Natural Selection a single gene traits can lead to change in allele frequencies and to change in phenotype frequencies.
In order to test the presence of starch, one has to treat with iodine. If the food turns blue-black in color, it is an indication of the presence of the starch.
Quite simple really.... The CNS actually doesn't receive as much nutrients or key components from the blood... The blood actually dumps it into the Cerebrospinal fluid. The Cerebrospinal fluid therefore is directly in contact with the brain and if you want to find an infection you take from a source as close to thing as you can.
