The Aquatic Ecosystem — Biological Importance of Water

About this lesson

This unit covers the biological importance of water, focusing on its role in living organisms and cells. It begins by explaining that water is the most abundant chemical substance in living organisms, making up about 70% of mammalian body mass, and is found both inside and outside cells. The text then describes the basic structure of cells, distinguishing between prokaryotes (like bacteria) and eukaryotes (including protists, fungi, plants, and animals), and details the components of a cell such as the cell wall, cell membrane, cytoplasm, nucleus, chloroplasts, vacuoles, mitochondria, and endoplasmic reticulum. It emphasizes water's importance as a universal solvent, a main component of cytoplasm, a temperature regulator due to its high specific heat, and a participant in metabolic processes. The unit also introduces metabolism, dividing it into catabolic and anabolic processes, and explains the role of enzymes as catalysts that lower activation energy, with a 'lock and key' mechanism and optimal temperature and pH conditions. The text includes objective and essay questions at the end for assessment.