discuss the apoplastic and symplastic mechanisms involved in sugar transport from the mesophyll cells to the phloem. your answer should indicate all the anatomical, physiological and biochemical processes that make this system movement of the sugars possible

Answer 1

The transport of sugars from the mesophyll cells to the phloem involves both apoplastic and symplastic mechanisms.

Apoplastic Mechanism:
1. Anatomical process: Apoplastic movement of sugars occurs through the extracellular spaces in the cell walls.
2. Physiological process: The sugars move from the mesophyll cytoplasm to the cell wall, and then through the interconnected cell wall spaces.
3. Biochemical process: The sugars diffuse through the cell wall spaces towards the nearest phloem sieve tubes. This movement is facilitated by concentration gradients and the pressure generated by source cells supplying sugars.

Symplastic Mechanism:
1. Anatomical process: Symplastic movement of sugars occurs through the plasmodesmata, which are cytoplasmic connections between neighboring mesophyll cells.
2. Physiological process: The sugars move from the mesophyll cytoplasm of one cell to the next through the plasmodesmata.
3. Biochemical process: The sugars are transported from cell to cell by specific membrane transporters present on the plasma membrane and tonoplast. These transporters facilitate the movement of sugars across these membranes, maintaining concentration gradients between cells.

Overall, both mechanisms work together to facilitate the transport of sugars from mesophyll cells to the phloem. The apoplastic pathway allows for the movement of sugars through the extracellular spaces, while the symplastic pathway involves the movement of sugars through the interconnected cytoplasm of adjacent cells. These mechanisms involve anatomical, physiological, and biochemical processes that enable the movement of sugars in plants.