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

2. Copyright © 2009 Pearson Education Inc. 1.1 Why Study Biology?  Biology helps you understand your body.  Biology helps you become an informed citizen.  Biology can open career opportunities.  Biology can enrich your appreciation of the world.

3. Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  The scientific method is the basis for scientific inquiry.  Life can be studied at different levels of organization.  Science is a human endeavor.  Scientific theories have been thoroughly tested.

4. Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  The scientific method Observation Question Hypothesis (proposed explanation) Prediction Experiment or observation Conclusion Communication to others

5. Copyright © 2009 Pearson Education Inc. Fig. 1-2 1.2 How Do Biologists Study Life?  The scientific method Observation Question Hypothesis Prediction Experiment or Observation Conclusion Hypothesis not supported: pose new hypothesis Hypothesis supported: make more predictions

6. Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life? PLAY Animation—Experimental Design

7. Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  What is a well-designed experiment? Each experiment has a control. Each experiment has a single variable. Example: spoiled meat experiment of Francesco Redi (1621–1697)

8. 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

9. Copyright © 2009 Pearson Education Inc. Fig. 1-3 1.2 How Do Biologists Study Life?  The scientific method in everyday life ObservationCar won’t start. Question Why won’t the car start? Hypothesis The car won’t start because the battery is dead. Prediction IF the hypothesis is correct, THEN the car will start if the battery is replaced. Experiment or Observation Replace the battery. Conclusion The car starts. The dead battery hypothesis is supported.

10. Copyright © 2009 Pearson Education Inc. 1.2 How Do Biologists Study Life?  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.

11. Copyright © 2009 Pearson Education Inc. Fig. 1-5 1.2 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

12. 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 Penicillium, 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.

13. Copyright © 2009 Pearson Education Inc. Fig. 1-7 1.2 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

14. Copyright © 2009 Pearson Education Inc. Fig. 1-8 1.3 What Is Life?  Characteristics of living things Living things are organized.

15. Copyright © 2009 Pearson Education Inc. Fig. 1-8 1.3 What Is Life?  Characteristics of living things Living things are complex

16. Copyright © 2009 Pearson Education Inc. Fig. 1-8 1.3 What Is Life?  Characteristics of living things Living things are organized and complex.

17. Copyright © 2009 Pearson Education Inc. Fig. 1-9 1.3 What Is Life?  Characteristics of living things Living things grow and reproduce.

18. Copyright © 2009 Pearson Education Inc. 1.3 What Is Life?  Characteristics of living things Living things respond to stimuli Light Sound Chemicals Hunger Pain Touch Heat Cold Motion Gravity

19. Copyright © 2009 Pearson Education Inc. Fig. 1-10 1.3 What Is Life?  Characteristics of living things Living things acquire and use material and energy.

20. Copyright © 2009 Pearson Education Inc. Fig. 1-11 1.3 What Is Life?  Characteristics of living things Living things use DNA to store information.

21. 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, from bacteria to whales. Its universal presence suggests that all organisms have descended from a common ancestor having the same molecule.

22. Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  DNA: The universal molecule of life (continued) DNA is passed from generation to generation during periods of reproduction. Organism diversity results from small changes in DNA accumulating over billions of years of evolution.

23. Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  Life’s unity and diversity is a result of evolution. Life 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.

24. Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  Life’s unity and diversity is a result of evolution (continued). Life’s unity arises from the fact that diverse descendents arise from single ancestors. The unifying principle of biology is that all of life’s features in today’s organisms arose through evolution.

25. 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.

26. Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  Natural selection is the basis of evolutionary change (continued). 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.

27. Copyright © 2009 Pearson Education Inc. 1.4 Why Is Life So Diverse?  Biodiversity is threatened by human activities. 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 aquatic organisms.

28. Copyright © 2009 Pearson Education Inc. Fig. E1- 4 1.4 Why Is Life So Diverse?  Logging activities remove trees and destroy the soil.