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Grade 8
Aug 22, 2022


The transmission of characters from parents to offspring is called heredity. Variations are the differences in DNA sequence or genes between individuals. The offspring of the same parent resemble each other, but they may vary in size, color, and several other characters.    


Genetic variation is a term used to describe the variation in the DNA sequence in each of our genomes. Genetic variation is what makes us all unique, whether in terms of hair color, skin color, or even the shape of our faces. 

Variation is defined as differences between individuals of the same species. Variation in size, behavior, biochemistry, or coloring is observed. The causes of the variation may be genetic, environmental, or more usually, a combination of the two.  

The origin of genetic variation can be traced by the recombination of the genetic material during the formation of the gametes and rarely a mutation.  

The environmental variation results in differences in the individuals of a species because of differences in nutrition, disease, population density, etc. Genetic variation improves the ability of a species to survive in a changing environment. There are chances that some of individuals will tolerate a change. Such individuals will survive and transmit the advantageous genes to their offspring. Populations always show variation in traits. No two individuals of the same species are the same.  


Variations Accumulate in Offspring during Reproduction: 

Variations that appear in a parental generation are passed to the next generation, and the offspring of one generation passes them to the offspring of the next generation and so on. In each generation, they acquire and add some new variations. Variations are passed on to more and more individuals in the next generations.  

Phenotypic variation

Phenotypic variation is the difference between individuals of the same species. These differences are caused by differences in genes, which is known as genetic variation. 

Phenotypic variation is divided into two types depending on how you are able to group the measurements: Phenotypic Variation 

  • Phenotypic variations are caused in two main ways: 
  • It can be genetic – controlled entirely by genes 
  • It can be environmental – caused entirely by the environment in which the organism lives 

Continuous Variation

Continuous Variation is when there are small degrees of differences for a particular characteristic between individuals, and they are arranged in an order and can usually be measured on a scale. 

Examples include height, mass, finger length, etc., where there can be many ‘in between’ groups. 


Discontinuous Variation

Discontinuous Variation is when there are distinct differences in a characteristic. 

For example, people are either blood group A, B, AB, or O; are either male or female; can either roll their tongue or not – there are no ‘in-betweens.’ 

When graphs of these data are plotted, continuous variation gives smooth bell curves (a result of all the small degrees of difference), whereas discontinuous gives a ‘step–like’ shape. 


Description automatically generated with low confidence

Genetic Variation 

  • Examples of genetic variation in humans include: 
  • Blood group 
  • Eye color 
  • Gender 
  • Ability to roll tongue 
  • Whether ear lobes are free or fixed
  • Whether earlobes are attached (lobe less) or free (lobed) is an example of genetic variation. 


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