2. IB Biology Concepts and Methods of Exploring Life

3. Biology: the study of life. IB Biology: a life of study! Seven characteristics of life: Order- DNA is the genetic code (instructions for building molecules) Reproduction Growth and development of cells Energy Processing- metabolism Responsiveness Homeostasis/Regulation Evolution

4. Some properties of life (c) (a) (d) (g) (f) (b) (e)

5. Some properties of life (c) (a) Order/instruction (d) (g) (f) (b) (e)

6. Some properties of life (c) (a) Order/instruction (d) (g) (f) (b) Evolutionary adaptation (e)

7. Some properties of life (c) Response to the environment (a) Order/instruction (d) (g) (f) (b) Evolutionary adaptation (e)

8. Some properties of life (c) Response to the environment (a) Order/instruction (d) Homeostasis (g) (f) (b) Evolutionary adaptation (e)

9. Some properties of life (c) Response to the environment (a) Order/instruction (d) Homeostasis (g) (f) (b) Evolutionary adaptation (e) Energy processing

10. Some properties of life (c) Response to the environment (a) Order/instruction (d) Homeostasis (g) (f) Growth and development (b) Evolutionary adaptation (e) Energy processing

11. Some properties of life (c) Response to the environment (a) Order/instruction (d) Homeostasis (g) Reproduction (f) Growth and development (b) Evolutionary adaptation (e) Energy processing

12. Seven Characteristics 1. DNA is the genetic code which is organized into genes within cells. Genes: sets of instructions for making proteins Mutation: Changes in DNA Heredity: the passing of traits from parents to offspring 2. Reproduction Everything living must reproduce either by producing new cells within oneself or for the purposes of combining with another’s cells.

13. The molecular structure of DNA Accounts for its information-rich nature DNA Cell Nucleotide A C T A T A C C G G T A T A (b) Single strand of DNA. These geometric shapes and letters are simple symbols for the nucleotides in a small section of one chain of a DNA molecule. Genetic information is encoded in specific sequences of the four types of nucleotides (their names are abbreviated here as A, T, C, and G). (a) DNA double helix. This model shows each atom in a segment of DNA.Made up of two long chains of building blocks called nucleotides, a DNA molecule takes the three-dimensional form of a double helix. Nucleus

14. The Cell’s Heritable Information Cells contain chromosomes made partly of DNA, the substance of genes Nuclei containing DNA

15. The Cell’s Heritable Information Cells contain chromosomes made partly of DNA, the substance of genes Egg cell Sperm cell Nuclei containing DNA

16. The Cell’s Heritable Information Cells contain chromosomes made partly of DNA, the substance of genes Egg cell Sperm cell Nuclei containing DNA Zygote = Fertilized Egg with DNA from both parents Embyro’s cells with copies of inherited DNA

17. The Cell’s Heritable Information Cells contain chromosomes made partly of DNA, the substance of genes Which program the cells’ production of proteins and transmit information from parents to offspring Egg cell Sperm cell Nuclei containing DNA Fertilized egg with DNA from both parents Embyro’s cells with copies of inherited DNA Offspring with traits inherited from both parents

18. A Closer Look at Cells The cell Is the lowest level of organization that can perform all activities required for life 25 µm

19. Seven Characteristics 3. Growth and Development of Cells Cells typically grow in size before dividing into two new cells. Increase in overall number of cells is typical for organism that develop from zygotes to full size adults. Cells within an organism share the same DNA but may have different jobs associated with the genes that are used by particular cells.

20. Seven Characteristics 4. Metabolism: the sum of all chemical reactions Organisms use energy to do things Almost all energy that organisms use originally was captured from the sun by plants. Energy flows from sun to plants to other living things. 5. Responsiveness: change to environmental stimuli requires the use of receptors which can sense shifts in the surrounding world. 6. Homeostasis: the maintenance of a stable internal environment -Ex. Blood sugar levels in humans.

21. Biologists explore life from the microscopic to the global scale The study of life Extends from the microscopic scale of molecules and cells to the global scale of the entire living planet

22. Levels of Biological Organization The hierarchy of life Extends through many levels of biological organization

23. From the biosphere to organisms 1 The biosphere

24. From the biosphere to organisms 1 The biosphere 2) The ecosystem 3) The community 4) The population 5) The organism

25. From cells to molecules Cell 6 Organs and organ systems 50 µm 10 µm 1 µm Atoms

26. From cells to molecules Cell 6 Organs and organ systems 7 Tissues 50 µm 10 µm 1 µm Atoms

27. From cells to molecules Cell 8 Cells 6 Organs and organ systems 7 Tissues 9 50 µm 10 µm 1 µm Atoms

28. From cells to molecules Cell 8 Cells 6 Organs and organ systems 7 Tissues 10 9 Organelles 50 µm 10 µm 1 µm Atoms

29. From cells to molecules Cell 8 Cells 6 Organs and organ systems 7 Tissues 10 Molecules 9 Organelles 50 µm 10 µm 1 µm Atoms

