Answer:
The correct answer is - regulation of the heavy metal and their toxicity.
Explanation:
Metallothionein is a group of cysteine-rich, small in size, and highly conserved proteins that bind to various metal ions and regulate their activity or toxicity in transcriptional level.
Metallothionein IIA is one of the metallothioneins that binds to heavy metal and helps cells to be protected from the toxicity of these heavy metals. These proteins are present in almost every eukaryotic organisms virtually. These proteins are highly induced to express highly in the present of heavy metals.
Thus, the correct answer is - regulation of the heavy metal and their toxicity.
 
        
             
        
        
        
It is the producers. They make their own food and are food for the consumers to eat. Like us the, Humans.
        
                    
             
        
        
        
Microvilli which line down the luminal surface of those epithelial cells represent the resorptive function of the proximal tubule. 
<span>The high quantity of mitochondria inside the epithelial cells of the proximal convoluted tubule is needed in order to supply the energy for the active transport of sodium ions (to enter the cell from the luminal side).</span>