The Living World


What is Living?

Keshav Bhatia, Academic Content Writer at Edumarz


Criterion for growth.

Growth is a naturally occurring phenomenon that all life forms undergo.
The twin features of growth are a gain in mass and an increase in the number of individuals. Cell division is how a multicellular creature grows. Plants develop via the division of cells on a constant basis throughout their lives. This expansion is visible in animals only until they reach a particular age.

Cell division, on the other hand, happens in some tissues to replace any cells that have been lost. Cell division is how unicellular creatures grow. In vitro cultures may be easily observed by counting the number of cells under a microscope. Growth and reproduction are mutually exclusive phenomena in the majority of higher animals and plants. It’s important to note that growth is defined as a rise in bodily mass. If we use body mass as a criterion for growth, non-living objects grow as well.

Mountains, boulders, and sand mounds are all formed through erosion. Non-living things, on the other hand, demonstrate this type of development by accumulating material on the surface.
In living species, growth occurs from the inside out.
As a result, growth cannot be considered a distinguishing characteristic of living beings. It must be described under what conditions it may be observed in all live species before we can grasp that it is a property of living systems. It is impossible for a dead creature to grow.


In multicellular organisms, reproduction refers to the generation of offspring with characteristics that are comparable to those of their parents.

Sexual reproduction is always and implicitly mentioned. Asexual reproduction is also used by organisms. Due to the millions of asexual spores that fungi create, they may quickly proliferate and spread. We see budding in smaller species like yeast and hydra.
True regeneration is observed in Planaria (flatworms), in which a fractured organism regenerates the missing section of its body and transforms into a new creature.
Fungi, filamentous algae, and moss protonema may all easily reproduce through fragmentation. In unicellular organisms such as bacteria, unicellular algae, and Amoeba, reproduction is identical with growth, or a rise in the number of cells.

Growth is characterised as a rise in cell number or mass. As a result, we observe that the definitions of these two concepts – growth and reproduction – are not always apparent in single-celled organisms.

Furthermore, many creatures (mules, sterile worker bees, infertile human couples, etc.) do not reproduce. As a result, reproduction cannot be considered a universal distinguishing trait of living entities. Naturally, no non-living item can reproduce or replicate on its own.


Metabolism is another aspect of life. Chemicals are found in all living things. Small and large compounds of diverse classes, sizes, functionalities, and other characteristics are continually created and transformed into new biomolecules. Chemical or metabolic processes are involved in these transformations. All living creatures, whether unicellular or multicellular, have millions of metabolic events going on at the same time. Metabolism is found in all plants, animals, fungi, and microorganisms. The total of all chemical processes that take place in our bodies.

The human body is a metabolic machine. Metabolism does not exist in non-living objects.

Cellular Organisation

In cell-free systems, metabolic events may be demonstrated outside of the body. An isolated metabolic reaction(s) performed in a test tube outside the body of an organism is neither life nor non-living. As a result, whereas metabolism is a distinguishing trait of all living creatures, isolated metabolic processes in vitro are not live objects, but they are unquestionably living reactions.

As a result, the distinguishing trait of living forms is the cellular organisation of the body.


The capacity of all living creatures to detect their surroundings or environment and respond to these environmental stimuli, which can be physical, chemical, or biological, is perhaps the most evident and technically complex attribute.
Our sensory organs allow us to perceive our surroundings. External elements such as light, water, temperature, other species, contaminants, and so on affect plants.
Environmental signals may be sensed and responded to by all species, from prokaryotes to the most sophisticated eukaryotes. “Seasonal breeders, both plants and animals, are affected by photoperiod”. Chemicals that enter the body of an organism are processed in the same way by creatures of all species. As a result, all creatures are ‘conscious’ of their environment.

As a result, consciousness becomes the distinguishing characteristic of living beings.

Defining Life better
Tissue properties are not found in the component cells, but emerge as a result of interactions between them. Similarly, features of cellular organelles are not contained in the organelle’s molecular elements but occur as a result of interactions among the organelle’s molecular components.

Emergent features arise at a higher level of organisation as a result of these interactions. This phenomenon occurs at all levels of the organisational complexity hierarchy. As a result, living creatures may be described as self-replicating, evolving, and self-regulating interacting systems that can respond to external inputs. 

All living species, present, past, and future, are related to one another to differing degrees via the sharing of similar genetic material.


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