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Freeman Quillin Allison © 2014 Pearson Education, Inc. BIOLOGICAL SCIENCE FIFTH EDITION 1 Biology and the Tree of Life Lecture Presentation by Cindy S. Malone, PhD, California State University Northridge

© 2014 Pearson Education, Inc. Assignment  Read the ENTIRE syllabus  Read text sections listed on course calendar for today and tomorrow  Review with a friend (make a new one today!)  (Note: There WILL be a quiz)

© 2014 Pearson Education, Inc. Lecture Objectives  Bloom’s Taxonomy – Thinking about learning  What are the properties of life?  How are these properties connected?  Using Concept maps to make connections  What is science? –The Metric system –The scientific method –Manipulative experiments –Observational studies

© 2014 Pearson Education, Inc. Figure B16.1 Bloom’s Taxonomy

© 2014 Pearson Education, Inc. From: Krathwohl, D. R A Revision of Bloom's Taxonomy: An Overview. Theory into Practice 41: Two dimensions: Knowledge (below) and Cognitive processes

© 2014 Pearson Education, Inc. From: Krathwohl, D. R A Revision of Bloom's Taxonomy: An Overview. Theory into Practice 41:

© 2014 Pearson Education, Inc. Figure B16.1 Greater proficiency (and better grades!) Progression Decide which of a pair of competing theories, hypotheses or experiments is more convincing Design an experiment to test a novel hypothesis Analyze data Solve problems Explain, Contrast, Define, Recall

© 2014 Pearson Education, Inc. Roadmap 1 In this chapter you will learn about Key themes to structure your thinking about Biology starting with including firstthen including What does it mean to say that something is alive? Two of the greatest unifying ideas in Biology The cell theory The theory of evolution by natural selection The process of doing Biology The tree of life 1.4 predicts A simple “concept map” for Chapter 1

© 2014 Pearson Education, Inc. What Does It Mean to Say That Something Is Alive?  All living organisms share five fundamental characteristics: 1. Energy –All organisms acquire and use energy 2. Cells –All organisms are made up of membrane-bound cells 3. Information –All organisms process hereditary information encoded in genes as well as information from the environment

© 2014 Pearson Education, Inc. What Does It Mean to Say That Something Is Alive? 4. Replication –All organisms are capable of reproduction 5. Evolution –Populations of organisms are continually evolving These properties are all interrelated and evolution is an inevitable consequence of the other properties

© 2014 Pearson Education, Inc. All living things (organisms) are made up of cells –Cell membranes separate living stuff inside cell from other stuff outside –Cells may be further subdivided by additional membranes –Organisms may be unicellular or multicellular –Cells reproduce by cell division – they come from and give rise to other cells Characteristics of Living Things

© 2014 Pearson Education, Inc. Characteristics of Living Things  All living things (organisms) are highly organized –Cells are complex biochemical entities not in equilibrium with their environment –Entropy – in a closed system, things tend to become less ordered over time –Inputs of energy are required just to maintain this ordered state (homeostasis)

© 2014 Pearson Education, Inc. Fig. 6.3

© 2014 Pearson Education, Inc. A cell requires energy just to maintain its internal complexity

© 2014 Pearson Education, Inc.  All living things grow & develop –Increase in size and number of cells –Growth may be different in different locations, resulting in changes in shape –Individuals change as development proceeds throughout life Characteristics of Living Things

© 2014 Pearson Education, Inc. Growth and development require energy above that required for maintenance

© 2014 Pearson Education, Inc.  All living things acquire and use energy –Sum of all biological chemical reactions is metabolism –Extract energy from the environment for homeostasis - maintenance of complex, organized intracellular condition in the face of entropy –Need still more energy to grow, reproduce, etc. –Energy is lost to entropy as heat at every step Light energy used by plants for photosynthesis Energy in food used for life processes Energy in plant litter, other wastes processes dead bodies, feces, and used for life Heat energy loss (Entropy) Soil Entropy Carnivores Plants Decomposers Herbivores Entropy

© 2014 Pearson Education, Inc.  Replication -All living things reproduce by cell division –All life arises from previous living forms (i.e., “parents”) – No spontaneous generation! –Reproduction can be asexual: –Simple – cells merely split –Or complex – budding, parthenogenesis, etc. –Reproduction can be sexual: –Complex, involves formation of gametes (sex cells, such as eggs and sperm) which fuse to form a zygote (fertilized egg)

© 2014 Pearson Education, Inc.  All living things inherit and pass on information encoded in genes as DNA (Deoxyribonucleic acid ) –DNA code is transferred from parent to offspring –DNA code provides a “recipe” for metabolism, and thus affects the patterns of growth, development, reproduction, and behavior of organisms –DNA must be copied to be passed on. Copying errors (mutations) generate variation in the code

© 2014 Pearson Education, Inc.  Living things evolve & adapt to their environment –Entropy and the need for limited energy for growth, development, and reproduction place a premium on efficiency of metabolism –Metabolism, in turn, depends on the inherited DNA code –Those codes bearing the recipes for the most successfully reproducing organisms will increase in the population relative to less successful codes. –Populations of organisms adapt to the prevailing environment as the efficient codes predominate

© 2014 Pearson Education, Inc. Concept mapping time! The “5 Properties” Energy Cells Information Replication Evolution Additional terms (you may think of others) Entropy DNA Growth Mutation MetabolismCell division Development Efficiency Variation Population Adaptation

