Answer:
Humans—and other complex multicellular organisms—have systems of organs that work together, carrying out processes that keep us alive. ... Cells make up tissues, tissues make up organs, and organs make up organ systems. The function of an organ system depends on the integrated activity of its organs.
 
        
             
        
        
        
Since it’s natural environment is very acidic, putting pepsin in a very alkaline environment would cause it to denature. 
 
        
             
        
        
        
The given blank can be filled with cells. 
The extracellular matrix is the protective tissues present as a coating of the cells. Both animals as well as the plant cells have the extracellular matrix, this coating provides support, biochemical protection and mechanical protection from the external environment of the cells. In the plant cells, the cell wall is a type of extracellular matrix.
 
        
                    
             
        
        
        
Answer:
B. 
Explanation:
The resistance to sudden temperature changes makes water an excellent habitat, allowing organisms to survive without experiencing wide temperature fluctuation. Furthermore, because many organisms are mainly composed of water, the property of high heat capacity allows highly regulated internal body temperatures.
I'm pretty sure it's B . If I'm not I'm very sorry as I copied this from my textbook .