Biology For Dummies

Rene Fester Kratz

• Publisher: For Dummies
• Year: 2017
• ISBN:
  9781119345381
• Edition: 3
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

The ultimate guide to understanding biology

Have you ever wondered how the food you eat becomes the energy your body needs to keep going? The theory of evolution says that humans and chimps descended from a common ancestor, but does it tell us how and why? We humans are insatiably curious creatures who can't help wondering how things work—starting with our own bodies. Wouldn't it be great to have a single source of quick answers to all our questions about how living things work? Now there is.

From molecules to animals, cells to ecosystems, Biology For Dummies answers all your questions about how living things work. Written in plain English and packed with dozens of enlightening illustrations, this reference guide covers the most recent developments and discoveries in evolutionary, reproductive, and ecological biology. It's also complemented with lots of practical, up-to-date examples to bring the information to life.

• Discover how living things work
• Think like a biologist and use scientific methods
• Understand lifecycle processes

Whether you're enrolled in a biology class or just want to know more about this fascinating and ever-evolving field of study, Biology For Dummies will help you unlock the mysteries of how life works.

Part 1

Biology Basics

IN THIS PART …

Take a look at the big picture of life on Earth.

Go behind the scenes of scientific investigation.

Explore the connections between chemistry and biology.

Discover life at the level of a single cell.

Delve into the details of how cells get energy.

Chapter 1

Exploring the Living World

IN THIS CHAPTER

Seeing how cells are part of all living things

Finding out the fundamentals of where babies come from and why you have the traits you do

Recognizing that all of Earth’s ecosystems are interconnected

Surveying animal anatomy and physiology

Exploring the similarities and differences between plants and people

Biology is the study of life, as in the life that covers the surface of the Earth like a living blanket, filling every nook and cranny from dark caves and dry deserts to blue oceans and lush rain forests. Living things interact with all of these environments and each other, forming complex, interconnected webs of life. For many people, a hike in the forest or a trip to the beach is a chance to reconnect with the natural world and enjoy the beauty of life.

In this chapter, we give you an overview of the big concepts of biology. Our goal is to show you how biology connects to your life and to give you a preview of the topics we explore in greater detail later in this book.

It All Starts with a Cell

Quick. What’s the smallest living thing you can think of? (Here’s a hint: Try to recall the basic properties of life; if you can’t, head to Chapter 2 to discover what they are.) Your mind may automatically call up images of ants, amoebas, or bacteria, but that’s not quite the answer. The absolute smallest unit of life is a single cell.

Everything an organism’s body does happens because its cells make those actions happen, whether that organism is a single-celled E. coli bacteria or a human being made up of approximately 10 trillion cells.

Of course, the number of cells you have isn’t the only difference between you and E. coli. The structure of your cells is a little bit different — your cells have more specialized internal compartments, such as the nucleus that houses your DNA (we cover cell structure in Chapter 4). Yet you have some distinct similarities as well. Both you and E. coli are made up of the same raw materials (flip to Chapter 3 to find out what those are) and have DNA as your genetic material (more on DNA in Chapter 8). You also use food the same way (see Chapter 5), and you build your proteins in the same manner (see Chapter 8).

Life Begets Life: Reproduction and Genetics

You began life as a single cell, when a sperm cell from your dad met an egg cell from your mom. Your parents made these reproductive cells through a special type of cell division called meiosis (we explain meiosis in detail in Chapter 6). When their reproductive cells combined, your dad and mom each donated half of your genetic information — 23 chromosomes from mom and 23 from dad — for a total of 46 chromosomes in each of your cells. The genes on those 46 chromosomes determined your characteristics, from your physical appearance to much of your behavior. The science of genetics tracks the inheritance of genes and studies how they determine traits (see Chapter 7). Through genetics, you can understand why your skin is a certain color or why some traits seem to run in your family.

Your genes are found in your DNA, which is in turn found in your chromosomes. Each chromosome consists of hundreds of different blueprints that contain the instructions for your cells’ worker molecules (which are mostly proteins). Each type of cell in your body uses the blueprints found in your genes to build the proteins it needs to do its particular job. So what exactly does all that mean? Here it is, plain and simple: DNA determines your traits because it contains the instructions for the worker molecules (proteins) that make your traits happen.

Scientists are discovering more and more about DNA; they’re also developing tools to read and alter the DNA in cells (see Chapter 9). Chances are you’re already experiencing the impacts of scientists’ work with DNA, even if you don’t know it. Why? Because scientists use recombinant DNA technology to alter organisms used in food and medicines. This technology allows them to take genes from one organism and place them into the cells of another, changing the characteristics of the receiving organism. For example, scientists alter the cells of bacteria with human genes, turning them into tiny living factories that produce human proteins needed to treat diseases.

Making the Connection between Ecosystems and Evolution

As you discover in Chapter 10, the amazing diversity of life on Earth helps ensure that life continues in the face of environmental change. Each type of organism plays a role in the environment, and each one is connected to the other. Green organisms such as plants combine energy and matter to make the food on which all life depends, herbivores eat plants, predators hunt prey, and decomposers such as bacteria and fungi recycle dead matter so it becomes available again to other living things. (For more on the interconnectedness of all living things on Earth, head to Chapter 11.)

Organisms such as plants form the foundation of every web of life (ecosystem) because they can combine energy and matter from the environment to make food. All organisms use food to get the energy they need to stay alive and the matter they need to grow. Ultimately, energy flows from the sun to plants, to organisms that eat other organisms, and then back out to the atmosphere (and ultimately outer space) as heat. At the same time, matter constantly cycles from the environment to the bodies of living things, then back out to the environment again. (For more on the flow of matter and energy, head to Chapter 11.)

Humans are part of the natural world, and like all living things, use resources from the environment and produce wastes. However, the human species is unusual in its ability to use technology to extend its reach, drawing heavily on the natural resources of the Earth and changing environments to suit its needs. The human population has expanded to cover most of the Earth, and the numbers just keep on growing.

Yet as humans draw more heavily upon the Earth’s resources, we’re putting stress on many other species and possibly driving them to extinction. The great lesson of biological evolution (a topic we cover in Chapter 12) is that not only do populations change over time but they’re also capable of going extinct. The challenge that humans face today is discovering ways to get what we need but still live in balance with the Earth’s various ecosystems.

Getting Up Close and Personal with the Anatomy and Physiology of Animals

All animals work hard to maintain homeostasis, or internal balance, as change occurs in the environment around them (see Chapter 13 for more on homeostasis). In a complex, multicellular animal like you, all of your organ systems must work together to maintain homeostasis.

Following is a rundown of all of your organ systems, including what they do and what they consist of:

• Skeletal system: Provides support, helps with movement, and forms b...