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Biology is a Science  Science is a means of gaining new knowledge about the natural world through controlled observations –Science is not memorizing “facts” –Science neither invokes nor addresses the supernatural –Rather, science assumes there is a physical reality we can know through observation –Science requires observations of at least two conditions which differ in only one factor

© 2014 Pearson Education, Inc.  Science is quantitative  Observations must be reported in measurable units – scientists use the metric system –Basic metric units –Length:Meterm –Mass:Gramg –Time:Seconds –Volume:LiterL –Multipliers –x 1,000,000(10 6 )Mega-M –x 1,000(10 3 )Kilo-k –x 0.01(10 -2 )Centi-c –x 0.001(10 -3 )Milli-m –x (10 -6 )Micro-   Confidence in results can be measured with statistical tools

© 2014 Pearson Education, Inc. Statistical significance – usually p<0.05  i.e., when an event is likely to happen by chance less than one time in 20 if null hypothesis is correct  Depends on –difference between means (or slope of relationship, etc), –number of samples (replication) –variation or “spread” in data

© 2014 Pearson Education, Inc.  Science is self-correcting –If results cannot be repeated they are not considered reliable –Replication by other scientists –Replication within an experiment  statistical confidence  Science provides tentative answers that are open to revision as new data come to light –Science cannot yield absolute proof –Data may be interpreted to mean different things

© 2014 Pearson Education, Inc. The Scientific Method  Observation – must “see” something that needs explaining  Question  Hypothesis – a tentative answer or explanation –Always accompanied by a null hypothesis  Predictions – derived logically from hypotheses –If hypothesis is testable, there must be one or more possible observations that would lead to its rejection  Test – new set of controlled observations –If outcome supports either null or alternative hypothesis, tentatively accept that hypothesis –If outcome supports neither, consider additional alternative hypotheses –Results often stimulate further questions or refinements of hypotheses  Repeat process, integrating new information, until question is answered convincingly

© 2014 Pearson Education, Inc. Observation: The light does not turn on Question: Why not?

© 2014 Pearson Education, Inc. Hypothesis: ??? Prediction if hypothesis is correct: ??? Prediction if hypothesis is incorrect: ??? Null hypothesis: ??? Test of prediction: ??? Possible outcomes: ??? Next Hypothesis if not satisfied: ???

© 2014 Pearson Education, Inc. Experiments and other tests  Manipulative experiments –A powerful scientific tool because they allow researchers to test the effect of a single, well- defined factor on a particular phenomenon –Experimenter sets up control and experimental treatments –Example: Louis Pasteur’s test of spontaneous generation

© 2014 Pearson Education, Inc. Figure 1.2 Cells arise spontaneously from nonliving materials. Cells are produced only when preexisting cells grow and divide. Do cells arise spontaneously or from other cells? Pasteur experiment with straight-necked flask: 1. Place nutrient broth in straight-necked flask. 2. Boil to sterilize the flask (killing any living cells that were in the broth). 3. Preexisting cells enter flask from air. No cells Cells Cells will appear in broth. Cells Cells arise from preexisting cells, not spontaneously from nonliving material. No cells Spontaneous generation hypothesis rejected Cells will not appear in broth. Cells will appear in broth. 1. Place nutrient broth in swan-necked flask. Cells Pasteur experiment with swan-necked flask: Cells No cells 2. Boil to sterilize the flask (killing any living cells that were in the broth). Condensation settles in neck 3. Preexisting cells from air are trapped in swan neck. Both hypotheses supported

© 2014 Pearson Education, Inc. Louis Pasteur’s Experiment  What was his hypothesis (a testable statement that explains something observed)?  What was his prediction? (a result that would be observed if the hypothesis is valid)?  What would the null hypothesis be?  What were the control and experimental treatments?

© 2014 Pearson Education, Inc. Experiments are not the only way to test hypotheses Observational studies can also be used to test hypotheses  Still follows scientific process: 1.State the hypothesis as precisely as possible 2.List the predictions it makes 3.Determine what observations would suffice to test those predictions 4.Make observations to see if predictions are borne out

© 2014 Pearson Education, Inc. Why Do Giraffes Have Long Necks?  The food competition hypothesis argues that long necks evolved because those with long necks can reach food unavailable to other mammals –Prediction: –Giraffes feed high in trees, reaching upward for food, at least during times of low food availability

© 2014 Pearson Education, Inc. Figure 1.7 Males Average height of males Average height of females Females Feeding height (meters) (b) Typical feeding posture in giraffes Percentage of feeding bites  Simmons and Scheepers tested the food competition hypothesis and found –The prediction does not hold true –Thus, there may be better alternative hypotheses to explain neck length in giraffes

© 2014 Pearson Education, Inc. The Sexual Competition Hypothesis  An alternative hypothesis is that giraffes evolved long necks because –Longer-necked males win more fights than shorter- necked males –Longer-necked males can then father more offspring  Predictions –Necks are important in males dominance contests –Sexual dimorphism in necks, with males having longer necks than females

© 2014 Pearson Education, Inc. Males Females Males – especially mature males – have proportionally larger heads and necks than females Results

© 2014 Pearson Education, Inc. Results (continued)  Giraffe males (and only males) fight by “necking”  No other ungulate does this  Data support sexual selection hypothesis!  Note: No Experimental Manipulations! –Experimenter simply made controlled observations

© 2014 Pearson Education, Inc. THE THERAPY CHAIR  Time for a demonstration! –Use scientific method to determine the function of controls on the chair –Practice measuring using metric units and (tomorrow) explore variation graphically and statistically Variation in human morphology