UNIFYING THEMES OF BIOLOGY Copyright © 2009 Pearson Education, Inc. Cells are the structural and functional units of life . Two distinct groups of cells exist – Prokaryotic cells – Simple and small – Bacteria are prokaryotic – Eukaryotic cells – Possess organelles separated by membranes – Plants, animals, and fungi are eukaryotic Copyright © 2009 Pearson Education, Inc. Prokaryotic cell Eukaryotic cell DNA (no nucleus) Membrane Nucleus (contains DNA) Organelles Cells are the structural and functional units of life (continued) . Unicellular organisms . Multicellular organisms Copyright © 2009 Pearson Education, Inc. Cells are the structural and functional units of life (continued) . Form generally fits function – By studying a biological structure, you can determine what it does and how it works (from molecules to organisms!) – Life emerges from interactions of structures – Combinations of structures (components) provide organization called a system Copyright © 2009 Pearson Education, Inc. In life’s hierarchy of organization, new properties emerge at each level . Life’s levels of organization define the scope of biology . Life emerges through organization of various levels . With addition of each new level, novel properties emerge—called emergent properties Copyright © 2009 Pearson Education, Inc. Biosphere Ecosystem Florida coast Community All organisms on the Florida coast Population Group of brown pelicans Organism Brown pelican Spinal cord Organ system Nervous system Brain Nerve Organ Brain Tissue Nervous tissue Cell Nucleus Atom Nerve cell Organelle Nucleus Molecule DNA Reproduction and Inheritance . Organisms pass their traits from one generation to the next generation via reproduction. DNA is the molecular basis of life (ALL life on Earth) DNARNAProtein . The inheritance of genetic material through reproduction explains the continuity of life Copyright © 2009 Pearson Education, Inc. Reproduction and Inheritance (continued) . Continuity of life is based on heritable information in the form of DNA . DNA–the genetic material–carries biological information from one generation to the next EVOLUTION--THE CORE THEME OF BIOLOGY “Nothing in biology makes sense except in the light of evolution.” --Theodosius Dobzhansky Copyright © 2009 Pearson Education, Inc. Evolution . Evolution explains the unity and diversity of life. Unity What do organisms have in common? Why do similarities exist? . Diversity Are there differences between organisms of the same species? . Unity . Shared genetic code . Evolutionary relationships . Connected through a common ancestor . Diversity . Differences in DNA structure among organisms . Natural selection: selection of some DNA structures over others . Adaptations: naturally selected traits . Natural selection was inferred by connecting two observations . Individuals within a population inherit different characteristics and vary from other individuals . A particular population of individuals produces more offspring than will survive to produce offspring of their own (Lamarckian evolution and giraffes) Copyright © 2009 Pearson Education, Inc. In this example: • Dark-colored beetles are selected for 1 Population with varied inherited traits • Light-colored beetles are selected against • Predation is the selective agent 2 Elimination of individuals with certain traits • Dark coloration becomes an adaptation for this population of beetles 3 Reproduction of survivors . Natural selection is an editing mechanism – It results from exposure of heritable variations to environmental factors that favor some individuals over others – Over time this results in evolution of new species adapted to particular conditions/environments – Evolution is biology’s core theme and explains unity and diversity of life Copyright © 2009 Pearson Education, Inc. The Three-Domain System Protists Plants Fungi Animals Domain Eukarya Domain Bacteria Bacteria (multiple kingdoms) Protists (multiple kingdoms) Kingdom Plantae Domain Archaea Archaea (multiple kingdoms) Kingdom Fungi Kingdom Animalia YOU ARE HERE Dr. R.M. Moody THE PROCESS OF SCIENCE Copyright © 2009 Pearson Education, Inc. Scientists use two main approaches to learn about nature . Two approaches are used to understand natural causes for natural phenomena – Discovery science—uses verifiable observations and measurements to describe science – Hypothesis-based science—uses the data from discovery science to explain science – This requires proposing and testing of hypotheses Copyright © 2009 Pearson Education, Inc. Scientists use two main approaches to learn about nature . There is a difference between a theory and a hypothesis – A hypothesis is a proposed explanation for a set of observations – A theory is supported by a large and usually