Biology is the fascinating science that studies all forms of life on Earth. From the smallest bacteria to the largest mammals, biology helps us understand how living organisms function, reproduce, and adapt to their environments. It encompasses everything from molecular processes within cells to complex ecosystems.
Biology is divided into many specialized branches, each focusing on different aspects of life. Botany studies plants and their processes. Zoology examines animals and their behavior. Microbiology investigates tiny organisms like bacteria and viruses. Genetics explores how traits are passed from parents to offspring. Ecology studies how organisms interact with each other and their environment.
The cell is the fundamental unit of all life on Earth. Every living organism, from the tiniest bacteria to the largest whale, is made up of one or more cells. There are two main types of cells: prokaryotic cells, which lack a nucleus and are found in bacteria, and eukaryotic cells, which have a nucleus and organelles, found in plants, animals, and fungi.
DNA, or deoxyribonucleic acid, is the molecule that carries genetic information in all living organisms. It has a famous double helix structure, like a twisted ladder. DNA is made up of four chemical bases: adenine, thymine, guanine, and cytosine. These bases pair up in specific ways to form the rungs of the DNA ladder, and their sequence determines the genetic code that makes each organism unique.
Evolution is the process by which species change over time through natural selection. Organisms with favorable traits are more likely to survive and reproduce, passing these traits to their offspring. This process has created the incredible biodiversity we see today. All life on Earth shares common ancestors, which we can visualize as a tree of life, with different branches representing different species that evolved over millions of years.