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The Study of life

Life is all around us. So, how do we study it? By getting to know more about the structure, functions, evolution and distribution patterns etc. of living organisms.
It is basically the science of living organisms and their characteristics like growth, development, reproduction and so many more basic properties of life.

i)Properties of Life
ii)Levels of Organization
iii)Diversity of Life

Surprised to see Chemistry in Biology? Actually chemistry makes life possible. Would you believe that we have approximately 60 elements within our body? Learn more about what they do and how they help us.

i)Atoms, Isotopes, Ions and Molecules

Carbohydrates, lipids, proteins and nucleic acids are the basic biological macromolecules. Macro – because they are very large molecules made up of subunits. Find out what they do.

iv)Nucleic Acids


Cell is the basic unit of life – is the first thing we learn in a biology class. But did you know that cells vary in size from tiny, microscopic bacteria to huge bird eggs. Click on the next level to know more.
A ‘Small room’ where a lot of activity takes place, is what best describes a cell. Let’s find out more about the cell.

i)Cell- The Basic Unit of Life
iii)Cell Theory

Here we go into the contents of the ‘room’. What does a cell contain? What inside the cell makes it live? Are all cells alike? So many questions to be answered.

i)Prokaryotic Cells
ii)Eukaryotic Cells
iii)The Endomembrane  System
iv)The Cytoskeleton
v)Connections between Cells and Cellular Activities

This membrane is like a fence around the cell. It physically separates the components within the cell from the external environment. In spite of this, certain substances still find their way in or out of the cells. How?

i)Components and Structure
ii)Passive Transport
iii)Active Transport
iv)Bulk Transport

Ever wondered how plants eat? Well most of them make their own food, especially the green ones. This is called photosynthesis and is performed by specialized cells. Like all other living things, cells too breathe but in a different way. Find out more.

i)Light-dependent Reactions
ii)Light-independent Reactions
iii)Cellular Respiration

Organisms may be single-celled or made up of many cells and they live in an environment. So they need to communicate with each other as well as with the environment. This is accomplished by sending and receiving signals.

i)Signalling Molecules (Paracrine, Autocrine, Endocrine)
ii)Cellular Receptors
iii)Response to Cellular Signal
iv)Signalling in Single-celled Organisms

Did you know that we have only ‘daughter cells’ in Biology and no ‘son cells’? Cells grow and divide into new cells. These new cells are always called ‘Daughter Cells’. Wondering why it is so? This lesson will make it all clear.

i)Cell Division
ii)Cell Cycle
iii)Prokaryotic Cell Division


It’s amazing how we look like our parents, grandparents and sometimes other relatives as well. Genetics explains how this is possible. It is the study of inheritance.
Gregor Johann Mendel was an Austrian monk who was a botanist as well as a scientist. As part of his studies on heredity, he experimented with the pea plant. He was posthumously recognized for his contribution to Genetics and awarded the title the ‘Father of Genetics’.

i)Mendel’s Experiments
ii)Laws of Probability
iii)Patterns of Inheritance
iv)Laws of Inheritance

How do we get to look like our parents? It seems as though certain characters are being passed on from one generation to the other while others are not. This theory tells us all about how this happens.

i)Chromosomal Theory
ii)Genetic Linkage

During a medical check up, we are often asked about the family health history. Ever wondered why? Just as we get the physical features of our parents, certain diseases or disorders too may pass on from parent to child. Interested?

i)Disorders in Chromosome Number
ii)Chromosomal Structural Rearrangements

The DNA tells us what we look like on the outside and how we work on the inside. It is a chemical that contains the instructions a living thing needs to develop, live and reproduce. It has a special shape, like a twisted spiral staircase.

i)DNA Structure and Sequencing
ii)DNA Replication
iii)DNA Repair

When you buy a new gadget, you are advised to read the manual before using it. Genes are like the instruction manuals for our bodies. All of us have the same set of genes with slight variations. For example, people with different hair colors have the same ‘gene for hair color’, but different versions of it.

