Invitation to Biology Chapter 1 Biology Concepts and Applications, Eight Edition, by Starr, Evers, Starr. Brooks/Cole, Cengage Learning 2011. Biology, Ninth Edition, by Solomon, Berg, Martin. Brooks/Cole, Cengage Learning 2011.

1.1 Life’s Levels of Organization Nature has levels of organization Unique properties emerge at successively higher levels Atoms are organized into molecules In multicelled species, cells are organized into tissues, organs, and organ systems All organisms consist of one or more cells

Organization of Groups of Organisms Population All individuals of one species in a specific area Community All populations in a specific area Ecosystem A community interacting with its environment Biosphere All regions of Earth that hold life Land, water, and atmosphere

Levels of Organization

Levels of Organization

KEY CONCEPTS: LEVELS OF ORGANIZATION We study the world of life at different levels of organization, from atoms and molecules to the biosphere “Life” emerges at the level of cells

1.2 Overview of Life’s Unity Organisms require energy and materials to sustain their organization and activities Nutrients are required for growth and survival Producers make their own food Consumers eat other organisms Ecosystems also depend on continuous energy input There is a one-way flow of energy through ecosystems Organisms can neither create energy or use it with complete efficiency During every energy transaction, some energy disperses into the environment as heat

The Producers Plants, algae, and some bacteria are producers (autotrophs) that produce their own food from simple raw materials Most producers use sunlight as energy for photosynthesis, which transforms light energy into chemical energy stored in chemical bonds of food molecules Photosynthesis synthesizes food molecules such as glucose (sugar) from carbon dioxide and water, and releases oxygen: carbon dioxide + water + light → glucose + oxygen

carbon dioxide + water + energy The Consumers Animals are consumers (heterotrophs) that obtain energy by breaking down food molecules produced in photosynthesis Primary consumers eat producers; secondary consumers eat primary consumers Chemical bonds are broken in the process of cellular respiration, and stored energy is made available: glucose + oxygen → carbon dioxide + water + energy

The Decomposers Most bacteria and fungi are decomposers, heterotrophs that obtain nutrients by breaking down nonliving organic material such as wastes, dead leaves and branches, and bodies of dead organisms In the process of obtaining energy, decomposers make the components of these materials available for reuse

Energy Flow Within and Among Organisms

Ecosystem: Energy Flow and Material Cycling

Overview of Life’s Unity Organisms sense change Receptors respond to stimulation Responses keep internal conditions within ranges that cells can tolerate (homeostasis)

Response to Stimulus

Overview of Life’s Unity Organisms grow and reproduce Based on information encoded in DNA Inheritance transmits DNA from parents to offspring through reproduction mechanisms Development transforms first cell into an adult

Organisms Grow and Develop Biological growth involves an increase in size of individual cells of an organism, in number of cells, or in both Some organisms (e.g. trees) grow throughout their lives Many animals have a growth period that ends at adult size Development includes all changes during an organism’s life Example: A human develops from a fertilized egg into a multicellular organism with structures and body form adapted to specific functions

Development

Organisms Regulate Their Metabolic Processes Metabolism includes all chemical activities that take place in an organism, including chemical reactions essential to nutrition, growth and repair, and conversion of energy Homeostatic mechanisms carefully regulate metabolic processes to maintain an appropriate, balanced internal environment (homeostasis) Example: Regulation of blood sugar (glucose)

Instructions Assemble Materials

KEY CONCEPTS: LIFE’S UNDERLYING UNITY All organisms are alike in key respects: Consist of one or more cells Live through inputs of energy and raw materials Sense and respond to changes in their external and internal environments Cells contain DNA (molecule that offspring inherit from parents; encodes information necessary for growth, survival, and reproduction)

1.3 So Much Unity, So Many Species The world of life, past and present, shows great diversity Classification systems organize species in ever more inclusive groups Taxonomy, is the science of naming and classifying organisms

Genus and Species Species: One kind of organism A species is a group of organisms with similar structure, function, and behavior

Binomial System The binomial system of nomenclature is used to name each species, it is called such because each species has a two-part name The first part of the name is the genus Closely related species are grouped into a genus (genera) The second part, the specific epithet, designates a particular species in that genus Example: The domestic dog, Canis familiaris (or C. familiaris), and timber wolf, Canis lupus (C. lupus), are in the same genus

Taxonomic Classification is Hierarchical Related genera are grouped in a family Families are grouped into orders, orders into classes, and classes into phyla (phylum) Phyla are assigned to kingdoms, and kingdoms are grouped in domains Each level is a taxon (taxa)

Classification of the Cat, Human, and White Oak Tree Table 1-1, p. 11

DOMAIN Eukarya KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Figure 1.10: Classification of the chimpanzee (Pan troglodytes). Primates FAMILY Pongidae GENUS Pan SPECIES Pan troglodytes Fig. 1-10, p. 12

Domains Current classification groups all species into three domains Bacteria (single-celled prokaryotes) Archaea (single-celled prokaryotes) Eukarya (protists, plants, fungi, and animals)

Life’s Three Domains

Figure 1.11: A survey of the three domains of life. Domain Bacteria (a) The large, rod-shaped bacterium Bacillus anthracis, a member of domain Bacteria, causes anthrax, a disease of cattle and sheep that can infect humans. Bacteria Common ancestor of all organisms Domain Archaea Archaea (b) These archaea (Methanosarcina mazei), members of the domain Archaea, produce methane. Domain Eukarya (c) These unicellular protozoa (Tetrahymena) are classified in one of the protist groups. (d) Plants include many beautiful and diverse forms, such as the lady’s slipper (Phragmipedium caricinum). (e) Among the fiercest animals, lions (Panthera leo) are also among the most sociable. The largest of the big cats, lions live in prides (groups). (f) Mushrooms, such as these fly agaric mushrooms (Amanita muscaria), are fungi. The fly agaric is poisonous and causes delirium, raving, and profuse sweating when ingested. Protists Plants Animals Fungi Figure 1.11: A survey of the three domains of life. Biologists assign organisms to three domains and to several kingdoms and other groups. The protists do not form a clade and are no longer considered a kingdom. They are assigned to five “supergroups” (not shown).

