Where air pollution is not especially severe, predators have much more impact on leaf-beetle populations than parasites do
        
             
        
        
        
Answer:
red will be the bottom layer
Explanation:
in order to find its density you have to do mass/volume. 
Blue: 12/3 = 3  
Clear: 10/5= 2
Red: 15/3= 5
Yellow: 18/9 = 2
The one with the greates valua aka greatest density will be at the bottom layer/
 
        
             
        
        
        
Answer:
Cell Theory
1.  All living organisms are made of cells
2. Cells arrive from previously existing cells
3. Cells are the basic unit of structure...
Explanation: