Slide 2:Chapter: Exploring and Classifying Life Table of Contents Section 3: Where does life come from? Section 1: What is science? Section 2: Living Things Section 4: How are living things classified?


Slide 3:Asking questions is one way scientists find out about anything in the world and the universe. Science is often described as an organized way of studying things and finding answers to questions. The Work of Science What is science? 1


Slide 4:Many types of science exist. For example, energy and matter have a relationship. That’s a topic for physics. Types of Science What is science? 1 On the other hand, a life scientist might study any of the millions of difference animals, plants, and other living things on Earth. Life scientists who study plants are botanists, and those who study animals are zoologists.


Slide 5:Suppose your CD player stops playing music. To figure out what happened, you have to think about it. That’s called critical thinking, and it’s the way you use skills to solve problems. Critical Thinking What is science? 1 You separate important information from unimportant information—that’s a skill. Identifying the problem is another skill you have.


Slide 6:Besides critical thinking, which is a process that uses certain skills to solve a problem, requires organization. Solving Problems What is science? 1 In science, this organization often takes the form of a series of procedures called scientific methods.


Slide 7:Solving Problems What is science? 1 State the problem. Gather information Form a hypothesis Test the hypothesis with an experiment


Slide 8:A control is the standard to which the outcome of a test is compared. Controls What is science? 1 A variable is something in an experiment that can change. An experiment should have only one variable.


Slide 9:5. Analyze Data: Look at what the results tell you 6. Draw conclusions: Figure out what you learned. 7. Report results: Tell everyone what you learned.


Slide 10:When using scientific methods, it is important to share information. Report Results What is science? 1 In science it is important to explain how an experiment can be made better if it is done again.


Slide 11:After scientists report the results of experiments supporting their hypotheses, the results can be used to propose a scientific theory. Developing Theories What is science? 1 A scientific theory is an explanation of things or events based on scientific knowledge that is the result of many observations and experiments. It is not a guess or someone’s opinion.


Slide 12:If data collected from several experiments over a period of time all support the hypothesis, it finally can be called a theory. Developing Theories What is science? 1


Slide 13:A scientific law is a statement about how things work in nature that seems to be true all the time. Laws What is science? 1 They are less likely to change than theories. Laws tell you what will happen under certain conditions but do not necessarily explain why it happened.


Slide 14:An important part of most scientific investigations is making accurate measurements. Measuring with Scientific Units What is science? 1


Slide 15:Measuring with Scientific Units What is science? 1 You will use the same standard system of measurement scientists use to communicate and understand each other’s research and results. This system is called the International System of Units, or SI.


Slide 16:Laboratory safety is important. Safety First What is science? 1 In many states, a student can participate in a laboratory class only when wearing proper eye protection. Following safety rules will protect you and others from injury during your lab experiences. Click image to view movie.


Slide 17:1 Section Check Question 1 This diagram shows a way to use scientific methods to solve a problem. According to the diagram, if a hypothesis is not supported by data then you should _______.


Slide 18:1 Section Check change the data so that they do support the hypothesis B. find a different problem to solve C. propose a scientific theory D. revise the hypothesis and perform new experiments


Slide 19:1 Section Check Answer The correct answer is D. Scientific methods are an organized way to solve a problem in science. This series of procedures involves forming a hypothesis that can be tested.


Slide 20:1 Section Check Question 2 What is the definition of a control in a scientific experiment? Answer A control is the standard to which the outcome of a test will be compared. Controls help you determine how to interpret your data.


Slide 21:1 Section Check Question 3 A statement about how things work in nature that seems to be true all the time is a _______. A. conclusion B. hypothesis C. law D. variable


Slide 22:1 Section Check Answer The correct answer is C. Although laws can be modified as more information becomes known, they are less likely to change than theories.


Slide 23:What are living things like? What does it mean to be alive? Any living thing is called an organism. They have different behaviors and food needs. In spite of these differences, all organisms have similar traits. Living Things 2


Slide 24:Living Things Are Organized A cell is the smallest unit of an organism that carries on the functions of life. Cells take in materials from their surroundings and use them in complex ways. Each cell has an orderly structure and contains hereditary material. Living Things 2 The hereditary material contains instructions for cellular organization and function.


Slide 25:Living Things Respond Living things interact with their surrounds. Anything that causes some change in an organism is a stimulus (plural, stimuli). Living Things 2 The reaction to a stimulus is a response. Often that response results in movement.


Slide 26:Living Things Respond Living things also respond to stimuli that occur inside them. Living Things 2 An organism’s ability to keep the proper conditions inside no matter what is going on outside the organism is called homeostasis. Homeostasis is a trait of all living things.


Slide 27:Living Things Use Energy The energy used by most organisms comes either directly or indirectly from the Sun. Living Things 2 Plants and some other organisms use the Sun’s energy and the raw materials carbon dioxide and water to make food.


Slide 28:Living Things Use Energy You and most other organisms can’t use the energy of sunlight directly. Instead, you take in and use food as a source of energy. Living Things 2


Slide 29:Living Things Grow and Develop Growth of many-celled organisms is mostly due to an increase in the number of cells. Living Things 2 In one-celled organisms, growth is due to an increase in the size of the cell. Organisms change as they grow. All of the changes that take place during the life of an organism are called development.


Slide 30:Living Things Reproduce Living things reproduce themselves in many different ways. Living Things 2 Cats, dogs, alligators, fish, birds, bees, and trees eventually reproduce. Beetles, like most insects, reproduce by laying eggs.


