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.
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.
Scientific Method Summary 1)Ask questions, make observations 2)Gather information 3)Form a hypothesis (educated guess) 4)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 Asking a Question Many years ago, people wanted to know how living things came into existence. They asked: How do organisms come into being?
Aristotle 2300 y.a people thought that some “special force” brought some things into being from nonliving material Ex: Beetles just “appeared” on cow dung Mice were “found” on grain Maggots “showed up” on meat
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 Redi’s Experiment Controlled Variables: jars, type of meat, Location, temperature, time Covered jars Uncovered jars What do you think are the manipulated and responding variables in this experiment??
Copyright Pearson Prentice Hall Redi’s Experiment Manipulated Variable: Gauze covering that keeps flies away from meat Responding Variable: whether maggots appear Maggots appear. Several days pass. No maggots appear.
John Needham – mid 1700’s English Scientist who tried to attack Redi’s work. He had a flask with a sealed cork and it had no microorganisms growing in it. Next, he heated it for a short time and corked the flask and microorganisms appeared. He believed that the little “animalcules” must have come from the gravy!
Copyright Pearson Prentice Hall Repeating Investigations Spallanzani's Test of Redi's Findings Gravy is boiled. Which variables are controlled??
Copyright Pearson Prentice Hall 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 HallH 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 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 Pasteur’s Experiment Broth is boiled Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.
Copyright Pearson Prentice Hall The Impact of Pasteur’s Work He began to uncover the nature of infectious diseases, showing that they were the result of microorganisms. Pasteurization of dairy products
Copyright Pearson Prentice Hall 1-3 Studying Life
Copyright Pearson Prentice Hall What are some characteristics of living things?
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”
Characteristics of Living Things 2.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
Make a table with the heading “CAR” LivingNonLiving