Roots are to collect water and leafs are to collect sunlight I’m pretty sure and the stem is to take water to the leafs I think
        
             
        
        
        
Answer: Lipid molecules. 
Explanation: Biological membranes are bilayer of phospholipids that control the entrance and exit of molecules in the cells. The major components of phospholipids are the fatty acids. Phospholipids have two components: the fatty acyl chains and the phosphate group. The fatty acyl chains of the phospholipids molecules face each other at the core of the bilayer, forming a fluid hydrophobic interior while the phosphate (polar head) groups face outward. Proteins are embedded in this bilayer held by hydrophobic interactions between the membrane lipids and hydrophobic domains in the proteins. Both proteins and lipids move laterally in the plane of the bilayer but movement from one face of the bilayer to another is restricted.
 
        
             
        
        
        
Answer:To be considered a source of water pollution, the source must include a chemical. 
Explanation:
 
        
                    
             
        
        
        
Answer:
1 = natural, 2 = Natural, 3 = synthetic, 4 = Natural, 5 = Natural, 6 = Natural, 7 = synthetic 
Explanation:
Hope it will help 
<em>please markas a brainlists</em> 
 
        
             
        
        
        
Answer:
They keep toxic substances out of the cell
Explanation:
They contain receptors and channels that allow specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular and extracellular activities to pass between organelles