Lab 1 - Scientific Method Lab Sheet Answer Key PDF

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Here is the Lab 1 - Scientific Method Lab Sheet Answer Key, This is covered in Week 1-2 of intro to biology. Will receive 100%...

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"One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike and yet it is the most precious thing we have." - Albert Einstein Introduction 1. Define science 2. Name a few disciplines of science 3. Discuss and use the steps of the scientific method 4. Identify the control, control variables, independent variable(s) and dependent variable(s) 5. Ask a question/make an observation 6. Make a hypothesis 7. Design an experiment to test a hypothesis 8. Interpret data collected

The dictionary defines science as “knowledge about or study of the natural world based on facts learned through experiments and observation.” In other words, science is a method of investigation by testing hypotheses through experimentation. Science is all around us…from the gas used to drive your car to boiling water to make pasta for dinner to shampoo used to clean your hair. Science is typically divided into two major groups: 1. Social sciences – the study of human behavior and societies 2. Natural sciences – the study of natural phenomenon Natural sciences includes physical science (examples: physics, chemistry and earth science) and life science (examples: biology, zoology, human biology, botany). Science includes many disciplines (far too many to list here). Here are, however, a few examples:  Anatomy – study of structure  Neurology – study of nervous system  Botany – study of plants  Paleontology – study of fossils  Chemistry – study of elements  Physics – study of matter  Cytology – study of cells  Physiology – study of function  Genetics – study of heredity  Taxonomy – identification and  Histology – study of tissues naming of organisms  Microbiology – study of microorganisms  Zoology – study of animals

The scientific method is a process that provides a guide for problem solving and investigations. While you may think of the scientific method as something only to be used in biology class, you probably use it on a daily basis to solve day-to-day problems without even realizing it. Think about the last time you couldn’t get the TV

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remote to work or your cell phone wouldn’t turn on. You probably formed an educated guess as to why the remote or phone wouldn’t work and then tested to see if you were right. The scientific method includes the following steps: Observation/Question – This step involves noticing something that sparks your Observation/Question interest and asking a question about it. Research

Research – This step involves learning about your observation/question by reading literature and/or textbooks.

Hypothesis

Hypothesis – This step involves forming a tentative answer to the problem. Although we don’t necessarily think of hypotheses on a daily basis, you use them in solving problems in your everyday life.

Prediction

Experiment

Prediction – This step involves using logic to test your hypothesis and is usually written in the “if…then” format. Experiment – This step involves the actual data collection that is necessary to test your prediction.

Results/Conclusion – This step involves analyzing the data from the experiments and coming to a conclusion based on your results. Experimental design is very important in the scientific method. An investigator must identify key variables in order to make the experiment as successful as possible. A poorly designed experiment usually leads to more unanswered questions rather than answering the initial question you sought to answer. Here are a few important variables to think about when designing your experiment:  Control variable – a variable that is the same in both the control and experimental group  Independent variable – the variable being tested in an experiment  Dependent variable – a variable that is measured by the scientist; a variable that changes as a result of the independent variable  Control group – an experimental sample or set of samples that are not exposed to the independent variable  Experimental group – an experimental sample or set of samples that are exposed to the independent variable For example, if you were testing the effect of a fertilizer on the growth of plants, you might have the followi ng groups: 1. Plants watered with tap water (control group) 2. Plants watered with 25% fertilizer solution (experimental group) 3. Plants watered with 10% fertilizer solution (experimental group) 4. Plants watered with 1% fertilizer solution (experimental group) Results/Conclusion

Control variables – using the same plants, using the same tap water to make your solutions, growing the plants in the same soil, growing them in the same growing conditions (light, moisture, air, etc.), etc. Independent variable – the concentration of fertilizer Dependent variable – the growth of the plant (measured however you decided)

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Procedure 1 - Fizz Fizz If you have ever used Alka-Seltzer to relieve heartburn or indigestion, you know that the tablets fizz when dropped into water. In this lab you are going to design an experiment to determine factors that make the Alka-Seltzer tablets dissolve faster. Question: What factors will make an Alka-Seltzer tablet dissolve faster? You and your group should decide on ONE of the following set of variables to test: A. Effect of Salt C. Effect of Surface Area D. Effect of Stirring Please circle the set of variables above that your group has decided to test. Hypothesis/Prediction: Please develop a hypothesis and prediction with your group and write it below:

I believe that the Alka Seltzer will dissolve faster in a change in temperature because in hot water

___________________________________________________________________________________________

molecules are faster because they gain energy in hotter temperature while they are slower in colder wate ___________________________________________________________________________________________

___________________________________________________________________________________________ Experimental Design: Identify the following variables in your experiment

The amount of water and size of the Alka Seltzer Control variables: ____________________________________________________________________________ The Water and Alka Seltzer Control group: ______________________________________________________________________________ Does temperature affect the time it takes for Alka Seltzer to dissolve?

