The flower featured on the cover of this book and in Figure 1.1 is from a magnolia, a tree ofancient lineage that is native to Asian and American forests. The magnolia blossom is a sign of the plant's status as a living organism, for flowers contain organs of sexual reproduction, and reproduction is a key property oCHfe, as you will learn later.
Like all organisms, the magnolia tree in Figure 1.2 is living in close association with other organisms, though it is a lone specimen far from its ancestral forest. For example, it depends on beetles to carry pollen from one flower to another, and the beetles, in turn, eat from its flowers. The flowers are adapted to the beetles in several ways: Their bowl shape allows easy access, and their multiple reproductive organs and tough petals (see Figure 1.1) help ensure that some survive the voracious beetles. Such adaptations are the result of evolution, the process of change that has transformed life on Earth from its earliest beginnings to the diversity oforganisms living today. As discussed later in this chapter, evolution is the fundamental organizing principle of biology and the main theme of this book.
Although biologists know a great deal about magnolias and other plants, many mysteries remain. For instance, what exactly led to the origin of flowering plants? Posing questions about the living world and seeking science-based answersscientific inquiry-are the central activities ofbiology, the scientific study of life. Biologists' questions can be ambitious.
They may ask how a single tiny cen becomes a tree or a dog, how the human mind works, or how the different forms of life in a forest interact. Can you think ofsome questions about living organisms that interest you? When you do, you are already starting to think like a biologist. More than anything else, biology is a quest, an ongoing inquiry about the nature of life.
Perhaps some of your questions relate to health or to societal or environmental issues. Biology is woven into the fabric of our culture more than ever before and can help answer many questions that affect our lives. Research breakthroughs in genetics and cell biology are transforming medicine and agriculture. Neuroscience and evolutionary biology are reshaping psychology and sociology. New models in ecology are helping societies evaluate environmental issues, such as global warming. There has never been a more important time to em·bark on a study of life.
But what is life? Even a small child realizes that a dog or a plant is alive, while a rock is not. Yet the phenomenon we call life defies a simple, one-sentence definition. We recognize life by what living things do. The following figure highlights some of the properties and processes we associate with life.
Order. This close-up of asunflower illustrates the highly Qrdered structure that characterizes life.
Evolutionary adaptation. The appearance of this pygmy sea horse camouflages the animal in this enviroment. Such adaptations evolve over many generations by the reproductive success of those individuals with heritable traits that are best suited to their environments.
Reproduction. Organisms (living things) reproduce their own kind. Here an emperor penguin protects Its baby.
Energy processing. This hummingbird obtains fuel in the form of nectar from flowers. The hummingbird will use chemical energy stored in its food to power flight and other work.
The picture above reminds us that the magical world of life varies. How do biologists make sense of this diversity and complexity? This opening chapter sets up a framework for answering this question. The first part of the chapter provides a panoramic view of the biological "landscape;' organized around some unifying themes. We then focus on bioJogy's overarching theme, evolution, with an introduction to the reasoning that led Charles Darwin to his explanatory theory. Finally, we look at scientific inquiry how scientists raise and attempt to answer questions about the natural world.
No comments:
Post a Comment