i)The Genetic Code
ii)Eukaryotic Transcription
iii)RNA Processing
iv)Ribosomes and Protein Synthesis

Remember those painful shots, the big pills and the not so tasty syrups? Well they are actually vaccines and antibiotics. We use them to overcome infections. Biotechnology is a big word but simply means combining biology and technology. Although the term may not be familiar, the applications like the vaccine and the antibiotic are. Who hasn’t heard of Dolly, the first cloned sheep! Learn all about it here.

iii)Genetic Engineering and GMOs
iv)Biotechnology in Medicine
v)Vaccines, Antibiotics and Hormones

Evolution and Origin of Species

Ever watched a nature based channel. So many varieties of plants and animals around us. Haven’t we all marvelled at the diversity of nature? Darwin explains it all in his theories of ‘Natural Selection’ and ‘Survival of the Fittest’. Dig in deep and find out more.
Charles Darwin was a naturalist and geologist. During one of his travels, he came across the Galapagos Islands in the Pacific Ocean. These islands are home to a great variety of birds and animals that are not seen anywhere else in the world. Astonished with this diversity, Darwin collected many specimens and studied them. He came to the conclusion that each animal had evolved from its ancestors in an attempt to survive the changing environment. Sounds interesting? We’ll tell you more.

i)Charles Darwin and Natural Selection
ii)Processes and Patterns of Evolution

One of the birds that Darwin studied was the Finch. He noticed that there were 13 different species of finches and they were all from islands which had the same geographic and climatic features. Now this was surprising.

i)Reproductive Isolation

When Darwin presented his findings to the Zoological Society, the question put forward was ‘How can you prove it?’ Darwin had the answer. The fossils he had collected turned out to be the bones of extinct animals, relatives of the present-day ones. On closer examination, the former were seen to have certain features which were not seen in the latter.

i)Fossil Formation and Record
ii)Vestigial Structures

Evolution more prominent at the population level than at the individual level. To understand this better, let’s go back to our finches. These birds fed mostly on the large, hard seeds that were more plentiful. Birds with larger, deeper beaks were better able to crack and eat these large seeds, and they survived at a higher rate than finches with smaller
beaks. So finches with the bigger beaks became the more dominant population.

i)Population Genetics
ii)Genetic Variation
iii)Genetic Drift
iv)Gene flow and Mutation
v)Adaptive Evolution

Imagine a tree with wide-spread branches. Now place the evolved members of a species on each branch, with the last evolution on the highest branch. What you have just made is a Phylogenetic tree.

i)Phylogenetic Tree
ii)Levels of Classification
iii)Similar Traits


Everybody’s heard of pirates. Viruses infect and take over the cell like pirates hijacking a ship. They are found anywhere and everywhere and can infect every form of life.
Viruses behave in strange manners. They dangle between life and death. When in contact with a living system, they are up in action. All other times, whether floating in the air or sitting on an inert object, they play ‘dead’. Curious to know more? Find all the answers here.

i)Viral Morphology
ii)Virus – Classification

Germs cause infections but can a germ be infected? The answer is yes. Viruses can infect all types of life forms, including bacteria. They tend to be picky in selecting which cells to infect and which to take over and destroy.

i)Steps in Viral Infection
iii)Animal Viruses
iv)Plant Viruses

How can we kill something that is not alive? A virus is not even a cell. It is just like an envelope carrying a message, the message being the genetic material and its only mission is to ‘spread the message’. So what can protect us?

i)Vaccines and Immunity
ii)Anti – Viral Drugs

Classification of Living Things

When we think about the different life forms – animals, plants, mushroom, microbes and so many more, we often wonder how different they are from each other. How do we categorize them? How do we say that this is an eagle, not a falcon and that is a crocodile, not an alligator?
They are the single-celled organisms that are the earliest and most primitive forms of life on earth. They can live in various types of environments including extreme conditions like the volcano.

i)Archaea and Bacteria
ii)Extremophiles and Biofilms
iii)Structure and Reproduction
iv)Bacterial Diseases in Humans and Antibiotics
v)Beneficial Prokaryotes and Bioremediation

