Heredity and Variation Explained : Notes on Science for Class 10th


  • The transmission of characters (or traits) from the parents to their offspring is called heredity.
  • In most simple terms, heredity means continuity of features from one generation to the next.
  • Recognizable feature of a human being (or any other organism) like height, complexion, shape of hair, color of eyes, and shape of nose and chin, etc. are called ‘characters’ or ‘traits’.
  • By virtue of being the progeny of the parent, the progeny individual, need not just be the replica of what its parents are
  • Inheritance of characters from the parents to the progeny (i.e. ,Heredity) ensures the passing of the parental characters to the progeny

Variation- The difference or change in the characteristics between the individuals is called Variation.

  • Human population shows a great deal of variation.
  • For example, human height is a trait which shows variation.
  • This is because some people are very tall, some are less tall, some have medium height, some have short height whereas others are very short.
  • If we take a very close look at the rules of inheritance, both father and mother contribute equal amount of genetic material to the child.
  • This means that each trait can be influenced by both paternal and maternal genetic material – i.e, DNA.

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