The Science of Biology Chapter 1

What is science? Section 1.1

What Science Is Not Science is not just a collection of never-changing facts or unchanging beliefs about the world. Some scientific “facts” will change soon—if they haven’t changed already. Scientific ideas are open to testing, discussion, and revision.

What is Science? “knowledge or a system of knowledge covering general truths or the operation of general laws especially as obtained and tested through scientific method; knowledge concerned with the physical world and its phenomena”

What is Science? “the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment”

What Science Is Science is an organized way of gathering and analyzing evidence about the natural world. For example, researchers can use science to answer questions about how whales communicate, how far they travel, and how they are affected by environmental changes.

Science as a Way of Knowing Science deals only with the natural world.

Scientists collect and organize information in an orderly way, looking for patterns and connections among events. Scientists propose explanations that are based on evidence, not belief. Then they test those explanations with more evidence.

The Goals of Science The physical universe is a system composed of parts and processes that interact. All objects in the universe, and all interactions among those objects, are governed by universal natural laws. One goal of science is to provide natural explanations for events in the natural world. Science also aims to use those explanations to understand patterns in nature and to make useful predictions about natural events.

Science, Change, & Uncertainty Despite all of our scientific knowledge, much of nature remains a mystery. Almost every major scientific discovery raises more questions than it answers. This constant change shows that science continues to advance. Learning about science means understanding what we know and what we don’t know. Science rarely “proves” anything in absolute terms. Scientists aim for the best understanding of the natural world that current methods can reveal. Science has allowed us to build enough understanding to make useful predictions about the natural world.

Scientific Methodology: The Heart of Science

Observing and Asking Questions Scientific investigations begin with observation, the act of noticing and describing events or processes in a careful, orderly way. For example, researchers observed that marsh grass grows taller in some places than others. This observation led to a question: Why do marsh grasses grow to different heights in different places?

Inferring and Forming a Hypothesis After posing questions, scientists use further observations to make inferences, or logical interpretations based on what is already known. Inference can lead to a hypothesis, or a scientific explanation for a set of observations that can be tested in ways that support or reject it.

Inferring and Forming a Hypothesis For example, researchers inferred that something limits grass growth in some places. Based on their knowledge of salt marshes, they hypothesized that marsh grass growth is limited by available nitrogen.

Designing a Controlled Experiment Testing a scientific hypothesis often involves designing an experiment that keeps track of various factors that can change, or variables. Examples of variables include temperature, light, time, and availability of nutrients. Whenever possible, a hypothesis should be tested by an experiment in which only one variable is changed. All other variables should be kept unchanged, or controlled. This type of experiment is called a controlled experiment.

Controlling Variables It is important to control variables because if several variables are changed in the experiment, researchers can’t easily tell which variable is responsible for any results they observe. The variable that is deliberately changed is called the independent variable (also called the manipulated variable). The variable that is observed and that changes in response to the independent variable is called the dependent variable (also called the responding variable).

Control and Experimental Groups Typically, an experiment is divided into control and experimental groups. A control group is exposed to the same conditions as the experimental group except for one independent variable. Scientists set up several sets of control and experimental groups to try to reproduce or replicate their observations.

Collecting and Analyzing Data Scientists record experimental observations, gathering information called data. There are two main types of data: quantitative data and qualitative data.

Quantitative data are numbers obtained by counting or measuring Quantitative data are numbers obtained by counting or measuring. In the marsh grass experiment, it could include the number of plants per plot, plant sizes, and growth rates.

Qualitative data are descriptive and involve characteristics that cannot usually be counted. In the marsh grass experiment, it might include notes about foreign objects in the plots, or whether the grass was growing upright or sideways.

Research Tools Scientists choose appropriate tools for collecting and analyzing data. Tools include simple devices such as meter sticks, sophisticated equipment such as machines that measure nitrogen content, and charts and graphs that help scientists organize their data.

Sources of Error Researchers must be careful to avoid errors in data collection and analysis. Tools used to measure the size and weight of marsh grasses, for example, have limitations, such as accuracy. Data analysis and sample size must be chosen carefully. The larger the sample size, the more reliably researchers can analyze variation and evaluate differences between experimental and control groups.

Drawing Conclusions Scientists use experimental data as evidence to support, refute, or revise the hypothesis being tested, and to draw a valid conclusion.

New data may indicate that the researchers have the right general idea but are wrong about a few particulars. In that case, the original hypothesis is reevaluated and revised; new predictions are made, and new experiments are designed. Hypotheses may have to be revised and experiments redone several times before a final hypothesis is supported and conclusions can be drawn.

When Experiments are Not Possible It is not always possible to test a hypothesis with an experiment. In some of these cases, researchers devise hypotheses that can be tested by observations. Animal behavior researchers, for example, might want to learn how animal groups interact in the wild by making field observations that disturb the animals as little as possible. Researchers analyze data from these observations and devise hypotheses that can be tested in different ways.

Sometimes, ethics prevents certain types of experiments—especially on human subjects. For example, medical researchers who suspect that a chemical causes cancer, for example, would search for volunteers who have already been exposed to the chemical and compare them to people who have not been exposed to the chemical. The researchers still try to control as many variables as possible, and might exclude volunteers who have serious health problems or known genetic conditions. Medical researchers always try to study large groups of subjects so that individual genetic differences do not produce misleading results.