KEY CONCEPTS: LIFE’S DIVERSITY The world of life shows great diversity Many millions of kinds of organisms (species) have appeared and disappeared over time Each species is unique in at least one trait—in some aspect of its body form or behavior

1.4 An Evolutionary View of Diversity Life’s diversity arises from mutations Changes in molecules of DNA which offspring inherit from their parents In natural populations, mutations introduce variation in heritable traits among individuals

Variation in Heritable Traits Some trait forms are more adaptive than others Bearers are more likely to survive and reproduce Over generations, adaptive forms of traits tend to become more common in a population Less adaptive forms of the same traits become less common or are lost

Evolution Populations evolve Evolution Traits that help characterize a population (and a species) can change over generations Evolution Change which occurs in a line of descent

Selection Natural selection Artificial selection In natural populations Differential survival and reproduction among individuals that vary in one or more heritable traits Artificial selection Breeding of captive populations Traits selected are not necessarily adaptive

KEY CONCEPTS: EXPLAINING UNITY IN DIVERSITY Theories of evolution (especially a theory of evolution by natural selection) help explain why life shows both unity and diversity Evolutionary theories guide research in all fields of biology

1.5 Critical Thinking and Science Critical thinking is a self-directed act of judging the quality of information as one learns Science is a way of looking at the natural world Helps minimize bias in judgments Focuses on testable ideas about observable aspects of nature

Evidence-Based Thinking

1.6 How Science Works Researchers generally Observe something in nature Form hypotheses (testable assumptions) about it Make predictions about what might occur if the hypothesis is not wrong Test their predictions by observations, experiments, or both

Experiments Tests used to support or falsify a prediction Variable characteristic is measured and changed Dependent variable: is presumably affected by the independent variable (ex. Severity of hangover) Independent variable: controlled by the experimenter in order to explore its relationship with the dependent variable (ex. Prophylactic treatment for a hangover) In the control group, variables do not change

A Scientific Approach

Scientific Theory A well-tested hypothesis Explains a broad range of observations Can be used to make useful predictions about other phenomena A good hypothesis has three characteristics: It is reasonably consistent with well-established facts It is capable of being tested; and test results should be repeatable by independent observers It is falsifiable (can be proven false) Opinion and belief are not scientific theory !!!!

A Falsifiable Hypothesis Can Be Tested A well-stated hypothesis can be tested If no evidence is found to support it, the hypothesis is rejected The hypothesis can be shown to be false A hypothesis can be supported by data, but it can’t really be proven true

Some Scientific Theories Atomic Theory All Substances consist of atoms Big Bang The universe originated with an explosion and continues to expand Cell Theory All organisms consist of one or more cells, the cell is the basic unit of life, and all cells arise from existing cells Evolution Change occurs in the inherited traits of a population over generations Global Warming Human activities are causing Earth’s average temperature to increase

1.7 The Power of Experiments Biological systems have many variables Experiments simplify observations of nature Focus on cause, effect, or function of one variable at a time Researchers design experiments to minimize potential bias in interpreting results

A Controlled Experiment

Hypothesis Prediction Experiment Control Group Experimental Group Olestra® causes intestinal cramps. Prediction People who eat potato chips made with Olestra will be more likely to get intestinal cramps than those who eat potato chips made without Olestra. Experiment Control Group Experimental Group Eats regular potato chips Eats Olestra potato chips Results 93 of 529 people get cramps later (17.6%) 89 of 563 people get cramps later (15.8%) Conclusion Percentages are about equal. People who eat potato chips made with Olestra are just as likely to get intestinal cramps as those who eat potato chips made without Olestra. These results do not support the hypothesis. Fig. 1.11, p. 14

Butterflies and Birds: A Behavioral Experiment Wing Spots Wing Sound Total Number of Butterflies Number Eaten Number Survived Spots Sound 9 9 (100%) No Spots 10 5 5 (50%) No Sound 8 8 (100%) 2 (20%)

Stepped Art a Wing spots painted out d Wings painted but spots visible e Wings cut but not silenced f Wings painted but spots visible; wings cut but not silenced b Wing spots visible; wings silenced c Wing spots painted out; wings silenced Stepped Art Fig. 1-14, p. 18

1.8 Sampling Error in Experiments Difference between results derived from testing an entire group and results derived form testing a subset of the group. Small sample size increases the likelihood of sampling error in experiments In such cases, a subset may be tested that is not representative of the whole 1.8 Sampling Error in Experiments

KEY CONCEPTS: HOW WE KNOW Biologists make systematic observations, predictions, and tests in the laboratory and field They report their results so others may repeat their work and check their reasoning

Animation: Building blocks of life CLICK HERE TO PLAY

Animation: Insect development CLICK HERE TO PLAY

Animation: Life's diversity CLICK HERE TO PLAY

Animation: Life's levels of organization CLICK HERE TO PLAY

Animation: One-way energy flow and materials cycling CLICK HERE TO PLAY

Animation: Sampling error CLICK HERE TO PLAY

Animation: Three domains CLICK HERE TO PLAY