Plant Biology - Advanced
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Plant Biology - Advanced Douglas Wilkin, Ph.D. Barbara Akre Say Thanks to the Authors Click http://www.ck12.org/saythanks (No sign in required) AUTHORS Douglas Wilkin, Ph.D. To access a customizable version of this book, as well as other Barbara Akre interactive content, visit www.ck12.org EDITOR Douglas Wilkin, Ph.D. CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-source, collaborative, and web-based compilation model, CK-12 pioneers and promotes the creation and distribution of high-quality, adaptive online textbooks that can be mixed, modified and printed (i.e., the FlexBook® textbooks). 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Printed: January 24, 2016 www.ck12.org Chapter 1. Plant Biology - Advanced CHAPTER 1 Plant Biology - Advanced CHAPTER OUTLINE 1.1 Why Study Plants? - Advanced 1.2 Evolution of Plants - Advanced 1.3 Classification of Plants - Advanced 1.4 Plant Life Cycles - Advanced 1.5 Bryophytes - Advanced 1.6 Diversity of Nonvascular Plants - Advanced 1.7 Human Uses of Nonvascular Plants - Advanced 1.8 Vascular Plants - Advanced 1.9 Evolution of Vascular Plants - Advanced 1.10 Early Vascular Plants - Advanced 1.11 Ferns - Advanced 1.12 Seed Plants - Advanced 1.13 Seed Plants Evolution - Advanced 1.14 Diversity of Seed Plants - Advanced 1.15 Flowering Plants - Advanced 1.16 Characteristics of Angiosperms - Advanced 1.17 Evolution of Flowering Plants - Advanced 1.18 Diversity of Flowering Plants - Advanced 1.19 Eudicots - Advanced 1.20 Monocots - Advanced 1.21 Flowering Plant Tissues - Advanced 1.22 Plant Cells - Advanced 1.23 Dermal Tissue of Plants - Advanced 1.24 Ground Tissue of Plants - Advanced 1.25 Vascular Tissue of Plants - Advanced 1.26 Growth of Plants - Advanced 1.27 Roots - Advanced 1.28 Root Types - Advanced 1.29 Root Structure - Advanced 1.30 Root Function - Advanced 1.31 Root Growth - Advanced 1.32 Stems - Advanced 1.33 Stem Types - Advanced 1 www.ck12.org 1.34 Stem Structure and Function - Advanced 1.35 Stem Growth - Advanced 1.36 Leaves - Advanced 1.37 Leaf Types - Advanced 1.38 Leaf Structure and Function - Advanced 1.39 Life Cycles of Non-flowering Plants - Advanced 1.40 Life Cycles of Bryophytes - Advanced 1.41 Life Cycles of Seedless Vascular Plants - Advanced 1.42 Life Cycles of Gymnosperms - Advanced 1.43 Life Cycles of Angiosperms - Advanced 1.44 Structures of Flowering Plants - Advanced 1.45 Pollination of Flowering Plants - Advanced 1.46 Fertilization of Flowering Plants - Advanced 1.47 Fruits of Flowering Plants - Advanced 1.48 Seeds of Flowering Plants - Advanced 1.49 Fruit and Seed Dispersal - Advanced 1.50 Seed Dormancy and Germination - Advanced 1.51 Vegetative Reproduction in Plants - Advanced 1.52 Propagation in Plants - Advanced 1.53 Hydrophytes - Advanced 1.54 Xerophytes - Advanced 1.55 Epiphytes - Advanced 1.56 Carnivorous Plants - Advanced 1.57 Plant Hormones - Advanced 1.58 Abscisic Acid - Advanced 1.59 Auxins - Advanced 1.60 Cytokines and Gibberellins - Advanced 1.61 Ethylene and Brassonosteroids - Advanced 1.62 Plant Responses - Advanced 1.63 Hormones and Plant Growth - Advanced 1.64 Tropisms of Plants - Advanced 1.65 Nastic Movements of Plants - Advanced 1.66 Photoperiodism and Circadian Rhythms in Plants- Advanced 1.67 Protective Responses of Plants - Advanced 1.68 References 2 www.ck12.org Chapter 1. Plant Biology - Advanced Introduction Can you see all the photosynthesis? This lush, green landscape is thickly carpeted with trees and a myriad of other plants. Much of Earth’s land is dominated by plants. Yet compared to our active existence as animals, plants are —literally —rooted to the ground. Their sedentary lives may seem less interesting than the active lives of animals, but plants are very busy doing extremely important work. All plants are chemical factories. Each year, they transform huge amounts of carbon (from carbon dioxide) into food for both themselves and virtually all other land organisms. Plants are complex organisms that carry out complex tasks. But unlike animals, they don’t have nerves, bones, or muscles to do their work. How do plants do it? These concepts will tell you. 3 1.1. Why Study Plants? - Advanced www.ck12.org 1.1 Why Study Plants? - Advanced • Compare the human life cycle to the life cycles of the earliest plants. • Analyze the role of plants in supplying food and