Scientific Thinking & Cells: Biology Notes - PDF

Lesson 4: Scientific Thinking (Part 2) and Cells (Part 1) Section 4.1: Scientific Thinking (part 2)  Hypothesis o A hypothesis is a proposed explanation for a phenomenon o A good hypothesis leads to testable predictions o A hypothesis can be supported or revised ba...

Lesson 4: Scientific Thinking (Part 2) and Cells (Part 1) Section 4.1: Scientific Thinking (part 2)  Hypothesis o A hypothesis is a proposed explanation for a phenomenon o A good hypothesis leads to testable predictions o A hypothesis can be supported or revised based on the results of the test  Scientific Theory o A theory is a hypothesis for natural phenomena that is exceptionally well-supported by the data o If a hypothesis is supported by many different experimentations using many different variables, again and again and again, then this becomes scientific theory.  Theories in Science VS Theories in General Usage Scientific Theory Everyday Theory Supported by Evidence Not supported by evidence Describe universal natural Describe only specific situations phenomenon  Important Theories in Biology o Cell Theory: All organisms are composed of cells and all cells come from preexisting cells o Theory of Evolution: Species change over time and are all related to each other through common ancestry  Limitations of the Scientific Method o The Scientific Method does not provide answer to: 1. Artistic and creative processes 2. Value judgements such as religion and faith 3. Moral judgements 4. Social or Ethical Problems  Pseudoscience o Pseudoscience manipulates you with misleading “scientific sounding” language  Act like a scientist to debunk Pseudoscience o Do not draw conclusions from anecdotes o Be dubious if it’s too good to be true o Demand for scientific evidence  o Read the source material instead of trusting statements by new media  News media reporting is often inaccurate as it emphasises sensationalism  Press releases by companies or academic institutes are too optimistic, as they are motivated by financial gain  Google Scholar o A search engine for academic articles o Peer-reviewed research articles  Most reliable o Peer-reviewed review articles Reliable o Book chapter Not as reliable  Drugs or Dietary Supplement? Drugs Dietary Supplement Prescription and over the counter Dietary supplements are not drugs must pass rigorous tests regulated No quality control No safety testing Drug quality and safety is closely Government intervenes only is monitored by the FDA or Health safety concern is raised Canada o All new drugs must pass Phase 3 clinical trail stage before they hit the market o Dietary Supplements are sold without proper clinical trials  Does MMR Vaccine Associate with Autisms Incidence? o MMR vaccine is a combination vaccine for 3 common childhood infectious illnesses: Measles, Mumps and Rubella o No, it does not associate with autism o Science is clear there is no link between vaccination and autism o Yet, anti-vaxxers continue to campaign against vaccination o This is causing revival of childhood illness, long-term complication, and unnecessary deaths o Although Wakefield’s study was criticized by other scientists from the beginning, new media focused only sensationalism to stir up fears o Dr. Wakefield’s press conference statements were motivated by his financial gain o Anti-vaccine campaigners continue to fund Dr. Wakefield  What to look for: Bad Science VS Good Science o Study Types   Is it an observational study? Or a hypothesis testing study? If it's an observational study, you can never establish the causation o Study Subject o Control group/experiment o Sample size and Statistics o Author affiliation o Funding source o Study reproducibility  Study Types Observational Studies Hypothesis-Testing Studies Establish possible correlation Aims to establish causation Does not establish causation Comparison between treatment and control groups Observations should yield hypotheses that can be tested  Observation: Cohort VS Case-Control o Cohort Study: Observe 2 or more groups of people over time to see the disease frequencies in 2 groups  EX: Comparison of lung cancer frequencies between smokers and non-smokers o Case-Control Study: Observe people with and without disease to determine of other factors associate with disease occurrence  EX: Comparison of smoking habit between lung cancer patients and health individuals  Observational: Retrospective VS Prospective o Retrospective: Based on recall. May not be reliable  EX: asking lung cancer patients if they were exposed to second hand cigarette smoke o Prospective: Observe people before disease appears. Then asses the disease frequence over time o EX: In 1951, Doll and Hill surveyed approx. 40,000 medical doctors about their smoking habit. Then they followed mortality rate among study participants over 10 years  Correlation does not mean Causation o Hypothesis-testing experiments can determine causation, but experiments are not always possible  Clinical Trials: Hypothesis-Testing Studies in Clinical Setting  o Open-Label: The experimental subjects know that they ae receiving the treatment. Conclusions are less reliable o Blind: The experimental subjects do not know which treatment (if any) they are receiving o Double-Blind: Neither the experimental subjects not the experimenter knows which treatment the subject is receiving o Randomized: The subjects are randomly assigned into experiential and control groups o Gold Standard: the best type of hypothesis-testing clinical trial would be a randomized double-blind study  Clinical Trial Stages for Drugs 1. Pre-Clinical o Purpose: Establish scientific base, safety testing o Study subject: Human cells, animal study, other model organisms 2. Phase 1 o Purpose: safety testing, determination of dosage and administration protocol o Format: open label o Sample size: