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Intro to Life Science What is Science? Living Things Where Does Life Come From? Classifying Life
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1-1: What is Science ? How do you define science? Science: an organized way of studying things and finding answers to questions Critical thinking: a process that uses certain skills to solve problems
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Solving Problems Solving problems requires organization Scientific methods: an organized way to solve a problem using a series of procedures ◦ requires critical thinking
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Scientific Methods State the problem/Ask a question Gather information Form a hypothesis: a prediction that can be tested
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Scientific Methods Experiment: ◦ Control: standard of comparison in an experiment; cannot change ◦ Variable: something in an experiment that can change An experiment should have only one variable. tests the hypothesis
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Scientific Methods Analyze data Draw conclusions Report results ◦ allows other scientists to repeat same experiment
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7 Steps to Solve a Problem State the Problem Gather Information Form a Hypothesis Perform an Experiment Analyze Data Draw Conclusions Hypothesis Supported Hypothesis not Supported Repeat Many Times Revise Hypothesis
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Developing Theories The results can be used to develop a scientific theory ◦ an explanation of things or events based on scientific knowledge; the result of many observations and experiments Not just simply a guess or opinion!!!
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Laws Scientific law: a statement/description about how things work in nature; seems to be true all the time ◦ Ex. Law of Gravity Less likely to change than theories
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Scientific Units Must make accurate measurements in experiments and investigations Scientists use: ◦ International System of Units (SI) Standard system of measurements used by scientists Uses Gram Meter Liter Second Celsius Mass Length Volume Time Temperature
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Lab Safety Must be safe in the lab Follow all safety rules and teacher’s instructions at all times
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1-2: Living Things What does it mean to be alive? Any living thing is called an organism May have different behaviors and food needs, but all organisms have similar traits.
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Characteristics of Life 1. Organization ◦ Living things are organized ◦ Made of cells: the smallest unit of an organism that carries on the functions of life ◦ Each cell has: an orderly structure hereditary material (DNA)
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Characteristics of Life 2. Responsiveness ◦ Living things respond ◦ Stimulus: anything that causes some change in an organism ◦ Response: the way an organism reacts to a stimulus Ex: Someone hitting you ◦ Homeostasis: maintaining proper conditions inside an organism
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Characteristics of Life 3. Energy ◦ Living things use energy ◦ Animals get energy from food ◦ Some organisms use the sun to make energy Ex: plants
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Characteristics of Life 4. Growth and Development ◦ Living things grow and develop ◦ Growth can be an increase in number of cells (multi- cellular organisms) can also be an increase in the size of the cell (unicellular organisms) ◦ Development: changes that take place during the life of an organism
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5. Reproduction ◦ Living things reproduce ◦ Creating offspring ◦ Without reproduction, organisms would cease to exist Characteristics of Life
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What Do Organisms Need? A Place to Live ◦ provides for all the organism’s needs ◦ environment limits where organisms can live Raw Materials ◦ Water, proteins, fats, and sugars ◦ Water is important for all organisms
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1-3: Where Does Life Come From? Can mice come from grains? Can earthworms come from the rain? Spontaneous generation: idea that living things come from non-living things Theory finally disproved by Louis Pasteur Biogenesis: living things only come from other living things
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Life’s Origins How did life on Earth begin? 5 billion years ago, Earth was formed from dust and gas Earth’s atmosphere had no oxygen but it did have ◦ Ammonia ◦ Hydrogen ◦ Methane ◦ Water vapor
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Life’s Origins Alexander Oparin hypothesized that the gases combined to form more complex compounds found in living things Miller and Urey tested Oparin’s hypothesis ◦ Found that chemicals in living things could be produced ◦ Did not prove that life began this way
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1-4: Classifying Life What is classification? ◦ Grouping similar items Organisms can also be classified into groups Aristotle ◦ first classification system more than 2000 years ago ◦ grouped organisms into plants and animals
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Classifying Life Carolus Linnaeus ◦ Developed a new system based on similar structures of organisms Scientists now study fossils, DNA, and embryos to classify based on phylogeny ◦ evolutionary history of an organism ◦ shows how an organism has changed over time Today, we have 6 kingdoms of classification ◦ Kingdom—Phylum—Class—Order—Family— Genus—Species
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Six Kingdoms Kingdoms are the first and largest category Smallest classification category is a species ◦ Organisms belonging to the same species can mate and produce fertile offspring
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A. Bow-Head whale family Balaenidea B. Ganges dolphin family Platanistidae C. Killer Whale family Delphinidae D. Right whale family Balaenidea This is the classification of the bottle-nosed dolphin. Which of the following organisms from the order Cetacea is most closely related to the bottle-nosed dolphin?
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Scientific Names Common names can be extremely misleading Binomial nomenclature ◦ Two-word system used by Linnaeus to name species; used today ◦ First word identifies the genus: group of similar species ◦ Second word tells something about the species
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Haliaeetus leucocephalus
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Using Scientific Names Scientific names are used to: ◦ Avoid mistakes ◦ Show that organisms in the same genus are related ◦ Give descriptive information ◦ Allow information to be organized easily
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Identifying Organisms 2 types of tools used ◦ Field guides: descriptions or illustrations of organisms Ex. Bird watching ◦ Dichotomous keys: detailed lists of identifying characteristics that include scientific names arranged in steps with two descriptive statements at each step
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Example: 1. Does the organism have a round body? Yes = Go to number 2 No = Go to number 4 2. Does the organism have 2 eyes? Yes = BOT TOT No = Go to number 3 3.Does the organism have 4 antennae? Yes = BOT FOT No = BOT BOT Dichotomous Key
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