Biology

What is Biology?

The term "biology" is derived from the Greek words "bios," meaning life, and "logos," meaning study or science. Biology is defined as the study of living organisms, their origins, anatomy, morphology, physiology, behaviours, distribution, and evolution. Aristotle is known as the father of biology. According to the International Union for Conservation of Nature (IUCN), approximately 8.7 million species exist on Earth, but only 1.2 million have been scientifically described and cataloged. Biology is a broad and diverse field that encompasses many subdisciplines, including molecular biology, cell biology, anatomy and physiology, animal behavior, population biology, ecology, systematics, microbiology, virology, botany, and zoology and deals with all the physicochemical aspects of life. This article explains the definition of biology, branches of biology, important topics, history of biology, examples, and biology preparation for various competitive exams in 2025.

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This Story also Contains

1. What is Biology?
2. Branches of Biology
3. Example of "Biology"
4. Important Topics in Biology
5. History of Biology
6. Biology for Various Competitive Exams

So, biology is a science concerned with studying life and living things including how they interact with the environment and other organisms. The origin, structure, function, evolution, development, distribution, and classification of all living things are studied under biology. It also explains the cellular and bacterial forms of life. New technology has helped us understand more about living things. For example, when scientists discovered viruses, it made them think about what it means to be alive. Modern biology explains the more complex forms and systems that support life. Biology is a constantly changing science; new developments, including genetic engineering and synthetic biology- change our notions of what life is and will be.

Class 11 biology mostly focuses on foundational concepts such as cell biology, whereas class 12 biology includes advanced topics related to genetics and evolution. Biology is important for Central Board of Secondary Education (CBSE) exams of classes 6 to 12 and several competitive exams, such as National Eligibility cum Entrance Test (NEET-UG), AIIMS BSc Nursing.

Why is biology important?

As a field of science, biology helps us understand the living world and the ways its numerous species (including humans) function, evolve and interact. Advances in medicine, agriculture, biotechnology, and many other areas of biology have brought improvements in the quality of life. Fields such as genetics and evolution give insight into the past and can help shape the future, and research in ecology and conservation informs how we can protect the precious biodiversity of this planet.

Where do biology graduates work?

Biology graduates can pursue a variety of careers, some of which may require additional education. A person with a degree in biology could work in agriculture, health care, biotechnology, education, environmental conservation, research, forensic science, policy, science communication, and many other areas.

Branches of Biology

The study of Biology includes several branches of biology that embrace different dimensions of life and often relate to other scientific streams. For example, Synthetic Biology applies knowledge of Biology to engineering principles to design and construct new biological parts, devices, and systems.

Similarly, Systematic Biology focuses on complex interactions within biological systems. Using both computational and experimental approaches, it explains how networks of genes, proteins, and other cellular components interact to perform functions with each other.

Some of the other important divisions within biology studies are:

Divisions of Biology

The entire study of biology, therefore, has been divided into several divisions of biology to study the details of specific aspects of life. Some of the branches of biology have further combined with other subjects like chemistry and physics and resulted in the discovery of new fields of study.

Key divisions of biology include:

Anatomy

Anatomy is the branch of biology that deals with the study of structure and organisation in living organisms. It includes the study of humans, plants, and animals concerning the internal and external features related to other body parts or systems.

Molecular Biology

Molecular Biology deals with the molecular basis of biological activity. It describes in detail DNA, RNA, and proteins, and how these molecules regulate cell functions.

Genetics

The study of heredity and variation is known as genetics. It explains how traits are inherited from one generation to another through genes. The two important fields of genetics are classical genetics, dealing with Mendelian inheritance; and molecular genetics, studying genes at the DNA level.

Biotechnology

This branch applies biological systems and organisms to develop or alter products for use by humans. Examples of such recent biotechnology inventions include genetic engineering, cloning, and the use of CRISPR technology.

Microbiology

Microbiology is the study of microorganisms, including bacteria, viruses, and fungi. The discipline is important in understanding diseases, antibiotics, and microbes' ecological roles.

• Bacteria
• Virus
• Fungi

Zoology

The course of zoology covers the study of animal behaviour, physiology, and classification. Subjects ranging from minute insects to large mammals are taken up for study by zoologists.

