Levels of Organization of Life PDF
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This document describes the levels of organization of life, from the basic chemical level to the complex systems level. It explains how atoms and molecules combine to form cells, tissues, organs, and systems, ultimately creating complex organisms.
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# Levels of Organization of Life ## 1.2 Levels of Organization of Life Generally, recognizing life is easier than defining it. Everyone can tell that a cat is alive and a rock is not. What are the characteristics that distinguish living things from non-living things? Rocks, though complex, are co...
# Levels of Organization of Life ## 1.2 Levels of Organization of Life Generally, recognizing life is easier than defining it. Everyone can tell that a cat is alive and a rock is not. What are the characteristics that distinguish living things from non-living things? Rocks, though complex, are composed of various minerals. However, their organization is simple when compared to living organisms. When studying living things, we observe an increase in complexity as we examine organisms. ### The Chemical Level This is the most basic level of organization. It includes atoms and molecules. An atom is the smallest unit of a chemical element, possessing the characteristic properties of that element. For example, two hydrogen atoms combine chemically with an oxygen atom to form a water molecule. ### The Cellular Level Life evolved from atoms and molecules to form cells. Within cells, various molecules combine to form specialized compartments called organelles. A cell is the basic structural and functional unit of all living things, being the simplest unit that can perform all necessary functions of life. There are both single-celled (unicellular) and multicellular organisms. * **Unicellular:** Composed of a single cell, like bacteria. * **Multicellular:** Composed of more than one cell, like animals. ### The Tissue Level Cells with similar properties are grouped together to form tissues (e.g., muscle tissue, nervous tissue in animals). ### The Organ Level Tissues are organized into functional units called organs (e.g., heart, liver). ### The System Level Major biological functions are carried out by coordinated groups of tissues and organs, called systems (e.g., circulatory system, digestive system).
