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| Biology - A Science of Exceptions |
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| Physical, chemical and mathematical sciences follow a specific set of rules and regulations. They are governed by a set of laws such as the law of gravity, the laws of thermodynamics, the law of conservation of mass and so on. However, biological sciences, in the strict sense, do not follow any rules or regulations. The reason for this is that living organisms show a rich diversity that has resulted from mutations, genetic re-combinations and evolution. Biology is thus, regarded as 'a science of exceptions'. Look at some of the interesting exceptions in biology. |
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 Parallel venation is a characteristic feature of monocot leaves and reticulate venation is a characteristic feature of dicot leaves. However, the leaves of some monocots like Smilax and Colocasia show reticulate venation and the leaves of some dicots like Calophyllum and Corymbium show parallel venation. |
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The embryo of dicots show the presence of two cotyledons. However, the embryo of a dicot plant Cuscuta totally lacks cotyledons. |
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Roots are positively geotropic growing towards the soil. However, the roots of some mangrove plants like Rhizophora and Sonneratia grow away from gravity, that is negatively geotropic. |
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Blood of all vertebrates is red in colour due to the presence of haemoglobin in the RBC, but the blood of a shark, Carcharhinus is colourless. |
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Fishes do not have lungs and respire through gills, but some fishes like Protopterus possess both gills and lungs. |
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The heart of all reptiles is three chambered, but in crocodiles it is four chambered. |
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Usually the embryo develops from a fertilized egg. However, in the bee colony, male bees, called drones develop from unfertilized eggs. |
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| These are only a few examples of the innumerable exceptions that we come across in the living organisms. Such examples have made biology a science of exceptions. |
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Nature and Scope of Biology
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