The Living World Class 11 Notes - Chapter 1

The world that we live in is over 4.6 billion years old, and within that span of time, evolution has led to an innumerable and spectacular biodiversity in the living world. But what exactly is “life” and how is it defined?

Over the ages, the definition of “life” has been widely disputed, and often, life was attributed to characteristics such as movement, mobility and growth. At a certain point in history, plants were considered non-living. But today, we can tell apart all the organisms that we see into “living” and “non-living.” But when we delve deeper – into the microscopic scale, the line between the two is even more blurred.

What is Living?

We do know that all living organisms reproduce, grow and metabolize. But when we look at the microscopic realm, the actual definition of life is rather blurred. For instance, viruses are basically a nucleic acid that is protected by a protein coat. They exhibit no typical characteristics of living organisms such as reproduction, until and unless it is inside a host.

Another “organism” that borders between the living and non-living are Prions. These are essentially misfolded proteins can reproduce by making other healthy proteins to misfold. These entities are responsible for causing diseases such as Spongiform Encephalopathy, fatal familial insomnia, which are almost always fatal. In conclusion, the realm between the living and the non-living differs even now as the definition of “life” is ambiguous.

Discover more interesting concepts on Biology Notes for Class 11 Chapter 1. Find detailed answers to important questions such as – How all life on Earth is classified, what are viruses and more.

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Practise This Question

Genetic dwarfness in some plants may be solved by treatment with: