The most powerful approach to isolating a single mutant from a population of billions is positive selection.
 
        
                    
             
        
        
        
A. 
<span>f(-2) = 2^(-2 - 2) </span>
<span>f(-2) = 2^(-4) </span>
<span>f(-2) = 1/2^4 </span>
<span>f(-2) = 1/16</span>
        
             
        
        
        
Answer:
The substance moves from low to high concentration, against the concentration gradient.
Explanation:
When molecules move from high to low concentration, it is known as Diffusion. It moves with the concentration gradient and does not require energy.
However, when molecules move from low to high concentration, it is against the concentration gradient and cannot proceed without Energy. This process is called Active transport.
Cell membrane is not thick, it is thin and semi permeable.
 
        
             
        
        
        
I think you wrote this wrong? Is it not round rr vs wrinkled RR?? I'll answer it with that assumption:
You are crossing a rr with an RR:
You only get Rr back so they will phenotypically be all wrinkled
If you are crossing rr with an Rr (so a heterozygote wrinkled):
50% will be Rr (wrinkled)
50% will be rr (round)
See my picture for the Punnett Squares for both answers!