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Unformatted text preview: 411 Plant Form and Function: How Do Plants Live in the World? All flesh is grass, and the goodliness thereof is as the flower of the field. —Book of Isaiah 40:6 Chapter opening photo For the past 400 million years, plants have dominated the terrestrial landscape, as they do in this Brazilian tropical rainforest. Overview Wherever you live, if you look out your window on a summer’s day, you will probably spot something green. If you live in the country, most of the landscape may be covered in green. Even the places you cannot see from your window, such as lakes, streams, and oceans, are teeming with green life. 13 412 C HAPTER 13 Plant Form and Function: How Do Plants Live in the World? Plants and other photosynthetic organisms are among the most successful living things. Their diversity and abundance are unsurpassed. The secret of their success is their ability to adapt to nearly every kind of environment and to exploit nearly every kind of habitat. The challenges faced by plants are not all that different from those faced by animals. Regardless of where they live, plants need food and water; they need to exchange gases with the environment; they need to grow, develop, and reproduce, just as animals do. This chapter tells how plants meet the challenges of living. We will see that, although the needs of plants are not that different from those of animals, the strategies plants use to meet those needs are unique. Even among the different kinds of plants, there are many styles for coping, so many, in fact, that it is necessary to organize our study of plant physiology within a meaningful framework. Though the plant kingdom is vast and varied, the connections in plants’ life strategies are more obvious if we consider the important events in their history that have molded and influenced their form and function. Thus, we begin our study of plant life by looking at some key events in plant evolution. 13-1 What Important Events Define the History of Plant Life? Over 3.5 billion years ago, the first cells became established on this hot, young planet. Prior to that, nearly a billion years of volcanic eruptions, intense heat, and relentless ultraviolet radiation from the sun had provided sufficient energy to create simple organic compounds from the various elements found on Earth.Earth’s early atmosphere was de-void of oxygen, and these compounds were able to accumulate without being oxidized. This abiotic process (i.e., occurring in the absence of life) enriched the primordial seas with organic compounds, including amino acids, lipids, nucleotides, and sugars.The ear-liest cells were probably heterotrophic , meaning that they could not make their own food.They depended upon ready-made organic materials for food,absorbing these com-pounds directly from their environment.As these early cells divided and their numbers increased, competition for this finite source of chemical energy became keen. A cell with the ability to provide its own organic food—an...
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This note was uploaded on 01/08/2011 for the course CJS 212 taught by Professor Smith during the Summer '10 term at University of Phoenix.
- Summer '10