Botany is the scientific study of plants. This definition requires an understanding of the concepts “plants” and “scientific study”. Most plants have green leaves, stems, roots and flowers. But, there are some exceptions to these general notions.
The concept of scientific study can be understood by examining earlier approaches to studying nature. Until the15th century, several methods for analyzing and explaining the universe and its phenomena were used, with religion and speculative philosophy being especially important. Starting with 14th century, a new method, called the scientific method, began to develop slowly. Several fundamental tenets were established.
Sources of Information: All accepted information can be derived only from carefully documented and controlled observation or experiments. Claims emanating from priests or prophets – or scientists – cannot be accepted automatically. They must be subjected to verification and proof.
Phenomena that can be studied: Only tangible phenomena and objects are studied, such as heat, plants, minerals and weather. We cannot see or fell magnetism or neutrons, but we can construct instruments that detect them reliably.
Constancy and universality: Physical forces that control the world are constant through time and the same everywhere. Water has always been and will always be composed of hydrogen and oxygen. Gravity is the same now as it has been in the past. The world itself changes – mountains erode, rivers change course, plants evolve – but the forces remain the same.
Basis: The fundamental basis of the scientific method is skepticism, the principle of never being certain of a conclusion, of always being willing to consider new evidence. No matter how much evidence there is for or against a theory, it does no harm to keep a bit of doubt in our minds and to be willing to consider more evidence.
According to scientific evidence, life on Earth began about 3.5 billion years ago. At first, living organisms were simple like present-day bacteria, in both their metabolism and structure, however, over thousands of millions of years, cells gradually increased in complexity through evolution by natural selection. As organisms reproduce their offspring differ slightly differ each other in their features – they are not identical. Offspring with features that cause them to be well-adapted grow well and reproduce abundantly, passing on the beneficial features to their own offspring. This is called natural selection. New features come about periodically by mutations and natural selection determines which new features are eliminated and which are passed on to future generation. Evolution by natural selection is a model consistent with observations of natural organisms, experiments and theoretical considerations.
As early organisms became more complex, major advances occurred. One was the evolution of the type of photosynthesis that produces oxygen and carbohydrates. This photosynthesis is present in all green plants, but it first arose about 2.8 billion years ago in bacterium-like organism called cyanobacterium. Later, cell structure became more efficient as subcellular components evolved. These components called organelles, each provide a unique structure and chemistry specialized to a specific function.
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