Section 1-1 Understanding Chihuahuan Desert Fossils In the Trans-Pecos area of Texas, many fossilized shark teeth have been found. This area of Texas is covered by the Chihuahuan Desert. The fossils are believed to be 100 million years old. The Gulf of Mexico is more than 450 miles away. How could fossils of sharks have formed in the Chihuahuan Desert?

Section Working with a partner, think of several questions that a scientist might ask in order to understand why there are shark fossils in the desert of Texas. Write these questions on a sheet of paper. 2.Discuss your questions with your partner, and suggest a possible answer to each question. 3.How could a scientist go about finding an answer to each of the questions?

1–1What Is Science? A. Goal of Science B. Thinking Like a Scientist C. Observation vs. Inference Section 1-1 Section Outline

The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions. Science – organized way of using evidence to learn about the natural world Section 1-1

Scientific thinking observation-the process of gathering information about events in a careful, orderly way data-information gathered from observation quantitative-expressed as numbers obtained by counting or measured qualitative-descriptive characteristics that cannot usually be counted inference-logical interpretation based on prior knowledge or experience Section 1-1

hypothesis-proposed scientific explanation for a set of observations Section 1-1

StatementObservation Inference Object A is round and orange. Object A is a basketball. Object C is round and black and white. Object C is larger than Object B. Object B is smooth. Object B is a table-tennis ball. Each object is used in a different sport. X X X X X X X X Section 1-1 Observation and Inference

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Mystery Worms Section 1-2 A teacher collected some beetles from a rotting log and placed them in a container of dry oatmeal in her classroom. She kept the box covered with a light cloth so that the beetles could not escape. She also asked one of her students to add potato and apple pieces once a week to provide food and moisture for the beetles. After several weeks, the student reported that there were some strange-looking, wormlike organisms in the container.

Section Formulate a hypothesis that might explain the presence of the “worms” in the container. 2.How could you test your hypothesis? 3.Identify the variables in your proposed experiment. Identify the control in your proposed experiment.

1–2How Scientists Work A.Designing an Experiment 1.Asking a Question 2.Forming a Hypothesis 3.Setting Up a Controlled Experiment 4.Recording and Analyzing Results 5.Drawing a Conclusion B.Publishing and Repeating Investigations 1.Needham’s Test of Redi’s Findings 2.Spallanzani’s Test of Redi’s Findings 3.Pasteur’s Test of Spontaneous Generation 4.The Impact of Pasteur’s Work C.When Experiments Are Not Possible D.How a Theory Develops Section 1-2 Section Outline

Designing an Experiment Section 1-2 State the Problem Form a Hypothesis Set Up a Controlled Experiment Record Results Analyze Results Draw a Conclusion Publish Results

manipulated variable-variable that is deliberately changed independent variable responding variable-variable that is observed and that changes in response to the manipulated variable dependent variable Section 1-2

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Controlled Variables: jars, type of meat, location, temperature, time Manipulated Variables: gauze covering that keeps flies away from meat Uncovered jarsCovered jars Several days pass Maggots appearNo maggots appear Responding Variable: whether maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur. Section 1-2 Figure 1-8 Redi’s Experiment on Spontaneous Generation Late 17 th Century

Needham’s Experiment Needham questioned Redi’s results and devised a test to prove that spontaneous generation could occur under the right conditions. He heated a sealed container holding gravy. He claimed that the heat would kill any “animalcules” that were living in it. After several days, the gravy was swarming with “little animals”.

Gravy is boiled.Flask is open. Gravy is teeming with microorganisms. Gravy is boiled. Flask is sealed. Gravy is free of microorganisms. Section 1-2 Figure 1-10 Spallanzani’s Experiment

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment

Impact of Pasteur’s work related to microorganisms: French wine industry Silk industry Early research of infectious disease

Developing a Theory As evidence from numerous investigations builds up, a hypothesis may become so well supported it is considered a theory. A theory is a well-tested explanation that unifies a broad range of observations

Shells and Snowflakes How can we distinguish between living and nonliving things, such as a radiolarian (left) and a snowflake (right)? A radiolarian is a tiny living thing that is covered with a glasslike shell and lives in the ocean. A snowflake is a crystal made of frozen water. Section 1-3

Work with a partner to answer the following questions. 1.What are some similarities between the snowflake and the glass shell of the radiolarian? 2.What are some differences between the snowflake and the glass shell? 3.Would you classify the shell as a living thing or a nonliving thing? Explain your answer. Section 1-3

1–3Studying Life A.Characteristics of Living Things 1.Made Up of Cells 2.Reproduction 3.Based on a Genetic Code 4.Growth and Development 5.Need for Materials and Energy 6.Response to the Environment 7.Maintaining Internal Balance 8.Evolution B.Branches of Biology C.Biology in Everyday Life Section 1-3 Section Outline

