Chemistry and Life

Chemistry and Life

Humans are only one of a wide variety of forms of life inhabiting the earth. People have always been fascinated by the different forms of life they see around them. What is the difference between humans and other forms of life? Today we believe that humans are one of many forms of life that obey certain basic principles of chemistry. This idea has slowly evolved during the past century from the work of many scientists in many fields.
The view that humans are a unique form of life was first seriously challenged about 100 years ago by the theory of evolution. This theory states that the various forms of life are not constant, but, rather, continually evolve. That is, they continually change to create slightly different forms, some of which are better adapted to survival. Furthermore, this indicates that the basic principles of the living stats are the same in all living forms.
Scientists believe today that life is a series of complex chemical reactions. All these chemical reactions obey the laws of science. Therefore, there is no special chemistry of the living system, and cells, the basic unit of living systems, must obey the laws of chemistry.
One unavoidable conclusion is reached from this view of living systems. To understand the process of life, you must understand the principles of chemistry.
The International System of Units (Sl)
The first international system of measurement was the metric system. It was adopted fay the United States and 16 other nations in 1875. This is a decimal system, which means that larger and smaller parts of the basic unit are obtained by multiplying or dividing by ten. The metric system was extensively revised in I960 and was given a new name. "International System of Units". Its official abbreviation is Sl. Sl is still a decimal system, and many of the units are the same in Sl and the metric system.
There are fractions and multiples of each basic unit of Sl. Each has a characteristic name obtained by adding a prefix to the basic name of the unit. The prefix tells us how many times the basic unit has been divided or multiplied by ten. The names of the most commonly used prefixes are given in Table 1.