Copyright © 2009 Pearson Education, Inc.. Lectures by Gregory Ahearn University of North Florida Chapter 1 An Introduction to Life on Earth

Copyright © 2009 Pearson Education Inc. 1.1 Why Study Biology?  Biology helps you understand your _____________.  Biology helps you become an _____________ ____________.  Biology can open ____________ opportunities.  Biology can enrich your appreciation of the ___________.

Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  THE SCIENTIFIC METHOD 1) 2) 3) 4) 5) 6)

Copyright © 2009 Pearson Education Inc. Fig How Do Biologists Study Life? Observation Question Hypothesis Prediction Experiment or Observation Conclusion Hypothesis not supported: pose new hypothesis Hypothesis supported: make more predictions

Copyright © 2009 Pearson Education Inc. Fig How Do Biologists Study Life?  The scientific method in everyday life Observation Question Hypothesis Prediction Experiment or Observation Conclusion

Copyright © 2009 Pearson Education Inc. Fig. E1-1 Flies swarm around meat left in the open; maggots appear on the meat. Why do maggots appear on the meat? Place meat in each jar Obtain identical pieces of meat and two identical jars Flies produce the maggots. If flies are kept away from the meat, then no maggots will appear. Experimental variable: gauze prevents entry of flies Controlled variables: time, temperature, place Results Control situation Experimental situation Spontaneous generation of maggots from meat does not occur; flies are probably the source of maggots. Flies swarm around and maggots appear Leave jar uncovered Leave exposed for several days Flies kept from meat; no maggots appear Cover jar with gauze Leave covered for several days Conclusion: Observation: Question: Hypothesis: Prediction: Experiment

Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  *A well-designed experiment tests a single variable and controls all other variables.* Question: Have all other variables been eliminated? Example: loose battery cables Example: broken electrical wires Solution: Control for other variables Make sure cables are tight. Make sure electrical wires are in good condition.  A _________ ________ is a general explanation of natural phenomena supported by extensive, reproducible tests and observations.

Copyright © 2009 Pearson Education Inc. Fig How Do Biologists Study Life?  LIFE CAN BE STUDIED AT DIFFERENT LEVELS OF ORGANIZATION nerve cell community tissue organ organism population cell nervous tissue brain snakes, antelope, hawks, bushes, grass herd of pronghorn antelope pronghorn antelope

Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  SCIENCE IS A HUMAN ENDEAVOR Scientists are real people and sometimes make mistakes. One of the greatest medical advances in history was made by mistake, by Alexander Fleming. The mold _______________, which kills bacteria, was discovered by chance by Fleming. This led to the discovery of penicillin, an important antibiotic that has saved millions of lives.

Copyright © 2009 Pearson Education Inc. Fig How Do Biologists Study Life?  Penicillin kills bacteria. A petri dish contains solid growth medium Bacteria grow in a pattern created by streaking A substance from the mold diffuses outward and inhibits the growth of nearby bacteria A colony of the mold Penicillium

Copyright © 2009 Pearson Education Inc. Fig What Is Life?  LIVING THINGS ARE BOTH ____________ AND ________________

Copyright © 2009 Pearson Education Inc. Fig What Is Life?  LIVING THINGS CAN __________ AND ______________  LIVING THINGS RESPOND TO ___________ Light, Sound, Chemicals, Hunger, Pain, Touch, Heat, Cold, Motion, Gravity

Copyright © 2009 Pearson Education Inc. Fig What Is Life?  LIVING THINGS ACQUIRE AND USE _______________ AND ______________

Copyright © 2009 Pearson Education Inc. Fig What Is Life?  LIVING THINGS USE _______ TO STORE INFORMATION Each segment of DNA that contains a set of instructions is called a ______. ___________: offspring inheriting their parents’ characteristics/genes.

Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  DNA: THE UNIVERSAL MOLECULE OF LIFE DNA is found in the bodies of all organisms Its universal presence suggests that all organisms have descended from a common ancestor having the same molecule. DNA is passed from generation to generation during periods of reproduction. Organism diversity results from small changes in DNA over billions of years of evolution.

Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  LIFE’S UNITY AND DIVERSITY ARE A RESULT OF EVOLUTION An organism changes over long periods of time. Groups of organisms change from generation to generation. The changes that accumulate in populations of organisms over time is called evolution. Life’s unity arises from the fact that diverse descendants arise from single ancestors. The unifying principle of biology is that all of life’s features in today’s organisms arose through evolution.

Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  NATURAL SELECTION IS THE BASIS OF EVOLUTIONARY CHANGE Characteristics of individuals in a group vary. Some characteristics help individuals survive and reproduce. Those that reproduce pass on these traits to future generations. The favored traits are accumulated in populations over time, changing the individuals within the group. Example: Big teeth in beavers favor survival and are passed on to future generations.

Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  BIODIVERSITY IS THREATENED BY HUMAN ACTIVITY Biodiversity is the wealth of species in the world and the interrelationships that sustain them. Human expansion in the world has severely reduced habitats for these interrelationships to flourish. Extinction of many organisms have followed from the growth of human populations on all the world’s continents. Pollution and chemical wastes kill organisms.