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CharacteristicExamples Living things are made up of units called cells. Living things reproduce. Living things are based on a universal genetic code. Living things grow and develop. Living things obtain and use materials and energy. Living things respond to their environment. Living things maintain a stable internal environment. Taken as a group, living things change over time. 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. Leaves and stems of plants grow toward light. Despite changes in the temperature of the environment, a robin maintains a constant body temperature. Plants that live in the desert survive because they have become adapted to the conditions of the desert. Section 1-3 Characteristics of Living Things

Biosphere Ecosystem Community Population The part of Earth that contains all ecosystems Community and its nonliving surroundings Populations that live together in a defined area Group of organisms of one type that live in the same area Biosphere Hawk, snake, bison, prairie dog, grass, stream, rocks, air Hawk, snake, bison, prairie dog, grass Bison herd Section 1-3 Figure 1-21 Levels of Organization

Organism Groups of Cells Molecules Individual living thing Tissues, organs, and organ systems Smallest functional unit of life Groups of atoms; smallest unit of most chemical compounds Bison Nervous tissue Nervous system Brain Nerve cell Water DNA Section 1-3 Figure 1-21 Levels of Organization continued

Putting Size in Perspective Here are some measurements: A young child is just over 1 m in height. The marble in the child’s hand has a diameter of about 0.01 m. A cell in the palm of the child’s hand has a diameter of about m. How can you put these numbers in perspective? You can use a ratio of the larger object to the smaller one. This requires dividing the larger number by the smaller number. Another way to compare these numbers is to look at the place value of the number 1. Each time the number shifts one place value to the right, it decreases by a factor of 10. Thus, 1 is ten times greater than 0.10, and 10 is one hundred times greater than Section 1-4

1–4Tools and Procedures A.A Common Measurement System B.Analyzing Biological Data C.Microscopes 1.Light Microscopes 2.Electron Microscopes D.Laboratory Techniques 1.Cell Cultures 2.Cell Fractionation E.Working Safely in Biology Section 1-4 Section Outline

1.How does the height of the child compare to the diameter of the marble? 2.How does the marble diameter compare to the diameter of the cell? 3.How does the height of the child compare to the diameter of the cell? Section 1-4

Water Released and Absorbed by Tree Time Absorbed by Roots (g/h) Released by Leaves (g/h) 8 AM 10 AM 12 PM 2 PM 4 PM 6 PM 8 PM Water released by leaves Water absorbed by roots Relative Rates (g/h) 20 Time AM10 AM12 PM2 PM4 PM6 PM8 PM Section 1-4 Analyzing Data

Microscopes compound light microscope – produce magnified images by focusing visible light rays (1000X) transmission electron microscope – shine a beam of electrons through a thin specimen scanning electron microscope – shine a beam of electrons on the surface of a specimen Section 1-4

Laboratory Techniques Cell cultures – produce a group of cells from a single cell used for tests cell fractionation – procedure used to separate out different cell parts for individual study Section 1-4

Section 1 Answers What other kinds of fossils have been found here? Is there evidence that a lake or inland sea existed in Wyoming at the time the fish lived here? Students may not be able to suggest answers for all of their questions. Students may know that most fish fossils formed in layers of mud and sand, which is evidence that the area was once under water. Scientists would have to dig to look for more fossils and catalog what is found in the same layers with the fish. Geologists would have to map the fossil deposit and look for evidence of a lake shore or inland sea. 1.Working with a partner, think of several questions that a scientist might ask in order to understand why there are fish fossils in the desert of Wyoming. Write these questions on a sheet of paper. 2.Discuss your questions with your partner, and suggest a possible answer to each question. 3.How could a scientist go about finding an answer to each of the questions? Interest Grabber Answers

Section 2 Answers Students may say that the “worms” are immature beetles, or that there might have been worm eggs or worms in the oatmeal. If students thought that the worms were immature beetles, they may suggest isolating some of the worms to see if they develop into beetles. If students thought that there were eggs in the oatmeal, they may suggest taking a fresh sample of the oatmeal to see if worms hatch in it. Student answers should indicate that the control remains unchanged and is a standard of comparison. Variables are the factors that are subject to change. 1.Formulate a hypothesis that might explain the presence of the “worms” in the container. 2.How could you test your hypothesis? 3.Identify the variables in your proposed experiment. Identify the control in your proposed experiment. Interest Grabber Answers

Section 3 Answers Interest Grabber Answers Work with a partner to answer the following questions. 1.What are some similarities between the snowflake and the glass shell of the radiolarian? 2.What are some differences between the snowflake and the glass shell? 3.Would you classify the shell as a living thing or a nonliving thing? Explain your answer. Both are tiny; both look crystalline. Possible answer: The snowflake was not formed by a living thing, but the glass shell was. Students will likely say that the shell is nonliving, although it once surrounded the living thing that formed it.

Section 4 Answers Interest Grabber Answers 1.How does the height of the child compare to the diameter of the marble? 2.How does the marble diameter compare to the diameter of the cell? 3.How does the height of the child compare to the diameter of the cell? The child’s height is 100 times the diameter of the marble. The diameter of the marble is 100 times the diameter of the cell. The height of the child is 10,000 times the diameter of the cell.

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