Inheritance

In living beings, the young ones have characters similar to their parents. These characters have been transferred from parents to offsprings. This transfer of characters maintains the continuity from generation to generation. Let’s find out more about Inheritance.

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Introduction

Transfer of different characters from one generation to next generation in a living being is called inheritance. The characters which transferred from one generation to the next are called hereditary characters. It refers to the physical features that offspring inherit from their parents. Such as eye color, the shape of nose and mouth, height and other physical characteristics.

Variation

Similarities are maintained by the parent with the offspring from generation to generation but it is known that none of the two organisms are similar. Even different offspring of the same parent differ to each other. This is known as a variation, because of this variation each organism is different from the other organism in shape, behavior, color etc. Variation is divided into two parts:

1. Hereditary Variation

The variations which get transferred from one generation to next generation are called hereditary variations. Hereditary variations and control of characters transfer from one generation to next generation are performed by genetic material, which is found in the genes. Genes are made up of D.N.A (chemical Molecule) changes in their number, arrangement, and structure cause hereditary variations.

Example: Colour of eyes, hair, skin and blood group etc are examples of hereditary variation. The reasons for hereditary variations are as follows:

• Any change in gene structure causes variation.
• Changes in chromosome’s number cause change in the hereditary material due to which variation occurs in offspring.
• If there is any change in the structure of chromosome this cause variation among the organisms of the same species.

2. Environmental Variation

The variation which causes due to the effect of environment and which are not transferred from one generation to next are called environmental variation. Temperature, humidity food habits etc. are the causes of environmental variation and are originated doing the individual development of the organisms. Therefore these characters are called acquired characters.

Mendel’s law of inheritance

Mendel was an Australian scientist. For seven years he did experiments on 28,000 plants. He worked hard and collected many observations. The rules of inheritance of characters depend upon the fact that there are two possibilities for each character to appear in offspring. In 1865 Mendel described all these possibilities of the appearance of characters in next generation in the form of laws. These are called the Law of Heredity or Inheritance.

Mendel studied seven different hereditary characters in pea plants. Mendel selected pea plant for his experiments because of the following reasons:

• Pea plant is an annual plant and with a short life cycle.
• The plants can be grown easily.
• Self-pollination occurs in the plant.

Mendel crossed a pair of pea plants having two contrasting characters by a dihydric cross and observed characters of one gamete transmitted to next generation independently.

Solved Example

Q1. What is inheritance?

Ans: Transfer of different characters from one generation to next generation in the living being is called inheritance. The characters which transferred from one generation to the next is called hereditary characters.

Q2. Give some examples of heredity variations.

Ans: Colour of eyes, hair, skin and blood group etc are some examples of hereditary variation.

Q3. What are the characters make us what we are?

Ans:  There are some traits or habits which we get from our family. Some things and skills we learn from our environment.