CHAPTER 1 Introduction: The Scientific Study of Life

2. CHAPTER 1Introduction: The Scientific Study of Life Modules 1.1 – 1.3

3. THE SCOPE OF BIOLOGY • Biology is the scientific study of life • Interactions between different kinds of organisms affect the lives of all

4. 1.1 Life’s levels of organization define the scope of biology • A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology • An ecosystem consists of: • all organisms living in a particular area • all nonliving physical components of the environment that affect the organisms (soil, water)

5. ECOSYSTEM LEVELEucalyptus forest • Ecosystems include: • all the organisms in an area, which make up a community • interbreeding organisms of the same species, a population • At the top of life’s hierarchy is the ecosystem COMMUNITY LEVELAll organisms ineucalyptus forest POPULATION LEVELGroup of flying foxes ORGANISM LEVELFlying fox Brain Spinal cord ORGAN SYSTEM LEVELNervous system ORGAN LEVELBrain Nerve TISSUE LEVELNervous tissue CELLULAR LEVELNerve cell MOLECULAR LEVELMolecule of DNA Figure 1.1

6. organ systems • organs • tissues • cells • molecules ECOSYSTEM LEVELEucalyptus forest • Organisms are made up of: COMMUNITY LEVELAll organisms ineucalyptus forest POPULATION LEVELGroup of flying foxes ORGANISM LEVELFlying fox Brain Spinal cord ORGAN SYSTEM LEVELNervous system ORGAN LEVELBrain Nerve TISSUE LEVELNervous tissue CELLULAR LEVELNerve cell MOLECULAR LEVELMolecule of DNA Figure 1.1

7. THE PROCESS OF SCIENCE 1.2 Scientists use two main approaches to learn about nature • In discovery science, scientists describe some aspect of the world and use inductive reasoning to draw general conclusions • Example: scientists have described how newborn flying foxes cling to their mother’s chest for the first weeks of life Figure 1.2

8. In hypothesis-driven science, scientists use the “scientific method”

9. 1.3 With the scientific method, we pose and test hypotheses Observation • The main steps of the scientific method Question Hypothesis Prediction Test does notsupport hypothesis; revise hypothesis or pose new one Test supports hypothesis; make additional predictions and test them Test: Experiment oradditionalobservation Figure 1.3A

10. Observation Skills • Observe the following scene quietly for 30 seconds.

12. Are there cars parked on the sides of the road? • What color is the pickup truck driving in the road? • Any minivans around? • What does the blue sign say? • What's the speed limit? • Are there any pedestrians on the road?

14. Eye Witness • 1 witness, 1 investigator

16. If a hypothesis is correct, and we test it, then we can expect a particular outcome • Case study: flashlight failure • Deductive reasoning is used in testing hypotheses Figure 1.3B

17. Control groups must be tested along with experimental groups for comparison • Experiments designed to test hypotheses must be controlled experiments

18. Case study: spider mimicry Figure 1.3C Pounce rate (% of trials in which spider jumped on fly) Control group(untreated flies) Experimental group(wing markings masked) Figure 1.3D

19. Another test of the spider mimic hypothesis: wing transplants Number of stalk andattack responsesby spiders Wingmarkings Wingwaving Normalspidermimic Mimic withmimic wing transplant Mimic withhousefly wing transplant Housefly withmimic wing transplant Normalhousefly Figure 1.3E Controls Experimentals

20. EVOLUTION, UNITY, AND DIVERSITY 1.4 The diversity of life can be arranged into three domains

21. order of taxa in biology • (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species) • Dear King Philip Come Over For Good Soup

22. Domain Bacteria • No nucleus • 1 chromosome • Most classification schemes group organisms into three domains: • Domain Archaea Figure 1.4A, B

23. Domain Eukarya - cells have a membrane bound nucleus and organelles Figure 1.4C-F

24. 1.5 Unity in diversity: All forms of life have common features • All organisms share a set of common features, signs of unity in life’s vast diversity • All are made of cells • All have DNA as their genetic blueprint Figure 1.5A

25. Each species has its own nucleotide sequence • DNA is made of chemical units called nucleotides Figure 1.5B

26. Order and regulation • Growth and development • Use of energy from the environment • Response to environmental stimuli • Ability to reproduce • Evolutionary change • The genetic information in DNA underlies all of the features that distinguish life from nonlife

27. 1.6 Evolution explains the unity and diversity of life • Charles Darwin is a central figure in biology • He synthesized the theory of evolution by natural selection • A theory in science is a comprehensive idea with broad explanatory power • Evolution is the core theme of biology Figure 1.6A

28. The theory of natural selection explains the main mechanism whereby all species of organisms change, or evolve (1) Population with varied inherited traits (2) Elimination of individuals with certain traits (3) Reproduction of survivors Figure 1.6B

29. Evolution happens when populations of organisms with inherited variations are exposed to environmental factors that favor the success of some individuals over others • Natural selection is the editing mechanism • Evolution is based on adaptations Figure 1.6C

30. 1.7 Living organisms and their environments form interconnecting webs • The theory of natural selection applies to all levels in life’s hierarchy • Video: #75 (natural selection CCR) • http://www.youtube.com/watch?v=aTftyFboC_M • In an ecosystem, these interactions make up a complex web of relationships

31. A web of interactions in a rain forest ecosystem Figure 1.7A

32. This African sunbird is consuming nectar, a plant product • Plants, or plant products, are the ultimate sources of food in an ecosystem Figure 1.7B

33. Energy flows in and out constantly Sun • Chemical nutrients cycle within an ecosystem’s web Inflowoflightenergy Lossofheatenergy Air Chemicalenergy Cyclingofchemicalnutrients Organisms Soil Figure 1.7C ECOSYSTEM

34. BIOLOGY AND EVERYDAY LIFE 1.8 Connection: Biology is connected to our lives in many ways • Biology is connected to a great number of important issues • Environmental problems and solutions • Genetic engineering • Medicine Figure 1.8A

38. Process of Science (1.3)

39. Observation • A farmer notices that his neighbors wheat yields are consistently higher than his own.

40. Testable Question • What causes the other farmers fields to produce more grain?

41. Possibilities • Farming Practices • Variety of Seed • Time of planting • Summer fallow • Fertilizing • Pesticides

42. Outside Factors • Less moisture due to varying weather patterns • Poor Soil • Other Neighbors fields holding pests

43. Hypothesis • The farmer thinks that it is most likely the result of the seed variety.

44. Prediction • If the farmer plants the same seed variety as his more successful neighbor, then his yields will be higher than with the old variety.

45. Controlled Experiment • Independent Variable – The variable that will be changed by the conductor of the experiment. • The variety of wheat seed

46. Controlled Experiment • Dependent Variable – The variable that will be measured to determine the effect of the Independent Variable. • The wheat yield

47. Controlled Experiment • Controlled Variables – The variables that may have an effect on the dependent variable, but are not being tested, so must remain the same. • Fertilizer, time of planting, seeding rate, moisture, weather damage, etc.

48. Controlled Experiment • Controlled Variables – The variables that will not be allowed to change. Any measured difference will be due to the effect of the Independent Variable. • Fertilizer, Pesticide, Time of Planting, Weather

49. Controlled Experiment • Experimental Group- the group in which the Independent variable is changed. • Control Group- group in which the independent variable is left unchanged. Controls other possible variables, used for comparison.

50. Controlled Experiment • The farmer 10 separate strips and alternately plants 5 strips to his old variety and 5 to the new variety. • The field is treated exactly the same for each variety.