrier proteins	The molecules move with the help of carrier proteins.
The molecules move until equilibrium is established.	The equilibrium is not necessary.
Water, gases transport freely through diffusion.	Proteins and other ions are transported through active transport.
Example- Diffusion of gases through stomata.	Example- Uptake of nutrients from the root hair cells.

Note: The energy required for the active transport is synthesised by the mitochondria. The carrier proteins or the channel proteins required for the active transport are specific for the specific molecules or ions. There are many carrier proteins present in the cell membrane which facilitate active transport of ions.