BIOL 123 Lecture Notes - Lecture 23: Radiometric Dating, Deductive Reasoning, Genetic Variability

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19 Nov 2020

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Document Summary

The scientific method is the basis for scientific inquiry. Scientific inquiry is a rigorous method for making observations of specific phenomena and searching for the order that underlies those phenomena. Biology uses the scientific method, which consists of six interrelated elements: observation, question, hypothesis, prediction, experiment, and conclusion. The observation leads to a question: how did this happen? . Hypothesis = a supposition, based on previous observations, that is offered as an answer to the question and a natural explanation for the observed phenomenon. Prediction = typically expressed in if then language. The prediction is tested by carefully controlled experiments. These experiments produce results that, when analyzed, either support or refute the hypothesis, allowing the scientist to reach a conclusion about the validity of the hypothesis. A single experiment is never an adequate basis for a conclusion; the results must be repeatable.

Related Questions

Scientific Method Exercise
Identify a situation in which you applied the scientific approach to solving a problem. Share your thinking! The problem you choose to write about can be very simple, such as: my flashlight won't work, or my car won't start, or I baked muffins and they were flat ( didn't rise properly) , or the toilet won't flush properly, or better yet, think of your own. These probably don't sound like "science" problems, but it is most likely that you would use the scientific method to solve them, without even realizing it. Avoid using people problems and child or pet behavior issues as your "problem." Follow these steps to create your first writing assignment:

1. Describe the situation and your observation,
2. Describe your hypothesis to explain the observation.
3. Describe your further observations or experiments to test the hypothesis. Be sure your hypothesis is one that can be tested. Consider what you might use for "controls".
4. Was the hypothesis correct? If not, can you find a better one? Or do you need a better experiment? If so, what would it be?

The assignment should be formatted as follows: Be sure to include the labels, so it is clear that you recognize and identify each step in the process.
Problem: (briefly describe your problem here)
Question: (This may be a "how" or "why" question that you will formulate a tentative answer to. Your tentative answer is your hypothesis.)
Hypothesis: (State the answer to your question above. This is your "best guess" regarding the answer to the question.)
Prediction: (This describes your experiment very briefly and states the outcome you expect that would support your hypothesis)
Experiment: (Describe how you tested your hypothesis)
Results: (Describe what happened, and whether the results supported or failed to support your hypothesis)

The Scientific Method

For any controlled scientific study, a scientist starts with an observation, does some research to develop a hypothesis, and then designs an experiment that compares some baseline group with a test group. Data are then collected to confirm or refute the hypothesis.

As you review the following study, consider whether the researchers correctly followed the scientific method.

In the late 1990s, gastroenterologist Andrew Wakefield, along with a research team, set out to determine if bowel disease caused by vaccines led to autism.

He compiled a group of 12 children who had loss of acquired skills, developmental delays in language, diarrhea, and abdominal pain-essentially, those with both bowel disease and autism. He questioned each parent about the behavior and personality of the child before the child was vaccinated with the Measles, Mumps, and Rubella (MMR) vaccine. He then ran tests on the children to determine the health of the gastrointestinal tract, brain, and nervous system.

His reported data (tabulated below) included that children experienced either gastrointestinal or autism-like symptoms, sometimes within a short period after being vaccinated. From these data, the researchers concluded that there was no link between autism and the MMR vaccine. Wakefield though, contradicted this conclusion and stated that the vaccine caused changes in the gastrointestinal tract of the children, which then led to autism (Wakefield, et al., 1998). Currently, he still contends that the MMR vaccine contributes to autism (Ziv, 2015).

Many researchers tried to duplicate this study and could not replicate Wakefield's results. In fact, they found no link between the vaccines, bowel disease, and autism. In the United Kingdom, the MMR vaccine was not introduced until 1988. If Wakefield's conclusions were correct, one would then expect a jump in autism cases after 1988, but this was not observed, even when hundreds of children were studied (Taylor et al., 1999). In these additional studies, children who had not been vaccinated were included as a control group, and no difference in the rates of autism was observed.

In 2011, Brian Deer reviewed Wakefield's study and all available records from the National Health Service (NHS) in the United Kingdom for these 12 children. He found that at most, two children showed symptoms days after vaccinations. At least five children showed developmental delays before being vaccinated. Six out of the 12 children may have had autism symptoms. None of the 12 children tested had all three-regressive autism, colitis, and symptoms days after vaccination.

Symptom	Wakefield	Wakefield NHS Records (Deer)
Symptoms days after vaccination	8	2?
Non-specific colitis	12	3
Regressive autism	9	6?
Intestinal/autism/symptoms after vaccine	12	0

(Wakefield, et al., 1998; Deer, 2011)

Wakefield's statements led to a worldwide panic about the safety of vaccines, but after Deer's report, Wakefield's study was retracted and his medical license was revoked for falsifying data. Click on the following links to review materials to enhance your knowledge of the scientific method and to support your analysis of Wakefield's experiment:

Steps of the Scientific Method: A simplified explanation of how the scientific method works, the steps taken to investigate phenomenon with diagrams

Do Vaccines Cause Autism?: A review of research demonstrating that vaccines and their components are not the cause of autism

Fifteen years after a vaccine scare, a measles epidemic: An analysis of vaccination trends and an increase in measles cases seen the UK

Answer the following 4 questions:

What was wrong with Wakefield's study? Discuss at least 1 variable or approach that should have been controlled or assessed.

Consider the source of some of his data (parental memory, for example), the small sample size, and whether he considered other variables (genetics, diet, and so on) that could have resulted in symptoms in these children.

Discuss the importance of a control group when using the scientific method.

Did Wakefield deserve to be barred from medical practice?

What were the consequences of his inflated conclusions?

Question1.1. Accidental alterationsduring DNA replication that give rise to variations in organismsare __________. (Points : 1)

adaptive traits
mutations
symbioses
random distributions

Question2.2. The largest reservoir ofcarbon in the carbon cycle is comprised of _________. (Points :1)

freshwater systems andoceans
plants and animals
sedimentary rock andfossil fuels
atmosphere

Question3.3. The principle of utility________. (Points : 1)

holds that any naturalresource should be available for use in manufacturing
holds that something isright when it produces the greatest benefit for the greatest numberof people
is not an ethicalstandard
cannot be used toestimate the value of natural resources

Question4.4. The two processes thatdetermine current biodiversity on a global scale are __________.(Points : 1)

allopatric speciation andimmigration
mutation and habitatselection
mutation and globalclimate change
extinction andspeciation

Question5.5. The conservation ethicholds that we should ________. (Points : 1)