growing body of evidence Copyright © 2009 Pearson Education, Inc. With hypothesis-based science, we pose and test hypotheses . We solve everyday problems by using hypotheses – An example would be the reasoning we use to answer the question, “Why doesn’t the flashlight work?” – Using deductive reasoning we realize that the problem is either the (1) bulb or (2) batteries. – The hypothesis must be testable – The hypothesis must be falsifiable Copyright © 2009 Pearson Education, Inc. Observations Question Hypothesis #1: Hypothesis #2: Dead batteries Burned-out bulb Hypothesis #1: Hypothesis #2: Dead batteries Burned-out bulb Prediction: Prediction: Replacing batteries Replacing bulb will fix problem will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis BIOLOGY AND EVERYDAY LIFE Copyright © 2009 Pearson Education, Inc. CONNECTION: Biology, technology, and society are connected in important ways . Many of today’s global issues relate to biology (science) – Many of these issues resulted from applications of technology – Science and technology are interdependent, but their goals differ – Science wants to understand natural phenomena – Technology applies science for a specific purpose Copyright © 2009 Pearson Education, Inc. EVOLUTION CONNECTION: Evolution is connected to our everyday lives . How is evolution connected to our everyday lives? – It explains how all living species descended from ancestral species – Differences between DNA of individuals, species, and populations reflect evolutionary change – The environment matters because it is a selective force that drives evolution – An understanding of evolution helps us fight disease and develop conservation efforts Copyright © 2009 Pearson Education, Inc. Inferences Observations Natural selection: Individual unequal reproductive variation success Overproduction Evolution of offspring of adaptations in a population Types of Inference (Reasoning) . INDUCTIVE INFERENCE: Arriving at a conclusion based on repeated observation. Repeated observation of the phenomenon supports my hypothesis. The sun came up yesterday and today, so I predict it will come up tomorrow. Can only say that our conclusion is probably true. Types of Inference (Reasoning) . DEDUCTIVE INFERENCE: Logical process of using accepted facts to draw conclusions. Expressed using syllogisms: If A then B (Premise) A (Premise) therefore, B (Conclusion) . Problem: If the premises are not true, then the conclusions might be wrong. 1. All men are mortal. Socrates is a man, therefore Socrates is mortal. 2. All mammals are warm-blooded. All dogs are warm-blooded. Therefore, all dogs are mammals. 3. All people sweat profusely after running a marathon. You are sweating a lot. Therefore, you must have just run a marathon. Critical Thinking and Science . Critical thinking is the deliberate process of judging the quality of information before accepting it. Critical thinking should be a part of your everyday life: . When listening to the media . Surfing the internet . Listening to me, reading textbooks, etc. HOWEVER: YOU MUST BE KNOWLEDGEABLE ABOUT A SUBJECT BEFORE YOU CAN EFFECTIVELY ARGUE OR DISCUSS IT! Scientists use two main approaches to learn about nature: . Two approaches are used to understand natural causes for natural phenomena: – Discovery/observational science—uses verifiable observations and measurements to describe natural phenomena (e.g., fossil record, astronomy, etc.) – Hypothesis-based /Experimental science—uses the data from discovery science to explain natural phenomena. – This requires proposing and testing hypotheses Hypotheses . A HYPOTHESIS is a testable explanation for a natural phenomenon. Hypotheses are: . Formed based on observation and current theory. “Rejected” or “Not rejected”, never “Proven” . *Hypotheses guide the design of experiments* . Often stated as an “If…then…” statement Example: Effects of fertilizer and light on plant growth The Scientific Method: Testing Hypotheses . Explore a phenomenon & make observations . Construct a question to investigate based on your observations . Construct a hypothesis . State a prediction based on the evidence . Plan and test the hypothesis with an experiment . Analyze the data and evidence . Form a conclusion based on your results and construct new knowledge . Was the hypothesis rejected or supported? . Form an explanation (model) based on your conclusions and supporting evidence . Connect your new knowledge to your prior knowledge and the knowledge of others (existing theories) . Consider follow-up questions for investigations Theories and Laws . LAWS describe how a system behaves (e.g., the law of gravity). Biological Rules are Biological laws . Help describe patterns and relationships but not explain how they work. THEORIES