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CHAPTER 1 - CHAPTER 1 A VIEW OF LIFE THREE BASIC THEMES...

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CHAPTER 1 – A VIEW OF LIFE THREE BASIC THEMES Evolution o Populations have changed over time, from earlier life forms Information Transfer o The survival and function of every call and every organism depend on the orderly transmission of information Energy for Life o All life processes, including the thousands of chemical transactions that maintain life’s organization, require a continuous input of energy CHARACTERISTICS OF LIFE Organisms are composed of cells Cells o Basic unit in all organisms Cell theory o Fundamental unifying concept of biology Unicellular organisms o Consists of a single cell Multicellular organisms o Organism is made up of billions of cells o Life processes depend on the coordinated functions of component cells that may be organized to form tissues, organs, and organ systems Plasma Membrane o Envelopes cells o Protects cells from the surrounding external environment DNA o Deoxyribonucleic acid o Specialized molecules that contain genetic instructions and transmit genetic information Organelles o Internal structures that are specialized to perform specific functions Prokaryotic cells o Exclusive to bacteria and to microscopic organisms called archea Eukaryotic cells o Typically contain a variety of organelles enclosed by membranes Nucleus o Houses DNA Organisms grow and develop Biological growth o Increase in the size of the individual cells of an organism, the number of
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cells, or both Development o Includes all the changes that take place during an organism’s life o The structures and body form that develop are exquisitely adapted to the functions the organism must perform Organisms regulate their metabolic processes Metabolism o The sum of all chemical activities of the organism Homeostasis o An appropriate, balanced internal environment Organisms respond to stimuli Stimuli o Physical or chemical changes in their internal or external environment Amoeboid movement o The slow oozing of the cell Cilia o Tiny, hair like extensions Flagella o Structures similar to cilia, but longer Sessile o Do not move from place to place Organisms reproduce Asexual reproduction o A single organism reproduces by splitting in half to form two new organisms Genetic mutation o A permanent change in the genes Sexual reproduction o Fusion of an egg and a sperm cell to form a fertilized egg Populations evolve and become adapted to the environment Adaptations o Inherited characteristics that enhance an organism’s ability to survive in a particular environment LEVELS OF BIOLOGICAL ORGANIZATION
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