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Biology: Chapter One The Science of Biology The Goal of Science Investigate and understand nature Explain events in nature Use those explanations to make useful predictions Observations An observation involves using one or more of the senses to gather information. This evidence is called data. Quantitative observations involves numbers, such as measurements. Qualitative observations involve characteristics that cannot easily be measured or counted, such as texture and color. Inferences An inference is a logical interpretation of an observation based on prior knowledge and experience. Observation and Inference Statement Object A is round and orange. Observation Inference X X Object A is a basketball. Object C is round and black and white. X Object C is larger than Object B. X Object B is smooth. X X X Object B is a table-tennis ball. Each object is used in a different sport. X Object A is a basketball. Object B is a tabletennis ball. Object C is a soccer ball. Scientific Method State the problem Form a hypothesis (educated guess that must be testable). Design a controlled experiment. Record and analyze data. Form a conclusion When a hypothesis is well-supported, it may be consider to be a theory. A theory is a well-tested explanation that unites a broad range of observations. Section 1-2 Designing an Experiment State the Problem Analyze Results Form a Hypothesis Draw a Conclusion Set Up a Controlled Experiment Publish Results Record Results Experimental variables An independent variable is the variable that is changed in a scientific experiment. A dependent variable is the variable being tested in a scientific experiment. As the experimenter changes the independent variable, the change in the dependent variable is observed and recorded. Example: Fertilizer vs. Plant Growth In a study measuring the influence of different quantities of fertilizer on plant growth, the independent variable would be the amount of fertilizer used. The dependent variable would be the growth in height or mass of the plant. The controlled variables would be the type of plant, the type of fertilizer, the amount of sunlight the plant gets, the size of the pots, etc. Characteristics of Living Things Made up of cells Reproduce Based on universal genetic code Grow and develop Obtain and use materials and energy Respond to the environment Maintain a stable internal environment Change over time as a group Characteristics of Living Things CHARACTERISTICS OF LIVING THINGS Characteristic Examples Living things are made up of units called cells. Living things reproduce. Living things obtain and use materials and energy. Many microorganisms consist of only a single cell. Animals and trees are multicellular. Maple trees reproduce sexually. A hydra can reproduce asexually by budding. Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees. Flies begin life as eggs, then become maggots, and then become adult flies. Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat. Living things respond to their environment. Leaves and stems of plants grow toward light. Living things maintain a stable internal environment. Despite changes in the temperature of the environment, a robin maintains a constant body temperature. Taken as a group, living things change over time. Plants that live in the desert survive because they have become adapted to the conditions of the desert. Living things are based on a universal genetic code. Living things grow and develop. Cells are the basic unit of life Unicellular organisms are made up of one cell. Example: amoeba Multicellular organisms are made up of diverse cells. Cells are specialized in some organisms to perform a different function. Example: plants and animals Reproduction Budding hydra Asexual reproduction requires a single parent to produce a new organism. Sexual reproduction requires two cells from different parents to join to form the first cell of the new organism. The genetic code transferred during reproduction determines the inherited traits of every organism on Earth. Metabolism is the combination of chemical reactions through which an organism builds up or breaks down materials. Homeostasis is the process by which organisms keep their internal conditions relatively stable. If this process is disrupted in a major way, the organism cannot survive. Evolution describes the changes in a group of organisms over time. Branches of Biology “Biology” means the “study of life”. The divisions of biology are based on the types of organisms being studied. For example: zoology is the study of animals, botany is the study of plants, and microbiology is the study of microorganisms such as bacteria. Levels of Organization The many levels at which live can be studied include the following: MOLECULES, CELLS, GROUPS OF CELLS and ORGANISMS, POPULATIONS, COMMUNITIES, ECOSYSTEMS, and the BIOSPHERE (Planet Earth) Figure 1-21 Levels of Organization Biosphere Ecosystem The part of Earth that contains all ecosystems Biosphere Community and its nonliving surroundings Hawk, snake, bison, prairie dog, grass, stream, rocks, air Community Populations that live together in a defined area Hawk, snake, bison, prairie dog, grass Population Group of organisms of one type that live in the same area Bison herd Figure 1-21 Levels of Organization continued Organism Individual living thing Bison Bison Groups of Cells Tissues, organs, and organ systems Nervous tissue Brain Nervous system Cells Smallest functional unit of life Molecules Go to Section: Groups of atoms; smallest unit of most chemical compounds Nerve cell DNA Water