Levels of Organization of Life

Biology can be visualized as a hierarchy of units, ordered from the smallest to the largest. These units are molecules, cells, tissues, organs, organisms, populations, communities, and the biosphere (Figure 1.6).

The organism is the central unit of study in biology; Parts Six and Seven of this book discuss organismic biology in detail. But to understand organisms, biologists study life at all its levels of organization. They study molecules, chemical reactions, and cells to understand the functioning of tissues and organs. They study organs and organ systems to determine how organisms maintain homeostasis. At higher levels in the hierarchy, biologists study how organisms interact with one

Organ System Hierarchy

Cells of many types are the working components of living organisms.

A tissue is a group of many cells with similar and coordinated functions.

Cells of many types are the working components of living organisms.

A tissue is a group of many cells with similar and coordinated functions.

Organ (brain)

Organs combine several tissues that function together. Organs form systems, such as the nervous system.

Organ (brain)

Organs combine several tissues that function together. Organs form systems, such as the nervous system.

Levels Biological Organization

Community (coral reef)

Biological communities exchange energy with one another, combining to create the biosphere of Earth.

Biosphere

Community (coral reef)

Biological communities exchange energy with one another, combining to create the biosphere of Earth.

Biosphere

1.6 From Molecules to the Biosphere: The Hierarchy of Life another to form social systems, populations, and ecological communities, which are the subjects of Part Eight of this book.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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Responses

  • costanzo
    What are the levels of organization of life?
    8 years ago
  • afwerki
    What level of organization are membranes?
    7 years ago

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