Dad: TtBb
Mom: ttbb
You have to use distribution for dihybrid crosses.  Meaning, the first allele of each trait has a equal chance of being paired with the other allele of the other trait.  So for example with Dad, I will number the traits:
T(1)t(2)B(3)b(4)
To set up the possibilities from Dad, it would be 13, 14, 23, 24: TB, Tb, tB, tb.  Same idea goes for Mom, except since all alleles are the same, you only need to make one column for Mom, since if you did all 4, the other 3 would just be repeats of the 1.
Cross:
                  tb
TB           TtBb
Tb           Ttbb
tB            ttBb
tb            ttbb
The phenotypic ratio is 1 Tall Brown: 1 Tall Blue: 1 Short Brown: 1 Short Blue
 
        
             
        
        
        
The answer to this question would be: increased food height
Giraffe becomes tall because its food height is increased. In this case, the environmental pressure on Giraffe would be the increased height of the food. 
The taller giraffe has access to higher food. Then, the giraffe with the higher chance of survival in this scenario would be the giraffe with a taller height. 
        
             
        
        
        
First way it will affect the enviroment is that there wont be any trees to soak up water from rainstorms
Second Water wont be brought up to the surface due to the fact there are no roots to do that
Hope this helps
        
             
        
        
        
The organelle that temporarily breaks apart so that the DNA can divide up is the nucleus. Nucleus store most of the cell's DNA it is responsible for carrying genetic information. It is also responsible for generating genetic expression to ensure the proper activities of the entire cells.