(B) Natural Sciences: The various fields which deals with understanding natural phenomena are grouped within the natural sciences. These fields are as follows:

1. Physical Sciences: The branches within the physical sciences study processes operating with the non-living system. The two main branches falls within physical sciences are physics and chemistry.

2. Earth Sciences: The branches within the earth sciencs study planet earth. The topics within these branches are atmosphere, hydrosphere, oceans, biosphere as well as solid earth. The main branches falls within earth sciences are ecology, oceanography, geology and meteorology.

3. Life Sciences: The branches within the life sciences study living organisms such as plants, animals and human etc. The main branches falls within life sciences are zoology, biology, botany etc. many of the life sciences branches are interdiscliplinary and interact with subjects to understand better understanding of living organism.

But big question at this moment is “What Defines living object”? To answer this question, we can perform comparative analysis of living system with non-living system (diesel engine) as given in the Table 1.1.

Based on this comparative analysis, number of charterstics observed in a living organism can be define. These properties are as follows:

• Self Growth or Self Renewal   
• Endogenous ability to produce energy
• Movement with an exception in the case of Plants as they don’t Move
• Ability to self replicate.