Biology For Dummies

Introduction

Life is all around you, from invisible microbes and green plants to the other animals with whom you share the Earth. What’s more, these other living things aren’t just around you — they’re intimately interconnected with your life. Plants make your food and provide you with oxygen, microbes break down dead matter and recycle materials that all living things need, and insects pollinate the plants you rely on for food. Ultimately, all living beings rely on other living beings for their survival.

What makes biology so great is that it allows you to explore the interconnectedness of the world’s organisms and really understand that living beings are works of art and machines rolled into one. Organisms can be as delicate as a mountain wildflower or as awe-inspiring as a majestic lion. And regardless of whether they’re plants, animals, or microbes, all living things have numerous working parts that contribute to the function of the whole being. They move, obtain energy, use raw materials, and make waste, whether they’re as simple as a single-celled organism or as complex as a human being.

Biology is the key you need to unlock the mysteries of life. Through it, you discover that even single-celled organisms have their complexities, from their unique structures to their diverse metabolisms. Biology also helps you realize what a truly miraculous machine your body is, with its many different systems that work together to move materials, support your structure, send signals, defend you from invaders, and obtain the matter and energy you need for growth.

About This Book

Biology For Dummies, 2nd Edition, takes a look at the characteristics all living things share. It also provides an overview of the concepts and processes that are fundamental to living things. We put an emphasis on looking at how human beings meet their needs, but we also take a look at the diversity of life on planet Earth.

Conventions Used in This Book

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

 Italics highlight new words or terms that are defined in the text. They also point out words we want to emphasize.

 Boldface indicates key words in bulleted lists or the action parts of numbered steps.

 Monofont points out Web addresses so you can recognize them easily.

 Sidebars are gray-shaded boxes that contain text that’s interesting to know but not necessarily critical to your understanding of the chapter or section topic.

Also, whenever we introduce scientific terms, we try to break the words down for you so that the terms become tied to their meanings, making them easier to remember.

What You’re Not to Read

Throughout this book you’ll find paragraphs marked with a Technical Stuff icon and sidebars (gray-shaded boxes). The Technical Stuff paragraphs provide more in-depth explanation of a topic or concept, and the sidebars include stories or information related to the main topic. They’re fun to read, but they’re by no means necessary for a thorough understanding of biology. So skip over them if you want to or read them to your heart’s content — the choice is yours!

Foolish Assumptions

As we wrote this book, we tried to imagine who you are and what you need in order to understand biology. Here’s what we came up with:

 You’re a high school student taking biology, possibly in preparation for an advanced placement test or college entrance examination. If you’re having trouble in biology class and your textbook isn’t making much sense, try reading the relevant section of this book first to give yourself a foundation and then go back to your textbook or notes.

 You’re a college student who isn’t a science major but is taking a biology class to help fulfill your degree requirements. If you want help following along in class, try reading the relevant sections in this book before you go to a lecture on a particular topic. If you need to fix a concept in your brain, read the related section after class.

 You’re someone who just wants to know a little bit more about the living world around you. Good news . . . this book is your oyster! Read it at your leisure, starting with whatever topic fascinates you most. We include several examples of how biology impacts everyday life to help keep your interest piqued.

How This Book Is Organized

Biology For Dummies, 2nd Edition, is organized so that it mirrors the order of topics covered in a typical biology class. Like all For Dummies books, each chapter is self-contained, so you can pick up this book whenever you need it and jump straight into the topic you’re working on.

Note: After we explain a subject, we use that information in later topics. 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, we refer you to the appropriate chapter.

Part I: Biology Basics

If biology is the study of life and life is so complex, then you may be wondering where to even begin in your study of biology. Never fear. This part breaks down the all-encompassing field of biology into smaller, more palatable chunks.

First, we take a look at the living world and then explain exactly how biology is studied (hint: the scientific method is a huge part of it). Next, we give you a review of the types of molecules that are important to a cell’s functioning (yes, this means delving into some basic chemistry; sorry!). Then we spotlight the most 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 actually have millions). Finally, because cells need energy to function, we explain just where that energy comes from.

Part II: Cell Reproduction and Genetics: Let’s Talk about Sex, Baby

How do you get a multicellular human from a one-celled embryo? Cellular reproduction, of course! Cells can make exact copies of themselves in order to repair, grow, or produce offspring that are genetically identical to the parent cell. You find out all about that in this part, as well as how some organisms mix things up by engaging in sexual reproduction, creating offspring that have combinations of genes that are different from those of their parents.

Regardless of whether organisms reproduce asexually or sexually, the traits of the parents are visible in the offspring because parents pass DNA on to their offspring. As you discover in this part, DNA contains the blueprints for proteins that do the work in cells and thus determine the characteristics of the offspring.

Part III: It’s a Small, Interconnected World

All the amazingly diverse forms of life on Earth interact with each other (if they didn’t, life on this planet would be in big trouble). This part allows you to explore all the ways life on Earth is connected, as well as how biologists classify organisms. You also get to discover how yesterday’s living beings are connected to today’s living beings through biological evolution.

Part IV: Systems Galore! Animal Structure and Function

Organisms respond to changes in their environment, trying to maintain their internal conditions within a range that supports life. Animals have many different systems designed to support this struggle for balance. In this part of the book, we present most of the systems that support the structure and function of the human body, as well as those of other animals. These systems coordinate many functions in animals, such as digestion, movement, circulation, gas exchange, and defense.

Part V: It’s Not Easy Being Green: Plant Structure and Function

Plants, your green neighbors, often get overlooked in the hustle and bustle of animal life. However, the importance of plants to life on Earth simply can’t be overstated. After all, without them, you wouldn’t have any food. When you take the time to study plants, you find that they’re actually pretty interesting. Just like animals, they’re made of cells and have systems to transport materials around their bodies and exchange matter and energy with their environment, all of which you find out in this part.

Part VI: The Part of Tens

No For Dummies book would be complete without The Part of Tens and its chapters containing fun and interesting facts. When you venture to this part, prepare to find out about ten great biology discoveries and ten ways biology affects your life.

Icons Used in This Book

We use some of the familiar For Dummies icons to help guide you and give you new insights as you read the material. Here’s the scoop on what each one means.

The information highlighted with this icon is stuff we think you should permanently store in your mental biology file. If you want a quick review of biology, scan...