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Introduction to Biology BIOS 1010 7A Sarah Jeffers Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Chapter 1 Introduction to Life on Earth Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Levels of Organization of Matter & Species Fig. 1-1 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. What Are The Characteristics of Living Things? Living things are composed of cells – Living things are both complex and organized Fig. 1-8 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Cell Is the Smallest Unit of Life Fig. 1-2 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Cell Is the Smallest Unit of Life • A characteristic of all living things is organization. • Thus the name of all living things as organisms. •All organisms consist of one or more cells •The cell is the simplest structural and functional unit of life. •Cells are the building blocks of all •plants and animals. •All new cells come from the division •of pre-existing cells. •Nutrients •Division •Cell •Cells are the smallest units that perform •all vital physiological functions. •O2 •Wastes •CO2 •Growth •New •cells •The cell theory Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Domains and Kingdoms of Life The “Tree of Life” Fig. 1-11 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. How Do Scientists Categorize the Diversity of Life? Categorizing life – There are exceptions to any simple set of rules used to distinguish the domains and kingdoms, but three characteristics are particularly useful – Cell type – The number of cells in each organism – Energy acquisition Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. How Do Scientists Categorize the Diversity of Life? Classification into a domain or kingdom is based on 3 characteristics: 1. Cell type •Bacteria •Archaea Biology: Life on Earth, 9e •Eukarya Copyright © 2011 Pearson Education Inc. How Do Scientists Categorize the Diversity of Life? Classification into a domain or kingdom is based on 3 characteristics: 2. Number of cells •Bacteria •Archaea Biology: Life on Earth, 9e •Eukarya Copyright © 2011 Pearson Education Inc. How Do Scientists Categorize the Diversity of Life? Classification into a domain or kingdom is based on 3 characteristics: 3. Energy Acquisition Autotroph Self-feeding Photosynthesis Plants, some Archaea some Bacteria some Protists Biology: Life on Earth, 9e vs. Heterotroph Other-feeding Digest external food Fungi, Archaea Bacteria Animals some Protists Copyright © 2011 Pearson Education Inc. How Are Organisms Named And Classified? Taxonomy – naming and classifying organisms – Scientific name: two part Latin name – Genus (closely related species) – species (populations that can interbreed) Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. How Are Organisms Named And Classified? Taxonomy – naming and classifying organisms – Scientific name: two part Latin name – Examples: Sialia (Bluebirds) Sialia sialis (eastern) Biology: Life on Earth, 9e Sialia mexicana (western) Sialia currucoides (mountain) Copyright © 2011 Pearson Education Inc. How Are Organisms Named And Classified? Phylogeny – evolutionary history – Similarities from a common ancestor – Not similarities from convergent evolution – Phylogenic trees Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Review Questions 1. List the three precepts of the cell theory. 2. Can you describe the levels of biological organization? 3. Can you name and briefly describe the three domains of life? 4. Can you explain how scientists discovered that prokaryotes fall into two domains? 5. Can you explain how scientists name and categorize diverse forms of life? 6. Can you explain why phylogenetic classifications sometimes change? Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. •What is Science? Historical approaches to studying life – The belief that some events happen through supernatural forces (e.g., the actions of Greek gods) – The belief that all events can be traced to natural causes that we can comprehend (natural causality) – Corollary: Evidence gathered from nature has not been deliberately distorted to fool us Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. What is Science? Scientific principles underlie all scientific inquiry – Natural causality is the principle that all events can be traced to natural causes – Natural laws apply to every time and place – Scientific inquiry is based on the assumption that people perceive natural events in similar ways Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. What is Science? The scientific method is the basis for scientific inquiry – – – – – – Observation Question Hypothesis Prediction Experiment or Observation Conclusion Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. What is Science? The scientific method 1. Observation of a specific phenomenon 2. The observation, in turn, leads to a question 3. The question leads to formulation of a hypothesis, based on previous observations, that is offered as an answer to the question 4. The hypothesis leads to a prediction, typically expressed in “if…then…” language 5. The prediction is tested by carefully controlled manipulations called experiments 6. The experiments produce results that either support or refute the hypothesis, allowing the development of a conclusion Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. What is Science? The scientific method – Scientific experimentation tests the assertion that a single variable causes a particular observation – Controls are incorporated into experiments – Controls keep untested variables constant Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Scientific Method Fig. 1-4 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Experiments of Francesco Redi Fig. E1-1 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Experiments of Malte Andersson Fig. E1-2 Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Scientific Method Limitations of the scientific method – One can never be sure all untested variables are controlled – Conclusions based on the experimental data must remain tentative Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Scientific Method Communication is crucial to science – Results of experimentation must be communicated thoroughly and accurately to other scientists for repetition – Repetition by other scientists add verification that findings can be used as the basis for further studies Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. The Scientific Method Science can be accidental – In the 1920s, bacteriologist Alexander Fleming grew bacteria in cultures – One of the bacterial cultures became contaminated with a mold(Penicillium) – Fleming nearly destroyed the culture when he noticed the mold Fleming hypothesized that the mold produced an antibacterial substance Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Scientific Theory What does Scientific theory mean? – A scientific theory differs in definition from that of everyday usage – Many people use the word theory to mean hypothesis, or an “educated guess” Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Scientific Theory – A scientific theory is a general explanation for important natural phenomena – It is extensively and reproducibly tested – If compelling evidence arises, a theory may be modified – Described as a natural law – New scientific evidence may prompt radical revision of existing theory – For example, the discovery of prions Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc. Scientific Theory The discovery of prions – Before 1980, all known infectious diseases contained DNA or RNA – In 1982, Stanley Prusiner showed that the infectious sheep disease scrapie is caused by a protein (a “protein infectious particle,” or prion) – Prions have since been shown to cause “mad cow disease” and diseases in humans – The willingness of scientists to revise accepted belief in light of new data was critical to understanding and expanding the study of prions Biology: Life on Earth, 9e Copyright © 2011 Pearson Education Inc.