Chapter 1 Lecture PDF

Chapter 1 Lecture Learning About Life PowerPoint® Lectures created by Edward J. Zalisko for Campbell Essential Biology, Seventh Edition, and Campbell Essential Biology with Physiology, Sixth Edition – Eric J. Simon, Jean L. Dickey, and Jane B. Reece © 20...

Chapter 1 Lecture Learning About Life PowerPoint® Lectures created by Edward J. Zalisko for Campbell Essential Biology, Seventh Edition, and Campbell Essential Biology with Physiology, Sixth Edition – Eric J. Simon, Jean L. Dickey, and Jane B. Reece © 2019 Pearson Education, Inc.  What the heck is that? If you’ve wondered what an unusual or especially beautiful animal is called, you’re curious about biology. © 2019 Pearson Education, Inc.  The Scientific Study of Life: An Overview of the Process of Science Biology is the scientific study of life. What does it mean to study something scientifically? How do we tell the difference between science and other ways of trying to make sense of the world? © 2019 Pearson Education, Inc.  An Overview of the Process of Science Science is an approach to understanding the natural world that is based on inquiry—a search for information, evidence, explanations, and answers to specific questions. Scientists seek natural causes for natural phenomena. They focus solely on the study of structures and processes that can be verifiably observed and measured. © 2019 Pearson Education, Inc.  An Overview of the Process of Science: Testing A hypothesis is a proposed explanation for a set of observations. A valid hypothesis must be testable and falsifiable. – Some hypotheses (such as ones involving conditions that can be easily controlled) lend themselves to experiments, or scientific tests. – Other hypotheses (involving aspects of the world that cannot be controlled, such as ecological issues) can be tested by making further observations. – The results of an experiment will either support or not support the hypothesis. © 2019 Pearson Education, Inc.  Testing a common problem using the process of science © 2019 Pearson Education, Inc.  Hypotheses, Theories, and Facts A theory is a comprehensive and well- substantiated explanation, much broader in scope than a hypothesis. – Theories become widely accepted by scientists only if they are supported by a large, varied, and growing body of evidence. – A theory can be used to explain many observations and to devise many new and testable hypotheses. – However, a theory, like any scientific idea, must be refined or even abandoned if new, contradictory evidence is discovered. © 2019 Pearson Education, Inc.  Controlled Experiments To investigate a hypothesis, a researcher often runs a test multiple times with one factor changing and, ideally, all other factors held constant. – Variables are factors that change in an experiment. – A controlled experiment is one that compares two or more groups that differ only in one variable that the experiment is designed to test. – The control group lacks or does not receive the specific factor being tested. – The experimental group has or receives the specific factor being tested. © 2019 Pearson Education, Inc.  Controlled Experiments – The independent variable is what is being manipulated by the researchers as a potential. – The dependent variable is the response, output, or effect under investigation that is used to judge the outcome of the. The dependent variable is affected by the independent (manipulated) variable. – Well-designed experiments often test just one independent variable at a time. © 2019 Pearson Education, Inc.  Evaluating Scientific Claims (Cont.) One of the best ways to evaluate scientific claims is to consider the source of the information. – Science depends upon peer review, the evaluation of work by impartial, qualified, often anonymous experts who are not involved in that work. – Publishing a study in a peer-reviewed journal is often the best way to ensure that. © 2019 Pearson Education, Inc.  Recognizing a reliable source © 2019 Pearson Education, Inc.  Major Themes in Biology Five unifying themes recur throughout our investigation of biology: 1. the relationship of structure to function, 2. information flow, 3. pathways that transform energy and matter, 4. interactions within biological systems, and 5. evolution. © 2019 Pearson Education, Inc.  The Relationship of Structure to Function The correlation between structure and function can be seen at different levels within biological systems, such as molecules, cells, tissues, and organs. – The branched structure of the lungs provides a tremendous surface area over which a very high volume of air may pass (the function of the lungs). – The indentations of red blood cells increase the surface area through which oxygen can diffuse. – Throughout your study of life, you will see that the structure and function principle applies to all levels of biological organization. © 2019 Pearson Education, Inc.  Structure and function: human lungs © 2019 Pearson Education, Inc.  Structure and function: red blood cells Checkpoint: Explain how the correlation between structure and function applies to a tennis racket. © 2019 Pearson Education, Inc.  Information Flow For life’s functions to proceed in an orderly manner, information must be received, transmitted, and used. Such information flow is apparent at all levels of biological organization. – For example, information about the amount of glucose in the bloodstream is received by organs such as your pancreas. – The pancreas acts on that information by releasing hormones (including insulin) that regulate the levels of glucose in the blood. © 2019 Pearson Education, Inc.  Information Flow (Cont.) Every cell contains genes, hereditary units of information consisting of specific sequences of DNA passed on from the previous generation. ‒ At the organismal level, as every multicellular organism develops from an embryo, information exchanged between cells enables the overall body plan to take shape in an organized fashion. ‒ The language of life has an alphabet of just four letters. The chemical names of DNA’s four molecular building blocks are abbreviated as A, G, C, and T. © 2019 Pearson Education, Inc.  Information stored in DNA © 2019 Pearson Education, Inc.  Transformations of energy and matter in an ecosystem. © 2019 Pearson Education, Inc.  Interactions within Biological Systems The study of life extends from the microscopic level of the molecules and cells that make up organisms to the global level of the entire living planet, the biosphere. – There are many interactions within and between these levels of biological systems. – At each new level, the complexity increases and novel properties emerge that are absent from the preceding one. These emergent properties are due to the specific arrangement and interactions of many parts into an increasingly complex system. © 2019 Pearson Education, Inc.  Zooming in on life © 2019 Pearson Education, Inc.  Evolution Life is distinguished by its unity and its diversity. Multiple lines of evidence point to life’s unity: – the similarities seen among and between fossil and living organisms, – the common cellular processes, and – the universal chemical structure of DNA. The scientific explanation for this unity and diversity is evolution, the process of change that has transformed life on Earth from its earliest forms to the vast array of organisms living today. © 2019 Pearson Education, Inc.  Evolution (Cont.) Evolution is the fundamental principle of life and the core theme that unifies all of biology. – The theory of evolution by natural selection is the one principle that makes sense of everything we know about living organisms. – Evolution can help us investigate and understand every aspect of life. – Therefore, every biology student should strive to understand evolution. © 2019 Pearson Education, Inc.  Evolution (Cont.) In the struggle for existence, those individuals with traits best suited to the local environment are more likely to survive and leave the greatest number of healthy offspring. It is this unequal reproductive success that Darwin called natural selection because the environment “selects” only certain heritable traits from those already existing. © 2019 Pearson Education, Inc.  Evolution (Cont.) Natural selection does not promote or somehow encourage changes. – Rather, mutations occur randomly. – Natural selection “edits” those changes that have already occurred. – If those traits can be inherited, they will be more common in the next generation. – The results of natural selection are evolutionary adaptations, inherited traits that enhance survival in an organism’s specific environment. © 2019 Pearson Education, Inc.  Natural selection in action © 2019 Pearson Education, Inc.  Evolution Connection: Turtles in the Tree of Life Each species on Earth today represents one twig on a branching tree of life that extends back in time through ancestral species more and more remote. Comparing DNA sequences from different species provides evidence of evolutionary relationships. Such evidence can be used to generate an evolutionary tree. Species that are very similar share a common ancestor at a relatively recent branch point on the tree of life. © 2019 Pearson Education, Inc.  A partial family tree of animals © 2019 Pearson Education, Inc.