Assignment 1: Scientific Method Assignment - Biological investigations can take on two broad formats: experiments and observational studies. An experiment is a formal method of testing a variable. It has control and experimental groups and data analysis

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Home >Biology homework help >Assignment 1: Scientific Method Assignment - Biological investigations can take on two broad formats: experiments and observational studies. An experiment is a formal method of testing a variable. It has control and experimental groups and data analysis

THE SCIENTIFIC METHOD

OBJECTIVES

After completing this exercise, the student will be able to:

· Define and differentiate between scientific method, hypothesis, prediction, observation, experiment, controls, conclusion, theory

· Understand the nature of scientific knowledge

· Outline and explain the steps of the scientific method process

· To formulate a hypothesis and develop conclusions based on data from previous experiments

INTRODUCTION

Science can be defined as a systematic approach to acquiring knowledge. We, as humans, have many senses that we rely on to interpret our surroundings and other inhabitants of the world around us. However, sometimes these senses can “fool” us and we must rely on technical equipment and tools to conduct experiments and enhance/expand our existing senses. Science is based upon facts and evidence rather than beliefs or superstitions.

To understand Biology and science, you must first examine how scientific knowledge is obtained. Science is a process that involves several steps. We will now explore these steps:

1. The process begins with making an observation about nature or some research done previously on a topic.

Example: Studies suggest that using Hydro-T plant food will make my tomatoes grow twice as fast and big.

2. The next step is to formulate a question about the observation.

Example: Does a weekly dose of 1 cup of Hydro-T plant food really enhance my yield of tomatoes and stimulate the plant’s growth?

3. Next, a hypothesis is needed. This is just merely an educated guess to answer the question you proposed in #2 above. Or put another way, a tentative explanation of the observed phenomenon. The hypothesis MUST be testable! Before stating your hypothesis, you should gather as much data from as many sources as possible. Also, please note: Hypotheses are NOT always correct, and often times you must formulate alternative hypotheses.

Example: Under normal conditions, supplementing my tomato plants weekly with 1 cup of Hydro-T plant food will make them grow bigger and faster.

4. A prediction is made next based upon your hypothesis. The prediction is a way to put your hypothesis to a test. It is usually phrased in an “If…then….” manner. If the prediction is found out to be true, then you will accept your hypothesis. If it is found to not be true, then you will need a new hypothesis.

Example: If weekly supplements with 1 cup of Hydro-T plant food cause tomato plants to grow twice as big and fast, then tomato plants receiving a weekly dose of 1 cup of Hydro-T plant food will grow twice as fast as tomato plants which do not receive a weekly dose of the plant food when both are exposed to identical conditions.

5. Next, a controlled experiment is designed and conducted in order to test the hypothesis. There are 3 types of variables involved. The independent variable (in our example, the Hydro-T plant food) is the condition or event under study for its effect on the dependent variable (in our example, growth rate and tomato yield). Put another way, the dependent variable is the condition or event that may change due to the independent variable. The controlled variables are conditions/events that COULD affect the outcome of your experiments, but do not because they are kept constant by the scientist. During a controlled experiment, the individuals under study are divided into 2 groups. The experimental group is exposed to the independent variable, while the control group is not. All other variables are kept constant.

Example: Gather a group of young tomato plants that have been grown in a laboratory and are all genetically identical. Randomly select 50 of them and put them into the experimental group, which will receive a weekly dose of 1 cup Hydro-T plant food over the period of 1 month. Also, randomly select 50 of the plants and put them into he control group. The control group will NOT receive the weekly dose of plant food. All other variables (i.e., water, sunlight, soil, etc) will be kept identical for each group. After 1 month, the plants are examined for growth rate and yield.

6. The results are collected and analyzed. Keep in mind that the experiments MUST be reproducible!

Example: The plants from the experimental group grew an average of 20 cm over the month, while the plants in the control group grew an average of 10 cm.

7. A conclusion is made as to accept or reject the hypothesis based upon the results. A conclusion often times leads to the formation of a new hypothesis and additional experiments.

