Biol 1107 Chapter 1 I Biology science of life A What is life 1 Characteristics of all living things a Made of cells basic unit of organisms i May be unicellular ex bacteria ii May be multicellular ex us trees ants b Living things grow size and or number of cells increase i May grow continuously ex trees ii May only grow during a short period ex animals c Have metabolisms sum of all the chemical reactions in the organism i Energy is essential for life needed to maintain function grow repair etc ii Metabolism is carefully controlled iii Must maintain homeostasis balanced internal environment d Respond to stimuli changes in internal or external environment i Stimuli include light sound temperature chemicals etc ii Response always involves some sort of movement Not always visible or large scale e Organisms reproduce make more of themselves i May be asexual one parent gives rise to identical offspring Ex bacteria some plants ii May be sexual two parents give rise to non identical offspring Ex almost all animals most plants f Organisms evolve populations change over time to become better adapted to their environment i Ex thick layers of blubber on animals that live arctic regions ii Adaptations come in different forms Structural ex spines on cactii Physiological biochemical lizards secrete nitrogenous waste as a dry paste daylight Behavioral most desert animals are inactive during peak B Life requires constant energy input 1 Most originates from the sun a Some bacteria and archaea are exceptions 2 Autotrophs produce food from simple ingredients a Also called producers i Plants algae some bacteria b Most use photosynthesis i Capture light energy to make chemical bonds ii CO2 H2O sugar O2 3 Heterotrophs breakdown food made by autotrophs a Also called consumers i Animals fungi most bacteria b Usually use cellular respiration i Chemical bonds are broken to release energy ii Sugar O2 CO2 H20 c Producers also use cellular respiration 4 Uses for energy a Make building blocks b Maintain homeostasis c Growth d Repair e Movement f etc C Life requires a lot of information 1 Organisms have to do a lot of complex things just right a Requires accurate and timely information 2 Information must be transmitted internally a Very important in multicellular organisms i Endocrine system uses hormones ii Nervous system uses electrical impulses and chemicals b Have to coordinate activities 3 Information is transmitted between individuals a May be same or different species b May be chemicals sounds visual displays etc i Animals marking territory with scents ii People talking 4 Information must be transmitted between generations a Extremely important that it be accurate b Information is stored as a chemical i DNA deoxyribonucleic acid ii DNA is the building block for genes genes are individual pieces of information c DNA is passed from parent to offspring i Carries information on how to do all the life processes D Evolution is the central underpinning of biology 1 Theory of evolution explains how populations of organisms have changed over time a Over time populations adapt to their environment i Adaptations always come from changes in the DNA information ii Evolution is the accumulation of adaptations 2 Evolution is driven by natural selection mechanism by which beneficial traits become more common in populations over time a Four basic observations support this i Individuals of a species have variation ii Organisms produce more offspring than will survive to reproduce iii Organisms compete for resources Helpful adaptations make for better competitors Better competitors are more likely to survive and iv Survivors pass on their adaptations to offspring Over time larger and larger part of the population has the reproduce adaptation II Biology uses the scientific method A Systematic process with defined steps 1 Observation closely examine something a Formulate a question 2 Hypothesis come up with a plausible explanation a Look into what others have found b Adapt existing information to your scenario 3 Experiment test your hypothesis a Must set up experiments properly i Controls large sample size repeatable etc 4 Analyze does experimental data support or reject hypothesis a b Reject go back to step 2 and alter or replace hypothesis Support test hypothesis in new ways to see if it still holds B A hypothesis can never be proven true 1 Always possible some new experiment will reject it a Scientists try to prove hypotheses false 2 The more times a hypothesis stands up to experiment the more trust is placed in it 3 Very strong hypotheses may become part of a theory C Theory an integrated explanation of something in the natural world 1 Based on numerous well tested hypotheses a Note the difference between the scientific use and popular culture usage of theory 3 When we talk about the theory of evolution a It s an integrated explanation of a natural phenomenon i ie species change over time b Based on many well tested hypotheses i Better adapted individuals reproduce more ii DNA stores information iii DNA passed to offspring iv Good adaptations become more common