Essentials of the Living World Second Edition George B. Johnson Jonathan B. Losos Chapter 1 The Science of Biology Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

1.1 The Diversity of Life Biology is the study of living things Living things are diverse There are enough similarities among some living things that they can be grouped into the same kingdom Members of different kingdoms are usually very different from each other Point out the text is appropriately titled, The Living World

The Six Kingdoms of Life Figure 1.1

1.2 Properties of Life What qualifies something as “living” versus “non-living?” Consider these points complexity movement response to stimulation A life-defining property must be exclusive to living things Prompt students to decide what properties the living things in the kingdoms have? Are those properties exclusive to living things? What properties are?

1.2 Basic Properties of Life 1. Cellular organization all living things are comprised of at least one cell 2. Metabolism all living things process energy which is used to power other processes 3. Homeostasis all living things maintain stable internal environments to optimize conditions for metabolism and other processes All organisms share 5 properties that are unique to life.

1.2 Basic Properties of Life 4. Growth and reproduction all organisms have the capacity for growth and reproduction 5. Heredity all organisms pass genetic information across generations from parents to offspring

1.3 The Organization of Life Living things function and interact with each other on many levels The organization of life is a hierarchy of levels of increasing complexity cellular organismal populational The following slide sequence shows the hierarchy of transitions from one level of complexity to the next—emphasize the interconnectedness.

Fig. 1.4 Cellular Level

Fig. 1.4 Organismal Level

Fig. 1.4 Population Level

1.3 The Organization of Life At higher levels of the living hierarchy, new properties become apparent that were absent at the lower levels These emergent properties result from the interaction of diverse but simpler components Many higher order processes that are hallmarks of life are emergent properties metabolism consciousness

1.4 Biological Themes The study of life is organized around general themes 5 biological themes emerge repeatedly at any hierarchical level of biological study refer to Table 1.1

1.4 Biological Themes 1. Evolution evolution is genetic change in a species over time the mechanism for evolution is natural selection the diversity of life is explained by evolutionary processes

1.4 Biological Themes 2. The Flow of Energy all living things require energy energy from the sun flows through the living world organisms acquire energy differently how much energy is available determines how many and what kinds of organisms can live together in an ecosystem

1.4 Biological Themes 3. Cooperation as energy and other resources are limiting, many organisms have evolved cooperation as a means of survival symbiosis describes when two species live in direct contact

1.4 Biological Themes 4. Structure Determines Function evolution favors structures that function in an adaptive manner many structures are specialized for a particular function the convergence of structure and function occurs at levels of the organizational hierarchy

1.4 Biological Themes 5. Homeostasis homeostasis is a physiological condition of “steady-state” the internal environment of organisms is remarkably stable organisms act to control their internal environments so that the complex processes of metabolism function efficiently

1.5 How Scientists Think Science is a process of investigation, using observation, experimentation, and reasoning There are different philosophical approaches to reasoning May mention that a Ph.D. is actually a doctorate of philosophy.

1.5 How Scientists Think Deductive reasoning uses general principles to explain specific observations This form of reasoning is common to many disciplines, including mathematical proofs politics computing

1.5 How Scientists Think Inductive reasoning is the way of discovering general principles from examination of specific observations Scientists employ inductive reasoning by forming and testing possible explanations for specific observations These possible explanations are called hypotheses

Figure 1.5 Deductive and inductive reasoning Compare and contrast the two forms of reasoning and emphasize which one is more scientific.

1.6 Science in Action: A Case Study Scientist Joseph Farman observed in 1985 that ozone levels in Anarctica are alarmingly low Pollution by chloroflourocarbons (CFCs) was later found to be the culprit CFCs were common components of many synthetic products, such as coolants used in air conditioners propellants in aerosols foaming agents in Styrofoam

Figure 1.6 How CFCs attack and destroy ozone

1.6 Science in Action: A Case Study Ozone depletion is a serious matter ozone acts as a sunscreen against ultraviolet rays from the sun a 1% drop in ozone leads to a 6% increase in skin cancer A world-wide reduction in CFC production has helped alleviate ozone depletion

1.7 Stages of a Scientific Investigation Biology is a dynamic science with new ideas appearing and replacing old ones Scientists systematically conduct experiments to evaluate hypotheses about observed phenomena

1.7 Stages of a Scientific Investigation The scientific process has six stages 1. Observation science begins with careful observation of natural phenomena 2. Hypothesis scientists make an educated guess that might be true often scientists formulate multiple ideas about a phenomenon; these are called alternative hypotheses

1.7 Stages of a Scientific Investigation 3. Predictions if a hypothesis is correct, then specific consequences can be expected 4. Testing scientists conduct experiments to attempt to verify predictions made by hypotheses

1.7 Stages of a Scientific Investigation 5. Controls experiments usually employ a parallel design scientists use a control to assess the influence of potential factors, called variables conditions stay the same in the control in comparison to the variable condition 6. Conclusion a hypothesis that has been tested and not rejected is tentatively accepted Most experiments lead to future experiments!

Fig.1.7 The scientific process

1.7 Stages of a Scientific Investigation Scientific research involves analyzing data before reaching any conclusion Scientists must present their results carefully so that others can interpret them

1.8 Theory and Certainty The term “theory” means different things to different audiences to scientists, a theory represents certainty and is a unifying explanation for a broad range of observations to the general public, a theory implies a lack of knowledge or guess

1.8 Theory and Certainty Scientists’ acceptance of theory is provisional the possibility always remains that future evidence will cause a theory to be revised The process of science is not just trial-and-error but involves judgement and intuition

1.8 Theory and Certainty science has limitations it is limited to organisms and processes that can be observed and measured supernatural and religious phenomena are beyond the scope of science there are also practical limits science cannot be relied upon to solve all problems

1.9 Four Theories Unify Biology as a Science 1. The Cell Theory 2. The Gene Theory 3. The Theory of Heredity 4. The Theory of Evolution

The Cell Theory all organisms are composed of at least one cell the cell is the most basic unit of life all cells come from pre-existing cells

The Gene Theory genetic information is encoded in molecules of deoxyribonucleic acid (DNA) genes encode specific proteins or RNA or act to regulate other genes the proteins and RNA encoded by an organism’s genes determine what it will be like in terms of form and function

Figure 1.12 The gene theory

The Theory of Heredity genes are passed down generations as discrete units Mendel’s theory of heredity gave rise to the field of genetics chromosomal theory of inheritance located Mendelian genes on chromosomes

The Theory of Evolution Charles Darwin’s theory of evolution explains the unity and diversity of life as “descent with modification” All living organisms are related to one another in a common tree of descent

Fig. 1.15 The tree of life

Classifying Life’s Diversity Scientists group organisms, based on similarities, into six kingdoms Each of the six kingdoms are assigned, on the basis of cell structure into one of three domains

Figure 1.16 The three domains of life

Inquiry & Analysis What is the dependent variable? Is the size of the ozone hole increasing? Why are the rates of increase different between 1980 - 1990 and 1995 - 2005? Insert figure of History of the Ozone Hole: Peak Size