Botany

Botany deals with life in plants that is growth, reproduction, metabolism, and disease. For life to exist on Earth, it needs plants to provide oxygen, food, and a habitat.

Ecology

Ecology deals with the study of the relationship between living organisms and their environment, that is ecosystems, biodiversity, and conservation.

Immunology

Immunology deals with the study of the immune system, mainly how the body protects itself from the pathogenic attacks of viruses and bacteria. It includes the mechanism of immune responses and the role of antibodies in protecting the body from infections. This topic is extensively covered in class 12 biology.

• Role of Antibodies

Physiology

It studies the functioning of living organisms and their systems, and how organs, tissues, and cells work together to provide life. It includes processes like respiration, blood circulation, and digestion, which regulate body functions and its response to the environment. This topic is included in the syllabus of Biology class 12.

Example of "Biology"

The biology definition explains living organisms and biology examples show how these organisms grow, work and interact with their environment:

• Photosynthesis: The biological process in which plants convert sunlight into chemical energy.
• Ecosystem: Relationship between living organisms as well as their environment including food webs and nutrient cycles
• Cell division: Mitosis and meiosis are examples of how cells divide and pass on the genetic information
• Evolution: The process by which species evolve based on selection over many generations.
• DNA Replication: It is the biological process of creating two identical replicas of DNA from one original DNA molecule.
• Human Anatomy: The study of the human body and its system
• Immune Response: How the body protects itself against disease and pathogens
• Neuroscience: The study of the nervous system, especially concerning the brain and how it controls body functions.

Important Topics in Biology

Below are the most important topics of biology. These topics are included in the biology ncert and students can also get biology notes easily on these topics:

Properties of Carbon

Carbon is a very versatile element, it makes the basic framework of organic molecules. Due to the special properties of its electronic structure, carbon can exist in all three important types of chain bonds-simple, double, and triple-along with rings and complex ring systems that are necessary for living systems.

• Carbon Cycle

Human Biology

Human biology studies the structure, function, and processes of the human body. The circulatory, respiratory, and nervous systems along with many other systems keep the individual healthy and in homeostasis.

• Human Brain

• Circulatory System

• Human Nervous System

• Regulation of Kidney Function

• Kidney: Structure, Function and Related Diseases

Macromolecules

Large biological molecules are defined as macromolecules. Examples include proteins, carbohydrates, lipids, and nucleic acids. They are highly important molecules for cell structure, storage of energy, and passage of genetic information.

• Proteins

• Nucleic Acid and Genetic Code

Energy and Enzymes

The energy within living systems is largely derived from chemical reactions. The substances that accelerate chemical reactions are known as catalysts and, in living organisms, enzymes. Enzymes would lower the activation energy for all sorts of life processes, which include metabolism and digestion.

• Enzymes

• ATP - Energy Currency of the Cell

Structure of a cell

A cell is the smallest unit of life. Organelles which constitute the cell include the nucleus, mitochondria, and endoplasmic reticulum. These organelles interact in carrying out vital functions of the cell that include energy production, synthesis of proteins, and waste removal, among others. Cell Biology topic is covered in class 11 biology.

• Discovery of Cells

• Prokaryotic Cells

• Eukaryotic Cells

Membranes and Transport

Cell membranes are formed by lipid bilayers that regulate the movement of substances in and out of the cell. The internal environment of the cell is regulated by various transport mechanisms across the membrane, including diffusion, osmosis, and active transport.

• Cell Wall

• Plasma Membrane

• Diffusion

• Reverse Osmosis

• Active Transport

• Passive Transport

Cellular Respiration

Cellular respiration is the process through which cells use glucose and oxygen to form ATP, the energy currency of the cell. It involves changes in glycolysis, the Krebs cycle, and the electron transport chain, releasing energy to fuel cellular activities.

• Cellular Respiration

• Difference Between Glycolysis and Krebs Cycle

Photosynthesis

Light energy is transformed into chemical energy by photosynthesis in plants, algae, and some bacteria, producing glucose and oxygen. It occurs in the chloroplasts and is of immense importance regarding the flow of energy within ecosystems.

