IB Biology Practice Exam

Carbohydrates are primarily composed of carbon, hydrogen, and oxygen atoms. These biomolecules follow a general formula of (CH₂O)n, where 'n' can vary to indicate the number of repeating units of monosaccharides, the simplest form of carbohydrates. The structural arrangement of these atoms allows for the formation of simple sugars like glucose and more complex carbohydrates such as starch and cellulose. The presence of carbon is central to the framework of carbohydrates, while hydrogen and oxygen are essential for forming the hydroxyl (-OH) groups that contribute to the solubility and reactivity of these molecules. The unique ratio of these elements distinguishes carbohydrates from other macromolecules, such as proteins or nucleic acids, which have different elemental compositions. Understanding that carbohydrates are primarily made up of these three elements is fundamental in studying their role in biology, particularly in energy storage and structural functions in living organisms.