1. The Nature of Science Unit I

2. Measurement   What kind of data can be collected?  qualitative data  quantitative data   What system is used for quantitative data?  the (metric mostly) uses powers of 10 and certain prefixes; used by scientists throughout world to avoid confusion  the SI system (metric mostly) uses powers of 10 and certain prefixes; used by scientists throughout world to avoid confusion

3. Measurement  Value (unit)  Length (meter, m)   Mass (gram, g)   Volume (liter, L)   Time (second, s)   Temperature  (degree Celsius, C)  Standard Equipment  Meter stick, ruler  Triple-beam balance  Graduated cylinder, syringe, micropipette  Stopwatch  Thermometer

4. Metric Prefixes & Values  the SI system is based on powers of 10  kilo - hecto - deca - base unit - deci - centi – milli  k h D *** d c m  1000 - 100 - 10 - *** - 1/10 - 1/100 - 1/1000  Example: a kilometer = 1000 meters  How long is a millimeter?  Is a decaliter larger or smaller than a deciliter?  How many centigrams are in a gram?

5. Metric Conversions  Because the SI system is based on powers of 10 it is easy to convert between units  kilo – hecto – deca – base unit – deci – centi – milli  “King Henry died by drinking chocolate milk”  K -- H -- D -- B -- D -- C -- M  See demonstration on board…

6. Science…  …tries to disprove rather than prove  Difficult to do enough experiments to truly prove  …can be done well, or poorly  Must examine with a critical eye  …is not democratic  Based on confirmed observations  …does not follow neat little steps (lab packet)  Though basic steps always followed…

7. Scientific Method Scientific investigations start with an observation and a question!

8. Scientific Method  The following steps will be followed when conducting labs in this class…  I. Problem/Purpose  II. Background/Research  III. Hypothesis  IV. Experiment  V. Data Analysis  VI. Conclusions ~ see Lab Report Format for more specifics!

9. Steps of the Scientific Method 1. Problem/Question: Develop a question or problem that can be solved through experimentation.

10. Steps of the Scientific Method 2. Observation/Research: Make observations and research your topic of interest.

11. Do you remember the next step?

12. Steps of the Scientific Method 3. Formulate a Hypothesis: Predict a possible answer to the problem or question. Example: If soil temperatures rise, then plant growth will increase.

13. Steps of the Scientific Method 4. Experiment: Develop and follow a procedure. Include a detailed materials list. The outcome must be measurable (quantifiable).

14. Steps of the Scientific Method 5. Collect and Analyze Results: Modify the procedure if needed. Confirm the results by retesting. Include tables, graphs, and photographs.

15. Steps of the Scientific Method 6. Conclusion: Include a statement that accepts or rejects the hypothesis. Make recommendations for further study and possible improvements to the procedure.

16. Steps of the Scientific Method 7. Communicate the Results: Be prepared to present the project to an audience. Expect questions from the audience.

17. Think you can name all seven steps?

18. Experimental Design  Large sample size  Replicated many times  Control Group  The “baseline”…what results compared against  Controlled Variables  Remain the same between all groups, so that they are NOT factors in the experiment

19. Experimental Design - Variables  Independent Variable (“I” set up beforehand) ~ is the only variable that is changed between experimental groups ~ example: color of light on plants  Dependent Variable (“Data” collected “During” experiment) ~ is the effect of the independent variable ~ it is what you measure as you experiment ~ ex: height plants grow

20. Data Tables Independent Variable (unit) Dependent Variable (unit)

21. Data Tables Color of Light Sunflower Height (cm) White (daylight) 7 Red 6 Blue 8 Green 3 Table 1. Height of Sunflowers when Grown in Varying Colors of Light

22. Graphing Data Tables M anipulated I ndependent X axis D ependent R esponds Y axis Graph 1. Height of Sunflowers when Grown in Different Colors of Light

23. Graph Color of Light Height of Sunflowers (cm) Graph 1. Height of Sunflowers when Grown in Different Colors of Light

24. Characteristics of Life What processes or traits must all living organisms exhibit be considered a live?

25. Characteristics of Life…  How do you know something is alive??? (With a group of 4 students…) -Identify the characteristics that are common to all living organisms.  Put your ideas on chart paper…  Be prepared to share your findings with the class…

26. Characteristics of Living Things Organisms are living things. All living things: 1. are composed of one or more cells 2. contain similar chemicals 3. Take in and expend energy 4. Grow and develop 5. Respond to their surroundings 6. Reproduce – on the cellular & organismal level

27. All Living Things Are Made Of Cells  A cell is the basic unit of structure and function in an organism.  Unicellular organisms are single-celled organisms. Bacteria, the most numerous organisms on Earth, are unicellular.  Multicellular organisms are composed of many cells. The cells of organisms use energy to grow and repair injured parts.