• Calvin Cycle or Dark Reaction

• Light Dependent Reactions

• Photorespiration in C3 and C4 plants

Cell Division

Cell division involves mitosis and meiosis, processes in which cells form other cells. Mitosis produces genetically identical cells for growth and repair, while meiosis generates genetically diverse gametes for sexual reproduction.

• Cell Division

• Mitosis - Equational Division

• Cell Cycle

• Stages Of Meiosis

Classical and Molecular Genetics

Classical genetics studies the study of inheritance patterns. This is mainly based on Mendel's laws. Molecular genetics involves the study of genes at a molecular level that includes a great emphasis on DNA, RNA, and the synthesis of proteins.

• Genetics Definition

• Mendelian Genetics

• Mendel's Laws of Inheritance

• Mendelian Disorders

• Genes

DNA as Genetic Material

DNA stands for deoxyribonucleic acid. It is the very molecule that contains genetic information stored in living organisms. DNA dictates cellular processes by coding for proteins and, upon its replication, ensures that genetic information is passed on to offspring.

• DNA

Central Dogma

The central dogma of molecular biology is the movement of genetic material from DNA to RNA to protein. It gives information about how DNA transcribes mRNA by translating into proteins that carry on different cellular functions.

• Central Dogma of Molecular Biology

• Process of Transcription

• Process of Translation in Biology

Gene Regulation

Gene regulation is a control function that allows the cells to express genes properly at required times and in adequate amounts, ensuring the proper production of proteins. It is important in both cell differentiation and cell development and in the ability of the cell to respond to environmental changes.

• Gene Regulation and Gene Expression

Biotechnology

The use of biological agents to develop goods and technologies that improve human lives is studied under this topic. This involves the use of genetic engineering, cloning, and medicine and biofuel development.

Bacteria and Archaea

Bacteria and archaea are kinds of prokaryotic microorganisms. Bacteria exist in several different ecological environments, archaeons tend to be in extreme environmental conditions. Both organisms have greater ecological roles in nutrient cycling and biotechnology.

• Difference Between Archaea and Bacteria

• Archaebacteria

Viruses

A virus is a small infectious agent that requires a living host cell for replication. It possesses genetic material, DNA or RNA, enclosed in protein. Viruses infect all life forms-from bacteria to humans-causing diseases.

• Virology

• Viruses

Evolution and the Tree of Life

Evolution is the gradual modification of species in such a way that life becomes diverse. It is driven by natural selection, mutation, and genetic drift. The Tree of Life maps the relationships among organisms, providing a visible guide to their evolutionary history.

• Darwin's Contribution: The Theory of Evolution

• Darwin Theory of Natural Selection

History of Life on Earth

From the least simple single-celled organisms to the most complex biodiversity today, life has been in existence on Earth for billions of years. Some key events included in this topic are the origin of life, the rise of multicellular life and mass extinctions.

• Origin and Evolution of Man

Ecology

Ecology is the interaction of living organisms among themselves and with their environment. Learn more about ecology, ecosystems, population dynamics, food chains, and the impact of human activity on natural habitats:

• Energy Flow in Ecosystem

• Nitrogen Cycle

• Population Growth

• Ecological Succession

• Food Chain & Food Web

• Biogeochemical Cycles

• Binomial Nomenclature

Biodiversity and Conservation

Biodiversity refers to the variety in life on Earth which includes species diversity, ecosystem diversity, and genetic diversity. Learn more about biodiversity and conservation here:

• Biodiversity Loss and Causes

• In situ and Ex situ conservation of Biodiversity

Plant Biology

It includes the structure, function, growth, and reproduction of plants. The process of photosynthesis, transpiration and the ecological role of primary producers are studied under this topic.

• Parts Of Plants

History of Biology

Biology as a science is deeply rooted in history and evolved significantly over time.

The Term "Biology"

Before the term biology was adopted, disciplines such as Natural History defined the study of plants, animals and fungi in their natural environments, and those who studied it were called natural historians or naturalists. Other disciplines also include Natural Theology and Natural Philosophy.

The word "Biology" was coined by Michael Christoph Hanow in 1766 and independently by Thomas Beddoes, in 1799, Karl Friedrich Burdach, in 1800, Gottfried Reinhold Treviranus, in 1802 and Jean-Baptiste Lamarck, in 1802.

