Characteristics of Growth — Definition

Definition

Growth is one of the most fundamental and easily observable characteristics of all living organisms. Simply put, it refers to an irreversible increase in the size, mass, or volume of an organism or its parts.

Think about a tiny seedling growing into a large tree, or a baby developing into an adult – these are all examples of growth. However, it's crucial to understand that biological growth is much more than just getting bigger.

It's a complex, highly regulated process that involves several key aspects.

Firstly, growth in living organisms is primarily an internal (intrinsic) process. This means the increase in size or mass comes from within the organism itself, through metabolic activities. For instance, a crystal might 'grow' by adding material to its surface, but this is external accumulation, not true biological growth. Living organisms synthesize new protoplasmic material, which is the living substance of a cell, leading to an increase in cell size or number.

Secondly, growth is typically irreversible. Once an organism or a part of it has grown, it generally cannot shrink back to its original size (except in specific cases like dehydration or loss of turgor, which are not true reversals of growth). This permanent change is a hallmark of biological growth.

Thirdly, growth often involves both an increase in cell number (through cell division, primarily mitosis) and an increase in cell size (cell enlargement). In multicellular organisms, cell division is crucial for increasing the total number of cells, which then differentiate to form various tissues and organs. In unicellular organisms, growth primarily refers to an increase in the size of the single cell before it divides.

Fourthly, growth is a metabolically expensive process. It requires a constant supply of energy and raw materials because it involves the synthesis of complex organic molecules (anabolism) from simpler ones. This anabolic activity must exceed catabolic (breakdown) activity for growth to occur.

Finally, growth is often accompanied by differentiation and development. As cells grow and divide, they also specialize to perform specific functions, forming tissues, organs, and organ systems. This overall process of change and maturation is known as development, and growth is an integral part of it. So, while growth is about getting bigger, it's also about becoming more complex and specialized.