Life at Its Many Levels

Transcription

1 Slide 1 THE SCOPE OF BIOLOGY Biology is the scientific study of life Slide 2 Life at Its Many Levels Biologists explore life at levels ranging from the biosphere to the molecules that make up cells Slide 3 Ecosystems Each organism interacts continuously with its environment

2 Slide 4 Sunlight The dynamics of any ecosystem depend on two processes Ecosystem Heat Heat Consumers (such as animals) Producers (plants and other photosynthetic organisms) Chemical energy (food) Figure 1.3 Slide 5 Sunlight Energy flows one way (from sunlight to producers to consumers) Ecosystem Heat Heat Consumers (such as animals) Producers (plants and other photosynthetic organisms) Chemical energy (food) Nutrients are recycled (Between producers, consumers and decomposers) Figure 1.3 Slide 6 The biosphere is enriched bya great diversity of ecosystems including,

3 Slide 7 Humans are organisms that now have some presence, often disruptive, in all ecosystems Slide 8 Remember, an ecosystem consists of all the organisms and nonliving factors affecting life in a particular area. And, all organisms are composed of Cells Slide 9 A cell is the lowest level of structure that can perform all activities required for life, including the capacity to reproduce.

4 Slide 10 A cell is the lowest level of structure that can perform all activities required for life, including the capacity to reproduce. The ability of cells to divide to form new cells is the basis for: Slide 11 We can distinguish two major types of cells Prokaryotic Eukaryotic Slide 12 The prokaryotic cell is simple and contains no internal membraneous organelles They do not contain a nucleus Nucleus (contains DNA) Eukaryotic cell Prokaryotic cell The eukaryotic cell is more complex and contains organelles The nucleus is the largest organelle in most eukaryotic cells DNA (no nucleus) Organelles Figure 1.4

5 Slide 13 All cells use DNA as the chemical material of genes Slide 14 The language of DNA contains just four letters A, G, C, T Slide 15 A genome is the entire book of genetic instructions an organism inherits The nucleus of each human cell packs a genome that is about 3.2 billion chemical letters long

6 Slide 16 The emerging field of genomics is a striking example of human curiosity about life at its many levels - Genomics is the branch of biology that studies whole genomes Slide 17 Life in Its Diverse Forms Diversity is the hallmark of life The diversity of known life includes 1.7 million species Estimates of the total diversity range from 5 million to over 30 million species Slide 18 Grouping Species: The Basic Concept Biodiversity can be both beautiful and overwhelming Figure 1.7

7 Slide 19 Grouping Species: The Basic Concept Biodiversity Taxonomy Figure 1.7 Slide 20 The Three Domains of Life Domain Bacteria Domain Archaea The three domains of life are Bacteria Archaea Eukarya Domain Eukarya Kingdom Protista Kingdom Plantae Kingdom Fungi Kingdom Animalia Figure Slide 21 Bacteria and Archaea are both prokaryotic domains Domain Bacteria Domain Archaea Figure 1.8.2

8 Slide 22 Eukarya includes at least four kingdoms Protista Plantae Fungi Animalia Kingdom Protista Domain Eukarya Kingdom Plantae Kingdom Fungi Kingdom Animalia Figure Slide 23 Unity in the Diversity of Life Underlying the diversity of life is a striking unity, especially at the lower levels of structure Example: the universal genetic language of DNA Slide 24 EVOLUTION: BIOLOGY S UNIFYING THEME The history of life is a saga of a restless Earth billions of years old Fossils document this history Figure 1.10

9 Slide 25 Life evolves Each species is one twig of a branching tree of life extending back in time Giant Spectacled Sloth panda bear bear Sun Amer ican Asiatic Polar bear black bear black bear bear Brown bear Ancestral bear Figure 1.11 Slide 26 The Darwinian View of Life The evolutionary view of life came into focus in 1859 when Charles Darwin published The Origin of Species Figure 1.12 Slide 27 Darwin s book developed two main points Descent with modification Natural selection

10 Slide 28 Natural Selection Darwin was struck by the diversity of animals on the Galápagos Islands He thought of adaptation to the environment and the origin of new species as closely related processes As populations separated by a geographic barrier adapted to local environments, they became separate species Chapter 1 Study Objectives: 1. Describe the two main dynamic processes of an ecosystem. 2. Compare the structure of prokaryotic and eukaryotic cells. 3. Distinguish between the three domains and four eukaryotic kingdoms of life. 4. Describe the two main points that Darwin makes in The Origin of Species. 5. Describe the two observations that led Darwin to his inescapable conclusion. State this conclusion. 6. Explain how changes in the effectiveness of antibiotics illustrate natural selection. 7. Compare artificial and natural selection, noting similarities and differences. 8. Compare discovery science and hypothesis-driven science. Provide examples of each. 9. Describe the snake mimicry experiment presented in the text, noting the logical steps of the experimental process. 10. Describe the two key features that distinguish science from other styles of inquiry. 11. Distinguish between a hypothesis and a theory.