Campbell Essential Biology and Campbell Essential Biology with Physiology - Chapter 1 - PDF

Campbell Essential Biology and Campbell Essential Biology with Physiology Sixth Edition Chapter 1 Learning About Life Copyright © 2021 Pearson Education, Inc. All Rights Reserved What the Heck Is Tha...

Campbell Essential Biology and Campbell Essential Biology with Physiology Sixth Edition Chapter 1 Learning About Life Copyright © 2021 Pearson Education, Inc. All Rights Reserved What the Heck Is That? If You’ve Wondered What an Unusual or Especially Beautiful Animal Is Called, You’re Curious About Biology Copyright © 2021 Pearson Education, Inc. All Rights Reserved Biology and Society: A Passion for Life It’s very human to be curious about the world around us. Nearly all of us have an inherent interest in life, an inborn fascination with the natural world. Exploring life is relevant and important to you. The textbook authors will use this passion to help you develop an understanding of the subject of biology, an understanding that you can apply to your own life and to the society in which you live. Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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? Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved An Overview of the Process of Science: Exploration Biology, like other sciences, begins with exploration. During this initial phase of inquiry, you may simply watch the subject and record your observations. Recorded observations are called data—the evidence on which scientific inquiry is based. As you proceed with your exploration, your curiosity will lead to questions, which are the launching point for the next step in the process of science: testing. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.1 Scientific Exploration Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Testing a Common Problem Using the Process of Science Copyright © 2021 Pearson Education, Inc. All Rights Reserved An Overview of the Process of Science: Communications and Outcomes In fine-tuning their questions, scientists rely heavily on scientific literature, the published contributions of fellow scientists. Scientists also communicate with each other in seminars, meetings, and scientific publications. Before experimental results are published in a scientific journal, the research is evaluated by qualified, impartial, often anonymous experts who were not involved in the study. This process, intended to provide quality control, is called peer review. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.3 Scientific Communication Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.4 Scientific Outcomes Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.5 An Overview of the Process of Science Checkpoint: Why does peer review improve the reliability of a scientific paper? Copyright © 2021 Pearson Education, Inc. All Rights Reserved Hypotheses, Theories, and Facts (1 of 2) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Hypotheses, Theories, and Facts (2 of 2) A fact is a piece of information considered to be objectively true based on all current evidence. – A fact can be verified and is therefore distinct from opinions. – Many people associate facts with science, but accumulating facts is not the primary goal of science. The cornerstones of science are the explanations that apply to the greatest variety of phenomena. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Controlled Experiments (1 of 3) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Process of Science: Do Baby Turtles Swim? Background: After emerging from a 2-month incubation, turtle hatchlings dig out of the sand and then use moonlight to navigate to the sea. Can the juvenile turtles swim in ocean currents? Or do they just passively drift? Method: Researchers attached tiny satellite trackers to 24 green sea turtles, each between 1 and 2 years old, in the Gulf of Mexico. Results: The turtles moved faster and along different tracks than drifting buckets, suggesting that they travel by swimming. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.6 Tracking Baby Sea Turtles (a) Green sea turtle hatchlings (b) Satellite tracker (c) Graph showing the distance traveled by the scrambling to the sea on the back of a average turtle (red line) versus the average floating baby turtle bucket (blue line) Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.7 Independent Versus Dependent Variables Copyright © 2021 Pearson Education, Inc. All Rights Reserved Controlled Experiments (2 of 3) The turtle study was a controlled experiment. – The independent variable is what is being manipulated by the researchers as a potential cause— in this case, the object under investigation (either turtles or buckets). – The dependent variable is the response, output, or effect under investigation that is used to judge the outcome of the experiment—in this case, the speed of movement. The dependent variable is affected by the independent (manipulated) variable. – Well-designed experiments often test just one independent variable at a time. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Controlled Experiments (3 of 3) Many medical drug trials include a placebo, a medically ineffective treatment that allows the placebo group to serve as a control group. – Typically, the placebo group does not know that they are receiving an ineffective substitute. – An experiment in which neither the participant nor the experimenter knows which group is the control group is called a double-blind experiment. – The “gold standard” for a medical trial is a “double- blind placebo-controlled study.” Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.8 How to Recognize Blind Studies Test Subjects Know Researchers Know Which Group Is Which Group Is Type of Study Which? Which? Not blind Yes Yes Single blind No Yes Double blind No No Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evaluating Scientific Claims (1 of 2) Pseudoscience is any field of study that is falsely presented as having a scientific basis. – Given our access to huge amounts of information, much of it unreliable, the ability to recognize pseudoscience is a very important thinking skill. – There are several indicators that you can use to recognize pseudoscience. For example, a pseudoscientific study may be based solely or largely on anecdotal evidence, an assertion based on a single or a few examples that do not support a generalized conclusion. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.9 Features of Science Versus Pseudoscience Features of Science Features of Pseudoscience Adheres to an Does not adhere to generally established and well- accepted processes of recognized scientific science method Repeatable results Results that cannot be duplicated by others; results that rely on a single person or are solely opinion Testable claims that can Unprovable or untestable be disproven claims; reliance on assumptions or belief that are not testable A field biologist Open to outside review Rejection of external review collecting data or refusal to accept contradictory evidence A pyramid that is Multiple lines of Overreliance on a small claimed to channel evidence amount of data; underlying causes are not investigated energy Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evaluating Scientific Claims (2 of 2) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.10 Recognizing a Reliable Source Source reliability checklist Is the information current? Is the source primary (and not secondary)? Is/are the author(s) identifiable and well qualified? Does the author lack potential conflicts of interest? Are references cited? Are any experiments described in enough detail that they could be reproduced? Was the information peer reviewed? Is the information unbiased? Is the intent of the source known and valid? Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Properties of Life (1 of 2) Using a green sea turtle as an example, Figure 1.11 highlights the major properties we associate with life. – An object is generally considered to be alive if it displays all of these characteristics simultaneously. – On the other hand, a nonliving object may display some of these properties, but not all of them. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.11 a Green Sea Turtle Displays the Properties of Life Checkpoint: Which properties of life apply to a car? Which do not? Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Properties of Life (2 of 2) Even as life on Earth shares recognizable properties, it also exists in tremendous diversity. Biologists speculate that extraterrestrial life, if it exists, could be recognized by the same properties described in Figure 1.11. The Mars rover Curiosity has been exploring the surface of the red planet since 2012 and contains several instruments designed to identify substances that provide evidence of past or present life. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.12 A Sample of the Diversity of Life in a National Park in Namibia Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.13 Structure and Function: Human Lungs Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.14 Structure and Function: Red Blood Cells Checkpoint: Explain how the correlation between structure and function applies to a tennis racket. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Information Flow (1 of 3) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Information Flow (2 of 3) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.15 Information Stored in DNA Copyright © 2021 Pearson Education, Inc. All Rights Reserved Information Flow (3 of 3) People with type 1 diabetes often have a mutation (error) in a different gene that causes the body’s immune cells to attack and destroy the insulin- producing pancreas cells. – These cells are then unable to properly respond to information about glucose levels in the blood. – Some people with diabetes regulate their sugar levels by injecting themselves with insulin produced by genetically engineered bacteria. – These bacteria can make insulin because the human gene has been transplanted into them. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Pathways That Transform Energy and Matter (1 of 4) Movement, growth, reproduction, and cellular activities of life are work, and work requires energy. The input of energy, primarily from the sun, and the transformation of energy from one form to another make life possible. Most ecosystems are solar powered at their source. – Sunlight is captured by plants and other photosynthetic organisms (producers). – This energy is then converted into chemical energy, stored as chemical bonds within sugars and other complex molecules. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Pathways That Transform Energy and Matter (2 of 4) Organisms use food as a source of energy by breaking chemical bonds to release energy stored in the molecules or as building blocks for making new molecules needed by the organism. In these energy conversions between and within organisms, some energy is converted to heat, which is then lost from the ecosystem. Thus, energy flows through an ecosystem, entering as light energy and exiting as heat energy. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.17 Transformations of Energy and Matter in an Ecosystem Copyright © 2021 Pearson Education, Inc. All Rights Reserved Pathways That Transform Energy and Matter (3 of 4) Within all living cells, a vast network of interconnected chemical reactions (collectively referred to as metabolism) continually converts energy from one form to another as matter is recycled. Energy transformations can be disrupted, often with dire consequences. For example, cyanide is so toxic because it blocks an essential step within the metabolic pathway that harvests energy from glucose. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Pathways That Transform Energy and Matter (4 of 4) Checkpoint: 1. What is the key difference between how energy and matter move in ecosystems? 2. What is the primary way by which energy leaves your body? Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.18 Zooming in on Life Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (1 of 7) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (2 of 7) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (3 of 7) The evolutionary view of life came into focus in 1859 when Charles Darwin published one of the most influential books ever written: On the Origin of Species by Means of Natural Selection. Darwin presented two main points in that book. 1. Species living today arose from a succession of ancestors that were different from them in a process Darwin called “descent with modification.” 2. The process of natural selection is the driving force of evolution. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.19 Charles Darwin (1809–1882), the Origin of Species, and Blue-Footed Boobies He Observed on the Galápagos Islands Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (4 of 7) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (5 of 7) 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (6 of 7) The world is rich with examples of natural selection. Consider the development of antibiotic-resistant bacteria. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.20 Natural Selection in Action Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution (7 of 7) Figure 1.21 reviews the five unifying themes of biology. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.21 Applying the Major Themes of Biology to the Study of the Green Sea Turtle Copyright © 2021 Pearson Education, Inc. All Rights Reserved Identifying Major Themes (1 of 3) As global climate changes, green sea turtles alter many aspects of their behavior. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2021 Pearson Education, Inc. All Rights Reserved Identifying Major Themes (2 of 3) Although green sea turtles consume a lot of vegetation, they get few nutrients from each mouthful, requiring them to graze frequently. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2021 Pearson Education, Inc. All Rights Reserved Identifying Major Themes (3 of 3) By comparing genes between green sea turtles and humans, insight can be gained into how those genes encode specific physical traits. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2021 Pearson Education, Inc. All Rights Reserved 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. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Figure 1.22 A Partial Family Tree of Animals Copyright © 2021 Pearson Education, Inc. All Rights Reserved