Lungs have a pulmonary circulation
        
             
        
        
        
Answer:
1/2
Explanation:
Let's assume that the allele "p" is responsible for PKU in the homozygous state. According to the given information, both the parents are unaffected by the disorder but have an affected child. This means that both the parents carry at least one copy of the recessive allele responsible for the disease. Therefore, the genotype of each of the parents is Pp. A cross between Pp and Pp would produce progeny in following ratio=
Pp x Pp = 1/4 PP: 1/2/ Pp: 1/4 pp
Therefore, the probability that their next child will carry just one recessive allele is 1/2.  
 
        
             
        
        
        
No if it is squared it is a parabola. To be linear it has to be. A straight line
        
                    
             
        
        
        
The first line is MORE dense 
Second line forming a PLATE.