BIO 101 Lab 1
BIO 101 LAB 1: SCIENTIFIC METHOD Objectives: ● Learn to apply the scientific method to scientific exploration ● Design an experimental procedure ● Identify the control group in the experiment ● Identify the independent, dependent, and control variables in the experiment ● Collect and analyze data ● Create appropriate graphs that best represent the data Background: Science is the process used to solve problems and to gain a better understanding of the natural world. Scientists are constantly looking for better and clearer answers to a wide range of questions. The basic method used to find the answers is called the Scientific Method. This method is based on a set of core assumptions: ● There are specific causes for observed events in the natural world ● The causes of these events can be identified ● There are patterns and rules that can be used to describe observations ● The patterns and fundamental rules of nature are universal ● Science is an ongoing process that results in an evolution of our understanding of the patterns and fundamental rules of nature The Scientific Method is a stepwise process used to develop answers: 1. Observation: Something that is seen or felt with the senses or knowledge gained from research or previous experience 2. Question: How or why did an event occur? 3. Hypothesis: A tentative and testable answer to the question 4. Experiment: The recreation of a controlled event that allows the researcher to support or reject the hypothesis The question formulated from an observation must be logical and answerable. Hypotheses that are developed from questions must be 1) based on relevant information, 2) testable, and 3) falsifiable (proven false). If a hypothesis can be proven false, then it cannot be used to develop a theory. Experiments should be designed to minimize variability, meaning only small details/variables (preferably only one) should be altered to test the hypothesis. Controlled experiments work best when only one variable is changed. Experiments must also be repeatable to help ensure there is no bias in the results. Experiments are often submitted for peer review and are repeated by other scientists. The results might even lead to additional hypotheses being made that can be tested and reported to the scientific community. Over time, hypotheses that address an observable phenomenon and result in repeatable and consistent results are develop into a consensus view to explain an observation. When this occurs, a theory is formed. In some branches of science (e.g., physics, chemistry) a theory develops into a law, which is generally expressed by a mathematical formula used to explain and predict actions (i.e., the law of gravity). While experiments are conducted, the variables are measured and monitored closely. Controlled variables are the aspects of the experiments that remain consistent (the same) through every variation of the experiment. For example, a researcher testing the effect of a specific nutrient conditions on plant growth (Figure 1) will give each plant the same amount of 1 BIO 101 LAB 1: SCIENTIFIC METHOD water, sunlight, air conditions, temperature, soil, pot, age of plant, etc. The independent variables are the aspects of the experiment that the researcher changes in order to test the hypothesis. In the plant growth example, the differing nutrient conditions are the independent variable. Notice that in this experiment, all controlled variables are the same except for the nutrient applied in the soil. In this way, you can more easily isolate the variable that is causing a measurable effect. If the type of soil, the amount of water, or sunlight were different for each experimental plant, then you could not unequivocally say it was the different nutrients that produced differences in growth. The dependent variables are the aspects of the experiment that change as a result of changing the independent variable. In the plant growth example, change in plants such as height, color, flower production, or fruit production may occur as a result of modifying the nutrients. These are the dependent variables because you can measure and quantify the changes to the plants that occurred as a result of modifying the nutrients. The researcher acquires data by measuring and quantifying the changes in plants. The resulting data from an experiment can be recorded in tables or charted on graphs (Figure 2) to more easily show trends, correlations, or simply make the data easier to visualize. When graphing data, the independent variable is often on the horizontal (X) axis and the dependent variable is often on the vertical (Y) axis. For example, in the plant experiment, plant growth — the dependent variable — (measured as height in centimeters or cm) was graphed on the Y-axis. The type of nutrients — the independent variable — was graphed on the X-axis. Notice that the controlled variables (water, sunlight, etc.) are not graphed. And importantly, the title of a graph describes the purpose or aim of the experiment. For this lab, you will be working in groups of 4-6 students. Each student must turn in their own work, in their own words for credit (do not copy each other’s work even if you work together). Materials: ● ● Stopwatch/timer Calculator 2 BIO 101 LAB 1: SCIENTIFIC METHOD 3 BIO 101 LAB 1: SCIENTIFIC METHOD Safety: When exercising, keep a safe distance from others and objects around you. Do not exercise if you have any health issues that affect your ability to exercise. Use information on resting heart rate and recovery (HRR) to develop a question and design an experiment. In science, many researchers often work together to answer questions, and as such, you will also be working in groups. As a group, you will develop one question that can be experimentally tested, about your observations on HRR and a variable of your choice. You will collect data on your own heart rate and that of fellow students to complete a data set. The observation (previous research) is given to you and it is up to you. You will then identify your dependent and independent variables, test your hypothesis, and accept or reject your hypothesis based on your data. You will also graph your results. Lastly, you will identify any variables that may hinder your experiment (i.e., variables that skew data, incomplete data, etc.). Observation/previous research: Heart rate recovery (HRR) is the rate of decline of the heart rate (beats per minute or bpm) after stopping exercise. HRR is an important factor in determining heart health and has been associated with risk of coronary heart disease. HRR is influenced by 1) pre-existing health problems such as hypertension, diabetes, 2) behaviors such as smoking or sedentarism (low-level activity throughout the day), lack of exercise, and 3) demographic factors such as age and sex. Standard HRRs for humans have been developed from previous research, including at Cornell University. Test subjects exercised on a treadmill for two minutes straight. HRR of test subjects was then measured using radial pulse, by taking maximum heart rate at peak exercise and then taking heart rate at exactly 1 minute after stopping exercise. Based on this research, an HRR value of
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