Question

Differentiate between Apoplast and Symplast pathways of water movement. Which of these would need active transport?

Answer 1

System components:

• Apoplast: Apoplast includes cell walls and intercellular spaces.
• Symplast: Symplast includes the cytoplasm of the cells interconnected with plasmodesmata.

Type of cells:

• Apoplast: Apoplast components are made up of non living cells of the plant.
• Symplast: Symplast is made up of the living part of the plant.

Movement of water:

• Apoplast: In apoplast the water moves due to capillary action or free diffusion along the gradient.
• Symplast: In symplast the water moves with the help of osmosis along the gradient

Resistance ot movement to water:

• Apoplast: In apoplast the movement of water occurs through bulk or massflow and it doesn't provide any barrier to the movement of water.
• Symplast: In symplast the movement of water occurs from one cell to another cell through the plasmodesmata. The suberin of the casparian strips in the endodermis obstructs the flow of water through the cell wall forcing the water through the symplast route.

Summary:

Difference between Apoplast and Symplast.

Criteria	Apoplast	Symplast
System components .	Apoplast includes cell walls and intercellular spaces	Symplast includes the cytoplasm of the cells interconnected with plasmodesmata
Type of cells	It is made up of non living cells.	It is made up of living cells
Movement of water	Water moves by diffusion	Water moves by osmosis
Resistance to water movement	There is less resistance to the movement of water.	There is more resistance to the movement of water.
Flow of water	Water flow is fast.	Water flow is slow

Flow of water:

• Apoplast: In apoplast the water flows rapidly.
• Symplast: In symplast the water flows slowly.

Active transport: Symplast needs active transport due selective permeability of the plasma membrane