The Science of Biology Lab Safety Video

1. Chapter 1 The Science of Biology

2. Lab SafetyVideo • Contracts must be signed and returned to me immediately. • All Science students must complete the Safety contract before entering into the lab • Any student who does not have a lab safety contract signed will not be allowed to conduct labs.

3. What were your first questions? WHY? What? How?

4. What is Science? Science asks the same questions you did as a young child. What is that? Why does it do what it does? How does that happen? What happens if …? Science (knowledge) is a process that investigates and attempts to understand and explain events in nature.

5. Goal of Science • Provide natural explanations for events in the natural world. Give examples of this • Use explanations to understand patterns in nature and to make useful predictions about natural events Give examples of this

6. Since Science is a process, how do we go about doing “Science”? The Scientific Method of course!! • Ask a question based on an observation • Do some research or infer • Propose a hypothesis • Conduct a controlled experiment • Collect data and make observations • Analyze data • Draw a conclusion

7. Observingand Asking Questions • Scientific investigations begin with observation, the act of noticing and describing events or processes in a careful, orderly way. • Researchers observed that marsh grass grows taller in some places than others. • A question is formed: Why do marsh grasses grow to different heights in different places?

8. Inferring & Forming a Hypothesis • Through observations and research, scientists form inferences, or logical interpretations based on what is already known. • These lead to a hypothesis, or a scientific explanation for a set of observations that can be tested in ways that support or reject it.

9. What kind of hypothesis could be made concerning the marsh grass growth? • Researchers inferred that something limits grass growth in some places. Based on their knowledge of salt marshes, they hypothesized that marsh grass growth is limited by available nitrogen.

10. Design a Controlled Experiment • Design an experiment that keeps track of various factors that can change, or variables • Only one variable is changed at a time • Manipulative or Independent variable • The variable that is observed and that changes in response to the independent variable is called the dependent variable (also called the responding variable). • All other variables should be kept unchanged, or controlled • Controlled variable

11. For the marsh grass experiment, identify each of the following variables: • Manipulative or independent variable • Nitrogen fertilizer is added to the soil • Control variables • Similar plant density, soil, plant type, sunlight, amount of water, temperature… • Dependent or responding variable • The rate at which the grass grows or its height.

12. Control and Experimental Groups An experiment typically has two groups: • An experimental group contains the independent variable • A control group is exposed to the same conditions as the experimental group except for one independent variable.

13. How will scientists keep track of experimental observationsand then analyze the results? • Collecting Data • Quantitative data • Numbers • How many blades of grass were found per meter? • How high, wide, long…was the grass? • How much nitrogen was found in the blades of grass? • Qualitative • Describe • Which way did the grass grow? • What color was the grass? • Where there any other plants growing around it?

14. Recording the data How is data recorded? • Use charts, photos, drawings or graphs This graph shows how grass height changed over time.

15. What might have been a source of error in this experiment? The larger the sample size, the more reliably researchers can analyze variation and evaluate differences between experimental and control groups.

16. What conclusion could be drawn from the data collected? Use experimental data as evidence to support, refute, or revise the hypothesis being tested, and to draw a valid conclusion. Marsh grasses grew taller than controls by adding nitrogen.

17. What if our hypothesis is not supported in our experiment? • Close but no cigar. • Reevaluated and revised the original hypothesis • Make new predictions • Redesign the experiment

18. Do you know where bees come from? Recipe forBees • Kill a bull during the first thaw of winter • Build a shed • Place the dead bull on branches and herbs inside the shed • Wait for summer. The decaying body of the bull produces bees Words from a Roman poet about 2000 years ago

19. Spontaneous Generation Life arises from non-living matter or just suddenly appear. Abiogenisis Meat grows maggots Corn produces rats Bread breeds mold So what do you think of this theory?

