The Scientific Method: Notes and Past Answers

The Scientific Method

Biology is the study of living things.
An organism is a living thing.
There are many areas in which biology can be subdivided.

Area of study
Topic this area studies
Chemical reactions
Small organisms
Organisms and their environment

The Scientific Method is a process of investigation in which problems are identified and their suggested explanations are tested by carrying out experiments.

There are 7 steps to the scientific method:

1.     Observation: A statement based on something one has seen, heard or noticed. May be obtained directly by our senses, or indirectly by equipment such as microscopes & thermometers.

2.     Hypothesis: This is an educated guess based on observations.

3.   Experiment: Designed to test the hypothesis. Will either support or contradict the hypothesis.

4.  Data: Consists of the measurements, observations or information gathered from experiments.

5.     Conclusion: This will explain our results and will link back to our hypothesis.

6.     Relating conclusion to existing knowledge: This is tying the conclusion back to the existing knowledge. You can accept, reject or change the hypothesis depending on whether the results agree with it or not.

7.     Publishing the results: The results of the experiments should be written and reported so that they can be examined and analysed by others. The experiment should be able to be repeated.

A Theory is a hypothesis that has been supported by many different experiments.

A Principal or Law is a theory that has been shown to be valid when fully tested over a long period of time.

Principals of experimentation:

1.     Careful planning and design:

A variable is a factor that may change in an experiment.
In most experiments, only one variable is tested, and all other variables are kept constant.

2.     Ensure experiment is safe: While doing an experiment you must: Tie back long hair, Wear a lab coat, Where safety glasses when necessary, Do not put your hands to your mouth or eyes, Avoid contact between electrical equipment and water, Be aware of chemicals being used, report all accidents to the teacher.

3.     Design a control experiment:
A control is used to provide an standard against which the actual experiment can be judged.
There should only be one variable between the control and the actual experiment.

4.     Experiments must be fair:

Sample size: The larger the sample size, the less risk there is that the results are due to individual differences, rather than being caused by the factor that is being investigated.

Random selection: This is so that we don't select a certain type of sample, as this will mean the results are influenced by the factor that is selected. If a random samples are taken, then we can ensure that the experiment applies to all of the population, and the experiment is fair.

Experiment must be able to be replicated: A replicate  is a repeat of an experiment. If it can be repeated, the results can be shown to be always true and not caused by some unknown influence.

Double blind testing: This is when an individual is being tested, and neither the tester, or the person being tested, know who is receiving the real treatment and who is receiving the placebo. Therefore, the tester cannot influence the experiment by consciously or unconsciously giving clues to the person being tested. A placebo is a fake drug used in an experiment to set up a control.

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 Limitations to the value of the Scientific Method:

1.     The extent of our knowledge: Forming a hypothesis and designing an experiment depends on the amount we know relating to our observations.

2.     The basis of investigation: If an investigation is badly designed or improperly carried out it will not yield results that are as valid as they should be.

3.     Interpreting results: If the results of an experiment are interpreted wrongly, then faulty conclusions and hypotheses will be drawn.

4.     Changes in the natural world: Scientific methods may only apply to living things at one particular time. As living things are constantly evolving, hypotheses must constantly be changed. For instance, in recent times, antibiotic resistant bacteria have emerged.

5.     Accidental discoveries: New insights are often discovered accidentally which have contributed to the development of scientific thinking.

Ethical Issues:

Ethics relates to whether conduct is right or wrong. There are sometimes arguments as to whether the application of a scientific method is good or bad, such as cloning animals.

Past answers:

2011 HL Q7
(a) In relation to the scientific method, explain each of the following.
(i) Experiment: This is designed to test the hypothesis, and will either support or contradict it.
(ii) Theory: This is a hypothesis that has been supported by many different experiments.

 (b) Scientists investigated the effect of a certain mineral on the growth of wheat. Use your knowledge of biology and laboratory procedures to answer the following questions.
(i) Suggest a reason why the seeds used were all taken from one parent plant.
So that all results will have the same genetic make up.

2010 HL Q8
(a) Answer parts (i) and (ii) in relation to the scientific method.
(i) What is a hypothesis?
A hypothesis is an educated guess based on observations.

(ii) Why is a control normally used when carrying out an experiment?
A control is used to provide a standard against which the actual experiment can be judged.

2008 HL Q3
Answer the following, which relate to the scientific method, by completing the blank spaces.
(a) As a result of her observations a scientist may formulate a hypothesis. She will then progress her investigation by devising a series of experiments  and then carefully analysing the resulting conclusions.

(b) Why is a control especially important in biological investigations?
 It is important as we then have a standard against which the actual experiment can be judged.

(c) If a scientist wished to determine the effect of a certain herbicide on weed growth she would include a control in the investigation. Suggest a suitable control in this case.

(d) The use of replicates is an important aspect of scientific research. What, in this context, are replicates?
A replicate is a repeat of an experiment which can verify if it is valid.

(e) Suggest where a scientist may publish the results of her investigations
They can publish them in journals, magazines, newspapers, the internet and on TV.

2005 HL Q2
Explain each of the following terms in relation to the scientific method.
(a) Hypothesis:
This is an educated guess based on an observation.

(b) Control:
This is used to provide a standard against which the actual experiment can be judged.

(c) Data:
Data consists of measurements, observations and information gathered from experiments.

(d) Replicate:
A replicate is a repeat of an experiment, which can verify its validity.

(e) Theory:

This is a hypothesis that has been supported by many different experiments.

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