Origins as a Field of Study

The early human beings survived by knowledge of plants and animals, which was passed from generation to generation. More significant steps in Biology came with the transition from hunting and gathering into farming, furthering knowledge of agriculture and animal domestication.

Biology as a branch came into shape from early contributions by Aristotle. It was significantly developed during the 19th century with various discoveries and experiments.

Given below is the list of major scientists and their contributions which formed a base for the understanding of various concepts in Biology:

Biology for Various Competitive Exams

Biology is one of the most important subjects in the NEET (National Eligibility cum Entrance Test), contributing to half of the total questions in the exam. For NEET 2025, the Biology section will consist of 90 questions (out of a total of 180), divided between Botany and Zoology. Each question carries 4 marks, making Biology worth 360 marks out of the total 720.

Also read: How to prepare for NEET Biology

Biology Preparation

For an effective preparation of Biology subject for various competitive exams such as NEET 2025, understanding the Biology syllabus is the first and most important step. The syllabus for NEET Exam 2025 covers the chapters of CBSE Class 11 and 12. Having command of the topics and concepts of Biology classes 11 and 12 becomes the top priority for aspiring students.

CBSE Class 11 Biology Chapters

Given below is the list of important Biology chapters of class 11 for Exam preparation:

To cover the syllabus of class 11 NCERT Biology, read and practice diagrams and important definitions which are given. Practice the previous year's question papers along with mock tests to build up your problem-solving skills and time-management skills.

Also Read:

• NCERT solutions for class 11 Biology
• NCERT exemplar solutions for class 11 Biology

CBSE Class 12 Biology Chapters

Biology class 12 Chapters are highly important for board exam preparation. These chapters also form a good weightage in the NEET exam. Here's the list of Important Class 12 Chapters of Biology:

Prepare for class 12 CBSE Biology by studying the key concepts from the NCERT textbook supported by diagrams and flowcharts. One should regularly practice all question papers from previous years to self-examine their level of preparation.

Also Read:

• NCERT exemplar solutions for class 12 Biology
• NCERT solutions for class 12 Biology

Best Biology Books for Exams

The best Biology books for NEET preparation are:

• NCERT textbook Biology Class 11
• NCERT textbook Biology Class 12
• Trueman's Objective Biology
• MTG's NCERT at Your Fingertips
• Dinesh Objective Biology

All these books provide students with huge collections of MCQs, explanations, and practice papers for improvement in NEET preparation.

For More Details Read:

Best Biology Books for NEET 2025

Biology MCQ

Practice is very essential for NEET Biology since it improves the grasp of the important concepts. It increases accuracy and speed for solving questions. Through the regular practice of similar types of questions, students get used to the pattern and format of real exams. Hence, this further reduces the scope for mistakes and builds confidence. This will be the key to scoring good marks for the subject Biology in NEET.

MCQ Practice for NEET Biology

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Students can also download the NEET mock Test 2025 for all subjects from teh link given below:

Download other NEET related ebooks that will boost your NEET Exam preparation:

Recommended Videos Related to Biology

Biological Evolution:

• The video given below on Biological evolution describes the process through which species of organisms change over generations through variations in their genetic material.
• Students will get more clarity on the development of new species and adaptations to changing environments from this video.

Basics of Photosynthesis:

• This video describes the basics of photosynthesis which forms the base of the food chain, supporting life on Earth.
• It will help students understand the pathway of energy in an ecosystem, the role of plants in oxygen production, and the importance of sustainable agriculture and food security.

Recent Advances in Biology

Over the years, biology has been characterised by technology, which enables the probes of scientists into the vital mechanisms of living things. These are some of the latest breakthroughs:

Genomics and Proteomics: Whole-genome and proteome mapping for the understanding of genetic information and function of proteins.

Synthetic Biology: The design and engineering of new biological parts, devices, and organisms, for example for drug development or biofuels.

CRISPR and Gene Editing: A revolution in editing DNA with the potential to cure genetic disorders and improve crops.

Quantum Biology: Quantum biology is a new frontier in understanding how quantum mechanics can affect biological functions. Examples include studies on how enzymes catalyze reactions and how birds navigate using Earth's magnetic fields.

With its nature of interdisciplinarity, biology is going to continue changing the way we think about life and the world surrounding us, solving some of the major global problems.