1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 1 Themes in the Study of Life

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: Biology’s Most Exciting Era Biology is the scientific study of life Biologists are moving closer to understanding : – How a single cell develops into an organism – How plants convert sunlight to chemical energy – How the human mind works – How living things interact in communities – How life’s diversity evolved from the first microbes

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Themes of Biology: Evolution Ecosystems Biological organization Cells DNA Feedback mechanisms

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Life’s basic characteristic is a high degree of order Each level of biological organization has emergent properties Video: Seahorse Camouflage Video: Seahorse Camouflage

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6. The study of life extends from molecules and cells to the entire living planet Biological organization is based on a hierarchy of structural levels

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Hierarchy of Biological Organization 1.Biosphere: all environments on Earth 2.Ecosystem: all living and nonliving things in a particular area 3.Community: all organisms in an ecosystem 4.Population: all individuals of a species in a particular area 5.Organism: an individual living thing

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Hierarchy of Biological Organization (continued) 6.Organ and organ systems: specialized body parts made up of tissues 7.Tissue: a group of similar cells 8.Cell: life’s fundamental unit of structure and function 9.Organelle: a structural component of a cell 10. Molecule: a chemical structure consisting of atoms

9. Ecosystems The biosphere Organisms Populations Communities Cells Organelles Molecules Tissues Organs and organ systems Cell 1 µm Atoms 10 µm 50 µm

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Closer Look at Ecosystems Each organism interacts with its environment Both organism and environment affect each other

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ecosystem Dynamics The dynamics of an ecosystem include two major processes: – Cycling of nutrients, in which materials acquired by plants eventually return to the soil – The flow of energy from sunlight to producers to consumers

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Energy Conversion Activities of life require work Work depends on sources of energy Energy exchange between an organism and environment often involves energy transformations In transformations, some energy is lost as heat Energy flows through an ecosystem, usually entering as light and exiting as heat

13. LE 1-4 Sunlight Ecosystem Heat Chemical energy Consumers (including animals) Producers (plants and other photosynthetic organisms)

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Closer Look at Cells The cell is the lowest level of organization that can perform all activities of life The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms

15. LE 1-5 25 µm

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Cell’s Heritable Information Cells contain DNA, the heritable information that directs the cell’s activities DNA is the substance of genes Genes are the units of inheritance that transmit information from parents to offspring

17. LE 1-6 Sperm cell Nuclei containing DNA Egg cell Fertilized egg with DNA from both parents Embryo’s cells With copies of inherited DNA Offspring with traits inherited from both parents

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Each DNA molecule is made up of two long chains arranged in a double helix Each link of a chain is one of four kinds of chemical building blocks called nucleotides

19. LE 1-7 DNA double helixSingle strand of DNA Nucleotide Cell Nucleus DNA

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Two Main Forms of Cells Characteristics shared by all cells: – Enclosed by a membrane – Use DNA as genetic information Two main forms of cells: – Eukaryotic: divided into organelles; DNA in nucleus – Prokaryotic: lack organelles; DNA not separated in a nucleus

21. LE 1-8 Membrane Cytoplasm EUKARYOTIC CELL PROKARYOTIC CELL DNA (no nucleus) Membrane 1 µm Organelles Nucleus (contains DNA)

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Feedback Regulation in Biological Systems Regulatory systems ensure a dynamic balance in living systems Chemical processes are catalyzed (accelerated) by enzymes Many biological processes are self-regulating: the product regulates the process itself

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In negative feedback, the accumulation of a product slows down the process itself In positive feedback (less common), the product speeds up its own production Animation: Negative Feedback Animation: Negative Feedback Animation: Positive Feedback Animation: Positive Feedback

24. LE 1-11 Enzyme 1 A A B B C C D D D D D D D D D D D Enzyme 2 Enzyme 3 Negative feedback Enzyme 1

25. LE 1-12 W Enzyme 4 W X X Y Y Z Z Z Z Z Z Z Z Z Z Enzyme 5 Enzyme 6 Positive feedback Enzyme 4 Enzyme 6 Enzyme 5 Z Z Z Z Z Z Z Z Z

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Biologists explore life across its great diversity of species Biologists have named about 1.8 million species Estimates of total species range from 10 million to over 200 million

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

28. Grouping Species: The Basic Idea Taxonomy is the branch of biology that names and classifies species into a hierarchical order Kingdoms and domains are the broadest units of classification

29. LE 1-14 Ursidae Ursus Carnivora Mammalia Chordata Animalia Eukarya SpeciesGenus Family Order Class Phylum KingdomDomain Ursus americanus (American black bear)