Science in Context Section 1.2

Exploration & Discovery Scientific methodology is closely linked to exploration and discovery. It is inspired by scientific attitudes, practical problems, and new technologies.

Scientific Attitudes Most scientists share scientific attitudes or, habits of mind, that lead them to exploration and discoveries and new ideas. These include curiosity, skepticism, open-mindedness, and creativity.

Curiosity Strong desire to know or learn something Usually leads to more questions

Skepticism Questioning existing ideas and hypotheses Scientists will test hypotheses with experiments and observations

Open-mindedness Willing to accept different ideas that may not agree with your own hypothesis

Creativity Thinking outside the box This helps scientists design experiments better

Practical Problems Many ideas for scientific investigations arise from practical problems Ex. Flooding, pollution, genetic engineering Inspires scientific questions, hypotheses, and experiments

Role of Technology Technology, science, and society are closely linked. Discoveries in one field of science lead to new technologies that can be used in another field. Ex. Genetics, biotechnology This can help lead to more questions and gathering data.

Communicating Results: Reviewing & Sharing Ideas Scientists share their findings by publishing articles in journals to undergo peer review. Peer review- scientific papers are reviewed by anonymous, independent experts

Reviewers look for oversights, bias influences, fraud, or mistakes in techniques or reasoning Provide expert assessments Ensure the highest quality of research

Sharing Knowledge & New Ideas Published works may lead to new questions and new hypotheses.

Scientific Theories Evidence from many scientific studies may support several related hypotheses. This can lead researchers and scientists to propose a theory to tie them together.

The word theory applies to a well-tested explanation that unifies a broad range of observations and hypotheses Enables scientists to make accurate predictions about events and processes A thoroughly tested and supported theory may become the dominant view among the majority of scientists.

No theory is considered absolute truth. Remember, science is always changing, new evidence can be discovered. Theories can be revised or even replaced with enough evidence and exploration.

Science & Society Many questions that affect our lives require scientific information to answer. Scientific questions involve society in which we live, our economy, and our laws or moral principles.

Science, Ethics, & Morality Pure science does not include ethical or moral viewpoints. Science can explain what life is and how it operates, but cannot answer questions about why life exists Science can tell how technology is used or applied , but cannot tell us whether it should be used or applied.

Avoiding Bias Science used in society can be affected by bias. Particular preference or point of view Personal-not scientific Sometimes, scientific data can be misinterpreted or misapplied by those who want to prove a point

Studying Life Section 1.3

Characteristics of Living Things Biology is the study of life No single characteristic is enough to describe a living thing. Some things, such as viruses, exist at the border between organism and nonliving things.

8 Characteristics of Living Things Living things are based on a universal genetic code. This is a complex genetic molecule called DNA. This information is passed down to offspring and is almost identical in all organisms.

Living things grow and develop. A single fertilized egg continuously divides again and again. During division, differentiation occurs that allows cells to develop into different structures such as skin, eyes, and muscles.

Living things respond to their environment. A stimulus is a signal to which an organism responses. Ex. A Venus flytrap catching insects, reaction to touching a hot stove

Living things reproduce. Reproduction- producing a similar organism, 2 types: Sexual- two parent cells combining to form a new single cell, not identical Asexual- single parent forming an identical new cell

Living things maintain a relatively stable internal environment. Homeostasis- expending energy to keep internal conditions within certain limits

Living things obtain and use material and energy to grow, develop, and reproduce. Metabolism- combination of chemical reaction which an organism builds up or breaks down molecules

Living things are made up of one or more cells. Cells- the smallest units considered fully alive, highly complex and organized despite their size

Over generations, groups of similar organisms evolve, or change over time. Evolutionary change links all forms of life to a common origin more than 3.5 billion years ago. Evidence is found in all aspects of living organisms including genetic information and fossilized remain.

Fields of Biology: Global Ecology Life on Earth is shaped by weather patterns and processes in the atmosphere that we are just beginning to understand. Activities of living things profoundly affect both the atmosphere and the climate. Global ecological studies enable us to learn about the global impact o our actions.

Biotechnology This field is based on our ability to read, edit, and rewrite the genetic code. This could mean learning to correct or replace damaged segments of genes that cause inherited diseases or acquired mutations. Biotechnology raises enormous ethical, logical, and social questions

Building the Tree of Life We have discovered and identified about 1.8 million different kinds of organisms. We estimate that there are somewhere between 2-100 million more life forms to be discovered. These numbers include current living and now extinct life forms.

In addition to identifying and cataloguing all these life forms, we aim to combine genetic information with computer technology to organize all living things into a single Tree of Life.

Ecology & Evolution of Infectious Diseases The relationship between hosts and pathogens are dynamic and constantly changing. Understanding the interactions of pathogens and hosts is crucial to safeguarding our future.

Genomics & Molecular Biology These fields focus on studies of DNA and other molecules inside cells. Computer analyses enable researchers to compare vast databases of genetic information. This allows us to understand some of the mysteries of growth, development, aging, cancer, and even the history of life on Earth.

Performing Biological Investigations: Scientific Measurements Most scientists use the metric system when collecting data. Metric system- universal decimal measurement system whose units are scaled on multiples of 10

Safety Scientists working in laboratories or the field are trained to use safe procedures when carrying out investigations.

Safety First! Read all instructions before proceeding any investigations. When in doubt, ask questions. Wash and clean work area before and after investigations, this includes your hands. Wear appropriate protective equipment at all times.