Answer:
1 st question ) Lack of food and oxygen and the presence of wastes limit their growth.
 
        
             
        
        
        
Answer:
The cluster of developing cells from conception until birth is called an embryo. 
 
        
             
        
        
        
Answer:
Index
Explanation:
An index fossil can be used to identify a specific period of time. Organisms that make good index fossils are distinctive, widespread, and lived briefly. Their presence in a rock layer can be used to identify that period of time over a large area.
 
        
                    
             
        
        
        
Answer:
it has partial charges
The hydrogen gives a positive partial charge
The oxygen gives a negative partial charge
Oxygen is way more electronegative than hydrogen therefore the molecule will be polar.