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Introduction

 

For thousands of years scientists from different countries have been contributing important discoveries and ideas that shaped a modern science. This chapter looks at some important discoveries in the field of biology.


Biology - Where did it all begin?

 

Biology is the study of living organisms. People have been studying the plants and animals around them for thousands of years.  Many ancient civilisations were dependent on agriculture and in order to develop agriculture, people had to know which plants were edible, how to grow these edible plants, what time of the year to sow and harvest the plants and how to capture and train animals for use in working or as food.  


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For people living in ancient civilizations, religion and science were the same thing. For example, people believed that the crops would only grow if the gods were happy. However, as civilizations began to develop, people began to look at the world differently and science as we know it now began to emerge with its many different branches such as astronomy, physics, medicine, biology and chemistry.


Xenophanes, an ancient Greek scientist, was one of the first people to record his observations of fossils (traces of ancient plants and animals preserved in rock). A famous Ancient Greek doctor, Hippocrates, was the first person to observe and record that the human body contains different types of fluids. Aristotle, the famousAncient Greek scientist we studied earlier, first used the biological terms genus and species to categorise (organise) links between different organisms.


The Ancient Greeks were not the only ancient people to make biological discoveries. The Ancient Arabs were also very advanced in their scientific thinking and compiled some of the first detailed medical encyclopedias.  


The microscope was one of the most significant medical inventions and remains an important tool even today. A microscope is an optical instrument which allows scientists to see very, very small objects and organisms like bacteria and cells (the basic structural unit of all organisms) that are too small to be seen by the naked eye. The first microscope was invented by Hans Janssen and his son Zacharias in the 16th century. This microscope was simply a tube with a magnifying glass on each end.


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Later, in the 17th century, the microscope was improved by the English scientist Robert Hook. After studying thin slices of cork (plant tissue) under the microscope he noticed that they were all made up of units that he called cells. Anton van Leeuwenhoek also made further improvements to the microscope during the 17th century, and was the first scientist to describe bacteria and protozoan's (single celled life).


In the 18th century the scientist Carolus Linnaeus came up with a way of classifying all living things. We still use this classification system today.  


In the 19th century the increase in exploring new continents and changing of science in to a profession led to huge contributions in the fields of genetics, evolution, germ theory and cell theory. ‘Cell theory' was formulated by German scientists Matthias Schleiden and Theodor Schwann. Cell theory states that:

 

  • All living things are made up of cells

  • All cells come from pre-existing cells

  • The cell is the smallest form of life.


The famous botanist and biologist Charles Darwin published his work called The Origin of Species during the 19th century. The book outlines the understanding of the evolution of living things. According to Darwin's theory of evolution, living organisms change over generations as a result of natural selection. Natural selection means that organisms that have best adapted to their environment are the ones that will survive and reproduce to make the next generation, passing on any favourable features.


Also during the 19th century, Louis Pasteur, a French biologist and chemist, proposed the ‘germ theory' of disease which states that microorganisms are the cause of many diseases.


Another significant contribution to biology during the 19th century occurred when Gregor Mendel, an Austrian monk, published a paper on genetics. Mendel was able to show that the inheritance of the characteristics of living organisms follows particular laws, which were later named after him.

 

During the 20th century, in 1953, scientists James Watson and Francis Crick discovered the structure of the DNA molecule. DNA contains the genetic instructions for making living organisms. The discovery of the DNA molecule led to the development of new branches of science, such as genetic engineering (see Topic 3 – Chapter 1 – Science and Human Health; for more details).


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Question 1/5

1. Gregor Mendel, an Austrian monk, produced a paper on how:

microorganisms are the cause of many diseases

to classify all living things

living organisms change over generations as a result of natural selection

the inheritance of the characteristics of living organisms follows particular laws

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