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Three Domains of Life At the highest level, life is classified into three domains: – Bacteria (prokaryotes) – Archaea (prokaryotes) – Eukarya (eukaryotes) Eukaryotes include protists and the kingdoms Plantae, Fungi, and Animalia

31. LE 1-15 Bacteria 4 µm 100 µm 0.5 µm Kingdom Plantae Protists Kingdom Animalia Kingdom Fungi Archaea

32. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Unity in the Diversity of Life Underlying life’s diversity is a striking unity, especially at lower levels of organization In eukaryotes, unity is evident in details of cell structure

33. LE 1-16a Cilia of windpipe cells Cilia of Paramecium 15 µm 5 µm

34. LE 1-16b Cilia of windpipe cells Cilia of Paramecium Cross section of cilium, as viewed with an electron microscope 0.1 µm

35. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Evolution accounts for life’s unity and diversity The history of life is a saga of a changing Earth billions of years old

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37. The evolutionary view of life came into sharp focus in 1859, when Charles Darwin published On the Origin of Species by Natural Selection

38. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Origin of Species articulated two main points: – Descent with modification (the view that contemporary species arose from a succession of ancestors) – Natural selection (a proposed mechanism for descent with modification) Some examples of descent with modification are unity and diversity in the orchid family

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40. Natural Selection Darwin inferred natural selection by connecting two observations: – Observation: Individual variation in heritable traits – Observation: Overpopulation and competition – Inference: Unequal reproductive success – Inference: Evolutionary adaptation

41. LE 1-20 Evolution of adaptations in the population Differences in reproductive success Overproduction and competition Population of organisms Hereditary variations

42. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings An example is the effect of birds preying on a beetle population

43. LE 1-21 Population with varied inherited traits Elimination of individuals with certain traits Reproduction of survivors Increasing frequency of traits that enhance survival and reproductive success

44. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Natural selection is often evident in adaptations of organisms to their way of life and environment Bat wings are an example of adaptation Video: Soaring Hawk Video: Soaring Hawk

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

46. Hypothesis-Based Science In science, inquiry usually involves proposing and testing hypotheses Hypotheses are hypothetical explanations

47. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Role of Hypotheses in Inquiry In science, a hypothesis is a tentative answer to a well-framed question A hypothesis is an explanation on trial, making a prediction that can be tested

48. LE 1-25a Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Observations Question

49. LE 1-25b Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Test prediction Test falsifies hypothesis Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test does not falsify hypothesis

50. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Closer Look at Hypotheses in Scientific Inquiry A scientific hypothesis must have two important qualities: – It must be testable – It must be falsifiable

51. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In mimicry, a harmless species resembles a harmful species An example of mimicry is a stinging honeybee and a nonstinging mimic, a flower fly A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations

52. LE 1-26 Flower fly (nonstinging) Honeybee (stinging)

53. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings This case study examines king snakes’ mimicry of poisonous coral snakes The hypothesis states that mimics benefit when predators mistake them for harmful species The mimicry hypothesis predicts that predators in non–coral snake areas will attack king snakes more frequently than will predators that live where coral snakes are present

54. LE 1-27 Scarlet king snake Eastern coral snake Scarlet king snake Key Range of scarlet king snake North Carolina Range of eastern coral snake South Carolina

55. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Field Experiments with Artificial Snakes To test this mimicry hypothesis, researchers made hundreds of artificial snakes: – An experimental group resembling king snakes – A control group resembling plain brown snakes Equal numbers of both types were placed at field sites, including areas without coral snakes After four weeks, the scientists retrieved the artificial snakes and counted bite or claw marks The data fit the predictions of the mimicry hypothesis

56. LE 1-28 (a) Artificial king snake (b) Artificial brown snake that has been attacked

57. In areas where coral snakes were present, most attacks were on brown artificial snakes. In areas where coral snakes were absent, most attacks were on artificial king snakes. LE 1-29 % of attacks on artificial king snakes % of attacks on brown artificial snakes Field site with artificial snakes 83% North Carolina South Carolina 17% 16% 84% Key

58. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Limitations of Science The limitations of science are set by its naturalism – Science seeks natural causes for natural phenomena – Science cannot support or falsify supernatural explanations, which are outside the bounds of science

59. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Theories in Science A scientific theory is much broader than a hypothesis A scientific theory is: – broad in scope – general enough to generate new hypotheses – supported by a large body of evidence

60. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Science, Technology, and Society The goal of science is to understand natural phenomena Technology applies scientific knowledge for some specific purpose