I need these type of questions answered. I’ll attach the document.

I need these type of questions answered. I’ll attach the document.
BIOL 106 Exercise 1 EXPERIMENTAL DESIGN PURPOSE This exercise illustrates some aspects of experimental design and differentiates among the different variables in biology experiments. OBJECTIVES After completing this exercise students should be able to:  define the following terms: variable, independent variable, dependent variable, controlled variables, control group, experimental or treatment group(s)  read a description of an experiment and identify the following where possible: independent variable, dependent variable(s), control group, experimental or treatment group(s), controlled variables  interpret data presented in graphs TERMINOLOGY Variable : Variables are properties or characteristics of some event, object, or person that can take on different values or amounts (as opposed to constants that do not vary). Independent variable : An independent variable is one that is manipulated by an experimenter in order to determine its relationship with some other quantity. The independent variable is sometimes called the predictor because the hypothesis (proposed explanation) of the experiment predicts that this variable will determine or allow one to predict the value of the other factor. When conducting research, experimenters often manipulate variables. For example, an experimenter might compare the effectiveness of three types of painkillers. In this case, the independent variable is the “type of painkiller”. Dependent variable : The dependent variable is the outcome or response that is the result of changes in the independent variable. It is what is measured as the outcome of the experiment. In the example above, the experiment seeks to determine the effect of the independent variable on relief from pain. In the painkiller example, “relief from pain” is the dependent variable. In general, the independent variable is manipulated by the experimenter and its effects on the dependent variable are measured. The hypothesis generally states cause and effect. In this experiment, the type of painkiller causes the amount of pain relief or, in other words, the level of pain relief depends on the type of painkiller used. Page 1 BIOL 106 Exercise 1 Controlled variables: In a controlled laboratory experiment, the scientist attempts to keep all important factors the same in all groups except the independent variable . The independent variable is manipulated by the investigator so that it differs or varies in each group. All other factors that could affect the outcome of an experiment should be controlled so that they are the same in all groups. These factors that are kept the same in all groups are the controlled variables. In the example above, the investigator manipulates or changes the type of painkiller administered to each group. Everything else that could affect the level of pain relief in the patients should be kept the same for all groups. What other factors (besides the type of painkiller) could affect the level of pain relief each group experiences? In this way, the independent variable (type of painkiller) is “isolated” and any differences among the groups in the amount of pain relief can be attributed to the type of painkiller used, not any other factors that could affect the amount of pain experienced. Control group and treatment groups : During many experiments, researchers often include treatment groups (the groups in which the treatment is applied to experimental subjects)and a control group which is the same as the treatment groups in every way except that the subjects in the control group either receive no treatment or a standard treatment. In this way, the researcher can study the effect(s) of the experimental treatment thoroughly. For the painkiller example, the investigator could divide the participants with headaches into three groups. One group is treated with Tylenol™, one group is treated with Advil™, and the third group is treated with Bayer Aspirin™. The investigator can then ask participants to rate the level of pain they are experiencing one hour after taking the assigned medication. If the amount of pain in one group goes down significantly more than the others, the investigator might conclude that one medication is more effective than the others in reducing headache pain. Given this design, however, the investigator cannot conclude that the painkiller medications were more effective than a pill with no active painkiller. Maybe there was a placebo effect, and simply getting a pill made people believe that their pain was reduced. The experiment, therefore, should include another group – a control group – that should be comprised of people with headaches who are treated and exposed to everything the other groups are except that they are given a placebo (maybe a sugar pill) instead of Tylenol™, Advil™, or Bayer Aspirin™. The groups of people receiving Tylenol™, Advil™, or Bayer Aspirin™ are the three treatment groups; whereas the group of people receiving the placebo pill is the control group. Levels of an independent variable: If an experiment compares an experimental treatment with a control treatment, then the independent variable (type of treatment) has two levels: experimental and control. If an experiment were comparing five types of diets, then the independent variable (type of diet) would have 5 levels. Page 2 BIOL 106 Exercise 1 REPORT PAGES Experimental Design Activity (8 pts) Example 1   Can blueberries slow down aging? Some studies have indicated that antioxidants found in blueberries may slow down the process of aging. In a recent study, 19-month old rats (equivalent to 60-year old humans) were fed either their standard diet or their standard diet supplemented with blueberry powder. After eight weeks of feeding rats the assigned diets, memory tests and motor tests were administered. The rats eating the diet supplemented with blueberry powder showed notable improvement in their test scores; whereas the rats eating the standard diet with no supplement showed no improvement. 