Answer:
Hydrochloric acid contributes to protein digestion by supplying H+ which activates pepsinogen, the precursor to pepsin. Pepsinogen is secreted by chief cells in the gastric glands of the body and antrum of the stomach.
Explanation:
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 no beacuse they are differnt parts of the human with different functions
 
        
             
        
        
        
Answer:
They have  helical thickening of lignin in their walls to prevent collapse
Explanation:
the primary function of Xylem and its conducting vessels tracheids is to provide  support and tranport  water and  minerals  in plants.
 Xylem vessels  have layers of dead materials in the walls called LIGNIN.   Lignin is a polymer; a  very strong, hard materials that stop water passage  through it,because it contains dead cells, 
Therefore  the presence of  deposit of these strong  impermeable, ligified  walls  in its  walls  prevent its collapse during mass flow of water of transpiration pull.