Unifying Themes of Biology

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

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

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)

DNARNAProtein

. The inheritance of genetic material through reproduction explains the continuity of life

. 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

. 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

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

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

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 explain those laws.

. Explains how laws work.

. In our everyday use of the word, it often means “imperfect fact” or “speculation.”

. Used similarly to a hypothesis

. This is not accurate

. In science, a theory is something VERY SPECIFIC!!! Theories and Laws . A SCIENTIFIC THEORY is something that has been tested many different times, in many different ways, and has not yet been refuted. . Theories are supported or rejected by testing hypotheses. . Theories can change! . HOWEVER, theories are rejected ONLY when they: . Are replaced by new theories that explain predictions of the old theory . AND make new predictions! Societal Conflicts

. Society’s traditional views of nature sometimes differ with scientific findings (e.g., Capernicus’ heliocentric model and Galileo).

. You have to remember that science can only describe and attempt to explain the physical world. Science vs Pseudoscience

. “Pseudo” = false . The only way to spot a fake is to know as much as possible about the real thing! Pseudoscience… Science vs Pseudoscience Science… . Results are not verifiable and cannot be reproduced . Results are verifiable and can be reproduced . Methods are often unknown . Clear what methods were used to reach conclusions . Failed predictions are ignored, . Focus on failed predictions of excused, or even hidden and lied a theory about . Progresses; more and more . is learned about the process No progress is made; nothing under study concrete is learned . Convinces by appeal to . Convinces by appeal to belief evidence or faith . No conflicts of interest; no personal financial stake in . Pseudoscientists often earn results of scientific studies some or all of their living selling their “services” Scientific Experiments

. Used to test hypotheses

. Conducted under carefully controlled conditions. where experimental variables can be controlled.

. Ideally, conditions should be the same for all groups; only change the variable you are interested in. Scientific Experiments

. The INDEPENDENT VARIABLE is the variable the scientist changes in the experiment . The DEPENDENT VARIABLE is what the scientist observes/measures in the experiment (the result) . A CONTROL group is a group in which no changes are made. It used as a standard for comparison. . A TREATMENT (experimental) group is subjected to the same conditions as the control group except for the variable(s) being studied. Qualitative vs Quantitative Data . QUALITATIVE DATA . Deals with descriptions (qualitative = quality) . Data that can be observed but not measured . E.g.) colors, textures, smells, tastes, appearance, relative size, etc. . QUANTITATIVE DATA . Deals with numerical descriptions (quantitative = quantity) . Data that can be measured . E.g.) length, height, area, volume, mass, temperature, time, velocity, etc. Fertilizer Experiment

1) State a hypothesis 2) State a prediction 3) Identify the experimental groups 4) What could be used as a control group? 5) Identify the dependent variable 6) Identify the independent variable Sampling Error and Replication

. It is important to conduct multiple trials with each independent variable. This is called replication. . Why replicate? . What do you do with data from multiple trials/observations?

. Researchers cannot measure every individual in a population; data collected from a sample of the population.

. Sampling errors occur when conclusions inferred from the collected sample differ from the whole population. . Occurs when sample sizes are small. . Sampling error can be reduced by using a larger sample size Vitamin C and Cancer in Mice

It has been suggested that vitamin C supplements lower the risk of cancer in mammals. You are given 100 mice that have been bred to have an identical genetic make-up. You are asked to design an experiment to address the question of whether vitamin C lowers the risk of cancer in mice. 1)Form a hypothesis 2)State a prediction 3)Design an experiment to test your hypothesis 4) Identify the following: a) Control group; b) Treatment group, c) Independent variable, and d) Dependent variable Graphs

. Graphs help you interpret and communicate your results. . Graphs show the relationship between your dependent and independent variables. . Independent variable (X-axis): What you change . Dependent variable (Y-axis): What is measured . Type of graph used depends on the type of data being presented: . Continuous Data . Discrete (categorical) Data Graphs

. Include: . Descriptive title . Axes labels . Appropriate scales . Change appearance of points/lines if plotting more than one data set on the same graph . Use different colors . Solid vs dashed lines