31. A Closer Look at Ecosystems Each organism Interacts with its environment Both organism and environment are affected by the interactions between them

32. Ecosystem Dynamics The dynamics of any ecosystem include two major processes Cycling of nutrients, in which materials acquired by plants eventually return to the soil The one-way flow of energy from sunlight to producers to consumers Dung Beetle Example

33. Energy Conversion Activities of life Require organisms to perform work, which depends on an energy source

34. All Living Things are Connected The exchange of energy between an organism and its surroundings Often involves the transformation of one form of energy to another

35. Energy flows through an ecosystem Usually entering as sunlight and exiting as heat Producers (plants and other photosynthetic organisms) Consumers (including animals) Sunlight Chemical energy Heat Ecosystem

36. Seven Characteristics 7. Evolution: a change in the inherited traits of a species over time Species: a group of organisms that can interbreed to produce fertile offspring Natural selection: process by which evolution takes place, survival of the fittest

37. Two Main Forms of Cells All cells share certain characteristics They are all enclosed by a membrane They all use DNA as genetic information Two Main Forms of Cells Eukaryotic cells Are subdivided by internal membranes into various membrane-enclosed organelles Prokaryotic cells Lack the kinds of membrane-enclosed organelles found in eukaryotic cells

38. Two Main Forms of Cells EUKARYOTIC CELL Membrane Cytoplasm Organelles Nucleus (contains DNA) 1 µm PROKARYOTIC CELL DNA (no nucleus) Membrane

39. Taxonomy seeks to classify Biologists explore life across its great diversity of species

40. Classifying life Domain Eukarya

41. Classifying life Kingdom Domain Animalia Eukarya

42. Classifying life Phylum Kingdom Domain Chordata Animalia Eukarya

43. Classifying life Class Phylum Kingdom Domain Mammalia Chordata Animalia Eukarya

44. Classifying life Order Class Phylum Kingdom Domain Mammalia Carnivora Chordata Animalia Eukarya

45. Classifying life Family Order Class Phylum Kingdom Domain Mammalia Ursidae Carnivora Chordata Animalia Eukarya

46. Classifying life Genus Family Order Class Phylum Kingdom Domain Mammalia Ursus Ursidae Carnivora Chordata Animalia Eukarya

47. Classifying life Species Genus Family Order Class Phylum Kingdom Domain Mammalia Ursus ameri- canus (American black bear) Ursus Ursidae Carnivora Chordata Animalia Eukarya

48. The Three Domains of Life At the highest level, life is classified into three domains Bacteria Archaea Eukarya

49. Domain Bacteria and domain Archaea Consist of prokaryotes Domain Eukarya, the eukaryotes Includes Protista, Plantae, Fungi, and Animalia

50. Life’s three domains 100 µm 0.5 µm 4 µm Bacteria are the most diverse and widespread prokaryotes and are now divided among multiple kingdoms. Each of the rod-shaped structures in this photo is a bacterial cell. Protists (multiple kingdoms) are unicellular eukaryotes and their relatively simple multicellular relatives.Pictured here is an assortment of protists inhabiting pond water. Scientists are currently debating how to split the protists into several kingdoms that better represent evolution and diversity. Kingdom Plantae consists of multicellula eukaryotes that carry out photosynthesis, the conversion of light energy to food. Many of the prokaryotes known as archaea live in Earth‘s extreme environments, such as salty lakes and boiling hot springs. Domain Archaea includes multiple kingdoms. The photo shows a colony composed of many cells. Kindom Fungi is defined in part by the nutritional mode of its members, such as this mushroom, which absorb nutrientsafter decomposing organic material. Kindom Animalia consists of multicellular eukaryotes that ingest other organisms. DOMAIN ARCHAEA

51. The History of Life Is a saga of a changing Earth billions of years old Evolution accounts for life’s unity and diversity

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

53. The Origin of Species articulated two main points Descent with modification Natural selection Ex. Orchids show remarkable similarities and differences in their ability to attract pollinators

54. Natural Selection The mechanism for evolutionary adaptation of populations to their environments Population of organisms

55. Natural Selection The mechanism for evolutionary adaptation of populations to their environments Population of organisms Hereditary variations Overproduction and struggle for existence

56. Natural Selection The mechanism for evolutionary adaptation of populations to their environments Population of organisms Hereditary variations Differences in reproductive success Overproduction and struggle for existence

57. Natural Selection The mechanism for evolutionary adaptation of populations to their environments Population of organisms Hereditary variations Differences in reproductive success Evolution of adaptations in the population Overproduction and struggle for existence

58. The products of natural selection Are often exquisite adaptations of organisms to the special circumstances of their way of life and their environment

