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BiologyNotes - Chapter 1 Control Group A standard for...

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Chapter 1 Control Group A standard for comparison Identical to experimental group except for variable being studied May use a placebo Sampling Error Nonrepresentative sample skews results Minimize by using large samples Scientific Theory: A hypothesis that has been tested for its predictive power many times and had not yet been found incorrect. Has wide ranging explanatory power. Darwin’s theory of evolution by natural selection is a good example Biological Therapy Experiments Can we use viruses that attack bacteria to fight infections? Experiment 1 Hypothesis: Bacteriophages can protect mice against infectious bacteria Prediction: Mice injected with bacteriophages will not die as a result of bacterial injection Test Experimental Group is injected with bacteria and bacteriophage Control group is injected with bacteria and saline (placebo) Results and Conclusion Experimental group: all mice lived Control group: all mice died Conclusion: Bacteriophage injections protect mice from bacterial injection Experiment 2 Prediction: Bacteriophage injections will be a more effective treatment than single dose of the antibiotic streptomycin Test: Mice injected with bacteria, then saline, streptomycin, or bacteriophage Results With second injection: Bacteriophage: 11/12 lived Low level of strep: 5/12 lived High level of strep: 3/12 lived Saline: all mice died Conclusion: Bacteriophage treatment can be as good or better than antibiotic Minimizing variables All mice were same age and sex, reared under same conditions
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Same treatment Same amount of saline Variable tested was antibiotic treatment versus bacteriophage treatment Limits of Science Can’t answer subjective questions Can’t provide moral or philosophical standards Conflict with supernatural beliefs Copernicus: Earth circles sun Darwin: evolution Chapter 2: Chemical Foundations for Cells We are chemical, and is every living and nonliving thing in the universe. Elements Fundamental forms of matter Can’t be broken apart by normal means 92 occur naturally on Earth Most Common Elements in Living Organisms Oxygen, Hydrogen, Carbon, Nitrogen, AND MANY MORE!! What are atoms? Smallest particles that retain properties of an element Made up of subatomic particles: Protons, Electrons, Neutrons Atomic Number Number of protons All atoms of an element have the same atomic number Atomic number of hydrogen = 1 Atomic number of carbon = 6 Mass Number Number of protons + number of neutrons Isotopes vary in mass number. Isotopes Atoms of an element with different numbers of neutrons (different mass numbers) Carbon 12 has 6 protons and 6 neutrons Carbon 14 has 6 protons and 8 neutrons Radioisotopes
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Have an unstable nucleus that emits energy and particles. Radioactive decay transforms radioisotope into a different element
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This note was uploaded on 04/25/2008 for the course V 021 taught by Professor Staff during the Fall '05 term at NYU.

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BiologyNotes - Chapter 1 Control Group A standard for...

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