Biology 112 Chapter 1 Overview (Accompanies GR Chap1) Holyoke Walsh

Copyright Pearson Prentice Hall The goal of science is to: investigate and understand the natural world. explain events in the natural world. use those explanations to make useful predictions. http://www.youtube.com/watch?v=VjE0Kdfos4Y Copyright Pearson Prentice Hall 2

Copyright Pearson Prentice Hall 1-2 How Scientists Work Scientists make educated guesses about how things work the way they do. These are called HYPOTHESIS. How do scientists test hypotheses? A hypothesis should be tested by an experiment in which only one variable is changed at a time. Copyright Pearson Prentice Hall 3

Copyright Pearson Prentice Hall Asking a Question Many years ago, people wanted to know how living things came into existence. They asked: How do organisms come into being? Copyright Pearson Prentice Hall 4

Copyright Pearson Prentice Hall Forming a Hypothesis One early hypothesis was spontaneous generation aka: abiogenesis. For example, most people thought that maggots spontaneously appeared on meat. In 1668, Redi proposed a different hypothesis: that maggots came from eggs that flies laid on meat. Copyright Pearson Prentice Hall 5

Copyright Pearson Prentice Hall Setting Up a Controlled Experiment manipulated variable (independent) responding variable (dependent) Copyright Pearson Prentice Hall 6

Copyright Pearson Prentice Hall Redi’s Experiment Uncovered jars Covered jars Controlled Variables: jars, type of meat, Location, temperature, time In a controlled experiment, only one variable is tested at a time. Redi designed an experiment to determine what caused the sudden appearance of maggots. In his experiment, the manipulated variable was the presence or absence of the gauze covering. The results of this experiment helped disprove the hypothesis of spontaneous generation. What do you think are the manipulated and responding variables in this experiment?? Copyright Pearson Prentice Hall 7

Copyright Pearson Prentice Hall Redi’s Experiment Manipulated Variable: Gauze covering that keeps flies away from meat Several days pass. Responding Variable: whether maggots appear Maggots appear. No maggots appear. Copyright Pearson Prentice Hall 8

Copyright Pearson Prentice Hall Drawing a Conclusion Scientists use the data from an experiment to evaluate a hypothesis and draw a valid conclusion. Copyright Pearson Prentice Hall 9

Repeating Investigations Spallanzani's Test of Redi's Findings  Gravy is boiled. Gravy is boiled. Spallanzani’s experiment showed that microorganisms will not grow in boiled gravy that has been sealed but will grow in boiled gravy that is left open to the air. Interpreting Graphics What variable was controlled in this experiment? Which variables are controlled?? Copyright Pearson Prentice Hall 10

Repeating Investigations Spallanzani's Test of Redi's Findings  Flask is open. Flask is sealed. Is the flask the manipulated or responding variable?? Copyright Pearson Prentice Hall 11

Repeating Investigations Spallanzani's Test of Redi's Findings  Gravy is teeming with microorganisms. Gravy is free of microorganisms. Helped prove the theory of BIOGENESIS!!!! Living things come from other living things! Copyright Pearson Prentice HallH 12

Copyright Pearson Prentice Hall Pasteur's Test of Spontaneous Generation Louis Pasteur conclusively disproved the hypothesis of spontaneous generation. Pasteur showed that all living things come from other living things. Copyright Pearson Prentice Hall 13

Copyright Pearson Prentice Hall Pasteur’s Experiment Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Pasteur’s experiment showed that boiled broth would remain free of microorganisms even if air was allowed in, as long as dust and other particles were kept out. Broth is boiled Copyright Pearson Prentice Hall 14

Copyright Pearson Prentice Hall The Impact of Pasteur’s Work Pasteur saved the French wine industry, which was troubled by unexplained souring of wine. He began to uncover the nature of infectious diseases, showing that they were the result of microorganisms. Copyright Pearson Prentice Hall 15

Scientific Method Summary Ask questions, make observations Gather information Form a hypothesis (educated guess) Set up a controlled experiment Manipulated variable - the variable that is deliberately changed (aka independent variable) Responding variable is variable that is observed (aka dependent variable) 5)Record and analyze results 6)Draw a conclusion 7)Repeat & share findings

Copyright Pearson Prentice Hall 1-3 Studying Life Photo Credit: © Andrew Syred/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall 17

What are some characteristics of living things? Copyright Pearson Prentice Hall 18

Copyright Pearson Prentice Hall Living things share the following characteristics: *REFERENCE PAGE – pages 16/17 of student text!! 1. made up of units called cells – smallest unit of life considered to be “alive” Copyright Pearson Prentice Hall 19

Characteristics of Living Things Reproduction

Characteristics of Living Things 3. Universal genetic code Genetic code is common, with minor variations, to every organism on Earth. That information, carried in DNA, is copied and passed from parents to offspring

Characteristics of Living Things 4. Grow & Develop

Characteristics of Living Things 5. obtain and use materials and energy

Characteristics of Living Things 6. respond to their environment

Characteristics of Living Things 7. Maintain a stable internal environment (called homeostasis)

Characteristics of Living Things 8. change over time