These are a collection of unicellular organisms that we can refer to as the ‘first plants’ and the ‘first animals’. Protists are a group made up of protozoa, algae, and slime molds. They include any organism that is not a plant, animal or fungus.

i)Cell Structure and Motility
iii)Food Sources and Symbionts
iv)Plant and Human Pathogens

The word ‘fungus’ brings to mind stale bread with a grey or black colored powdery coating. The fungal family is much more diverse. Fungi range from the single celled yeast to the multicellular, brightly colored mushrooms. Some are edible while others are poisonous. A good number of them are harmless and some, beneficial to the environment and other living things, even human beings.. We also have fungi which are deadly and infectious. Learn more about these unique organisms.

i)Characteristics, Structure and Function
iii)Decomposition and Recycling
iv)Mutualistic Relationships and Fungivores
v)Fungal Parasites and Pathogens
vi)Importance in Human Life

When we speak about nature and its diversity, we picture a lot of greenery or plants adorned with brightly colored flowers of all shapes and sizes. There are approximately 300-315 thousand species of plants known to man. Let’s learn all about the different kinds of plants.

i)Seedless Plants
iv)Plant Biodiversity

There was a popular TV show in the 70s called ‘Animals, Animals, Animals’. It was a favorite among children all across the globe. Like the title song says, there are ‘animals here and there’ and ‘animals everywhere’, but do we know all about animals? The members of this kingdom range from the tiniest mites to the huge blue whale, from those that live in the ocean depths to the ones on the highest peaks. Interested?

i)Characteristics and Classification

Fishes, frogs, Snakes, lions and humans – all have something in common. Any guesses? Yes, it’s the ‘backbone’ The backbone is called the ‘vertebral column’ and the animals possessing it are the ‘Vertebrates’. Let’s delve into the world of vertebrates.



We learnt about living things – the plants, animals, fungi, microbes etc. What makes them different from non living things? How do they move, eat, grow, and reproduce? Well, physiology tells you all about how living systems work.
Often, it is difficult to believe that plants are actually living. They don’t move from place to place. You don’t see them eating or breathing. So how does all this happen? The part of the plant that you see above the ground is just the tip of the iceberg. There is an equal sized or even larger portion of the plant under the ground. Let’s look at the plant body parts in detail in this lesson.

i)Plant Body
ii)Plant Development
iii)Transport of Water and Solutes
iv)Plant Sensory Systems and Responses
v)Plant Defense Mechanisms
vi)Plant Nutrition

We know that baby plants grow into big ones but where does the baby plant come from? Our biology text says it comes from the flower. Wondering how? Well the flower develops into a fruit and then…..

i)Reproductive Development and Structure
ii)Sexual Reproduction in Gymnosperms and Angiosperms
iii)Pollination and Fertilization
iv)Asexual Reproduction
v)Plant Life Spans

Look at yourself, your body. You can wiggle your toes, stretch your hands, hold your breath, and blink your eyes and what not. All this seems so simple. Look closer and you’ll find that they are not as simple as they seem. How does each body part work? Find out more.

i)Form and Function
ii)Primary Tissues
iv)Animal Nutrition

How long do you take to have a meal? Even if you go slowly, it will not stretch out to an hour. But how long does it take for the food you ate to be absorbed by the body? What happens to the chicken sandwich, the milk, the eggs etc.? Learn all about digestion here.

i)The Gastrointestinal Tract and Digestive Glands
ii)The Digestive Process
iii)Digestive System Regulation
iv)Nutrition and Energy Production

Let’s play a game. Close your eyes and think of ice-cream or burger or anything that you feel is delicious. The more you think of it, the more you feel it in your mouth. The aroma tingles your nostrils, the ice-cream melts in your mouth. It tastes so sweet. Now open your eyes. Where did the ice-cream disappear? Just the thought of ice-cream could trigger such a strong response. How does this happen? How are our actions connected to and coordinated by our thoughts? Interesting, isn’t it?