20. How are new living organisms produced? • Question is stated Where do flies come from? • Now we need to form a hypothesis • Francesco Redi (1668) Hypothesis: Flies lay small eggs on meat that become maggots Set up a controlled experiment to test his hypothesis Analysis: Found that by keeping flies away from meat, no maggots appear Conclusion: Maggots are the result of flies laying tiny eggs on meat that develop into maggots

21. Variables • Controlled variable: Jar, meat, location, temperature, time • Independent or Manipulative variable: Gauze covering the meat jars • Dependant (responding) variable: Whether maggots appear

22. LazzaroSpallanzani 1776 • Designed experiment to show that life did not arise spontaneously from food • Inferred that food spoils due to microbes in the food. • Took 2 flasks with broth in them • Boils on but leaves it open • Boils the other but has it closed Results – Only the closed one prevented growth

23. What was wrong with what Spallanzani assumed? No air Everyone “knows” that every living thing needs air to live Whose experiment solved Spallanzi’s air problem?

24. LouisPasteur - 1859 Tested Spallanzani’s work by using a curved neck flask to prevent microbes from entering flask but would let air in Boiled broth in control and experimental flasks. Result: No growth in curved neck flask. Microbes collecting in bend

25. Pasteur’s broth in the curved necked flask stayed sterile for years until he tilted it and the airflow carried the microbes into the broth

26. Conclusion Contamination is due to microbes in the air. Spontaneous generation theory died here!! Biogenesis is born!! All living things come from other living things.

27. Identify some scientific theories you have knowledge of. • Big Bang • Evolution • Relativity A theory is a well-tested explanation for a range of phenomena. A law is a concise, specific description of how some aspect of the natural world is expected to behave in a certain situation such as the Gas laws

28. Measurements in Science SI Measurements (Standard Increments) aka: The Metric System Unit Abbreviation Length Meters m Mass Gram g Volume Liter l Time Second s Temperature Celsius `C Kelvin `K Density Mass/Volume g/l or g/cm3

29. Symbols of measurement PrefixesAbbrevationFactor of base unit kilo k 1,000 deci d .1 or 1/10 centi c .01 or 1/100 milli m .001 or 1/1000 micro u .000001 or 1/1,000,000

33. Metric Conversions Convert: 5L = ______ml 1.025cm = _______ m .035um = ______ mm 2.5mm = ______um 7.2g = _____kg .017g = ______mg Metric Conversion worksheet Kilo Hecto Deka MeterDeciCenti Milli Micro Liter Gram

35. A recipe calls for 300ml of water. You add 0.25 L. Have you put in too much, too little or the right amount? • You are told that you need a jar with a volume of at least 150cm3. The label on the jar you find says 0.16L. Can you use it? Remember that 1cm3 = 1ml.

36. What is Biology? Biology is the study of living things and how they interact with each other.

37. What makes something living? Characteristics of Life All living things… • …are made up of cells. Unicellular or Multicellular.

38. 2…need a constant flow of energy. Necessary forMetabolism All the chemical processes taking place in the organism including those that are needed for growth and those that are needed to break down molecules (such as digestion) Some such as plants and some bacteria, make their own food from raw materials (Autotrophic) Others such as animals, need to process organic matter to obtain energy.(Heterotrophic)

39. 3… maintain a stable, internal environment by responding to stimuli. Maintain an internal steady state – Homeostasis. Stimulus – anything that causes an organism to react/respond Examples: • Increased heart rate when stressed • Goosebumps and shivering. • Pupillary response to light and darkness • Let’s give this one a try

40. 4. …Evolve …as a group • Evolution is a change in a species over time • Results from an species ability to adapt to changing conditions and reproduce.

41. 5…grow and develop. Your very first baby picture Process occurs by adding on more cells by cell division (making more cells of the same kind) and cell differentiation (cells becoming different to suit their various functions). Red blood cell White blood cell Nerve cells Easily flow through Change shape to Like a wire to capillaries squeeze through conduct electrical intracellular spaces impulses

42. 6...can reproduce. Adding on more cells or reproducing another organism Passing on of genetic information (DNA and genes) Not a necessary life process but needed for the continuation of the species. Sexual (involves the fusion of two cells) Asexual (involves only 1 cell dividing) reproduction.

43. 7. …all living things are based on a universal genetic code • DNA It doesn’t matter if the DNA of a bacterium or a human is analyzed, we all have the same 4 bases (ATCG) making up our DNA.