Mutations in these genes can produce new or altered traits, resulting in heritable differences (genetic variation) between organisms. ... One definition of a species is a group of organisms that can reproduce with one another and produce fertile offspring.
The answer is probably air.
So, you would make a punnet square. You would put the capital S and lowercase s on the top of it and then the capital Y and lowercase y on the side. Then you should have SY, sY, Sy, and sy as your outcomes.
CO2 + H2O = O2 m + C6H12O6 photosynthesis
C6H12Og + O2 = CO2 + H2O + ATP respiration