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An Introduction to the Science of Botany Chapter 1 TTU MS 43131 LEARNING OBJECTIVES Briefly describe the field of botany, and give short definitions of at least five subdisciplines of plant biology Summarize and discuss the features of plants and other organisms that distinguish them from nonliving things Distinguish among the six kingdoms and three domains, and give representative organisms for each Summarize the main steps in the scientific method, and explain how science differs from many other human endeavors LEARNING OBJECTIVE 1 Briefly describe the field of botany, and give short definitions of at least five subdisciplines of plant biology KEY TERMS BOTANY The scientific study of plants; also called plant biology Subdisciplines 1 Plant molecular biology Structures and functions of important biological molecules (proteins, nucleic acids) Plant cell biology Structures, functions, and life processes of plant cells Subdisciplines 2 Plant physiology How plants function (photosynthesis, mineral nutrition) Plant genetics Plant heredity and variation Subdisciplines 3 Plant ecology Interrelationships among plants, and between plants ands their environment Overgrazing in Africa p. 5 p. 7 LEARNING OBJECTIVE 2 Summarize and discuss the features of plants and other organisms that distinguish them from nonliving things KEY TERMS PHOTOSYNTHESIS Biological process that includes capture of light energy and its transformation into chemical energy of organic molecules that are manufactured from carbon dioxide and water CELLULAR RESPIRATION Cellular process in which energy of organic molecules is released for biological work KEY TERMS DEOXYRIBONUCLEIC ACID (DNA) A nucleic acid present in a cell’s chromosomes that contains genetic information KEY TERMS EVOLUTION Cumulative genetic changes in a population of organisms from generation to generation NATURAL SELECTION Mechanism of evolution (Charles Darwin) Tendency of organisms that have favorable adaptations to their environment to survive and become parents of next generation Levels of Biological Organization Atoms Hydrogen Biosphere Oxygen Molecule Ecosystem Water Community Chloroplast Macromolecule Population Organelle Cell Epidermis Organism Tissue Organ Fig. 1-3, p. 9 Characteristics of Living Things 1 Organization Plants and other organisms are highly organized with cells as their basic building blocks Energy Plants and other organisms take in and use energy Plant Cells Photosynthesis Characteristics of Living Things 2 Interaction with environment Plants respond to stimuli in their environment Plants undergo growth and development Reproduction Plants form new individuals by asexual or sexual reproduction Root Growth and Gravity Response to Stimuli Germination Asexual Reproduction Characteristics of Living Things 3 Heredity DNA molecules transmit genetic information from one generation to the next in plants and other organisms Evolution Plants and other organisms evolve Populations change or adapt to survive in changing environments Adaptation LEARNING OBJECTIVE 3 Distinguish among the six kingdoms and three domains, and give representative organisms for each KEY TERMS SPECIES A group of organisms with similar structural and functional characteristics In nature, they breed only with one another and have a close common ancestry KEY TERMS KINGDOM A broad taxonomic category made up of related phyla; many biologists currently recognize six kingdoms of living organisms DOMAIN A taxonomic category that includes one or more kingdoms Organisms are classified into a hierarchy The main categories of classification are: Domains, Kingdoms, Phyla, Classes, Orders, Families, Genera, and Species. (e.g. house, street, city, county, state, country, continent, planet) King Phillip Came Over Fearing Green Snakes Three-Domain Classification Archaea Bacteria Kingdom archaea Kingdom bacteria Eukarya All other kingdoms Euglena Kingdoms and Domains Six-Kingdom Classification 1 1. Archaea 2. Bacteria 3. Protista protozoa, algae, water molds, slime molds Six-Kingdom Classification 2 4. Fungi molds, yeasts 5. Animalia 6. Plantae Three Domains: Bacteria Archaea Eukarya Six Kingdoms: Bacteria Prokaryotes (lack membrane-bound organelles); unicellular; most are heterotrophic (obtain food by eating other organisms), but some are photosynthetic or chemosynthetic Archaea Prokaryotes; unicellular; microscopic; most live in extreme environments; differ in biochemistry and in cell wall structure from bacteria Protista Eukaryotes; mainly unicellular or simple multicellular; maybe heterotrophic or photosynthetic; include protozoa, algae, and slime molds Plantae Eukaryotes; multicellular; photosynthetic; life cycle with alternation of generations; cell walls of cellulose Animalia Eukaryotes; multicellular; heterotrophic; most move about by muscular contraction; nervous system coordinates responses to stimuli Fungi Eukaryotes; most multicellular; heterotrophic; absorb nutrients; do not photosynthesize; cell walls of chitin Fig. 1-11, p. 14 Classification (Binomial System) LEARNING OBJECTIVE 4 Summarize the main steps in the scientific method, and explain how science differs from many other human endeavors KEY TERMS HYPOTHESIS An educated guess (based on previous observations) that may be true and is testable by observation and experimentation THEORY A widely accepted explanation supported by a large body of observations and experiments The Scientific Method 1 1. Recognize a problem or an unanswered question 2. Develop a hypothesis to explain the problem 3. Design and perform an experiment to test the hypothesis The Scientific Method 2 4. Analyze and interpret the data to reach a conclusion 5. Share new knowledge with the scientific community Charles Darwin’s experiment with stems detecting light. Charles Darwin published his results on a number of different scientific studies in addition to his works on evolution. Through experimentation, he discovered that the tip of a stem detects light. (a) If the tip is covered, the stem does not grow toward the light. (b) If uncovered, the tip bends in the direction of the light. Forming and testing hypotheses. The scientific method consists of observations that lead to a question. One or more hypotheses tentatively answer the question. Each hypothesis is then tested by experiments, which either support it or do not support it. Based on experimentation, the hypothesis is either accepted or rejected. Conservation Biology Extinction as a consequence of human activities Loss of Plant and Animal habitats