59. The Tree of Life Darwin proposed that natural selection Could enable an ancestral species to “split” into two or more descendant species, resulting in a “tree of life ” Large ground finch Small ground finch Geospiza magnirostris Seed eater Sharp-beaked ground finch Camarhynchus psitacula Green warbler finch Large tree finch Large cactus ground finch Ground finches Tree finches Insect eaters Bud eater Warbler finches Common ancestor from South American mainland Gray warbler finch Certhidea olivacea Certhidea fusca Geospiza difficilis Cactus flower eater Geospiza scandens Seed eater Geospiza conirostris Geospiza fortis Medium ground finch Geospiza fuliginosa Mangrove finch Cactospiza heliobates Cactospiza pallida Woodpecker finch Medium tree finch Camarhynchus pauper Small tree finch Vegetarian finch Camarhynchus parvulus Platyspiza crassirostris Cactus ground finch Each species is on twig of a branching tree of life Extending back in time through ancestral species more and more remote

60. Using inquiry to explore life At the heart of science is inquiry A search for information and explanation, often focusing on specific questions Biology blends two main processes of scientific inquiry Discovery science Hypothesis-based science

61. The Scientific Method Step #1: Observation Step #2: Make hypotheses Step #3: Test or Experiment Step #4: Draw Conclusions Step #5: Publish or Communicate Results

62. The Scientific Process Observation: the act of noting or perceiving objects or events using the senses Asking a question: after making observations ask about what you want to find out. Hypothesis: an explanation to your question that might be true and is testable. Prediction: the expected outcome of the test, assuming the hyp. is correct

63. Induction in Discovery Science In inductive reasoning Scientists derive generalizations based on a large number of specific observations

64. Hypothesis-Based Science In science, inquiry that asks specific questions Usually involves the proposing and testing of hypothetical explanations, or hypotheses

65. The Role of Hypotheses in Inquiry In science, a hypothesis Is a tentative answer to a well-framed question, an explanation on trial Makes predictions that can be tested

66. We all use hypotheses in solving everyday problems Observations Questions Hypothesis # 1: Hypothesis # 2:

67. We all use hypotheses in solving everyday problems Observations Questions Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb

68. We all use hypotheses in solving everyday problems Observations Questions Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem

69. We all use hypotheses in solving everyday problems Observations Questions Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction

70. We all use hypotheses in solving everyday problems Observations Questions Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test does not falsify hypothesis Test prediction Test falsifies hypothesis

71. Deduction: The “If…then” Logic of Hypothesis-Based Science In deductive reasoning The logic flows from the general to the specific If a hypothesis is correct Then we can expect a particular outcome

72. A Closer Look at Hypotheses in Scientific Inquiry A scientific hypothesis must have two important qualities It must be testable It must be falsifiable

73. The Myth of the Scientific Method The scientific method Is an idealized process of inquiry Very few scientific inquiries Adhere to the “textbook” scientific method

74. Test or Experiment Experiment: planned procedure to test a hypothesis Control group: experimental group that receives no experimental treatment Independent variable: the factor that is varied. Dependent variable: the variable that is measured, result of experiment.

75. Types of Data Data Are recorded observations Can be quantitative or qualitative Jane Goodall observing chimpanzee behavior

76. Drawing conclusions: deciding if the data supports the hypothesis Publish: Usually communicate your findings with others.

77. In mimicry A harmless species resembles a harmful species Flower fly (non-stinging) Honeybee (stinging) A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations

78. Snake Mimicry case study Mimicry in king snakes is examined The 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 Scarlet king snake Key Range of scarlet king snake Range of eastern color snake Eastern coral snake North Carolina South Carolina

79. Field Experiments with Artificial Snakes To test this mimicry hypothesis Researchers made hundreds of artificial snakes, an experimental group resembling king snakes and a control group of plain brown snakes (a) Artificial king snake (b) Brown artificial snake that has been attacked

80. After a given period of time The researchers collected data that fit a key prediction In areas where coral snakes were present, most attacks were on artificial brown snakes Key % of attacks on artificial king snakes % of attacks on brown artificial snakes Field site with artificial snakes 17% 83% North Carolina South Carolina X X X X X X X X X X X X X X In areas where coral snakes were absent, most attacks were on artificial king snakes 84% 16% Key

81. Designing Controlled Experiments Experiments must be designed to test The effect of one variable by testing control groups and experimental groups in a way that cancels the effects of unwanted variables

82. Theories Theory: a set of related hypotheses that have been tested and confirmed many times. Theories to scientists are what they believe is true. Ex. Spontaneous Generation (Redi’s experiment followed by Needham & Spallanzani and finally Pasteur)

83. Limitations of Science Science cannot address supernatural phenomena Because hypotheses must be testable and falsifiable and experimental results must be repeatable