How differences in genotypes can cause variations in phenotypes?

Genotype and Phenotypes are directly connected. Genotype is the DNA makeup of some organism, while the Phenotype is the Physical being of the organism. An example is how a specific gene (genotype) causes changes in eye color (phenotype).

A variation in genotype may cause a change in phenotype, but a change in phenotype is the result of a change in genotype.

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