The Living World

Bookmark added to your notes.
View Notes
×

What is living world?

Simply put, the living world can be described as the world around us. It comprises all living creatures, plants and microorganisms that we cannot see. It has changed over the course of billions of years but the general composition has remained the same. The main components are still organic and inorganic matter. The organic matter includes amino acids, proteins, lipids etc. whereas the inorganic matter includes water and minerals. The following is a brief of the world of living that surrounds us.

[Image to be added Soon]

Essentials of the Living World

Basically, the essentials of the living are its components. Below is a summary of all the components that are needed to sustain the world of the living.

  • Water: The water content of the human body is around 70-90%. It plays an integral role in sustaining different biological processes.

  • Oxygen: The earth’s atmosphere is made of 20% oxygen. It is required during aerobic respiration to produce energy that is important for different metabolic activities.

  • Sodium Chloride: Sodium chloride in its ionic form plays an important part in the metabolic process of the human body.

  • Proteins: Proteins are long chains of amino acids connected by peptide bonds. It plays a significant role in forming the structure of the organism. It can be broken down with the release of energy.

  • Lipids: These are alcohol and fatty acid polymers and they perform several functions.

Characteristics of Living Organisms / Characteristics of Living Things

  1. Growth- All living organisms grow in number and mass. A multicellular organism replicates by cell division. In plants, growth in the meristematic area continues throughout life and in animals, it occurs till a certain age. Living organisms show internal growth due to addition of important materials and reproduction of cells in the body. Non living organisms like mountains, boulders, crystals also show growth but this is because of the addition of similar materials to their outer surface.

  2. Reproduction- It is the formation of new individuals of the similar species.  Reproduction is required for population and the survival of a race. In sexual reproduction two parents are involved to produce more or less similar organim, but in asexual reproduction, a single parent is involved and individual is the clone of the parent. Asexual reproduction may carry out by fermentation, fission, regeneration, vegetative propagation etc. In unicellular microorganism, growth and reproduction are the same. Numerous organisms such as mules, sterile worker bees, infertile human couples do not reproduce. Hence, reproduction is not an all-inclusive characteristic of all living organisms. However, no non-living object has the ability to replicate or reproduce.

  3. Metabolism- The sum of all types of chemical reactions taking place in an individual because of specific interactions between different types of molecules in the interior of cells is called metabolism. All activities of an organism including growth, development, movements, reproduction etc. are due to metabolism. Metabolism can be classified into anabolism and catabolism. Anabolism comprises all the building up reactions that increase the mass of an organism like photosynthesis. Catabolism includes breakdown reactions, such as respiration, digestion etc. 

  4. Consciousness- It is the awareness of the surroundings and responding to external stimuli. External stimuli may be physical, chemical or biological. Plants also respond to stimuli like light, water, gravitation, pollution etc. All living organisms prokaryotic to eukaryotic respond to different kinds of stimuli. Human being is the only organism who is aware of himself. Consciousness therefore, becomes a defining property of all living things.

  5. Homeostasis- In the world of living organisms, all living things have to maintain and control their internal states via homeostasis. This would involve balancing, temperature, internal pH levels and water levels. For example, the human body would adjust to the changes in the external weather by wearing a sweater or remove the clothing layers in the body so as to adjust their body temperature.

  6. Life Span- every living organism has a definite life span of birth, growth, maturity, senescence and death. 

  7. Living organisms are therefore, self-replicating, evolving and self-regulatory interactive systems capable of responding to external stimuli. Diversity in the living world or biodiversity is the occurrence of a wide range of life forms differing in physical features, size, colour, anatomy, habits and habitats. Each different type of microorganism, plant or animal represents a species.

FAQ (Frequently Asked Questions)

Q: Write a Note on Binomial Nomenclature.

Ans: It is the universally accepted principle to provide scientific names to known organisms. Each binomial name has two sections or components- the generic name (genus) and the specific epithet (species). This system of nomenclature was provided by Carolus Linnaeus.

The universal rules of nomenclature are as follows:

  1. Biological names are written in italics and generally in Latin.

  2. The first word in a biological or scientific name represents the genus while the second word represents the specific epithet.

  3. When both words in a biological name are handwritten, they are separately underlined.

  4. The first word that denotes the genus is written in capital and the specific epithet (species) starts with a small letter.

Classification- It is the process by which any organism or object or situation is grouped into convenient categories based on similar characteristics. Classification makes the study of organisms relatively convenient.

Taxonomy- It can be defined as the process of classification on the basis of internal and external structure along with the structure of the cell, the process of growth and development and ecological information.

Q: Write a Note on the Taxonomic Hierarchy.

Ans: The Taxonomic Hierarchy Follows the Below Categories

Species- Species are the natural population of individuals which resemble one another in all essential morphological and reproductive characteristics. They can interbreed freely and produce fertile offspring. For Humans, sapiens is a species of genus Homo.

Genus- Genus can be described as a group of related species which resemble one another in certain correlated characters. All species of a single genus are presumed to have evolved from a common ancestor. Tiger, lion, leopards are closely related species and therefore they are placed under the same genus Panther.

Family- Family is another taxonomic category that contains one or more related genera. All genera of a family have some common characteristics or features. For example, Family Solanaceae contains a number of genera like Datura, Withania etc 

Order- This taxonomic category includes one or several related families. Families Canidae and Felidae are included in the same order of carnivores.

Class- A class is formed of one or several related orders. All dicots in plants come under the class Dicotyledoneae and they are grouped into many orders such as  roales, polemoniales etc.

Division/Phylum- The term division is used for plants whilst phylum is used for animals. They are formed of one or many classes. The phylum chordate of animals contains not only the mammals but reptiles, amphibians several others.

Kingdom- It is the highest taxonomic category. All animals belong to kingdom Animalia, and all plants in the kingdom Plantae.

[Image to be added Soon]