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THE SCIENCE OF BIOLOGY Chapter 1

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1-1 What Is Science? What is the goal of science? To understand the world around us. So what is science? An organized way of using evidence to learn about the natural world.

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Thinking Like a Scientist Scientists record observations. Information gathered using the senses. Ex: there is a person standing in the front of the room. Data Qualitative data descriptive ; ex: rough or smooth Quantitative data numerical; counted or measured ; ex: 12 apples or 52.5 grams. Most experiments contain both types of data. An inference may follow an observation. A logical interpretation based on prior knowledge or experience. Ex: the person is a teacher.

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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 Object A is a basketball. Object B is a table-tennis ball. Object C is a soccer ball. Section 1-1 Observation and Inference

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Note the differences In laboratory exercises, record observations NOT inferences Inferences may be used when writing the conclusion to your lab. Lets test your observation skills Youll need a piece of paper and a writing utensil

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Answer these questions 1. Are there cars parked on the sides of the road? 2. What color is the pickup truck driving in the road? 3. Any minivans around? 4. What does the green sign say? 5. Were there any pedestrians on the road? 6. What's the speed limit?

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Question 1 Are there cars parked on the sides of the road?

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Question 2 What color is the pickup truck driving in the road?

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Question 3 Any minivans around?

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Question 4 What does the green sign say?

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Question 5 What's the speed limit?

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Question 6 Are there any pedestrians on the road?

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Observation vs. Inference On the next slide, state whether the statement is an observation or an inference.

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1. There is a representation of a face on one side of the coin. 2. The Latin word "Dei" means "God." 3. The coin was made by deeply religious people. 4. The date 1722 is printed on one side of the coin. 5. The coin was made in 1722. 6. The face on the coin is a representation of the nation's president.

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Try This Record observations for one minute.

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Explaining and Interpreting Evidence What is a hypothesis? A proposed explanation for an observed set of facts. Must be testable by performing controlled experiments and collecting data Some hypotheses may be supported, and others may not be supported.

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Science as a Way of Knowing Science is an ongoing process it continually changes. Good scientists are skeptics; they question new as well as existing ideas.

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1-2 How Scientists Work About 2000 years ago a Roman poet wrote these directions for producing bees: 1. Kill a bull during the first thaw of winter. 2. Build a shed. 3. Place the dead bull on branches and herbs inside the shed. 4. Wait for summer. The decaying body of the bull will produce bees.

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Spontaneous Generation Aristotle proposed 2300 years ago that a vital force was present in the air that caused living things to arise from nonliving things. This was called spontaneous generation. In the 1600s, scientists began to question this theory. To test this theory, scientists used the scientific method.

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

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A Different Hypothesis In the 1600s, people believed rotting meat produced maggots spontaneously. In 1668, Francesco Redi proposed that flies were landing on the meat and laying eggs, which hatched into maggots. He conducted a controlled experiment to test his hypothesis. In a controlled experiment only one variable is tested at a time.

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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 Independent Variable: gauze covering that keeps flies away from meat Uncovered jarsCovered jars Several days pass Maggots appearNo maggots appear Dependent 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 Redis Experiment on Spontaneous Generation

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REDI CONCLUDED THAT LIVING THINGS COULD ONLY COME FROM OTHER LIVING THINGS. Biogenesis

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Repeating Investigations In the 1700s John Needham, an English scientist, conducted an experiment to test Redis idea (skeptic). He said animalcules could arise from gravy, contradicting Redis work. He boiled gravy, sealed the flask, and days later microorganisms appeared in the flask thus supporting the theory of spontaneous generation.

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Repeating Investigations An Italian scholar, Lazzaro Spallanzani, didnt believe Needhams results (skeptic). He said Needham didnt boil the gravy long enough, so he repeated his experiment with modifications

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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 Spallanzanis Experiment

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SPALLANZANI CONCLUDED THAT NONLIVING GRAVY DID NOT PRODUCE LIVING THINGS. THE MICROORGANISMS CAME FROM THE AIR. Biogenesis again

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Repeating Investigations By the 1800s, some scientists still supported the theory of spontaneous generation. They felt sealing the flask cut off the vital life force in the air. In 1864, Louis Pasteur settled the debate. He designed a flask that could keep airborne microbes out without being sealed.

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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 Pasteurs Experiment

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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 Pasteurs Experiment

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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 Pasteurs Experiment

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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 Pasteurs Experiment

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Pasteurs Work Louis Pasteurs work revolutionized the food and wine industry. The process of heating foods until microorganisms are killed before packaging is called Pasteurization.

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Alternative Investigations Controlled experiments are not always possible. Field studies - animals Medical research clinical trials Environmental research Scientific methodology is still used: Large study groups Controlled variables

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Theories The theory of biogenesis developed from many experiments that tested the hypothesis that new organisms come from existing organisms. When a hypothesis becomes very well supported it is considered a theory. A theory is defined as a well tested explanation that unifies a broad range of observations. Can theories change? Can a theory be proven true?

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1-3 Studying Life Biology -bios = life -logy = study of Living things share certain characteristics.

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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

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Branches of Biology Zoologists animals Botanists plants Paleontologists ancient life Microbiologists microscopic life Immunologists Disease Ecologists Organisms and their environment

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Levels of Organization Living things may be studied on many different levels. The largest and most complex level is the biosphere. The smallest level is the molecule.

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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 Levels of Organization

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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 Levels of Organization continued

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1-4 Tools and Procedures Scientists use a common measurement system: The metric system, or SI Some standard units of measurement are: Length Meter Ruler or meter stick Volume Liter Graduated cylinder or pipet Mass Gram balance Temperature Celsius thermometer

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Analyzing Data Data tables are used to stay organized when recording data. Graphs are used to make data easier to interpret and see trends (patterns).

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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 5 2 10 14 9 6 4 1 1 12 17 16 10 3 Water released by leaves Water absorbed by roots Relative Rates (g/h) 20 Time 0 15 10 5 8 AM10 AM12 PM2 PM4 PM6 PM8 PM Section 1-4 Making a Graph From A Data Table

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Microscopes Devices that produce magnified images of structures that are too small to see with the unaided eye. Three common microscopes are: Light microscope Can magnify up to 1000X Useful for viewing cells Electron microscope Can magnify up to 100,000X Useful for seeing parts of cells Dissecting (stereo) microscope Can magnify up to 5X Useful for dissections

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Laboratory Techniques Two common techniques for studying cells are cell culture and cell fractionation. Cell culture Cells are grown in sterile dishes Especially useful for growing stem cells Cell fractionation Cells are broken apart in a blender Cell parts are separated in a centrifuge

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