The Living World
On the basis of certain characteristics, everything that surrounds us can be classified into two categories: living and non-living.Some characteristics are common in both while some characteristics are unique. Growth, reproduction, metabolism and consciousness are the certain distinctive characteristics of living organisms. In plants, growth is limited to certain body parts and tissues. The sites of active growth in plants are meristems. Animal growth is not restricted to a specific tissue or body part. All parts of the animals show growth. Growth in non-living things is due to accumulation of material on the surface, e.g., sand mounds, boulder etc. Growth alone, therefore, cannot be considered as a defining property of living organisms.
Reproduction is a biological process in which an organism gives rise to young ones similar to itself.There are two types of reproduction:
• Asexual Reproduction: Involves only one parent
• Sexual Reproduction: Involves two parents
The various modes of asexual reproduction are budding, fission, fragmentation, vegetative propagation and regeneration.Another distinctive characteristic of living organisms is metabolism.Metabolism is the sum total of all chemical reactions occurring within the living organisms.
The chemical reactions involved in metabolism are known as metabolic reactions or biochemical reactions. There are two types of biochemical reactions; anabolic reaction and catabolic reaction.
Non-living bodies do not exhibit the process of metabolism.Hence, metabolism is a defining feature of the living beings.
Consciousness is the ability of an organism to sense its surroundings.The changes in the environment that produce certain responses in the living organisms are called stimulus. The human brain is the center of consciousness in humans. It has different centers for receiving different types of stimuli.
Biodiversity is variation of all life forms. It is a measure of the health of biological systems. More diversity means that a system is healthy.The living world is rich in diversity. There are millions of plants and animals have been identified and described. But still, large numbers of living organisms remain unknown.
The diversity we see today is the result of 3.5 billion years of organic evolution.
Biodiversity occurs at the molecular level also as different types of proteins and carbohydrates found in organisms. The species which are under the threat of extinction have been classified into; critically endangered species, endangered species and vulnerable species.
Systematics is the scientific study of kinds and diversity of organisms of any and all relationships among them. It includes; identification, classification and nomenclature.
The standard system of providing a name to an organism in two components is called binomial nomenclature.
Each scientific name has two components: generic name and specific name
The principles for classifying the organisms are framed under taxonomy. Taxonomy is the study for identification, classification and nomenclature of the organisms.
Taxonomic category is a rank or level in the hierarchial classification of organisms. A unit of classification is termed as taxon. All categories together constitute the taxonomical hierarchy.
The hierarchy of taxonomic categories is species, genus, family, order, class, phylum or division, kingdom.
Biologists have established certain procedures and techniques to store and preserve the information as well as the specimens. Some of the techniques are herbarium, botanical garden, museum, zoological parks etc.