Major Domains of the Earth – Biosphere

The earth is made of four main spheres or domains which play an important part in sustaining life on earth. The spheres combine and interact with each other, to form a complex and intricately balanced system of land, air, water and living creatures’ relationships with each other.

What are the four major domains of the earth?

1. Lithosphere : The lithosphere is the solid, exterior part of the earth. It is the most rigid of earth’s layers.
2. Atmosphere : The atmosphere is a complex 500 – 700 km of mixture of gases, including oxygen that we breathe and other elements. These are bound to earth through gravity and so do not disappear into space.
3. Hydrosphere : The hydrosphere consists of all the water sources on the planet and is interconnected through the water cycle.
4. Biosphere : The biosphere connects all the existing ecosystem into a network with the other spheres. It is the sphere where all life dwells.

What is biosphere?

The biosphere is a life supporting global ecosystem and is one of the major domains on the planet. In the biosphere, all living things depend on each other, and the existing, surrounding environment, which maybe living or may consist of abiotic factors.

The biosphere is also known as the ecosphere.

When did the biosphere originate?

The biosphere is said to have originated maybe around 3.5 billion years ago and has originated from the abiogenesis process which eventually led to the biogenesis process. The term biosphere was coined by geologist Eduard Suess in 1875. Consequently, Charles Darwin, Matthew F Maury, Vladimir I Vernadsky and Arthur Tansley have contributed towards considerable research to the study of the biosphere. Sir Arthur Tansley introduced the term ‘ecosystem’, in 1935.

How does life sustain itself in the biosphere?

• Scientists believe that the increase of atmospheric oxygen led to the evolution of the first forms of life.
• Energy is needed for the function that organisms perform, such as growth, movement, waste removal and reproduction. It is the only requirement that living organisms in the biosphere need apart from what is there in the four major domains.
• The source of this energy comes from the sun. Plants convert the sun’s energy into food and are very important to the biosphere.

What processes occur in the biosphere?

The organisms in the biosphere are constantly involved in one or more of the following processes :

1. Decomposition : The breakdown of complex molecules—molecules of which dead organisms are composed – into simple nutrients that can be re-utilized by living organisms.
2. Energy : Power that can be used to perform work, such as solar energy.
3. Nutrient cycle : The cycling of biologically important elements from one molecular form to another and back to the original form.
4. Photosynthesis : Process in which plants capture light energy from the sun and use it to convert carbon dioxide and water into oxygen and organic molecules.
5. Respiration : Chemical reaction between organic molecules and oxygen that produces carbon dioxide, water, and energy.

What is the Biosphere 2 project?

In order to study the biosphere and the impact of all life forms and the other spheres on the biosphere, scientists set up the Biosphere 2 project. Biosphere 1 is the planet earth.
The artificially replicated Biosphere 2 was set up on three acres, in the Arizona desert, in the 1980s. In 1991, September 26th, a group of four men and four women decided to enter Biosphere 2 for a period of two years. The artificial biosphere contained 3800 species of plants and animals and the human group experimented with growing their food and sustaining and surviving without any other resource.
Although the experiment was one of the first of the longest experiments of living in isolation, it was not successful for several reasons.