1-3 The study of Biology

Objectives Outline the steps of the scientific method Summarize how observations are used to form hypothesis List the elements of a controlled experiment Describe how scientists use data to draw conclusions Compare a hypothesis and theory State how communication & peer review prevent dishonesty

Scientific Method Organized approach Natural causes Not supernatural Have to be able to disprove something Uniformity: The laws of nature are the same everywhere

Steps of method Observation Hypothesis Prediction Exeperiment Analyze data Communicate findings

Experimental design Control Groups: provide a normal standard Experimental Group: Different from control by 1 factor  the independent variable Dependant variable: what is affected by independent variable

Quantitative vs. Qualitative

Analyzing Data Is the data reliable? Does it support your hypothesis or not?

Conclusions Can’t prove much Theories: when hypothesis is confirmed many times and it explains a lot Law: Theories that have been confirmed many many times Beyond a doubt

Scientific Method Bacon (1561-1626) and Descartes (1596-1650) were not scientists but did invent new habits of scientific thought scientific method as habits of disciplined creativity, careful observations, logical thinking & analysis of observations way of seeking trends & drawing generalizations Convinced governments of England & France to form academies of science that still exist today Scientific way of thinking based on assumptions & methods that are reliable, objective & testable

Making observations until capable of drawing generalizations and making predictions anatomy is a product of inductive method Proof in science can not go past “proved beyond reasonable doubt” reliable methods of observation tested and confirmed repeatedly not falsified by any credible observation In science, all truth is tentative Inductive Method

Hypothetico-Deductive Method Physiological knowledge gained by this method Ask a question and formulate a hypothesis -- an educated possible answer Good hypothesis consistent with what is already known capable of being tested and falsified with certain evidence If nothing could prove it wrong, it is not a scientific belief Hypotheses are written as If-Then predictions modified and rewritten after testing

Experimental Design Sufficient sample size to prevent chance event Control group and treatment group receive the same treatment except for the variable being tested Prevention of psychosomatic effects use of placebo in control group Experimenter bias prevented with double-blind study Statistical testing to be sure the difference between groups was not random, but was due to variable being tested Placebo: Latin for I shall please “Have your pirin” The bird cage Milgram Experiment Forcing the tester to hurt the subject.

Peer Review Critical evaluation by other experts in the field prior to funding verification and repeatability of results Ensures honesty, objectivity & quality in science

Health Minister Manto Tshabalala-Msimang of South Africa, known for putting vegetable remedies ahead of anti-retrovirals, endorses Dr Matthias Rath's vitamin treatments.

Dr. Rath and his cure for AIDS: Mega Doses of Vitamin C A doctor who worked with Nobel Prize winner Linus Pauling has taken the advocacy of vitamins into all-out war on the pharmaceutical companies Buys ad space in the NY Times, and fills them with editorials masked as facts Without getting confirmation of his studies is taking his cure to the people of Africa Problems: Too much Vitamin C can lead to Diarrhea which can kill an AIDS patient. Blames George Bush and Tony Blair for AIDS

Facts, Laws and Theories Scientific fact is information that can be independently verified by any trained person iron deficiency leads to anemia Law of nature is a description of the way matter and energy behave resulting from inductive reasoning & repeated observations written as verbal statements or mathematical formulae Theory is a summary of conclusions drawn from observable facts it provides explanations and predictions sliding filament theory of muscle contraction http://www4.dr-rath-foundation.org/

Logic is the anatomy of thought -John Locke Conditional arguments: the basis of hypothesis forming. Two parts Part 1: If p then q P = antecedent Q = Consequent Part 2 allows us to draw conclusions If P happens then Q happens (Modus Ponens If Q did not happen, P did not happen (Modus Tollens) Consider the following examples: If Chinua arrives late, he will miss the bus. Chinua will miss the bus if he comes late. Chinua, if he arrives late, will miss the bus Note you can change the way its said For economy, we might shorten that to "If arrive late, then miss bus." In this case, p=arrive late, and q=miss bus. In other words, if the original conditional is true, we can draw the following valid conclusions: Chinua arrived late and therefore missed the bus; or Chinua did not miss the bus, and therefore he must not have arrived late. These two valid conditional arguments are expressed by the following paradigms: Example 1. "If Chinua arrives late, he will miss the bus. And he does arrives late. Therefore, he misses the bus." This is a valid argument, because it fits one of the two forms for a valid conditional (in this case, modus ponens): If p (arrives late), then q (misses bus). P (arrives late) Therefore, Q (misses bus). Example 2. "If Chinua arrives late, he will miss the bus. And he does miss the bus. Therefore, he must have arrived late." This is an invalid argument, because it does not fit one of the two valid forms. In a valid conditional, the second premise must be either p or not q. In this case, the second premise ("miss bus") would be q, so no valid conclusion can be drawn. We say this second premise "affirms the consequent," which is invalid. (This may sound like a good argument, but it is easy to see why it is not, because the conditional says nothing about what might happen when Chinua does not miss the bus. Perhaps he arrived on time, or perhaps he got there late and the bus was delayed--we have insufficient information to conclude anything.) Example 3. "If Chinua arrives late, he will miss the bus. But he does not arrive late. Therefore, he did not miss the bus." This is an invalid argument, because it does not fit one of the two valid forms. In a valid conditional, the second premise must be either p or not q. In this case, the second premise ("not arrive late") would be not p, so no valid conclusion can be drawn. We say this second premise "negates the antecedent," which is invalid. (Again, this may sound like a good argument, but it is easy to see why it is not, because the conditional says nothing about what will happen if Chinua arrives on time. Perhaps he did catch the bus, perhaps he fell asleep and missed it anyway--we have insufficient information to conclude anything.) Example 4. "If Chinua arrives late, he will miss the bus. But he does not miss the bus. Therefore, he did not arrive late." This is a valid argument, because it fits one of the two valid forms (in this case, modus tollens): If p (arrives late), then q (misses bus). Not q (not miss bus). Therefore, not p (not arrive late). Note there can be problems with the original thing: If P then Q has to be a valid statement

There is a claim that lycopene, the reddish substance in tomatoes and peppers, is of value in protecting people from Alzheimer Disease. How would you, as a scientist, go about substantiating or refuting this suggestion?