Living World

The world around us has living and non-living things. Living things can grow and change. For instance, the Earth is full of different creatures, like plants and animals. Even though each one is unique, they follow basic rules. All living things grow, reproduce, and respond to their surroundings.

What is Living?

Living things move, breathe, and react to changes around them. But these signs alone aren’t always enough to define life. Take the example of a person in a coma: they may not move or respond to stimuli, yet their organs still function, and they are very much alive. So, studying life means looking beyond just movement and breathing, it’s about the presence of internal biological processes, even when external activity is minimal.

Characteristics of Living Organisms

Most living things have some common features, but not all of them. However, some features are found in every living being. These are the features that separate living things from non-living things.

Growth

Growth means an increase in size or the number of cells. In single-celled organisms, growth means making more individuals by cell division. In multicelled organisms, growth happens by both cell division and enlargement.

Reproduction

Reproduction is how living things make more of the same kind. There are two types:

Asexual reproduction: one parent makes identical offspring.
Sexual reproduction: Two parents produce offspring with different characteristics.

Defining Features of Living Organisms

Some features are present in all living things, without exception. These are called defining features, and they clearly separate life from non-life.

Metabolism

Metabolism is a chemical reaction in a living organism. It includes food breakdown and the making of new molecules. All living things show metabolism, even tiny bacteria. Non-living things don’t have metabolism.

Cellular Organisation

Living things are made up of cells. They are also called building blocks of life. Cells help perform all the needed functions of an organism. In bigger organisms, cells group to form tissues, organs, and systems. Non-living things don't have cells.

Diversity in the Living World

There are about 1.7 to 1.8 million known species on Earth. This is called biodiversity. To study them, we group organisms by similar traits. This method of grouping and naming is called classification.

Taxonomy

Taxonomy is identifying, naming, and classifying organisms. The taxonomy process involves three key steps.

Step	Description
Identification	Study of key features to differentiate organisms.
Classification	Grouping organisms with similar traits.
Nomenclature	Assigning a scientific name to an organism.

Binomial Nomenclature

Binomial nomenclature is a system to give every species a unique name. This helps avoid confusion. The name has two parts:

Genus (starts with a capital letter)
Species (starts with a small letter)

For example, Homo sapiens is the scientific name for humans. Names are in italics or underlined.

Summary

Living things are different from non-living things. They grow, reproduce, and have metabolism. Growth and reproduction are not always the only signs of life. All living things have cells and metabolism. There are millions of species on Earth. Taxonomy helps group and name them. Binomial nomenclature gives each species a two-part name.