What is a Scientist?

1. What is a Scientist? Ms. Moore 08/17/12 Albert Einstein physicist Stephen Hawking cosmology and quantum gravity

2. Scientists are… 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?

3. What is Science? 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.

4. Thinking Like a Scientist • 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.

5. Explaining Evidence • 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.

6. Designing an Experiment • 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.

7. Spontaneous Generation • 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

8. Replication • 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 Needham’s work by observing work of others (Redi); however, air was omitted and could not disprove spontaneous generation. • How did Pasteur finally disprove spontaneous generation?

9. When experiments are not possible… • 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?

10. Theory • 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

11. Activity: Scientific Method • 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

12. Studying Life Biology: the science that employs the scientific method to study living things.

13. Living Things: • Made up of cells: the smallest until 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

14. 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

15. Levels of Organization 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

16. Tools and Procedures Most popular system of measurement among scientists: metric system Metric System: decimal system of measurement whose units are based on multiples of 10

17. Length • 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)

18. Mass • 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)

19. Volume • 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 (cm3)

20. Temperature • Temperature is used to measure hotness or coldness. • How is temperature measured? • Common Metric Units • 0°C = freezing point of water • 100°C = boiling point of water

21. Metric-English Equivalents 2.54 centimeters (cm) = 1 inch (in.) 1 meter (m) = 39.37 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)

22. Analyzing Biological Data What methods of recording data are utilized in science? How can these tools help biologists analyze data quickly?

23. Microscopes • 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

24. Light Microscopes 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.

25. Electron Microscopes • 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

26. Laboratory Techniques • 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

27. Metric Measurement Lab 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