[...]... available evidence points to an origin of life some 4 billion years ago Natural selection has led to the current host of organisms inhabiting the planet There are specific characteristics of life, and the evolutionary roots of these characteristics can be traced through time • All life on Earth is organized in the Tree of Life based on molecular evidence When studying organisms from an evolutionary... (HAPHR Studying Lif� Important Concepts • with each other Organisms from one species living Biology is the study of living things • Ecology is the study of how different species interact together make up a population The many populations of different species in an area make up a community Living things are made up of cells They can be composed of one cell; unicellular, or multiple... the preceding step Two characteristics of science set it apart from other modes of inquiry One is the setting of hypotheses The other is the continual process by which it is carried out With each conclusion leading to a new set of hypotheses, science has the capacity to alter our overall base of knowledge Biologists have always used observation as a means to study life As we move forward, many new tools... weight of the molecule tinl.es 1 2 and adding that many grams of the substance to one liter of water The formula weight of this molecule is 342, so you would need 4104 g (UAPHR Macromolecules and the Origin of Life Important (on(�pts • Molecules have specific properties that enhance their amino acids Proteins may be made of single chains of biological activity • Functional groups are small groups of atoms... following activities on the Companion 3 7 Which of the follOwing are necessary for speciation to Website/CD: occur? Activity a Reproductive isolation of two groups of organisms 1.1 The Hierarchy of Life Activity 1.2 The Major Groups of Organisms c A reduction in the number of individuals in a Test Yourself population Know/edge and Synthesis Questions 1 Life arose on Earth approximately how many years... Textbook Reference: a Archaea 1.2 How Is All Life on Earth is/are the differences among organisms that allow for life in such a wide variety of environments on Earth c Homeostasis 1.1 What Is Biology? p 6 living organisms? a Regulation of internal environment b Composed of one or more cells c Ability to produce biological molecules d None of the above 1 1 What Is Biology? p 2 4 Photosynthesis was a major... effective coolant • The polar nature of water and the formation of hydrogen bonds contribute to the cohesive strength of Homeostasis is the maintenance of a constant internal environment A buffer is a mixture of a weak acid and lost during the freezing of water • The pH of a solution refers to the concentration of H+ ions and is measured as the 10glO of the H+ concen­ tration' pH -loglO[H+] Lower pH indicates... would be a difference of 10 x 10 x 10 x 10, or 10,000 11 b A solution with a pH of 2 is acidic, and one with a pH of 8 is basic The lower the pH value, the higher the concentration of H+ ions 12 ions? weigh t of 180 atomic mass units Because one mole is equal to the atomic weight 12 moles of a substance, how many molecules do you have of that substance? Suppose the 13 What Properties of Water Make So Important... Biological science has an impact on every h u man being and is the basis for many public policy decisions • All organisms are descendants of a single unicellular organism • Different species come about when two groups of organisms in one species are isolated from each other so that they can no longer mate and produce viable offspring • The Big Picture • Biology is the study of living things composed of cells... basic components of the macromolecules, memorizing Two major theories exist for the beginning of life on Earth One theory of the origin of life on Earth is based on the Avoid the temptation to memorize structures If you understand condensation and hydrolysis and know the messenger in many cellular processes • Make a table of macromolecule characteristics This will help you see the pattems of similarity