Example: In this case, the hypothesis is accepted since the results showed clearly that a supplement of 1 cup of Hydro-T plant food weekly caused the plants in the experimental group to grow twice as fast as compared to the plants in the control group. Scientists use statistical analysis to determine the significance of differences seen in the control group versus the experimental group. However, we will leave the statistics for another lab (

OBSERVATION

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QUESTION

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HYPOTHESIS

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PREDICTION

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CONTROLLED EXPERIMENT

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ANALYSIS

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CONCLUSION

YOU WILL NOW CONDUCT AN EXERCISE USING THE SCIENTIFIC METHOD

EXERCISE

In this exercise, you will be investigating how to obtain a perfectly hard boiled egg. It is common belief that many factors impact the quality of hard boiled eggs. Some hypothesized factors are:

1. Age of eggs

2. Type of eggs

3. Size of eggs

4. Temperature of eggs at the start of cooking

5. Crowding of eggs in pan

6. pH of the water

7. Temperature of water

8. Quantity of water

9. Use of a cold water bath to quickly stop cooking

10. Presence of a lid on pan

11. Type of pan

12. Shape of pan

13. Gas vs. electric stove

14. Altitude

15. Amount of cook time

We are going to investigate the effects one of these factors has on perfect egg boiling. That factor is time.

MATERIALS

· 12 eggs without any visible cracks

· water

· 4 pans

· timer

· 4 burner stove

· Large slotted spoon

PROCEDURE

Image taken from http://www.seriouseats.com/2009/10/the-food-lab-science-of-how-to-cook-perfect-boiled-eggs.html

First define a perfectly hard boiled egg. State it below:

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Second, you need to formulate a hypothesis. State it below:

1. Place one pan on each burner. Gently place three eggs in a single layer in each pan with enough cold water to cover eggs completely (approximately 1 inch of water over the top of the eggs).

2. Bring water to a rolling boil. Document the time each pan starts to boil. Then start counting the time for each time category. Each pan will be a different time category. The pan you designate as Pan 1 will boil for 5 minutes. The pan you designate as Pan 2 will boil for 10 minutes. The pan you designate as Pan 3 will boil for 15 minutes. The pan you designate as Pan 4 will boil for 20 minutes.

3. When time is up for a specific pan, take it to the sink and dump out the hot water. Make sure to use the spoon to hold the eggs in the pan, and fill the pan will cold water. Then dump out the cold water and fill the pan with cold water a second time. Then dump out the cold water and fill the pan with cold water a third time. Now, let the eggs soak for 15 minutes to cool off.

4. Peel eggs, and observe them. Record your observations for each egg characteristic in the table provided. (The characteristics are: yolk firmness, yolk color, peel-ability, and whites firmness.) Record your observations for each egg characteristic in fractions of the number of eggs that have that characteristic divided by the total number of eggs. For example: In the 5 minute cook time pan: If you observe 2 eggs that have firm yolks and one that does not, you would write 2/3 in the cell located in the column labeled ‘Yolk opaque, completely firm’ for the row labeled ‘5’. I have highlighted this cell yellow.

Table 1. Data on the Perfect Hard Boiled Egg.

Cook time (minutes)	Yolk opaque, completely firm	Soft inner yolk	What color is the yolk? Fraction of eggs with each color to total number of eggs in pan	Do not shred when peeled	Whites firmness Fraction of eggs with each firmness to total number of eggs in pan
Cook time after boiling starts	Time pan started boiling	Fraction of eggs with firm yolks to total number of eggs in pan	Fraction of eggs with soft inner yolks to total number of eggs in pan	Yellow	Greenish	Purplish	Fraction of non-shredding eggs to total number of eggs in pan	Runny	Firm	Rubbery
5
10
15
20
Perfect Egg Score	3/3	3/3	3/3	0/3	0/3	3/3	0/3	3/3	0/3

Based upon the data you collected in Table 1, explain each cook times affects on each egg characteristic.

What are some possible errors that could have occurred?

Compare your results with the ‘Perfect Egg Score’ located in the last row of the table. What is your conclusion on the perfect cook time?