The differences in the characters among the individuals of a species is called variation for example: free earlobe or attached earlobe is a variation found in human population.
The significant of a variation shows up only if it continues to be inherited by the offspring for several generation. the great advantage of variation to a species is that it increases the chance of its survival in changing enviroment
A gene is the unit of DNA on chromosomes which governs the synthesis of one protein that controls a specific characteristics of an organism. genes transfer CHARACTERISTICS from parents to offspring.