i)Neurons and Glial Cells
ii)Neuron Communication
iii)The Central  and Peripheral Nervous Systems
iv)Nervous System Disorders
v)Sensory Processes and Somatosensation
vi)Taste and Smell
vii)Hearing and Vestibular Sensation

Birthdays are special and on every birthday, you have your Mom saying, “I still remember the day you were born. It seems like yesterday. Now you’re all grown up.” Think about the process of growing up. You have all these milestones that you go through without even realizing it. Our body has a set of chemicals called hormones that work as a system to control and regulate all the body processes.

i)Hormones and How they Work
ii)Regulation of Body Processes
iii)Regulation of Hormone Production
iv)Endocrine Glands

Have you watched an athlete running in slow motion – on TV of course? Watch closely and you will see that there are so many muscles working together at the same time. So also when we sit, stand, reach up, bend down or even hold or throw something. We see only the muscles, so we don’t realize that our bones are also involved. Learn all about it.

i)Skeletal Systems
iii)Joints and Skeletal Movement
iv)Muscle Contraction and Locomotion

One of the things that makes a living thing different from a non-living thing is that it breathes. It is easy to make out whether an animal or a human being is breathing but does a plant breathe? If so, how? Each organism has its own breathing mechanism. Learn all about respiration, the process of breathing.

i)The Respiratory Apparatus
ii)Breathing Mechanism
iii)Transport of Gases
iv)Exchange of Gases

Children love to play doctor, especially to listen to the heart beat. Why does your heart beat? What causes the ‘lub dub’ sound? The heart is like a building that has four rooms connected to each other with doors. So the sound is caused every time a door slams shut and it is called a beat because it follows a rhythm, like a beat in music. And why does the blood have to circulate? Find out more in this lesson.

i)Role of the Circulatory System
ii)Components of Blood
iii)The Heart and Blood Vessels
iv)Blood flow and Regulation of Blood Pressure

Elimination of waste products from the body is much more important than you think it is. It actually helps in regulating the water balance in your body. All living organisms including the tiny ones have their own methods of waste disposal. Learn more and you’ll be surprised.

i)Osmoregulation and Osmotic balance
ii)Nitrogenous Waste and Excretion systems
iii)Human Excretory Systems
iv)Hormonal Control of Osmoregulatory Functions

Did you know that we have an army of our own and that ‘pus’ from a wound contains the dead bodies of our soldiers? Our soldiers are called ‘White Blood Cells’. Dust particles and microbes are so tiny that most often, we do not realize that we are being attacked. Our body, on the other hand is always prepared. We sneeze, cough, cry, itch – all of which are our defense mechanisms. How does the body know? Which part of our body protects us from such unseen danger?

i)Innate Immune Response
ii)Adaptive Immune Response
iv)Disruptions in the Immune System

“Go forth and multiply” is what the Creator commanded. Oh, don’t panic! You don’t have to learn the multiplication tables in Biology. Here, multiply refers to having young ones. As we discussed earlier, animals are so varied and hence follow different methods of reproduction. Let’s learn about some of these methods.

i)Reproduction Methods and Fertilization
ii)Human Reproduction-Anatomy and Gametogenesis
iii)Hormonal Control-Human Reproduction
iv)Fertilization and Early Embryonic Development
v)Organogenesis and Vertebrate Formation
vi)Human Pregnancy and Birth

Ecology and Biosphere

Ecology literally means ‘the study of the house’. House here refers to the environment in which organisms live. So here we learn all about how the surroundings of a living thing influence it. Biosphere, on the other hand, includes all the living things on the earth and the dead organic matter produced by them.
When you hear the word ‘house’, what comes to your mind? The building you live in, the other members of your family – even pets, your interactions with them etc. This is exactly what we learn in this lesson.

ii)Organismal and Population Ecology
iii)Community and Ecosystem Ecology

We already know that there are so many different kinds of plants, animals and microbes. Do they live in similar or diverse environments? How do they adjust to the conditions they live in? Find out all about it here.