Slide 31:Living Things Reproduce Without reproduction, living things would not exist to replace those individuals that die. Living Things 2 An individual cat can live its entire life without reproducing. However, if cats never reproduced, all cats soon would disappear.


Slide 32:What do living things need? To survive, all living things need a place to live and raw materials. Living Things 2 The raw materials that they require and the exact place where they live can vary.


Slide 33:A Place to Live The environment limits where organisms can live. Living Things 2 Not many kinds of organisms can live in extremely hot or extremely cold environments. Most cannot live at the bottom of the ocean or on the tops of mountains. An organism’s surroundings must provide for all of its needs.


Slide 34:Raw Materials Water is important for all living things. Living Things 2 Plants and animals take in and give off large amounts of water each day. Most organisms are composed of more than 50 percent water. You are made of 60 to 70 percent water.


Slide 35:2 Section Check Question 1 What is the smallest unit in a cat that carries on the functions of life? Answer The cell is the smallest unit. All organisms are composed of cells. Cells take in materials from their surroundings and use them in complex ways.


Slide 36:2 Section Check Question 2 Pulling your hand back when you accidentally touch a hot pan on the stove is an example of what characteristic of living things? A. growth and development B. organization C. reproduction D. response to stimuli


Slide 37:2 Section Check Answer The correct answer is D. The hot pan is an example of a stimulus. Living things can respond to both external and internal stimuli.


Slide 38:2 Section Check Question 3 Give an example of two raw materials that you need to survive. Answer Some possible answers include: water, food, and oxygen. Some bacteria and plants can make food from raw materials in their surroundings.


Slide 39:Life Comes from Life Before the seventeenth century, some people thought that insects and fish came from mud, that earthworms fell from the sky when it rained, and that mice came from grain. The idea that living things come from nonliving things is known as spontaneous generation. Where does life come from? 3 This idea became a theory that was accepted for several hundred years.


Slide 40:Spontaneous Generation and Biogenesis From the late seventeenth century through the middle of the eighteenth century, experiments were done to test the theory of spontaneous generation. Where does life come from? 3


Slide 41:Spontaneous Generation and Biogenesis It was not until the mid 1800s that the work of Louis Pasteur provided enough evidence to disprove the theory of spontaneous generation. Where does life come from? 3 It was replaced with biogenesis (bi oh JE nuh suss), which is the theory that living things come only from other living things.


Slide 42:Classification Libraries group similar types of books together. When you place similar items together, you classify them. How are living things classified? 4 Organisms also are classified into groups.


Slide 43:History of Classification Early classifications included grouping plants that were used in medicines. Animals were often classified by human traits such as courageous—for lions—or wise—for owls. How are living things classified? 4


Slide 44:History of Classification More than 2,000 years ago, a Greek named Aristotle observed living things. He decided that any organism could be classified as either a plant or an animal. How are living things classified? 4 Then he broke these two groups into smaller groups. Animal categories included hair or no hair, four legs or few legs, and blood or no blood.


Slide 45:Linnaeus Carolus Linnaeus developed a new system of grouping organisms. His classification system was based on looking for organisms with similar structures. For example, plants that had similar flower structure were grouped together. How are living things classified? 4


Slide 46:Modern Classification Modern scientists use similarities in structure to classify organisms. They also use similarities in both external and internal features. How are living things classified? 4 Phylogeny (fi LAH juh nee) is the evolutionary history of an organism, or how it has changed over time.


Slide 47:Six Kingdoms A kingdom is the first and largest category. Organisms are placed into kingdoms based on various characteristics. How are living things classified? 4


Slide 48:Six Kingdoms How are living things classified? 4 The smallest classification category is a species. Organisms that belong to the same species can mate and produce fertile offspring.


Slide 49:Binomial Nomenclature The two-word naming system that Linnaeus used to name the various species is called binomial nomenclature (bi NOH mee ul . NOH mun klay chur). How are living things classified? 4 It is the system used by modern scientists to name organisms.


Slide 50:Binomial Nomenclature The first word of the two-word name identifies the genus of the organism. How are living things classified? 4 A genus is a group of similar species. The second word of the name might tell you something about the organism— what it looks like, where it is found, or who discovered it.


Slide 51:Dichotomous Keys A dichotomous key is a detailed list of identifying characteristics that includes scientific names. How are living things classified? 4 Dichotomous keys are arranged in steps with two descriptive statements at each step.


Slide 52:4 Section Check Question 1 Over 2,000 years ago, Aristotle developed a system to classify all organisms _______. A. as either plant or animal. B. based on fossils. C. into six different kingdoms. D. using binomial nomenclature.


Slide 53:4 Section Check Answer The correct answer is A. Aristotle broke these two groups into smaller groups. Two of his smaller groups of animals would have been animals with hair and those with no hair.


Slide 54:4 Section Check Question 2 What word is used to describe the evolutionary history of an organism? Answer The word is phylogeny. Phylogeny explains how an organism has changed over time and is the basis for the modern classification of many organisms.


Slide 55:4 Section Check Question 3 Acer rubrum is the scientific name for a red maple tree. This name is an example of _______. A. a dichotomous key B. a hypothesis C. binomial nomenclature D. spontaneous generation


Slide 56:4 Section Check Answer The correct answer is C. Binomial nomenclature is the system used by modern scientists to name organisms. The first part of the scientific name identifies the genus of the organism.


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