Introduction to Biology

What is Biology?

Biology is the branch of science that talks about things that are alive or once were alive. The word Biology is derived from two Greek words “bios” which means life and “logos” which means study. Thus, in simple words, we can say that biology is a study of life. Biology is a very vast subject that includes the study of origin, development, distribution, growth, structure, function, naming and evolution of living organisms.

Biology is a natural science with a broad perspective and deals with each and every aspect of a living organism. It is a fascinating world that includes plants, animals, bacteria, viruses and almost everything that is living.

Who is a Biologist?

A person who studies everything about a living organism or who studies biology is a biologist.

What is meant by Living? How will you define “Living”?

Living means anything that can grow, divide and reproduce. For example, a butterfly, a fish, a cat, a dog, a human, a plant, an algae, etc. All these are living organisms as they have the ability to grow, divide and reproduce.

What Characteristic Features are Needed to be Alive?

Living beings have certain characteristic features that are necessary for their survival and even existence. These traits are not present in non-living things. The characteristic features that are only shown by living organisms are:

Organization: Any living organism whether a dolphin or a mulberry bush have a level of organization. A living organism is a highly organized structure made up of cells. A living organism can be unicellular (made up of one cell) and multicellular (made up of more than one cell). In the case of a multicellular organism, the cells of a kind make tissues, tissues form an organ and organs make a system.

Nutrition: Living organisms need energy for their growth and development. For this,  they have to depend on food. They can either make their own food (like plants) or depend on other plants and animals for their food. Nutrition is a process by which living organisms derive energy from various raw materials and break them into simpler forms.

Metabolism: Metabolism is a process by which living organisms convert food material into simpler forms. Numerous chemical reactions take place in a living organism that is important for the survival of that organism.

Homeostasis: This is a process by which a living organism maintains its body temperature and adapts itself to the changing environmental conditions.

Response: Every living organism has the ability to respond to external stimuli such as hot, cold, light, etc. Animals have specialized sense organs such as skin, eyes, nose, ears, etc to sense the changes in the environment. Plants also sense light. For example, sunflower moves in the direction of sunlight.

Growth: All living organisms grow i.e. their cell numbers increase and they increase in size. The cells inside a living organism divide and increase in numbers through cell division. Cell division takes place through binary fission, mitosis, and meiosis.

Reproduction: Like begets like. Every living organism has the ability to produce similar organisms by the process of reproduction. Reproduction can be of two types, asexual reproduction, and sexual reproduction.

Life-span: Every living organism has a definite length of life that it grows, survives and then dies.

Evolution: Living organisms can evolve through generations. They have the ability to adapt and survive in adverse conditions. Through the process of natural selection and adaptation, populations evolve.

Differences between Living and Non-living things

  • Living things need the energy to survive. Non-living things do not need energy.
  • Living things can grow and increase in size but non-living things do not grow.
  • Living things are motile i.e. they can move from one place to another whereas non-living things are immobile i.e. they cannot move from their places. Exceptions are plants because they do not move from their place but still are living.
  • Living things have a definite life span and after that they die. Non-living things do not die.
  • Living things can reproduce and produce their young ones but non-living things do not give reproduce.
  • Living things can communicate with each other while non-living things do not communicate with each other.
  • Living things have sense and emotions while non-living things do not have senses and emotions.
  • Living things respond to changes occurring in the environment whereas non-living things do not adapt to the changing environment.
  • Living things respire while non-living things do not respire.

Things to Remember:

  • Biology is a study of life and living beings.
  • A person who studies living organisms is called biologists.
  • Living things have the ability to move, divide, grow and reproduce.
  • Living things can respire and evolve.
  • Living things can respond to external stimuli and adapt to changing environmental conditions.

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