Chapter 1 The Science of Biology Ms Luaces

Chapter 1 The Science of Biology Ms. Luaces

Bell Ringer How would you find the answer to your HW question? Design an experiment in which you answer your own homework question. Write at least a paragraph detailing how you would carry out the experiment and what the results would reveal. We will review your answers and see how much they change after we finish today’s Power. Point lesson on Chapter 1.

What is Science? • What are the goals of science? • What procedures are at the core of scientific methodology?

What Science Is and Is Not Science is… • • • Changing An organized way of gathering and analyzing evidence about the natural world Observation Process Looking for patterns and connections among events Propose explanations that are based on evidence, not belief. Science is not… • Absolute • Fact • Collection of unchanging beliefs • Examining supernatural phenomena

The Goals of Science To provide a natural explanation for events in the natural world, and use those explanations to understand patterns in nature and/or predict natural events. However, science tends to raise more questions than give answers. Are we advancing or falling behind by doing this?

Science Scenario: Your car isn’t starting. What’s wrong with it? What steps do you take to find out?

Scientific Methodology: The Heart of Science Steps for the scientific methodology (a. k. a. the scientific method). Refer to Figure 1 -3 on Pg. 6 for an example • • • Make an observation and ask a question about it Form an inference and hypothesize an answer Conduct a controlled experiment -Independent variable -Dependent variable Collect and analyze the data from the experiment -Qualitative Data -Quantitative Data Draw conclusions The steps are not always in order though!! What about when you can’t make a controlled experiment? We can’t control elephants! -Qualitative or Quantitative? ? Is it ok to test on humans? Why or why not? Scientific Method: Discovery Education Video

The Importance of Data • • Watch out for sources of error Is it reproducible? Sample size? Experimenter’s bias? Don’t trust all the data you see… some may falsify it! In the late nineteenth century, a group of scientists called craniologists made measurements of brain and skull size to prove that women were intellectually inferior to men. These “scientific studies” were cited in attempts to deny women equal rights. Today, scientists know that among humans, brain size has nothing to do with intelligence.

Testing Our Scientific Methodology: Gizmos Seed Germination

Qualities of a Good Scientist • Curious • Skeptic • Need evidence to believe • Open-minded to ideas that don’t necessarily mix with their hypothesis • Creative

Communicating Results: Reviewing and Sharing Ideas Peer Review -Like high-powered version of your high school lab report -Reviewed by experts for scientific methodology and reproducibility -Doesn’t guarantee that the work is correct, and doesn’t make it a truth! New Ideas -Sometimes, the new published reports will spark more questions, or another scientist will have an epiphany about the subject

Let’s Peer Review! Look at the following two lab reports with your partner. Jot down your ideas about both. -Is it following scientific methodology? -Can you clearly follow directions? -Is it reproducible? -Anything that stands out? -Which one would you pick to receive an A and which one would you send back to be re-written?

Example One 1. Record the barometric pressure. 2. Measure about 10 g of ice using the chemical balance and place it into a 100 m. L beaker. Heat over a flame until half of the ice has melted. Remove from heat and measure the temperature as accurately as possible using your laboritory thermometer. Repeat with a 10. 0 g sample of your unknown. Be sure to record your unknown number. 3. Measure 50 m. L of water using your graduated cylindar and pour it into a 200 m. L beaker. Bring the liquid to a boil over a flame. After the liquid has been boiling for approximately 1 -2 minutes, measure the temperature of the boiling liquid. Repeat with a 10 g sample of your unknown. Record all data in your lab notebook and clean up. We followed all the steps above pretty much closely and pretty much got the results for water that we expected, except that the stockroom had cheap thermometers because one of them broke (this was my lab partner’s fault – she used it as a stirring rod which is exactly what you said not to do in your lecture) and the new one was off by a few degrees – but it was close enough for this simple experiment. The pressure in the room was 761. 2 and the temperatures we measured for our unknown were: -15 and 17. Correcting for our water results this made our measurements – 15. 2 and 17. 4 after the corrections. Based on these temperatures and the data we looked up in the library, our unknown was certainly “blabber gas. ” The error in our results was really small and the experiment worked really good. Other errors include: possible math errors in our calculations and human error. Overall the lab was really good and we learned quite a lot of stuff. I especially liked the part where the blabber gas exploded when heated scaring my partner (I think that may be why she broke thermometer). The only criticism of the lab is that the equiptment wasn’t really great and that we ran out of time but otherwise it was a really good experinence and I think it taught us a lot of chemistry. Notes: For references we used our textbook, lab manual, and the Chemical Handbook found on shelf 2 of the library (behind the reference desk).