energy to their ecosystems. • Explore the importance of plants to atmospheric oxygen, ozone, and temperature. • Explain the significance of plants for the water cycle and soil conservation. • Identify plants’ role in the nitrogen cycle and other biogeochemical cycles. • Describe the ways in which plants are interdependent with bacteria, fungi, and animals. • Relate the characteristics of plants to their needs. Why study plants? There are numerous reasons. One is the importance of materials from plants. Food is obvious. Bamboo, shown above, is a renewable resource that can be used in many products. Why Study Plants? Imagine that human life cycles resemble those of the earliest plants. If you think about this analogy, you may begin to realize that many plants actually lead secret lives of surprising variety. In a human life cycle, you develop from an infant into a sexually mature adult. We all began as a single cell and gradually develop into trillions of cells organized into tissues, organs, and organ systems, which make us complex and individual beings. None of us would question that the beings we are today are the same beings that began as single cells; each of us has a unique identity that we keep throughout our entire lives, until death marks our end. Unlike the human life cycle, the plant cycle does not include the joining of genes from two parents. Instead, a mature plant releases thousands of haploid spore cells. Small spores become males, and large spores become females. At some time during their relatively long lives, the male and female beings produce sperm cells and egg cells. Depending on which kind of plant we chose as our model, sperm might swim on their own from the male to the 4 www.ck12.org Chapter 1. Plant Biology - Advanced female being, they might be blown by the wind, or they may be carried by an animal. After sperm and egg join, the zygote begins its life as a single cell and grows into an “adult,” eventually producing its own haploid spores. Why do plants lead such complex lives? Life cycles make up one of several topics we will explore in this lesson’s introduction to the plant kingdom. Members of the plant kingdom play many crucial and sometimes surprising roles in the drama of life on Earth. Why should you understand how plants live? Because their gifts to us include, but are certainly not limited to, the following: 1. Supplying food and energy. 2. Maintaining Earth’s atmosphere. 3. Cycling water and nurturing soils. 4. Contributing to the nitrogen cycle and other biogeochemical cycles. 5. Interdependence with animals. 6. Interdependence with fungi. 7. Interdependence among plants. 8. Resources for humans. 9. Aesthetics for humans. 10. Scientific use by humans. 11. Causing problems. Supplying Food and Energy The sources of most terrestrial food chains begin with food produced by plants during photosynthesis. Photosyn- thesis provides energy and carbon-containing organic molecules for nearly all land-based organisms. Humans are no exception - the vast majority of our nutrition is derived directly (e.g. cereals, grains, vegetables, fruits, nuts) or indirectly (e.g. chicken, turkey, lamb, beef, pork) from plants. 5 1.1. Why Study Plants? - Advanced www.ck12.org Plants provide nearly all of human nutrition, either directly or indirectly through the food chain. Domesticated animal energy –for plowing or transport –also originally comes from plants. The above photo collage shows human foods and energy sources, but virtually all terrestrial life depends on plants for food and energy. Maintaining Earth’s Atmosphere Through photosynthesis, plants produce O2 and absorb CO2. Oxygen is essential for both animals and plants to perform vital process of aerobic respiration. Most biologists agree that plants, together with algae and bluegreen bacteria, are responsible for maintaining current levels of oxygen (21%) in the atmosphere. Moreover, these levels of oxygen maintain the layer of ozone in the stratosphere, which protects life from harmful ultraviolet radiation. Although CO2 represents a much smaller fraction of the atmosphere, its use and removal by plants is critical to regulating our planet’s temperature. As a greenhouse gas, CO2 traps heat within the atmosphere. As we burn more fossil fuels and increase deforestation, Earth’s CO2 levels rise past optimal levels, which have already begun to raise the average temperatures on Earth.