Origin of Life (Part-I)

Introduction: Study of living organisms such as plants, animals and human etc is the active area of life science. Now question is how you will define “LIFE”. Life is defined as “the ability of an organism to reproduce, grow, produce energy through chemical reactions to utilize the outside materials”. But scientists and philosophers have tried to understand two important questions related to life

1. How life originated on earth?
2. How different kinds of organisms are formed in the world?

So first the question is how earth formed and how its internal structure support the life? evidences suggest that earth and other planets in solar system came to existence around 4.5-5 billion years ago. Earth originally had two components: solid mass lithosphere and the surrounding gaseous envelope atmosphere. Once the temperature of primitive earth cooled down below 1000C, liquid components known as hydrosphere.

The formed earth consists of three parts as given in Figure 3.1. These parts are as follows:
1. Baryosphere: it is the central core of the earth. It is filled with molten magma with large quantity of iron and nickel. Baryosphere has two zones: inner core region (~800 miles radius) and outer core region (~1400miles radius).

2. Pyrosphere: it is the middle part of the earth, also known as mantle. It is ~1800 miles in thickness and mainly consists of silica, magnese and magnesium.

3. Lithosphere: it is the outermost region of the earth, also known as crust. It is 20-25 miles in thickness and mainly has silica and aluminium.