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Scientific Investigation

Exercise 1 Question and hypotheses

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1.     Does watching television before the age of one contribute to the development of autism in children?

a.     yes

2.     Did the use of the herbal supplement ephedra cause the death of the 1B-year old soccer player?

a.     no

3.     Does global warming cause an increase in frequency and intensity of forest fires?

a.     yes

4.     Do cactus spines reduce herbivory??

a.     no

5.     Should human embryonic stem cells be used to treat Parkinson’s disease?

a.     Yes

6.     How did you decide which questions can be answered scientifically?

a.     The question has to be falsifiable and testable it needs to contain measureable differences. It needs to be proven through research and scientific investigation.


1.     Does cell phone usage reduce auditory function?

a.     The usage of cellphones hinders the functions of auditory

2.     Do offspring of mothers who jog each day have a mental advantage over offspring of sedentary mothers?

a.     Mothers who jog each day have produce offspring that have a mental advantage over sedentary mothers.

1.     The death of unborn horses on Kentucky farms is due to toxic fungi growing on grass eaten by the mares.

a.     Yes this statement is enough. The amount of grass being consumed by the mares can be measured and sent to testing to see if the grass sample contains any fungi.

2.     Crime rates increase during the full moon.

a.     No due to the fact that crime can be interrupted in different forms and therefore cannot be measured. There is no set point for what is a crime and what’s not a crime. Everyone has their own interpretations.

3.     Positive emotions prolong life.

a.     This statement can be proven to be wrong due to the fact that there are many variables that can change the life expectancy of a person. There are too many variables

4.     Exposure to low levels of pesticides increase the risk of developing Parkinson’s disease.

a.     Yes due to the face that there is a set standard and the independent variables can be changed from more pesticides to less.

5.     Modern birds are closely related to dinosaurs?

a.     This is a prediction and there is no variable that is being measured. The statement is vague and does not have enough evidence to support the claim

Exercise 2 Designing experiments to test hypotheses

Lab study A. Determining the variables

The Dependent Variable

1.     Within the experiment, one variable will be measured or counted or observed in response to the experimental conditions. This variable is the dependent variable. For the soybeans, several dependent variables are measured, all of which provide information about reproduction. What are they?

a.     The dependent variable is the growth and the amount of soybeans produced.

The Independent Variable

2.     The scientist will choose one variable, or experimental condition, to manipulate. This variable is considered the most important variable by which to test the investigators hypothesis and is called the independent variable. What was the independent variable in the investigation of the effect of sulfur dioxide on soybean reproduction?

a.     The independent variable is how much SO_2 is being give each day to the plants.


3.     Can you suggest other variables that the investigator might have changed that would have had an effect on the dependent variables?

a.     The distance from the exposure site might have been changed as well as with the amount of natural sun and amount of water.


4.     Although other factors, such as light, temperature, time, and fertilizer, might affect the dependent variables, only one independent variable is usually chosen. Why is it important to have only one independent variable?

a.     So you know that independent variable caused the outcome. If you have multiple than you would not know which one caused the change. And it would be hard to track the results. One variable you can see the correlation and its easy to see what caused what.


5.     Why is it acceptable to have more than one dependent variable?

a.     It is acceptable because there can be more than one result. In order to get the most band for your buck you can look at many different things at once.

The Controlled Variable

1.     What are the controlled variables in this experiment? What variables other than those you may have already listed can you now suggest?

a.     I believe that the controlled variables are the amount of time and how much sulfur they receive. I think a good tip or advice would be to equally water the plants.

Lab Study B choosing or designing the procedure

1.     What was the level of treatment in the soybean experiment?

a.     I believe that the level of treatment in the soybean experiment was the amount of sulfur the plant gets introduced to.

2.     Describe replication in the soybean experiment

a.     They spitted the amount of soy beans from 48 to 24. Which were then split into groups of six. This technique allowed for more than one trial to be tested.

3.     What was the control treatment?

a.     The amount of sulfur each plant was given was the controlled treatment

4.     What is the difference between the control and the controlled variables discussed previously?

a.     The control was a specific variable that was used to gather information. When on the other hand a controlled variables are many different things that were put together in order to come to a conclusion.

Lab Study C. Making predictions

1.     What should the prediction be? State your predication.

a.     If this chemical does lower the chance of reproduction then the soybeans will not reproduce or grow if they are near a coal powered plant.

2.     Now consider an experiment you might design to test the second stage hypothesis. How will you measure “mental advantage?

a.     I would measure mental advantage by having the offspring complete mental task as they grow hold and get an average and see if there are above or under that average.

3.     State a prediction for this hypothesis and experiment.

a.     If mothers who jog have a positive effect on their offspring, then a mother who jogs will have a offspring that is smarter than a sedentary mother.


1.     From this exercise, list the components of scientific investigation from asking question to carrying out an experiment

a.     Asking questions.

b.     Form a hypothesis

c.     Look into other scientist work to see if your idea has been done before.

d.     Have dependent and independent variables

e.     Have a control

f.      Making and using your procedure

g.     Record data and showcase in an understandable for example charts and graphs

h.     Determine if hypothesis was wrong or right

2.     From this exercise, list the variables that must be identified in designing an experiment.

a.     You must identify and have dependent, independent, control variable.

