Q37.

37.. You are given three cells, a root hair, a cell of the inner cortical layer and a cell of the mesophyll arrange them in ascending order of DPD. 

(1) Root hair < Cortical cell < Mesophyll          (2) Cortical cell < Mesophyll < Root hair.
(3) Mesophyll < Root hair < Cortical cell          (4) Root hair < Mesophyll < Cortical cell

Dear student, 
​Please find below the solution to the asked query        

DPD is diffusion pressure deficit. Diffusion pressure of the pure solvent is maximum. Addition of solutes result in a decrease in the diffusion pressure. The deficit was termed diffusion pressure deficit. The greater the concentration of a solution, the greater is its DPD. Such a solution will tend to take up water and become normal, therefore water moves from low DPD to high DPD. Value of DPD is always positive. 

The root hair cells have low DPD. This is followed by DPD in the cells of inner cortical layer. Mesophyll cells ahve the highest DPD among these. Hence, option (1) is correct and DPD in ascending order is as follows: 
Root hair< cortical cell <mesophyll 
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Hope this information will clear your doubts about the topic.    Regards