1. What is the independent variable? 2. What is the dependent variable? 3. Which group is the control group? 4. Which group is the treatment group? 5. What variables should be controlled (kept the same in all groups) in this experiment? Example 2   Does beta-carotene protect against cancer? Beta-carotene supplements have been thought to protect against cancer. However, a study published in the Journal of the National Cancer Institute suggests that this is false. The study was conducted with 39,000 women aged 45 and up. These women were randomly assigned to receive a beta-carotene supplement or a placebo, and their health was studied over their lifetime. Cancer rates for women taking the beta-carotene supplement did not differ significantly from the cancer rates of those women taking the placebo. 1. What is the independent variable? 2. What is the dependent variable? 3. Which group is the control group? 4. Which group is the treatment group? Page 3 BIOL 106 Exercise 1 5. What variables should be controlled (kept the same in all groups) in this experiment? Example 3   How bright is right? An automobile manufacturer wants to know how bright brake lights need to be in order to minimize the time required for the driver of a car to see the brake lights of the car in front of him or her and hit the brakes. Design an experiment to figure out how bright the brake lights need to be. Briefly describe your experiment below. 1. What is the independent variable? 2. What is the dependent variable? 3. Is there a control group in this experiment? Explain. 4. What variables should be controlled (kept the same in all groups) in this experiment? Page 4 BIOL 106 Exercise 1 Example 4 A local ecologist observed several species of birds feeding on insects on the leaves of oak trees in a state forest in Maryland. She hypothesized that these birds control the populations of herbivorous (plant-eating) insects and would thereby reduce insect damage to those trees. She predicted that removal of these birds would increase the size of insect populations and result in more leaf damage. To test her prediction, she conducted a controlled experiment. She selected a total of 90 white oak trees that grew in a 3-acre section of state forest. She divided the trees into groups of three trees that were similar in size and shape and were within 25 meters of each other. For each group of three trees: one tree was assigned to be covered with a cage that excluded birds but no insects, one tree was assigned to be sprayed weekly with a pesticide (a chemical to kill insects) and the third tree received no treatment at all. All treatment assignments were random. She then measured the insect densities on the trees and the amount of leaf biomass each tree produced the following season. Her data are below. 051015 control cage sprayInsect Density TreatmentFigure 1 Insect Density per 100,000 sq. cm 0100200300400500 control cage spray Biomass TreatmentFigure 2 Leaf Biomass (g) Page 5 BIOL 106 Exercise 1 1. What is the independent variable? 2. What are the dependent variables? 3. Which of the three groups is the control group? 4. Which groups are the treatment groups? 5. List some of the controlled variables in this experiment. NOTE: recall that controlled variables are the same (or have the same value) in ALL groups including the control group. 6. Do her data support her hypothesis? Use the data in the graphs to explain your answer. Page 6 BIOL 106 Exercise 1 Example 5 Some researchers were interested in the effect of intraspecific competition (competition among members of the same species) on the growth, development, and survivorship of plant hoppers, insects that live on salt marsh grass. They performed field experiments to test the hypothesis that plant hoppers that live in dense populations would compete and suffer the impacts of competition. They performed field experiments in which they controlled the density of the populations by enclosing the plant hoppers in cages with marsh grass seedlings. The cages were set up at three different densities so that each cage contained 5, 10, or 40 plant hoppers. The researchers measured the growth and survivorship of the insects over a period of time. The figures below show their data.Planthopper Survival 0 20 40 60 80 100 0 20 40 60 Insects per Cage % survived Developmental Time 0 10 20 30 40 0 20 40 60 Ins ects per Cage Dev. time (days) Page 7 BIOL 106 Exercise 1Body Length 2.35 2.4 2.45 2.5 2.55 2.6 2.65 0 20 40 60 Insects per cage 1. What is the independent variable? 2. What are the dependent variables? 3. Is there a control group? Explain. 4. Which variables were controlled in this experiment? Which variables needed to be controlled? Reminder: a controlled variable has the same value in ALL groups. 