Independent variable: ________________________________________________________________________

Time it took __ for___________________________________________________________ the Alka Seltzer to dissolve. Dependent variable: _____________

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Procedure A. Effect of Salt Materials 2 Alka-Seltzer tablets 2 600 ml beakers 1 tablespoon Salt (NaCl) dH2O (deionized water) Timer Grease pencil (red) 1. 2. 3. 4. 5.

Obtain all the materials listed above With your grease pencil, label your beakers with the following labels: Control, NaCl Add 300 ml of dH2O (deionized water) to both the Control and NaCl beakers Add 2 tablespoons of salt to the NaCl beaker and gently swirl until all of the salt is dissolved Open both of your Alka-Seltzer tablets and have 2 members of your group simultaneously drop one into each beaker as the 3rd member of your group starts the timer. 6. Carefully watch each of the beakers until the Alka-Seltzer tablet has completely dissolved. 7. Record your results on the Table 1.1 below.

B. Effect of Temperature Materials 3 Alka-Seltzer tablets 3 600 ml beakers Warm dH2O Cold dH2O Timer Grease pencil (red) 1. 2. 3. 4. 5. 6.

Obtain all the materials listed above With your grease pencil, label your beakers with the following labels: Control, Cold, Warm Add 300 ml of room temperature dH2O to your beaker labeled ‘Control’ Add 300 ml of cold dH2O to your beaker labeled ‘Cold’ Add 300 ml of warm dH2O to your beaker labeled ‘Warm’ Open all 3 of your Alka-Seltzer tablets and have 3 members of your group simultaneously drop one into each beaker as the 4th member of your group starts the timer. 7. Carefully watch each of the beakers until the Alka-Seltzer tablet has completely dissolved. 8. Record your results on the Table 1.1 below.

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C. Effect of Surface Area Materials 2 Alka-Seltzer tablets 2 600 ml beakers 1 50ml graduated cylinder dH2O Timer Grease pencil (red) 1. 2. 3. 4. 5.

Obtain all the materials listed above With your grease pencil, label your beakers with the following labels: Control & Crushed Add 300 ml of dH2O to your each beaker Crush one of the Alka-Seltzer tablets while it is still in the package Open both of your Alka-Seltzer tablets and have 2 members of your group simultaneously drop the intact tablet into the ‘Control’ beaker and the crushed tablet into the ‘Crushed’ beaker as the 3rd member of your group starts the timer. 6. Carefully watch each of the beakers until the Alka-Seltzer has completely dissolved. 7. Record your results on the Table 1.1 below.

D. Effect of Stirring Materials 2 Alka-Seltzer tablets 2 600 ml beakers Stir rod dH2O Timer Grease pencil (red) 1. 2. 3. 4. 5.

Obtain all the materials listed above With your grease pencil, label your beakers with the following labels: Control & Stirred Add 300 ml of dH2O to your beaker labeled ‘Control’ Add 300 ml of dH2O to your beaker labeled ‘Stirred’ Open both of your Alka-Seltzer tablets and have 2 members of your group simultaneously drop one into each beaker as the 3rd member of your group starts the timer. 6. Continuously stir the ‘Stirred’ beaker with the stir rod. 7. Carefully watch each of the beakers until the Alka-Seltzer tablet has completely dissolved. 8. Record your results on the Table 1.1 below.

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Table 1.1 Beaker Control

Crushed

Dissolve Time (seconds)

1 Minute 11 Seconds 45 Seconds

What conclusion(s) can you make based on your results?

Although temperature can effect the experiment it was concluded that crushing the Alka Seltzer ___________________________________________________________________________________________ did make it dissolve faster than a whole tablet. The change in surface area changed the time it took for ___________________________________________________________________________________________

for the Alka Seltzer to fully dissolve in the water. ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________

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Procedure 2 – Hazardous Waste: Is There a Safe Dilution? Background Toxicology is the study of the harmful effects of chemicals on organisms. We tend to characterize chemicals as being toxic or nontoxic, but the fact is that any chemical can be toxic if the concentration is high enough. You shower each morning, and a small amount of shampoo goes down the sewage drain. This is probably not harmful. However, drinking a lot of shampoo will probably make you sick. How much is safe? It is essential to assess the toxicity of a chemical in order to set standards for acceptable maximum concentrations in drinking water, food, and the environment. In this lab, we will perform dose/response assays to determine the level of toxicity of common household products, such as shampoo, cologne, and household cleaner. If we do not know the toxic level for these chemicals, it is a good idea to test a wide range of concentrations. We will perform a serial dilution. This is a series of dilutions each of which is ten times more dilute than the one from which it was made (see figure 1). The assay or test will involve looking at the effect of these products on the germination (sprouting) of radish seeds and growth of the seedling.

Materials (per group/bench) Distilled water in a dropper bottle 4 microcentrifuge tubes Microcentrifuge tube rack 1 Sharpie pen Disposable pipette Forceps 8 radish seeds 4 pieces of paper towel, each approximately 4 cm X 4 cm. Solution of test substance Read over the procedure first so that you understand it. Fill out the first part of the scientific method section and show it to your instructor before beginning the actual procedure.

