What is a living thing

What is living is a question that is the overarching topic at the start of the whole study of the living world. Since the beginning, ancient philosophers were fascinated by the way living things existed and functioned. They tried to study the characteristics of life and what constituted this state of existence. That is how biology began. The biological definition of what is living is made of a number of factors and characteristics that scientists have arrived at after studying the nature of life.

Life and its history

Earth’s existence is considered to have happened about 4.5 billion years ago, with life on earth beginning approximately 3.5 – 4.2 billion years ago. It is such a complex phenomenon that to date there is no real consensus about what life really is. However, there are some things that are agreed upon about the origin of life.

• Abiogenesis: The non-living matter at the beginning of the Earth’s existence underwent natural processes and living matter was formed. These natural processes are known as abiogenesis
• Primordial soup: The theory that primitive Earth contained a mix of water and organic matter resembling a soup is called the primordial soup theory. It is said that this ‘soup’ served as the place where organic matter formed over the ages
• RNA hypothesis: There is a theory that all primitive life forms were based on RNA because it displays the characteristics of both genetic codes and the catalysts that cause the translation of genetic code in today’s life forms
• Multicellularity: About 600 million years ago life on Earth took on a multicellular form. It is assumed that cells of the same species eventually bunched together to form colonies. Gradually these colonies developed cells that perform specific functions
• The Cambrian explosion: This was a period about 541 million years ago when there was a sudden explosion in the diversity of life on Earth. All sorts of animals and plant species came into existence in the Cambrian explosion

What is living classification?

In biology what is living constitutes a complex answer. Presently most biologists agree to three main categories of classification for living things. They are:

• Eukarya: All organisms which have eukaryotic cells, or cells which have a nucleus bound by a membrane, are classified in this category
•  Bacteria: Microscopic organisms which have prokaryotic cells, that is their nuclei are not membrane-bound
•  Archaea: Microscopic life forms which are also prokaryotic but differ from bacteria in their RNA polymerase

What are living characteristics?

Living things differ from the nonliving world in a number of ways because they possess certain characteristics. These are as follows:

• Energy: The metabolic activities essential for the survival of an organism are fueled by energy. Organisms obtain this energy in different ways. Some organisms like plants, manufacture energy through photosynthesis, which involves synthesising energy through sunlight. Others, like most animals, get energy by biochemical reactions involving compounds such as glucose. This energy is then stored in energy-carrying molecules such as ATP
• Growth: In living things growth occurs when the cells either increase in number or increase in size. Cells increase in number by cell division and an iv=crease in cell size unusually means an increase in cytoplasmic mass. In most higher-order animals growth is determined by their genetic material. In animals, it is the stem cells and in plants, the meristematic cells are responsible for growth
• Respond to stimuli: Living thighs are able to detect changes in their environment and respond accordingly. They are able to do this because they possess receptor organs
• Motility: Living things or their cells are able to display motility
• Metabolism: Metabolism is the term used for all the processes inside the body that are required to keep a living thing alive. These processes are those that are involved in cell growth, reproductions, digestion, respiration, biomolecular syntheses, response to stimuli, etc. There are two types of metabolic processes:

1. Catabolism or the breakdown of complex molecules into simpler molecules.
2. Anabolism or the building up of molecules from simpler substances.

• Reproduction: Living things reproduce by sexual or asexual means. In sexual reproduction, the male and female cells of two parent organisms combine to form a zygote. In asexual reproduction, there is only one parent organism and the new cells arise from this parent. Asexual reproduction can happen through cell division, vegetative propagation, fragmentation, sporogenesis, nuclear embryony, etc
• Structural organisation: All living things display structural organisation. This is because all living things are made up of cells which are organised to form the organism in particular ways
• Death: Most living things eventually lose the ability to maintain life processes and die. When cells stop growing even if they are metabolically active it means that the organism is nearing the event of death

These are the characteristics of what is living in the field of biology. This is an important area of study and what is living study material can come in handy for most syllabus of biology.

Conclusion

In biology what is living is a matter of great study and research. Even today there is a lot of dispute regarding the exact nature of life and what is it that causes life. Though scientists are fairly certain about what constitutes the elements that make up life it is not an easy task to describe why these elements are able to make up life. So science is still working on these questions. In the meantime, students must keep delving into what is living study material to keep updated about the latest findings in the field.