Introduction

Biology is the exploration of the living world, from the bacteria that live on your skin to the green plants that cover the land to the majestic blue whales that swim through the ocean.

Have you ever taken a look at the single-celled creatures in a drop of pond water? Or have you ever thought about the many different ways your life depends on the actions of plants and bacteria?

A living organism can be as simple as a single cell or as complex as a human being, but no matter how different they may seem, all living things on Earth have fundamental similarities: They're made of cells that contain DNA, and they all grow, move, get energy, use raw materials, make waste, and reproduce. These similarities among all living things illustrate how all life on Earth is part of the same big family tree. And the differences in how each type of living thing achieves these same goals - well, the differences are what make biology fascinating.

Beyond increasing your appreciation for other kinds of life, the science of biology can help you understand your place in the living world. At first glance, you may think that people can do everything for themselves - get food from the grocery store, build their homes, and make their clothes - but a closer look quickly shows how dependent people are on the rest of the living world. People depend on plants and green bacteria to make the food that supports food chains that include agricultural species. These green organisms also make the oxygen that people need to sustain life. Bacteria and fungi in the soil break down dead organisms, recycling matter so that other living things can reuse it. Clearly, people can't survive on planet Earth alone.

Understanding our place in this world, and our connections to other organisms, is both fascinating and essential to our survival as a species. Developing your understanding of biology may be challenging, but it will definitely be worth it, and this book can help you by giving you many opportunities to practice as you learn.

About This Book

Biology Workbook For Dummies, 2nd edition is designed to help supplement your learning in a biology class or to use as a companion for your self-guided exploration of biology using Biology For Dummies, 3rd edition (Wiley). This workbook isn't intended to replace a textbook but rather to highlight essential information in an easy-to-understand format and then reinforce that information by giving you frequent opportunities to practice. I provide many straightforward lists of the fundamentals you need to know about the various subjects you'd typically encounter in a biology class, along with problems on which you can practice and reinforce your understanding. I provide answers to all the practice questions and include explanations of why some answers are right or wrong.

If you're taking biology, your instructor may present material in a different order than the organization I use here, so be sure to take advantage of both the table of contents and the index to navigate where you need to go.

Conventions Used in This Book

In order to explain topics as clearly as possible, I keep scientific jargon to a minimum and present information in a straightforward, linear style. I break dense information into main concepts and divide complicated processes into series of steps.

To help you find your way through the subjects in this book, I use the following style conventions:

• I use italic for emphasis and to highlight new words or terms that I define in the text.
• I use boldface to indicate key words in bulleted lists and the action parts of numbered steps.
• I use monofont for web addresses, so they're easy to recognize.
• When this book was printed, some web addresses may have needed to break across two lines of text. If that happened, know that I haven't put in any extra characters (such as hyphens) to indicate the break. So when using one of these web addresses, type in exactly what you see and ignore the line break.

Foolish Assumptions

As I wrote this book, I tried to imagine who you might be and what you might need to understand biology, and here are some assumptions I made:

• You may be a high school student taking biology and maybe preparing for an advanced placement test or a college entrance examination. For you, I've tried to extract the essentials about each subject and organize them into short lists that are easier to study than long paragraphs. I've also written problems for you to practice on and given you links to websites with great animations and tutorials.
• You may be a college student who isn't a science major but is taking a biology class to help fulfill your degree requirements. For you, I've tried to get the main ideas across with as little scientific jargon as possible. If you find that you get overwhelmed in your biology class, try reading a section in this workbook before you go to class to hear a lecture about the topic. That way, you'll have some of the big ideas in your mind before your instructor starts adding all the details. Also, many non-science students are a little shocked to find that their usual study habits don't work well for a science class, so be sure to read my tips in Chapter 20 on how to get an A in biology.
• You may be someone who just wants to know a little bit more about the living world around you. You may have picked up Biology For Dummies, 3rd edition, or some other biology text because you want to take a deeper look at the living world. For you, this workbook will make a nice companion and give you a chance to test yourself on the practice problems to see how well you're learning the information.

Whatever your reason for picking up this book, I've done my best to explain the topics of biology simply and effectively and to create some challenging practice problems to help improve your learning. I hope you find this workbook helpful.

How This Book Is Organized

I've arranged this book to follow the order of topics in many biology textbooks, with a few minor differences. Like all For Dummies books, each chapter is self-contained, so you can pick up the book whenever you need it and jump into the topic you're working on. After I explain a subject, I use that information in later topics. So if you don't read the book in order, you may occasionally have to refer back to an earlier section for some background information. When that's the case, I refer you to the appropriate section or chapter.

Part 1: Getting the Basics

Biology is the study of life, but as I'm sure you know, life is complex. To simplify it, I break the all-encompassing subject of biology into smaller, more palatable chunks. To start, I explain the way that scientists study biology. This scientific method holds not only for biology but also for chemistry, psychology, physics, geology, and other sciences and social sciences. Knowing how scientists conduct, challenge, check, and recheck research makes it easier to appreciate the value of scientific information.

In this part, I spotlight the basic unit of life: the cell. Every organism - whether it's a human, a dog, a flower, a strep throat bacterium, or an amoeba - has at least one cell; most have millions. After you have a grasp of how cells are the powerhouses of bodies, I review the types of molecules that are important to their functioning. Included in this first part is the often-dreaded but oh-so-necessary review of basic chemistry. To learn biology, you must understand some basic principles of how chemicals function. After all, the bodies of every living organism are big sacs of chemicals. Chemical reactions generate every process that occurs in your body, such as those that occur during the metabolic processes in plant and animal cells. So in this part you delve into topics such as enzymes, energy transfer, and how plants make food from scratch, using just carbon dioxide and water!

Part 2: Creating the Future

Cells reproduce, giving rise to other cells. Sometimes cells make exact copies of themselves in order to repair, grow, or produce offspring that are genetically identical to the parent. Some organisms mix it up a little by engaging in sexual reproduction, creating offspring that have combinations of genes that are different from those of their parents.

But whether organisms reproduce asexually or sexually, the parents' traits are visible in their offspring. Ducks make ducklings, and from little acorns, mighty oaks do grow. Offspring inherit their traits from their parents because parents pass DNA to their offspring. DNA contains the blueprints for proteins that do the work in cells and thus determine an organism's characteristics. Biologists today are busy unraveling the mysteries of DNA, giving humans unprecedented power over the very stuff of life. This part walks you through all these topics and gives you plenty of chances to test yourself on what you've read.

Part 3: Making Connections

All the amazingly diverse forms of life on Earth interact with one another. In this part, you become more aware of the living part of Earth as one big, interconnected ecosystem called the biosphere. Living things aren't just connected with one another today; they also have connections to the living things of the past....