ii)Energy Sources
iii)Temperature and Water
iv)Abiotic Factors

A biome is a particular region of the world where a community of animals and plants live together. They are exposed to similar conditions of weather, temperature, vegetation etc.

i)Tropical Wet Forests and Savannas
ii)Subtropical Desserts and Chaparrals
iii)Temperate Grasslands
iv)Temperate Forests
v)Boreal Forests and Arctic Tundra
i)Marine Biomes
iii)Freshwater Biomes

Have you ever been inside a greenhouse? A ‘greenhouse’, is not a house that is painted green but a huge glass house where plants are grown under regulated conditions. Well, if you have ever stepped inside, you will know how hot and humid it is. The earth’s atmosphere is slowly turning into a ‘greenhouse’. Why….? Find out more.

i)Climate and Weather
ii)Causes and Evidence of Climate Change
iii)Past and Present Effects of Global Climate Change

Population ecology concentrates mainly on factors that affect population size and composition. Many populations remain relatively stable over time, with only minor changes in population size. Community ecology includes study of the organization and functioning of communities, living in a particular area or habitat.

i)Population Demography
ii)Environmental Limits to Population Growth
iii)Human Population Growth
iv)Community Ecology
v)Innate Animal Behavior
vi)Learned Animal Behavior


We live in an environment which has both living and non living things, with which we interact. To get a clearer picture, think about all the things you do when you are at home or in school or any other environment. At home, you sit on the sofa, watch TV, open the fridge, play with your pet, speak to your parents or siblings etc. All of the above – the sofa, the TV, your pet, people – constitute your ecosystem. Let’s learn more about ecosystems.
An ecosystem is everything around including the living things – plants, animals, microbes and the non living things – the air, water, soil, furniture etc. An ecosystem can be of any size, from an area as small as a pinhead to the whole biosphere.

i)Ecosystem Dynamics
ii)Food Chains and Food Webs

The members of an ecosystem are connected to each other in various ways, one of which is the energy flow. The source of all energy is the sun. The sun’s energy is captured directly by the plants and passed on to the other components of the ecosystem. So are plants the super heroes? Find out more in this lesson.

i)Trophic Levels
ii)Ecological Pyramids

Big word? Don’t worry, we’ll break it down. So its life, earth and chemical cycles. Confused? It simply tells you how chemicals move from living things to non living things and then back again, like a cycle. Interesting, isn’t it?

i)Water Cycle
ii)Carbon Cycle
iii)Nitrogen Cycle
iv)Phosphorus Cycle
v)Sulfur Cycle

Conservation Biology and Biodiversity

When you read about the extinct animals, haven’t you sometimes wished that you were there to see them? It is this thought that made the Dinosaur movies and cartoons, super box-office hits. And it is the very same thought that prompted us to think about protecting those animals which are few in numbers. This is what Conservation is all about.
Are you a dog lover or maybe you have a cat? You can guess the next question. ‘What breed is your cat/dog?’ Dogs and cats vary in size, shape, color, ferociousness, etc. We learnt all about the biodiversity of life in an earlier chapter. It is the variety of life – seen in the plants and animals around you. Imagine a world in which all the flowers were of the same color and smell. Boring, right? So let us make sure that we preserve the varieties that we see in nature.

i)Loss of Biodiversity
ii)Types of Biodiversity
iii)Change through  Geological Time
iv)Human Health and Biodiversity
v)Agricultural Diversity
vi)Managing Fisheries

The next thought that comes to your mind would be ‘But what did I do?’ The question we should be asking is – What should I do to help? Well for starters, you can stop throwing waste around, especially those which do not degrade naturally like the plastics, synthetic cloth etc.

i)Habitat Loss and Sustainability
iii)Exotic Species
iv)Climate Change

Plants and animals help us in so many different ways. They give us food, shelter, the oxygen- rich air that we breathe, medicine and lots more. They also contribute to economic development through tourism. Nature also possesses the magic required to change human behavior. So many contributions for mankind; are we giving enough in return?

i)Measuring Biodiversity
ii)Changing Human behavior
iii)Ecological Restoration

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