1. Chapter 1 Biology is the scientific study of life

2. Life is investigated from the microscopic (microbiology) to the global scale (global warming) Biological organization is based on a hierarchy of structural levels Exploring Life

3. A Hierarchy (levels) of Biological Organization  Biosphere: all environments on Earth (the part of the earth, including air, land, surface rocks, and water, within which life occurs, and which biotic processes in turn alter or transform their envirnment).  Ecosystem: all living and nonliving things in a particular area.  Community: all organisms in an ecosystem  Population: all individuals of a species in a particular area.  Organism: an individual living thing.

4. A Hierarchy of Biological Organization (continued)  Organ and organ systems: specialized body parts made up of tissues.  Tissue: a group of similar cells.  Cell: life’s fundamental unit of structure and function.  Organelle: a structural component of a cell.  Molecule: a chemical structure consisting of atoms.

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

6. Life, a lot going on

7. 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  Each organism interacts with its environment  Both organism and environment affect each other

8. 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.

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

10. 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

11. 25 µm 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

12. 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

13. DNA double helixSingle strand of DNA Nucleotide Cell Nucleus DNA

14. Eukaryotic and Prokaryotic 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

15. Membrane Cytoplasm EUKARYOTIC CELL PROKARYOTIC CELL DNA (no nucleus) Membrane 1 µm Organelles Nucleus (contains DNA)

16.  Biologists explore life across a great diversity of species (1.8 million named)  Estimates of total species range from 10 million to over 200 million  Taxonomy is the branch of biology that names and classifies species into a hierarchical order  Kingdoms and domains are the broadest units of classification Taxonomy (naming species)

17. Ursidae Ursus Carnivora Mammalia Chordata Animalia Eukarya SpeciesGenus Family Order Class Phylum KingdomDomain Ursus americanus (American black bear)

18. The Three Domains of Life  Bacteria (Most of the Known Prokaryotes )  Archaea (Prokaryotes of Extreme Environments )  Eukarya (eukaryotes)  Eukaryotes include protists and the kingdoms Plantae, Fungi, and Animalia

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

20.  Evolution accounts for life’s unity and diversity  The history of life is a continuing saga of a changing Earth billions of years old How did we get where we are?

22.  The evolutionary view of life came into sharp focus in 1859, when Charles Darwin published On the Origin of Species by Natural Selection  “Darwinism” became almost synonymous with the concept of evolution  Gregor Johann Mendel 1822 - 1884 Evolution

23.  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

24. 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

25.  Natural selection can “edit” a population’s heritable variations  An example is the effect of birds preying on a beetle population Natural Selection (continued)

26. Population with varied inherited traits Elimination of individuals with certain traits Reproduction of survivors Increasing frequency of traits that enhance survival and reproductive success

27. The Tree of Life  Many related organisms have similar features adapted for specific ways of life.  Such kinships connect life’s unity and diversity to descent with modification.  Natural selection eventually produces new species from ancestral species.  Biologists often show evolutionary relationships in a treelike diagram.

28. Large ground finch Large cactus ground finch Sharp-beaked ground finch Geospiza magnirostris Geospiza conirostris Medium ground finch Geospiza fuliginosa Small ground finch Woodpecker finch Camarhynchus psittacula Large tree finch Medium tree finch Cactus ground finch Geospiza difficilis Cactus flower eaters Geospiza scandens Seed eater Ground finches Seed eaters Tree finches Common ancestor from South American mainland Insect eaters Bud eater Warbler finches Mangrove finch Geospiza fortis Cactospiza pallida Small tree finch Camarhynchus pauper Camarhynchus parvulus Green warbler finch Gray warbler finch Certhidea olivacea Certhidea fusca Vegetarian finch Platyspiza crassirostris Cactospiza heliobates

29.  Biologists use various forms of inquiry to explore life.  Inquiry is a search for information and explanation, often focusing on specific questions.  The process of science blends two main processes of scientific inquiry:  Discovery science (natural history): describing nature  Hypothesis-based science: explaining nature

30. Discovery Science (natural history)  Discovery science describes nature through careful observation and data analysis  Examples of discovery science:  understanding cell structure  expanding databases of genomes

31. Types of Data  Data are recorded observations  Two types of data:  Quantitative data: numerical measurements  Qualitative data: recorded descriptions

33. Induction in Discovery Science  Inductive reasoning involves generalizing based on many specific observations  The premises of an argument are believed to support the conclusion but do not ensure it. The stove top is hot: all stove tops are hot A bird flies: all birds fly Deduction: If the premises are true then the conclusion must be true

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

35. Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Observations Question Observation: Flashlight does not work

36. 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

37. Deduction: The “If…then”  Deductive reasoning, the logic flows from the general to the specific; thus, If a hypothesis is correct, then we can expect a particular outcome.  A scientific hypothesis must have two important qualities:  It must be testable  It must be falsifiable

38. The Myth of the Scientific Method  The scientific method is an idealized process of inquiry  Very few scientific inquiries adhere rigidly to the “textbook” scientific method – probably more true in biology than physics or chemistry.

39.  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

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

41.  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

42. 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

43. Field Experiments with Artificial Snakes  Artificial snakes:  An experimental group resembling king snakes  A control group resembling plain brown snakes

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

45.  Equal numbers of both types were placed at field sites, including areas without coral snakes  After four weeks the artificial snakes were retrieved and bite/claw marks recordered  The data fit the predictions of the mimicry hypothesis Field Experiments with Artificial Snakes (continued)

46. 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

47. QUESTION: How will the amount of fertilizer used affect plant growth? HYPOTHESIS: Increased dosages of fertilized will cause greater growth in tomato plants. TEST VARIABLE: The amount of fertilizer used. TEST CONSTANTS: The seeds must all come from the same package. All seeds must be planted in the same sized pots with similar soil. All plants must receive exactly the same amount of water and light. The temperature should be the same for all test plants. More than one plant should be used in each test group (in case one type of seed grows better at this time of year than another). More than one seed should be placed in each container (in case one seed is damaged). Set one group as the CONTROL GROUP. This group is not given fertilizer. Set up two other test groups. Once receives a certain amount of fertilizer and the other receives twice as much.