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9/7/2012 THE SCOPE OF LIFE The Properties of Life (a) Order (b) Regulation (c) Growth and development (d) Energy utilization THE SCOPE OF LIFE The Properties of Life (f) Reproduction (e) Response to the environment (g) Evolution Life at Its Many Levels – Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. Biosphere Ecosystems Communities Populations Organisms Organ Systems and Organs Tissues Organelles Nucleus Molecules and Atoms Atom Cells 1 9/7/2012 Life in Its Diverse Forms – Diversity is the hallmark of life. • The diversity of known life includes 1.8 million species. • Estimates of the total diversity range from 10 million to over 100 million species. Grouping Species – Biodiversity can be beautiful but overwhelming. – Taxonomy is the branch of biology that names and classifies species. The Three Domains of Life • The three domains of life are – Bacteria B i – Archaea – Eukarya Chemistry of Life – Matter is anything that occupies space and has mass. – Matter is found on the Earth in three physical states: • Solid • Liquid • Gas 2 9/7/2012 Chemistry of Life – Matter is composed of chemical elements. • Elements are substances that cannot be broken down into other substances. Change the number of PROTONS in the nucleus and you change the ELEMENT Atoms – Each element consists of one kind of atom. • An atom is the smallest unit of matter that still retains the properties of an element. 2 Protons 2 Neutrons 2 Electrons Nucleus Nucleus Cloud of negative charge (2 electrons) Chemistry of Life – Elements differ in the number of subatomic particles in their atoms. • The number of protons, the atomic number, determines which element it is. • An atom’s mass number is the sum of the number of protons and neutrons. j • Mass is a measure of the amount of matter in an object. 3 9/7/2012 Periodic Table of the Elements Legend Solid Liquid Gas Synthetic Alkali metals Alkali earth metals Transition metals Rare earth metals Other metals Noble gases Halogens Other nonmetals Atomic number = number of protons within the nucleus Chemistry of Life – Twenty-five elements are essential to life. – Four elements make up about 96% of the weight of Carbon (C): 18.5% the human body: • Oxygen Calcium (Ca): 1.5% Phosphorus (P): 1.0% Oxygen (O): • Carbon 65.0% Potassium (K): 0.4% Sulfur (S): 0 0.3% 3% • Hydrogen Sodium (Na): 0.2% Chlorine (Cl): 0.2% • Nitrogen Magnesium (Mg): 0.1% Trace elements: less than 0.01% Hydrogen (H): 9.5% Boron (B) Chromium (Cr) Cobalt (Co) Copper (Cu) Fluorine (F) Iodine (I) Iron (Fe) Nitrogen (N): 3.3% Manganese (Mn) Molybdenum (Mo) Selenium (Se) Silicon (Si) Tin (Sn) Vanadium (V) Zinc (Zn) Chemical Properties of Atoms – Electrons determine how an atom behaves when it encounters other atoms. First electron shell (can hold 2 electrons) Electron Outer electron shell (can hold 8 electrons) Hydrogen (H) Carbon (C) Atomic number = 1 Atomic number = 6 Nitrogen (N) Atomic number = 7 Oxygen (O) Atomic number = 8 © 2010 Pearson Education, Inc. 4