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The Science of Biology

The Science of Biology. What is Science? The Scientific Method Tools Used in Science What is Biology?. What is Science?. An organized way of using evidence to learn about the natural world Body of knowledge that scientists have built up.

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The Science of Biology

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  1. The Science of Biology What is Science? The Scientific Method Tools Used in Science What is Biology?

  2. What is Science? • An organized way of using evidence to learn about the natural world • Body of knowledge that scientists have built up

  3. Observation – using one or more of the senses to gather information Inference – a logical interpretation based on prior knowledge and experience Data – information gathered from observations Quantitative – involve numbers Qualitative – involve characteristics that cannot be easily measured or counted, such as color or texture Steps used in science…

  4. Observation vs. Inference Statement Observation Inference X Object A is round and orange. X Object A is a basketball. X Object C is round and black and white. X Object C is larger than Object B. X Object B is smooth. X Object B is a table-tennis ball. X X Each object is used in a different sport.

  5. Scientific Method • 1. Stating the Problem – based on observations, identify a problem to be solved

  6. Scientific Method cont. • 2. Forming a Hypothesis – a possible explanation for a set of observations or an answer to a scientific question • Prior knowledge • Logical inferences • Imaginative guesses

  7. Scientific Method cont. • 3. Setting up a Controlled Experiment – an experiment in which only one variable is changed at a time • Manipulated variable (independent) – the variable that is changed by the scientist • Responding variable (dependent) – the variable that changes in response to the manipulated variable • If an experiment cannot be done, field studies will be done

  8. Spontaneous Generation Experiment OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Uncovered jars Covered jars Controlled Variables: jars, type of meat, location, temperature, time Several days pass Manipulated Variables: gauze covering that keeps flies away from meat Responding Variable: whether maggots appear Maggots appear No maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

  9. Another Spontaneous Generation Experiment Gravy is boiled. Flask is open. Gravy is teeming with microorganisms. Flask is sealed. Gravy is free of microorganisms. Gravy is boiled.

  10. Another Spontaneous Generation Experiment Broth is boiled. Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.

  11. Scientific Method cont. • 4. Record and Analyze Results – keep written records of observations or data • Notebooks, journals, drawings, computer

  12. Scientific Method cont. • 5. Drawing a Conclusion – determine whether the hypothesis is supported or refuted Yes No

  13. Then what? • Publish study in a scientific journal • Other scientists review the procedures and may perform their own experiments to verify the results • If the hypothesis is continually supported it may become a theory ****No theory is considered absolute truth!!!!!

  14. Tools used in Science… • Microscopes • Three kinds: compound light microscope, transmission electron microscope, and scanning electron microscope • Magnification – determined by multiplying the eyepiece times the objective • Resolution – ability to distinguish between two objects

  15. Compound Light Microscope • Light passes through the object • Magnification up to 1000 times • Resolution up to 500 nanometers

  16. Compound Light Microscope

  17. Compound Light Microscope

  18. Transmission Electron Microscope (TEM) • Passes a beam of electrons through the object • Focused by magnets • Only dead cells can be viewed • Cells must be embedded in plastic and sliced thin • Much greater magnification & resolution (.2nm)

  19. Transmission Electron Microscope

  20. Scanning Electron Microscope (SEM) • Beam of electrons sweeps over and bounces off of object • Produces a 3-D image • Less magnification than TEM • Possible for living cells

  21. Scanning Electron Microscope

  22. Metric System or System Internationale (SI) • Reasons scientists use the metric system: • Based on the number 10 • Easy to convert • Universally understood

  23. Metric Units • Length – meter (m) • Mass – gram (g) • Volume (liquid) – liter (L) • Time – second (s) • Temperature – Celsius (°C) or Kelvin (K)

  24. Metric Prefixes Kilo k 1000 Hecto h 100 Deca da 10 METER GRAM LITER SECOND Deci d 1/10 Centi c 1/100 Milli m 1/1000 Micro  1/millionth Nano n 1/billionth King Henry Died By Drinking Chocolate Milk Monday Night

  25. What is Biology? • Bios – life or living things • -ology – study of • Study of life or living things

  26. Characteristics of Living Things • Living things are made of cells • Cells are the smallest units of an organism that can be considered alive • Unicellular – one-celled • Multicellular – many-celled

  27. Characteristics of Living Things • Living things reproduce • Production of new organisms

  28. Characteristics of Living Things • Living things are based on a universal genetic code (DNA)

  29. Characteristics of Living Things • Living things grow and develop • Growth – an increase in size • Development – changes that occur as an organism grows

  30. Characteristics of Living Things • Living things obtain and use materials and energy • Producers – make their own food • Consumers – eat other living things

  31. Characteristics of Living Things • Living things respond to their environment • Temperature • Ex. Birds fly south for the winter • Light • Ex. Plants grow towards the sunlight if placed in a window

  32. Characteristics of Living Things • Living things maintain a stable internal environment • Homeostasis – keep internal conditions relatively stable • What does your body do when you are cold? • shivers • What does your body do when you are hot? • sweats

  33. Characteristics of Living Things • As a group, living things change over time • Evolution – change over time • Ex. The brain cavity of human skulls is larger, our jaws are smaller, on average we are taller

  34. Characteristics of Living Things • Living things… • Are made of cells • Reproduce • Are based on a universal genetic code • Grow and develop • Obtain and use materials and energy • Respond to their environment • Maintain a stable internal environment • Change over time

  35. Levels of Organization • Organism – an individual living thing • A cow • Population – group of organisms • A herd of cows • Community – populations that live together • A herd of cows, the grass, and flies • Ecosystem – community & surroundings • The cows, grass, flies, rocks, and streams • Biosphere – contains all ecosystems • The entire Earth

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