3.     What are the components of an experimental procedure?

a.     The procedure needs to be recorded before starting the experiment. This is done so that it can be replicated and tested by others. If adjustments are made they should be recorded and made note of. It should include determine what is the control treatments as well as the levels of treatment.

Exercise 3 Designing An Experiment

1.     Record the body parts and the corresponding questions chosen by the class:

a.     Does the length and high of a student’s grow isometric with that of an infant?

b.     Hypothesis: A students length and arm span will become isometric to the rest of the body once they age.

The Experiment

            Protocol: When measuring height the back of heels need to be touching wall as well as the back of the head and we will use measuring tape to see the length of an individual. Measure from heal to the top of the head. When measuring Arm span measure from socket to the furthest point of the middle finger with arm extended to the side of their body with measuring tape.  Foot length can be measure over shoe from the tip to the heal. Everything is going to be measured in centimeters.

What is the dependent variable in your experiment?        

The dependent variable is body length, arm span, and foot length.

What is the independent variable?

The body parts

Controlled variables: Measuring tape, what is being measured, the wall, age in students

Control: Tip of heal to the tip of your head, starting from arm socket to the end of middle finger, and from the tip of toes to the back of heal. Newborn babies height and limb measurement.

Level of treatment:

Replication: The class has given their height, foot length, and arm span which gives different measurements.

Predictions: If the body grows allometriclly then everyone’s measurements will vary but if it grows isometric then everyone’s measurements will be near each other’s.

Arm Span


Height (cm)

Body Part Size (cm)

H/BP Ratio

Team member 1




Team member 2




Team member 3




Team member 4









Foot Length


Height (cm)

Body Part Size (cm)

H/BP Ratio

Team member 1




Team member 2




Team member 3




Team member 4









Application Page 21

1.     What was the independent variable for each experiment? On which axis would graph this?

a.     For exercise 3, the isometric growth of limbs and___________. When talking about the soybeans it was due to the amount of pollution in the air as well as the sulfur dioxide. These two measurements belong on the x-axis.

2.     What was the dependent variable? Write this on the appropriate axis.

a.      The dependent belong on the y- axis and for the soybean experiment the dependent variable was reproduction and amount produce and for exercise 3 it was length of arms and feet.

4.     Imagine an experiment similar to the one you have performed where it would be appropriate to use the line graph.

a.      The ling graph would come in handy when talking about continues data. This data is not continues. The thing that is continuous is that of the growth and development of newborns until they reach a certain age.

Application Page 23

1.     Using your tables and figures, analyze your results and discuss your conclusion with your group.

a.     The table shows that people vary but for the most part they have around the same measurements. There is a lot of change in between the foot length and length of their arm span.

2.     Write a summary statement for your experiment. Use your result to support or falsify your hypothesis. Be prepared to present your conclusion to the class.

a.     The idea of the experiment was to look at the ratios of between infants and students and specific body parts. The dependent variables of the experiment were length of their arm span and the length of their foot. The isometric growth of arm span and length of the foot were the independent variables. The controlled of this experiment was that the entire class was using the same unit of measurement and that they were all using the same format of taking measurements. My hypothesis was correct as the rest of the body was isometric and the data in my graphs shows this information. In table 3 you can see that most individuals were around the same measurements. Only some varied far from that of the average.

3.     Critique your experiment. What weakness do you see in the experiment? Suggest improvements.

a.     The only weakness I see in this experiment is that it lacks diversity in age. There is only college students who are roughly 18-22 years old and newborns. There needs to be more age groups rather it be in-between or older I think it would be interesting to see the effect over time.

4.     Suggest additional and modified hypotheses that might be tested. Briefly describe your next experiment.

a.     Does your nose and little features on your body grow at an isometric rate too? My next experiment would be that those who were born premature would still have the same growth rate as other individuals. I would want to see if this factor plays a role in isometric or allometric rate.

5.     Briefly describe the four major parts of a scientific paper. Want is the abstract? What information is found in a references Cited section?

a.     The four major parts of a scientific paper are the introduction, methods/results, discussion, and the work cited. The abstract is a short summary of the paper that includes the major points. The references cited is where credit is given to the sources that helped you right your paper.

Questions for Review

1.     Question 1

a.     Variables that are kept constant during the experiment (variables not being manipulated)

                                               i.     Controlled variables

b.    Tentative explanation for an observation

                                               i.     hypothesis

c.     What the investigator varies in the experiment ( for example, time, pH, temperature, concentration)

                                               i.     Independent variable

d.    Process used to measure the dependent variable

                                               i.     procedures

e.     Appropriate values to use for the independent variable

                                               i.     Level of treatment

f.      Treatment that eliminates the independent variable or sets it at a standard value

                                               i.     Control treatment

g.     What the investigator measures, counts, or records; what is being affected in the experiment

                                               i.     Dependent variables

h.    Number of times the experiment is repeated

                                               i.     replication

i.      Statement of the expected results of an experiment based on hypothesis

                                               i.     prediction

2.     Number 2

a.     The number of aborted foals counted for mares grazing in fields with and without black cherry trees on Kentucky horse farms.

b.    Scientists observed and recorded pecking patterns and underwing color markings of an unknown woodpecker to determine the species—common pileated woodpecker or, rarest-of-rare, ivory-billed woodpecker

c.     Number and size of cubs born to polar bears in 1990 and 2000.

