Answer:
Aa
Explanation:
In Punnett Square, you are bringing the letters on the top to the numbered squares, if that makes sense. It is to predict the genotype of offspring.
So square 1, on the left is A, and on the top is A, so it would be AA. 
For square 2, on the left is a, and on the top is A, so it would be Aa.
For square 3, on the left is A, and on the top is A, so it is AA.
Square 4, your question, has a on the left, and A on the top, so it is Aa.
Hope it makes sense. You should probably watch a Punnett Square tutorial online or something for a full and more general explanation.
 
        
             
        
        
        
You would find layers in a sedimentary rock, because it has different types of other rock combined in it.
        
             
        
        
        
the answer is CUAAGGCUGAU
IN the mRNA sequence the G switches to a C and the  other way around
the T switches to an A, but the A switches to a U
 
        
             
        
        
        
Charles Lyell: Principles of Geology. Charles Darwin read, and was much influenced by, Lyell's Principles of Geology while aboard HMS Beagle. This frontispiece image illustrates the main point of the book: that evidence of the forces of geological change that have been shaping Earth for millennia is observable today.