28. Cells Are Composed Of Similar Chemicals.  The most abundant chemical in cells is water.  Another chemical called carbohydrate is a cell’s energy source.  Proteins and lipids are the building materials of cells.  Nucleic acids are the genetic materials that direct the cell’s activities.

29. All Organisms Need Energy Some make their own food (energy)… Some don’t make their own food…  Organisms that can make their own food are called autotrophs.  Organisms that cannot make their own food are called heterotrophs.

30. Living Things Grow and Develop You weren’t born being the size you are now… Zygote…Embryo…Fetus…Newborn… Infant…Toddler…and so on…  Growth is the process of becoming larger.  Development is the process of change that occurs during an organism’s life to produce a more complex organism.

31. All Organisms React to their Surroundings The alternative to “responding” to your surroundings….EXTINCTION!!!  A change in an organism’s surroundings that causes the organism to react is called a stimulus. An organism reacts to a stimulus with a response—an action or change in behavior.

32. All Organisms Can Reproduce  Another characteristic of organisms is the ability to reproduce, or produce offspring that are similar to the parents.

33. Pre-AP Bio Exam Review  Define the independent variable  Define the dependent variable  Define experimental group  Define control group  Define constants  Review Safety Symbols Handout  Identify parts of the scientific method

34.  Interpret data tables and graphs  Be able to identify and know function of lab equipment  Be able to read lab equipment  Metric Measurements/Conversions  Characteristics of Life

35. The Chemistry of Water

36. Why is water essential for life?  Makes up most content of cells  Required for chemical reactions  Required to grow food  Provides shelter/protection  Aids in transport of materials

37. Why Water?  Water is neutral, but its electrons are a little off-set  The oxygen side is slightly negative  The hydrogen side is slightly positive  This is called POLARITY…it is the key to almost all of water’s special traits!

38. Properties of water: Polarity  Water’s polarity allows for “hydrogen bonds”  These H-bonds make water “stick” to itself and many other things…resulting in its special properties

39. Properties of water: Cohesion & Adhesion  What? Attraction between water and itself (or another molecule)  Why? Polar ends grab each other  Ex: Water moving up a stem

40. Properties of water: High Surface Tension  What? Difficult to break surface of water  Why? H-bonds make water stick to itself  Ex: Insects walking on water

41. Properties of water: High Specific Heat  What? Water holds its temp; is hard to change it  Why? Must break H-bonds for water to change temp  Ex: Bodies of water maintain stable envir. temps; temps within organisms remain stable

42. Properties of water: High Heat of Vaporization  What? Must remove lots of heat before water vaporizes  Why? Must break all H-bonds holding molecules first  Ex: Cooling systems in animals

43. Properties of water: Ice Less Dense Than Liquid Water  What? Ice will float in water  Why? H-bonds hold water molecules farther apart (more volume)  Ex: Ponds insulated in winter winter

44. Properties of water: Ice Less Dense than Liquid Water

45. Properties of water: Universal Solvent  What? Water dissolves many substances  Why? Charged ends pull on other charged particles  Ex: Most rxns require chemicals in solution

46. Water is neutral…so why does it “have charges”?  Water dissociates into ions (ions are particles with charges)  Not very many ions actually form, but it is enough to matter

47. Dissociation of Water  In pure water [H+] = [OH-]…which means pH is 7, or neutral  When acids dissolve in water …there are more H’s than OH’s  When bases dissolve in water …there are fewer H’s than OH’s

48. How do we know how acidic or basic something is?  pH scale measures how acidic/basic  Scale is 0-14 Neutral = 7  Acid 7  Each # is 10X greater than next #  Ex: pH 3 is 10X more acidic than pH 4 …how much more acidic is pH 2 than pH 5? …how much more acidic is pH 2 than pH 5?

49. pH Scale

50. Why does pH matter to life?  Most cells are at pH of about 7  Even slightest change in pH can be harmful/deadly because chemical rxns can be altered/inhibited  Acid rain harmful because organisms forced to take in acidic water…formed when fossil-fuels react with water in air

51. Acid Rain

52. The End