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Procedure 1. Label your microcentrifuge tubes C (control), 100%, 10%, and 1%. Each tube should also be labeled with the initials of the group members for identification purposes. 2. Place 10 drops of distilled water in the tube marked C. 3. Place 10 drops of undiluted chemical in the tube marked 100%. 4. Make your serial dilutions (see figure 1). Add 9 drops of distilled water to the tubes marked 10% and 1%. Add 1 drop of pure chemical to the water in the tube marked 10%. Mix it well by capping the tube tightly and flicking it several times on the bottom of the tube. 5. Then, take 1 drop of your 10% dilution and add it to the water in the tube marked 1%. Mix it well. 6. Take a small square of paper towel. It should be folded in half twice lengthwise to create a long “wick”. Then the narrow paper should be folded over 1 cm from the top to generate a “shelf”. After making the three folds, it should resemble the number seven. The purpose is to provide a substrate which will be immersed in the liquid while providing a place to put seeds that is moist, but above the level of the liquid. Make a total of 4 wicks. 7. Insert a paper-towel wick into each microcentrifuge tube. The towel should be completely moistened by the fluid, but the shelf should remain above the level of the liquid. 8. Use the forceps to place two radish seeds on the shelf in each tube. Make sure the seed is not sitting in the liquid. Close the caps and make sure that none of the wicks protrude outside the cap. 9. Set your tubes in the rack on the instructor bench. 10. After 7 days, examine the seeds and seedlings. You should determine if the seed germinated or not. For those that germinated, measure the length of the root and shoot of each seedling. Use the forceps to gently unwind the seedling. The shoot is the part of the seedling with the cotyledons (embryonic leaves) and hypocotyl (stem). The root is the part of the seedling that is away from the seed coat and embryonic leaves. The Scientific Method must be applied for a reliable dose/response experiment. 1. What is the QUESTION you want to answer? _____________________________________________________________________________________ Will the seeds germinate or not? _____________________________________________________________________________________ 2. State your HYPOTHESIS: Does the amount of undiluted and diluted chemicals effect the sprouting of the radish seed? _____________________________________________________________________________________ _____________________________________________________________________________________ 3. State your PREDICTION: _____________________________________________________________________________________

I believe that tube 1% will have the least negative effect on the sprouting of the radish seed _____________________________________________________________________________________

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4. How will you conduct the EXPERIMENT (general procedure)? I will have 3 different tubes, consisting of 100%, 10% and 1% diluted _____________________________________________________________________________________

chemical and 1 tube with nothing. I will then label each radish tube with _____________________________________________________________________________________ which % of chemical they received and watch the change in germination

between each raddish. _____________________________________________________________________________________ _____________________________________________________________________________________ 5. What is the independent variable (hint: the doses of your chemical)?

The independent variable is the variable that is changed so it would be the dose % in of the chemical. _____________________________________________________________________________________ _____________________________________________________________________________________ 6. What is the positive control tube (group) and why? I would say the positive control tube group would be the control tube since it gave _____________________________________________________________________________________

us the most sprouting of the seed. _____________________________________________________________________________________ 7. What are the dependent variables?

The dependent variable is the variable affected by the change so it would be the radish seeds. _____________________________________________________________________________________ _____________________________________________________________________________________ 8. List some control variables: Some control variables temperature, day and night time _____________________________________________________________________________________ _____________________________________________________________________________________

2 seeds per concentration 9. Number of replicates (how many seeds for each concentration): ________________________________

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RESULTS Record your results in the table below:

Toxic Chemical: ______________________________ Length of root in seedling 1 (mm)

Length of root in seedling 2 (mm)

Length of shoot in seedling 1 (mm)

Length of shoot in seedling 2 (mm)

3mm

Tube

Germinated? Yes or no

Control

Yes

5mm

4mm

6mm

100%

No

4mm

3mm 3mm

0mm

0mm

0mm

0mm

10% 1%

No Yes

3mm 4mm

4mm

3mm

3mm

CONCLUSION: EFFECT OF CHEMICAL ON GERMINATION: Did both of your positive control seeds germinate? What does this indicate about the quality of the seeds and growing conditions?

Yes, the amount of concentration changes the growth condition of the seeds _____________________________________________________________________________________ _____________________________________________________________________________________ Did either of the seeds germinate in the presence of undiluted chemical? What does that indicate about the toxicity? _____________________________________________________________________________________ _____________________________________________________________________________________ Did they germinate in the presence of 10% chemical? What does that indicate about the toxicity?

The 100% _____________________________________________________________________________________ and 10% concentration did not germinate, this indicates that the concentration increases the toxicity to the seeds _____________________________________________________________________________________

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Did they germinate in the presence of 1% chemical? What does that indicate about the toxicity?

Yes, the seed did germinate but it was not as big as the the seed that received 0 to concentration, _____________________________________________________________________________________ this indicates that slight toxicity changes the outcome of many seeds.

_____________________________________________________________________________________

If germination occurred in the lower dose but not in the higher dose, what does that indicate? How could you refine your experiment to find the dose that prevents germination? _____________________________________________________________________________________

The germination that occurred in the lower does clearly indicates that the high...