Figure 1.7 Scientists use two types of reasoning, inductive and deductive reasoning, to advance scientific knowledge. As is the case in this example, the conclusion from inductive reasoning can often become the premise for deductive reasoning. Course and book-specific resources including adaptive quizzing to personalise the experience for students.

Recall that a hypothesis is a suggested explanation that one can test. To solve a problem, one can propose several hypotheses. For example, one hypothesis might be, “The classroom is warm because no one turned on the air conditioning.” However, there could be other responses to the question, and therefore one may propose other hypotheses. A second hypothesis might be, “The classroom is warm because there is a power failure, and so the air conditioning doesn’t work.” The evolutionary relationships of various life forms on Earth can be summarized in a phylogenetic tree. A phylogenetic tree is a diagram showing the evolutionary relationships among biological species based on similarities and differences in genetic or physical traits or both. A phylogenetic tree is composed of branch points, or nodes, and branches. The internal nodes represent ancestors and are points in evolution when, based on scientific evidence, an ancestor is thought to have diverged to form two new species. The length of each branch can be considered as estimates of relative time.Achieve is more than just an online homework system—it’s a full online learning system. Studies show that a more structured course that includes smaller and more frequent assignments benefits students who are less prepared for the course without hindering well prepared students. Achieve supports that structure by providing content for all aspects of your course including pre-class preparation, in-class active learning, and post-class homework and assessment. A new online, interactive version of the in-text Statistics Primer offers students the opportunity to actually perform statistical analysis and calculations. Finally, the conclusion section summarizes the importance of the experimental findings. While the scientific paper almost certainly answers one or more scientific questions that the researchers stated, any good research should lead to more questions. Therefore, a well-done scientific paper allows the researchers and others to continue and expand on the findings.

Chromosomes, the carriers of DNA, are distributed evenly between the daughter cells during cell division. Therefore, each daughter cell will have the same chromosome set as the mother cell. Connect the Concepts foster thinking about the big picture—a task that can be overwhelming for introductory biology students—by demonstrating how certain important terms and concepts relate to discussions in another chapter. Figure 1.2 Formerly called blue-green algae, these (a) cyanobacteria, magnified 300x under a light microscope, are some of Earth’s oldest life forms. These (b) stromatolites along the shores of Lake Thetis in Western Australia are ancient structures formed by layering cyanobacteria in shallow waters. (credit a: modification of work by NASA; credit b: modification of work by Ruth Ellison; scale-bar data from Matt Russell) All of which also earn us Courier Printing Company’s Green Edition designation for reducing our environmental footprint. The environmental savings we have achieved on the first printing alone are:

Taking an active learning approach throughout, Life helps students learn by doing with a wealth of pedagogy that ensures they master key concepts and instructors benefit from an active learning guide providing invaluable resources and support for implementing active learning in the classroom. Leading by example and with a focus on critical thinking, the text exposes students to many thoughtful questions throughout, reinforcing the importance of asking questions in biology. For example, bioethicists may examine the implications of gene editing technologies, including the ability to create organisms that may displace others in the environment, as well as the ability to “design” human beings. In that effort, ethicists will likely seek to balance the positive outcomes -- such as improved therapies or prevention of certain illnesses -- with negative outcomes.

The engaging and powerful simulations are now outfitted with quizzes that will report to the Instructor grade-book. There is no complete agreement when it comes to defining what the natural sciences include, however. For some experts, the natural sciences are astronomy, biology, chemistry, earth science, and physics. Other scholars choose to divide natural sciences into life sciences, which study living things and include biology, and physical sciences, which study nonliving matter and include astronomy, geology, physics, and chemistry. Some disciplines such as biophysics and biochemistry build on both life and physical sciences and are interdisciplinary. Some refer to natural sciences as “hard science” because they rely on the use of quantitative data. Social sciences that study society and human behavior are more likely to use qualitative assessments to drive investigations and findings. The scientific method may seem too rigid and structured. It is important to keep in mind that, although scientists often follow this sequence, there is flexibility. Sometimes an experiment leads to conclusions that favor a change in approach. Often, an experiment brings entirely new scientific questions to the puzzle. Many times, science does not operate in a linear fashion. Instead, scientists continually draw inferences and make generalizations, finding patterns as their research proceeds. Scientific reasoning is more complex than the scientific method alone suggests. Notice, too, that we can apply the scientific method to solving problems that aren’t necessarily scientific in nature. Two Types of Science: Basic Science and Applied ScienceInsects generally survive mild winters better than harsh ones. Therefore, insect pests will become more problematic if global temperatures increase. Once one has selected a hypothesis, the student can make a prediction. A prediction is similar to a hypothesis but it typically has the format “If . . . then . . . .” For example, the prediction for the first hypothesis might be, “ If the student turns on the air conditioning, then the classroom will no longer be too warm.” Testing a Hypothesis A GREENER LIFEAnother first, the new edition of Life is printed on paper earning the Forest Stewardship Council (FSC) label, the “gold standard” in green paper products. Life paper includes 10% pre-consumer waste, 10% post-consumer waste, and is manufactured from wood from well-managed sustainable forests. Additionally, Life’s green initiatives include: Continuing in the tradition of Life, the 12th Edition Digital Update embraces an active learning approach that is seamlessly integrated throughout the text and media. Features are as follows:

Animals as diverse as humans, insects, and wolves all exhibit social behavior. Therefore, social behavior must have an evolutionary advantage. Learning objectivesguide students to the essential content as they read through each Key Concept section. A new in-text Visual Summary takes the place of standard text-only summaries to help students better master concepts and competencies via a visual trigger (a key in-text figure) and short concise text entries, to aid their memory. Relevant animations and activities are referenced in each summary entry. Figure 1.3 Escherichia coli ( E. coli) bacteria, in this scanning electron micrograph, are normal residents of our digestive tracts that aid in absorbing vitamin K and other nutrients. However, virulent strains are sometimes responsible for disease outbreaks. (credit: Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU) The Process of ScienceAll living organisms, regardless of their uniqueness, have certain biological, chemical, and physical characteristics in common. All, for example, are composed of basic units known as cells and of the same chemical substances, which, when analyzed, exhibit noteworthy similarities, even in such disparate organisms as bacteria and humans. Furthermore, since the action of any organism is determined by the manner in which its cells interact and since all cells interact in much the same way, the basic functioning of all organisms is also similar. Marta Laskowski is a Professor in the Biology Department at Oberlin College. Dr. Laskowski has mentored undergraduate students in research and has taught introductory biology, skills-based first year seminars (Feeding the World), plant physiology, and plant development. She heads an effort at Oberlin, funded by the HHMI Inclusive Excellence program, to enhance the climate for and success of a diverse student population in STEM. Links to media such as animations, simulations, and jaw-dropping videos appear throughout each chapter and allow students to interact with content in a variety of ways. Students needing extra practice with data analysis can use the Online Companions to every Work with the Data exercise in the book.