Example Two Introduction One of the primary methods used to characterize a new compound is the physical determination of its normal melting and boiling points. The “normal” melting and boiling point is the temperature at which a substance melts or boils when the barometric pressure is 760 mm. Hg or 1 atm. In this experiment we will first calibrate our thermometers using ice and water, whose normal melting and boiling points are well characterized as 0. 0 °C and 100. 0 °C, respectively[1]. Following this, we will measure the normal melting and boiling points of an unknown compound. We will use this data to determine the identity of our unknown from a list of possible unknown samples and physical data from the Chemical Handbook[2]. Experimental Procedure As described in the lab manual, [3] ice was placed in a beaker and warmed until approximately 50% had melted. The temperature of the ice/water mixture was then measured with a thermometer. This was followed by a similar measurement of our solid unknown. In part II, water was heated until boiling and the temperature of the liquid/gas mixture measured with a thermometer. This was followed by a similar measurement using our unknown compound. To get the best results possible, the procedure in the manual was modified by repeating each trial three times. Data & Result s The Barometric pressure in the lab was measured to be 761. 2 mm. Hg. Table One – Experimental Data Trial Water. Melting Pt. Water. Boiling Pt. Unknown 7 Melting Pt. Unknown 7 Boiling Pt. 1 0. 7 °C * 101. 2 °C 80. 2 °C 272. 7 °C 2 0. 1 °C 101. 1 °C 80. 7 °C 272. 8 °C 3 0. 0 °C 100. 9 °C 80. 4 °C 273. 0 °C 4 0. 1 °C n/a n/a Averages: 0. 15 °C 101. 1 °C 80. 4 °C 272. 8 °C Standard deviation (s): ± 0. 06 ± 0. 15 ± 0. 06 95% confidence limits: ± 0. 14 * This trial was eliminated because thermometer was broken (there was a bubble of air in the mercury). A new thermometer was obtained from the stockroom and used for all other data.

Example Two Cont. Observations : The unknown was yellowish-orange in color and had a fruity smell. As can be seen from our water data the experimental values for the melting and boiling points of water differed from theoretical values by +0. 15 °C and +1. 1 °C, respectively. These differences were used to calibrate the average data for the unknown. Thus the corrected values for the unknown boiling and melting points are given in Table 2. Table Two – Corrected Temperatures Unknown 7 Melting Pt. Unknown 7 Boiling Pt. Measured value 80. 4 °C ± 0. 4 (95%) 272. 80 ± 0. 14 °C (95%) Correction +0. 15 °C + 1. 1 °C Corrected value 80. 5 °C ± 0. 4 (95%) 273. 90 ± 0. 14 °C (95%) These values were used to identify our unknown. Table Three below lists possible unknowns and the melting and boiling points for these compounds found in the Chemical Handbook. 2 Based on these data we conclude that our sample was probably “Farsel Juice” since both the melting and boiling points fall within the confidence limits of our average melting and boiling points. Additional evidence to support our conclusion is that Farsel Juice is described in the Chemical Handbook as having a yellowish-orange in color and has a “peach-like” smell. Our unknown was this color and one of our group members observed a “fruity” smell when she opened the bottle. Although our measured melting and boiling points differed from theoretical data by a few percent, this difference was very small leading us to believe that our results were quite good. While there is still room for error in our results due to the change in boiling and melting points as a function of atmospheric pressure this difference should be very small. Other factors such as contaminates in the water used may have affected the results, but again every effort to minimalize such effects was made by using only deionized water. Finally we did encounter some problems with our thermometer in the first trial, but this was fixed by replacing it at the stockroom. Thus our careful work, our additional color and smell observations, and the fact that the corrected average of data exactly matched only one of the choices with 95% confidence, all suggest that our unknown was in fact Farsel Juice. Conclusions In this lab we determined the identity of our unknown to be Farsel Juice using normal melting and boiling points. A future experiment might include an additional calibration using the barometric pressure and/or inclusion of other chemical properties such as reactions of the compounds with acids and stuff to further test the nature of the chemicals and more positively identify the chemicals.

Scientific Theory When we say theory, you usually think of an idea, or a hunch. “I have a theory” “That’s just a theory” Scientific theory is very different. -Theory: a well-tested explanation that unifies a broad range of observations and hypotheses and that enables scientists to make accurate predictions about new situations. -Summary? ? Scientific theory is not absolute! New experiments and data may change theory, or eliminate all together.

Science and Society Remember, science only addresses natural phenomena. It cannot answer ethical questions! -Should the information in your genes be available for public use? - What is the meaning of life? -When does life begin? Eventually, you will be able to vote. You will realize that science gives us information, but it cannot tell us what to do with that information. We as citizens decide what to do with it, whether it’s important, and whether we should continue pursuing answers.

Studying Life

Biology: What is it? What’s it used for? The study of living things: bios (life) – logy (study of) • Studying human epidemics (bird flu) • The effect of illegal drugs • The migration patterns of African water buffalo • Cloning human cells to grow new organs •

Characteristics of Life • • Made up of basic units called cells -Unicellular vs. Multicellular Based on a genetic code -DNA Obtain and use materials and energy -Photosynthesis, Chemosynthesis, Metabolism Growth and development Reproduce Respond to the environment Maintain a stable internal environment -Homeostasis Change over time -Evolution Characteristics of Life: Discovery Education Video

Living or Non-Living? ?

What about Viruses? ?

Fields of Biology • • • Global Ecology Biotechnology Evolutionary Biologist Epidemiology Genetics Molecular Biology Careers in Biology: Discovery Education Video