Final answer:
Apparent free space in plant cells serves as a temporary holding area that facilitates the regulated uptake of nutrient ions into plant cells. The cytosolic sucrose synthesis pathway is an enzymatic process that converts glucose into sucrose for metabolism or transport within the plant.
Step-by-step explanation:
Apparent Free Space and Nutrient Ion Uptake
The concept of apparent free space refers to the region in the cell walls of plants that appears to be free for the diffusion of ions, but in reality, this space is filled with water, ions, and various organic substances. Even though it appears 'free', this space is dynamically involved in the regulation of ion movement. A key role of apparent free space in the uptake of nutrient ions is to act as a temporary storage zone, where ions can accumulate before being actively transported into the cytosol of plant cells.
Cytosolic Sucrose Synthesis Pathway
The cytosolic sucrose synthesis pathway involves a series of enzymatic reactions that convert glucose, obtained from the breakdown of starch or imported from other parts of the plant, into sucrose. Importance is the enzyme sucrose phosphate synthase (SPS) which catalyzes the transfer of a glucose from UDP-glucose to fructose 6-phosphate, forming sucrose-6-phosphate. Subsequently, sucrose-6-phosphate phosphatase (SPP) dephosphorylates this intermediate to yield sucrose, which can then be utilized for various metabolic needs or transported within the plant.