Copyright Pearson Prentice Hall 7-4 The Diversity of Cellular Life Photo Credit: ©CNSI/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall

Unicellular Organisms Unicellular organisms are made up of only one cell. Unicellular organisms dominate life on Earth. Copyright Pearson Prentice Hall

Multicellular Organisms Organisms that are made up of many cells are called multicellular. There is a great variety among multicellular organisms. Copyright Pearson Prentice Hall

Multicellular Organisms Cells throughout an organism can develop in different ways to perform different tasks. This process is called cell specialization. Copyright Pearson Prentice Hall

Multicellular Organisms Red blood cells transport oxygen. Photo Credit: ©Dr. Dennis Kunkle/Phototake Copyright Pearson Prentice Hall

Multicellular Organisms Cells in the pancreas produce proteins. Photo Credit: ©Don Fawcett/Photo Researchers, Inc. Copyright Pearson Prentice Hall

Multicellular Organisms Muscle cells allow movement. Photo Credit: ©Manford Kage/Peter Arnold, Inc. Copyright Pearson Prentice Hall

Multicellular Organisms Specialized Plant Cells Plants exchange carbon dioxide, oxygen, water vapor, and other gases through tiny openings called stomata on the undersides of leaves. Highly specialized cells, known as guard cells, regulate this exchange. Copyright Pearson Prentice Hall

Multicellular Organisms Stomata enclosed by guard cells. Photo Credit: ©Ron Boardman/Getty Images, Inc-Stone Copyright Pearson Prentice Hall

Levels of Organization The levels of organization in a multicellular organism are: individual cells tissues organs organ systems Copyright Pearson Prentice Hall

Levels of Organization Muscle cell Smooth muscle tissue Stomach Digestive system The levels of organization in a multicellular organism are individual cells, tissues, organs, and organ systems. In this example, muscle cells make up smooth muscle tissue, which, along with other tissues, makes up the stomach, an organ. The stomach, in turn, is part of an organ system, the digestive system. Copyright Pearson Prentice Hall

Levels of Organization In multicellular organisms, cells are the first level of organization. Copyright Pearson Prentice Hall

Levels of Organization Tissues Similar cells are grouped into units called tissues. A tissue is a group of similar cells that perform a particular function. Copyright Pearson Prentice Hall

Levels of Organization Copyright Pearson Prentice Hall

Levels of Organization Most animals have four main types of tissue: muscle epithelial nervous connective Copyright Pearson Prentice Hall

Levels of Organization Organs  Organs are groups of tissues that work together to perform a specific function. Copyright Pearson Prentice Hall

Levels of Organization Copyright Pearson Prentice Hall

Levels of Organization Organ Systems   In most cases, an organ completes a series of specialized tasks. A group of organs that work together to perform a specific function is called an organ system. Copyright Pearson Prentice Hall

Levels of Organization Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 7-4 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 7-4 Cell specialization is characteristic of bacteria. all unicellular organisms. yeasts. multicellular organisms. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 7-4 Which of the following cells is specialized for contraction? muscle cell red blood cell pancreatic cell nerve cell Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 7-4 The stomach is an example of a(an) tissue. organ. organ system. organism. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 7-4 Which of the following shows the levels of organization in an organism from the simplest to the most complex? organ system, organ, cell, tissue tissue, cell, organ, organ system cell, tissue, organ, organ system cell, organ, tissue, organ system Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 7-4 Which of the following would probably contain the greatest variety of specialized cells? an organ system a tissue an organ a multicellular organism Copyright Pearson Prentice Hall

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