3.     Question 3

a.     Frogs are captured from pons where the parasitic worm Robeiroia is abundant. The number of limb deformities is recorded.

                                               i.     Control treatment: pond

b.    Patients with the eating disorder anorexia nervosa are given Prozac to alleviate symptoms

                                               i.     Control treatment: anorexia nervosa

c.     Children with autism are given a diet free of gluten

                                               i.     Control treatment: autism

4.     What possible explanations for this correlation can you suggest?

a.     They were suppressing their symptoms for cancer which later when they went in for a checkup they realized that they had cancer. Another theory can be that the cancer found away to fight back the antibodies.

5.     What is the essential feature of science that makes it different from other ways of understanding the natural world?

a.     We need to observe and run experiments in order to understand what is going on.

Applying your knowledge

1.     What is the independent variable?

a.     Resist towards the common drug

2.     What is the dependent variable?     

                                               i.     Allowing the DDt to get sprayed in Africa on the interior walls.

a.     Why was a bar graph selected to present these data? Could the authors have used a ling graph?

a.     Bar graphs allow you to see the difference easier. The ling graph is for continuous concepts and this is not really a continuous data.

b.    Write a statement summarizing the results. Specifically address trends from 1972-1992; 1995-2000, and 2000-2004

a.     From 1972-1992 when the spray was being used the malaria and reached an all-time low for the next decade. From the ban in 1996-2000 the malaria went through the rough and managed to get to 60,000 individuals. When the ban was lifted it went down by half the reports.

c.     Which finches are able to crack the hardest seeds? State the trend.

a.     The finches that have a greater beak depth are often the ones that eat harder seed. This finches might have changed over time in order to have a bigger food supply due to the fact that the ones with small beaks wouldn’t be able to get into them.

d.    Compare the average beak depth for the offspring from 1976 and 1978.

a.     In 1976 the beak depth was 8.8 and only 2 years later the average beak depth grew to 9.8

e.     Approximately how many birds in the population each year had beaks larger than 9.3mm

a.     In 1976  about 30 finches had beaks longer than 9.3mm but in 1978 the number increase to about 103.

f.      During the drought of 1977, which group of medium ground finches were more successful in finding food and reproducing, those with large beaks or those with small beaks? Explain.

a.     Finches with larger beaks found it easier to survive due to the fact that they were able to eat and survive better than those with smaller beaks.

g.     Based on Figures 6 and 7 what kind of seeds were available in 1977, soft or hard?

a.     In 1977, for the most part there were soft seeds available.

h.     Using guidelines for graphs, how could you improve the axes labels on this figure?

i.      An improvement can be made by giving the number on the y-axis a number or measurement.

3.     Review the guidelines for graphs and critique Figure B below This figure 8 illustrates the changes in risk factors that are important in chronic diseases such as coronary heart disease, lung cancer, diabetes, and stroke.

a.     There can be a form of differentiate between the two things. In addition, I think a key would be useful in order to be able to tell what is what. I feel as though there is a gap that does not need to be there.

Practicing Experimental Design

1.     Using the criteria in Lab Study B, Developing Hypotheses, select the hypothesis you would pursue as a scientist and justify your choice.

a.     I think the first one seems the most interesting because it talks about emerging pathogens. This hypothesis seems about right because there can be a pathogen that eats away at them from the inside out.

2.     Describe a simple preliminary experiment to test your hypothesis, and state a prediction.

a.     Hypothesis

                                               i.     The grains contain compounds that help prevent gorillas from getting ill.

b.    Experiment

                                               i.     Give grain to half of the gorillas in zoo enclosure and see if those gorillas live a longer life than those who did not receive the compound.

c.     Prediction

                                               i.     If the compound does really help the half that did receive the “grains of paradise” than they become healthier and live a longer life.

3.     In this experiment, what is the independent variable?

a.      The artificial and non-artificial cavities

4.     What is the dependent variable?

a.     Total number of sites and locations, the abandoned and unoccupied

5.     Identify the controls

a.     Same artificially constructed nesting cavity

6.     How many replicates were used?

a.     In total there was 10 unoccupied and 10 abandoned artificial cavities. In addition,  with the 10 unoccupied and 10 abandoned non artificial cavities.

7.     What controlled variables might need to be considered in designing this experiment

a.     Trying to pick a forest that has many abundance of

8.     Did the results support the hypothesis

a.     The results support what was stated in the hypothesis. Due to the fact 9/10 red cockaded wood peckers were nested in artificial cavities.

9.     Based on these results, what would you recommend for conservation of this species?


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