In this punnett square the letter G represents the dominant allele, for example yellow. The letter g represents the green recessive allele. We can observe that when crossing between an organism with a homozygous dominant genotype GG and a homozygous recessive green genotype organism, all offspring that have a Gg genotype will be yellow because the G allele is dominant and masks the recessive allele g
the effect of external physical factor on cell division is clearly seen on in density dependent inhibition( a phenomenon in which crowded cell stop dividing)