Ms. Moore 1/8/13 Albert Einstein physicist Stephen Hawking cosmology and quantum gravity Scientist: a person who is studying or has expert knowledge of one or more of the natural or physical sciences Who are your favorite scientists? How many scientists are in this room? Science: organized way of using evidence to learn about the natural world The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions. Observation: the process of gathering information about events or processes in a careful, orderly way. Data: the information gathered from observations. Quantitative data: expressed as numbers, obtained by counting or measuring. Qualitative: Inference: logical interpretation based on prior knowledge or experience. Hypothesis: a proposed scientific explanation for a set of observations. These are generated by scientists using prior knowledge, logical inference, and informed, creative imagination. There can be more than one hypothesis for a question. Scientific Method : Asking a Question Forming a Hypothesis Setting up a Controlled Experiment Controlled experiment: constant Manipulated/Independent variable: deliberately changed Responding/Dependent variable: changes in response to manipulation Recording and Analyzing Results Written records of observations and data. Drawing a Conclusion Explanation of observations. Spontaneous Generation: Francesco Redi Observation: Flies land on meat that is left uncovered, then maggots appear. Hypothesis: Flies produce maggots Procedure: Covered and Uncovered Jars Controlled variables: jars, type of meat, location, temperature Manipulated (Independent) variable: gauze covering that keeps flies away from meat Responding (Dependent) variable: whether maggots appear Conclusion: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur Experiments are often repeated by other scientists to ensure accuracy of experimental procedures and results A key assumption in science is that experimental results can be reproduces because nature behaves in a consistent manner Needham vs. Spallanzani Spallanzani improved Needhams work by observing work of others (Redi); however, air was omitted and could not disprove spontaneous generation. How did Pasteur finally disprove spontaneous generation? It is not always possible to do an experiment to test a hypothesis: Ethical issues of humans Ex: Does this chemical cause cancer in humans? Disruption of a natural system Ex: How do animals in the wild interact with each other? As evidence from numerous investigations builds up, a particular hypothesis may become so well supported that scientists consider it a theory. In science, theory applies to a well tested explanation that unifies a broad range of observations. Biogenesis: generating from life Students will work with lab groups to understand the scientific method. Each group is assigned a story and they must Ask a question Form a hypothesis Design an experiment Including all variables that would be tested Biology: the science that employs the scientific method to study living things. What are living things? 8 characteristics Made up of cells: the smallest unit of an organism that can be considered alive. Reproduce Sexual reproduction: cells from two different parents unite Asexual reproduction: single parent produces offspring that are identical to itself Based on a universal genetic code written in DNA Grow and develop Differentiation: cells begin to look different from one another and perform different functions Obtain and use material and energy Metabolism: combination of chemical reactions through which an organism builds up or breaks down material Respond to their environment Stimuli: a signal to which an organism responds Living things maintain a stable internal environment Homeostasis: organisms need to keep conditions inside their bodies as constant as possible Living things evolve Molecules: groups of atoms Cells: smallest functional unit of life Groups of Cells: tissues, organs, organ systems Organism: individual living thing Population: group of organisms of one type that live in the same area Community: populations that live together in a defined area Ecosystem: community and its non-living surroundings Biosphere: the part of Earth that contains all ecosystems Learn more here! Learn more here! Working in pairs, create a Levels of Organization presentation using a unique organism. Figure 19 (p.21) Cover each of the 8 levels in the presentation. You may use a variety of presentations: flip books, comics, posters, etc. Be prepared to present your creation to the class. Most popular system of measurement among scientists: metric system Metric System: decimal system of measurement whose units are based on multiples of 10 Length is the distance from one point to another What can we use to measure length in the lab? Common Metric Units (meter = slightly longer than a yard) 1 meter (m) = 100 centimeters (cm) 1 meter = 1000 millimeters (mm) 1000 meters = 1 kilometer (km) The amount of matter in an object is defined as mass. How could we measure mass in lab? Common Metric Units (1 gram = 1 paperclip) 1 kilogram (kg) = 1000 grams (g) 1 gram = 1000 milligrams (mg) 1000 kilograms = 1 metric ton (t) Volume is the amount of space an object takes up. How is volume measured? Common Metric Units 1 liter (L) = 1000 milliliters (mL) 1 liter = 1000 cubic centimeters (cm 3 ) Temperature is used to measure hotness or coldness. How is temperature measured? Common Metric Units 0C = freezing point of water 100C = boiling point of water 2.54 centimeters (cm) = 1 inch (in.) 1 meter (m) = inches (in.) 1 kilometer (km) = 0.62 miles (mi) 1 liter (L) = 1.06 quarts (qt) 236 milliliters (mL) = 1 cup (c) 1 kilogram (kg) = 2.2 pounds (lb) 28.3 grams (g) = 1 ounce (oz) C = 5/9 x ( F 32) What methods of recording data are utilized in science? How can these tools help biologists analyze data quickly? Microscopes are devices that produce magnified images of structures that are too small to see with the unaided eye Types: Light microscopes: produce magnified images by focusing visible light rays Electron microscopes: produce magnified images by focusing beams of electrons Light microscopes can produce clear images of objects at a magnification of about 1000X Compound light microscopes: allow light to pass through the specimen and use two lenses to form an image Used to observe dead organisms and cells while they are still alive. Electron microscopes are used for objects smaller than 0.2 micrometers (1/50 the diameter of a typical cell) Electron microscopes can produce images almost 1000X more detailed than light microscopes Types: Transmission electron microscopes (TEMs): shine a beam of electrons through a thin specimen; give great detail inside the cell Scanning electron microscopes (SEMs): scan a narrow beam of electrons back and forth across the surface of a specimen; produce a realistic, 3D image of the surface of objects Cell cultures: cell is placed into a nutrient solution to replicate from a single original cell When would we use cell cultures? Cell fractionation: separate cell parts Disrupt membrane and release parts Add liquid and transfer into centrifuge Most dense parts of cell are now in the bottom and a biologist can remove the specific part based on density Using the knowledge we learned today, complete the worksheet using lab materials supplied at your table. Who has bigger hands: practice with the scientific method