 a  Order  b  Regulation  c  Growth and development  d  Energy utilization THE SCOPE OF LIFE The Properties of Life

 e  Response to the environment  f  Reproduction  g  Evolution THE SCOPE OF LIFE The Properties of Life

–Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. Life at Its Many Levels Biosphere Ecosystems Communities Populations Organisms Organ Systems and Organs Tissues Cells Organelles Molecules and Atoms Atom Nucleus

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 –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

–Matter is composed of chemical elements. Elements are substances that cannot be broken down into other substances. Chemistry of Life Change the number of PROTONS in the nucleus and you change the ELEMENT

Atoms Nucleus Protons Neutrons Electrons Nucleus Cloud of negative charge  2 electrons  –Each element consists of one kind of atom. An atom is the smallest unit of matter that still retains the properties of an element.

–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. Mass is a measure of the amount of matter in an object. Chemistry of Life

Periodic Table of the Elements Atomic number = number of protons within the nucleus Other nonmetals Halogens Noble gases Other metals Rare earth metals Transition metals Alkali earth metals Alkali metals Synthetic Gas Liquid Solid Legend

Chemistry of Life Carbon  C  : 18.5% Hydrogen  H  : 9.5% Nitrogen  N  : 3.3% Calcium  Ca  : 1.5% Trace elements: less than 0.01% Boron  B  Manganese  Mn  Oxygen  O  : 65.0% Magnesium  Mg  : 0.1% Phosphorus  P  : 1.0% Potassium  K  : 0.4% Sulfur  S  : 0.3% Sodium  Na  : 0.2% Chlorine  Cl  : 0.2% Cobalt  Co  Chromium  Cr  Iron  Fe  Iodine  I  Fluorine  F  Copper  Cu  Silicon  Si  Zinc  Zn  Vanadium  V  Tin  Sn  Molybdenum  Mo  Selenium  Se  –Twenty-five elements are essential to life. –Four elements make up about 96% of the weight of the human body: Oxygen Carbon Hydrogen Nitrogen

First electron shell  can hold 2 electrons  Outer electron shell  can hold 8 electrons  Hydrogen  H  Atomic number = 1 Carbon  C  Atomic number = 6 Nitrogen  N  Atomic number = 7 Oxygen  O  Atomic number = 8 Electron Chemical Properties of Atoms –Electrons determine how an atom behaves when it encounters other atoms. © 2010 Pearson Education, Inc.