BIOLOGY 111 1st Edition Lecture 2 Outline of Last Lecture I Introduction to Biology II Levels of Organization III IV V VI Reductionist advantages and disadvantages Biology Systems Cell Evolution Outline of Current Lecture I Methods II Reasonings III Experimentation IV Scientific Theory V Overview of Chemistry and Physics Current Lecture Initial scientific investigations are characterized as descriptive or discovery meaning an event of phenomenon is observed for hours days weeks months or even years just to gather enough data and record enough observations to gain insight and with the goal to describe define said event or phenomenon Hypotheses based research in order to be useful must be testable to check validity AND falsifiable opportunity to be proven not true In forming a hypothesis we are predicting the causes and explanations for events If the hypothesis is given a chance to fail through experimentation but doesn t the hypothesis is then strengthened Keep in mind however that just because a hypothesis is accepted that does not meant that is the ONLY TRUE hypothesis or explanation Reasoning Inductive reasoning derives generalizations after collecting and analyzing observations Deductive reasoning used after the hypothesis has been made and instead of a general conclusion we conclude more specifically Experimentation These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute in biology most experiments are controlled Controlled experiments are designed to keep everything constant i e environment except for the experimental group in which only one factor is changed Control group used as the basis for comparison in an experiment kept constant Experiment group the group that has changed factor that is being tested measured Scientific Theory I What s the question II What s the hypothesis III Experiment conducted A What s the control B What s the dependent variable C What the independent variable IV What is the conclusion Chapter 2 Biology is based on the basic principles of Chemistry and Physics Physics because we abide by the many laws thermodynamics energy gravity chemistry because EVERYTHING is made up of carbon and atoms i e ants secrete formic acid CO2H2 SMALL changes in a molecule have a BIG effect on organisms i e the differences in functional groups of Estradiol female and Testosterone male ALL life forms are made up of Matter anything that takes up space and contains space and is composed of elements There are 4 elements that make up 96 of organisms 1 Oxygen 2 Carbon most important 3 Hydrogen 4 Nitrogen most abundant in the atmosphere There are other elements that are also critical and that make up about 4 i e calcium sodium magnesium And then there are trace elements that make up about 01 i e copper iron zinc tin all of the most important elements of life can be found in the first 3 valence shells rows on the periodic table Valence shell outermost electron shell Valence electrons outer unpaired electrons that are available to make bonds with other atoms containing unpaired electrons o Hydrogen has one valence electron o Oxygen has two o Nitrogen has three o Carbon has four valence electrons the number increases as you move from left to right on the periodic table the more bonds that can be made the more valence electrons the more desirable an atom with a complete valence is unreactive meaning it will not react readily with other atoms these atoms are said to be inert chemically unreactive Covalent bonds formed by the sharing of a pair of valence electrons by two atoms most stable bonds to be formed Single bond pair of shared electrons by two atoms Double bond two pairs of shared electrons between to atoms Molecule two or more atoms held together by covalent bonds Elements pure substances that cannot be destroyed or broken down to other substances by chemical reactions chemists recognize there to be 92 occurring in nature Compound a substance consisting of two or more different elements combined in a fixed ratio each contain very different properties from the individual elements that construct it Atoms smallest unit of matter that still retains the properties of an element the structure determines element properties The protons charge the electrons charge Protons positively charged determines the element represent the atomic number A for a element Electrons negatively charged Determines chemical behavior Neutrons neutral no charge Determines isotopes differing forms of the same element having the same number of protons but different number of neutrons adding the protons and neutrons gives the mass number Carbon Dating determines the age of an object based on the decay rate of carbon in the object i e C12 isotope stays because its most stable whereas C14 decays within 60 000 years Energy b c energy cannot be created nor destroyed it is converted between potential and kinetic Potential energy stored energy in matter based on location and structure o Begins maxed out sitting at the top of the slide o Decreases as it is used and converted into kinetic energy sliding to the bottom Kinetic energy used energy sitting at the bottom of the slide Atoms have stored energy and varies based on its valence shells Third valence shell furthest from nucleus highest energy level can hold up to 8 electrons potential energy state Second valence shell midway from nucleus medium energy level can hold up to 8 electrons First valence shell closest to the nucleus lowest energy level can hold up to 2 electrons kinetic energy state as you move outward from first valence shell to the third energy is absorbed increase potential energy and decrease kinetic energy as you move inward from third valence shell to the first energy is released decrease potential energy and increase kinetic energy Electron Orbitals The three dimensional space where an electron is found 90 of the time First shell is 1s orbital which can hold 2 electrons Second shell is 2s orbital and three 2p orbitals which holds 8 electrons 2 per orbital