5. According to the data presented, what are the effects of intraspecific competition on the growth and survival of plant hoppers? Page 8 BIOL 106 Exercise 1 Scientific Method Lab Activity (12 pts) Name_______________________________________________________ Scientists (and non-scientists) need to have a way to find answers and explanations about why things are the way they are! The process of finding these explanations is called the scientific method . It is a method for testing ideas with observations. The scientific method typically follows certain steps. (Withgott and Laposata, 6 th ed) So basically making observations starts the process of the scientific method. Then you ask a question based on your observation. Next you develop a hypothesis , which is a statement that attempts to answer a scientific question. A hypothesis must be both testable and falsifiable . What does it mean to be testable and falsifiable? ______________________________________________________________________________ ______________________________________________________________________________ Page 9 BIOL 106 Exercise 1 Then you can use your hypothesis to make a prediction, usually in the form of an if…then statement. Then you test the prediction usually be doing an experiment. In an experiment you can alter or change conditions or variables. There are different types of variables such as independent variables and dependent variables. You (the scientist) manipulate or change the independent variable . The dependent variable is the variable being tested and measured and it depends on the independent variable. Usually you have a control group and a treatment group in your experiment. A control group does NOT receive any treatment, whereas a treatment group receives the treatment. This means that the control group is not altered and the treatment group is going to have something changed in it. Then you collect data, and analyze and interpret your results. Once you complete your experiment you have to decide if you accept or reject your hypothesis . It is ok to reject your hypothesis. If you do reject it, you just come up with another hypothesis to try to answer your original question! If you accept your hypothesis, that’s great but it doesn’t mean that you proved your hypothesis to be correct. It just means that your results support your hypothesis. Example of the scientific method Observation: You notice that the pond outside the science center has a lot of algae growing in it. Question : What is causing all of the algae to grow in the pond? Hypothesis: Fertilizers that are being used on the plants around the pond are running into the pond and causing the amount of algae to increase. Prediction: If fertilizer is added to a pond, then the amount of algae in the pond will increase. Test : Control Group – a pond with no fertilizer added to it Treatment Group – a pond with fertilizer added to it Independent variable: amount of fertilizer added to the pond Dependent variable: how much algae grows in the pond Procedure So for today’s lab you will be doing simple and fun experiments utilizing the scientific method. You must use the scientific method to answer TWO different questions in your everyday life. You will devise an experiment and then perform the experiment to determine if you should accept or reject your hypothesis. For example, I have three different types of gum (Wrigley’s Spearmint, Juicy Fruit, and Trident Watermelon) and my question is: which gum has the longest lasting flavor? Based on that question, I can develop my hypothesis. A hypothesis is typically a declarative statement so in this case my hypothesis is: Wrigley’s Spearmint is the gum with the longest lasting flavor. Now I can compose my If…then statement . If Wrigley’s Spearmint has the longest lasting flavor, then it will last for the most time compared to the other two types of gum. My independent variable is the type of gum. My dependent variable is how long the flavor lasts. Page 10 BIOL 106 Exercise 1 Next I need to devise my experiment . I will chew each type of gum, (noting the time I start) and I will chew it until the flavor is gone and determine how long the flavor lasts. Examine my results. I will determine if Wrigley’s Spearmint had the longest lasting flavor. Accept or reject my hypothesis. So now you must answer three questions in your everyday life utilizing the scientific method. I did the gum question so you can’t use that one again! First Question 1. What is the question you are asking? 2. Develop your hypothesis. 3. Compose your If…then statement. 4. Independent Variable____________________________________ 5. Dependent Variable______________________________________ 6. Devise your experiment and list the steps below. You need to give enough detail that I could recreate the experiment. 7. Now perform your experiment! You must take at least 3 pictures of you performing your experiment and include them in this lab activity . Page 11 BIOL 106 Exercise 1 8. What data did you collect? 9. Look at your data. Does it support your hypothesis? Are you going to accept or reject your hypothesis? Why? Second Question 1. What is the question you are asking? 2. Develop your hypothesis. 3. Compose your If…then statement. 4. Independent Variable____________________________________ 5. Dependent Variable______________________________________ 6. Devise your experiment and list the steps below. You need to give enough detail that I could recreate the experiment. 7. Now perform your experiment! You must take at least 3 pictures of you performing your experiment and include them in this lab activity . Page 12 BIOL 106 Exercise 1 8. What data did you collect? 9. Look at your data. Does it support your hypothesis? Are you going to accept or reject your hypothesis? Why? Other Questions 1. If a scientist rejected the hypothesis, what would the scientist have to do now if he or she were going to continue to try to answer this question? 2. If you accept your hypothesis, does that mean that your hypothesis is PROVEN to be correct? Why or why not? Page 13