Midterm Review Sheet: Scientific Method Name: Honors Biology Date: 1 Biology Objective #8: Microscopy The invention of the microscope is probably the most significant invention in science. Without this valuable scientific tool, we could not have developed the Cell Theory!!! The microscopes preceded the development and understanding of just about everything that we have discussed in Biology class!!! Here are a few key microscopy concepts to keep in mind: Determining TOTAL MAGNIFICATION OF A MICROSCOPE:! Total Magnification = Eye piece x Objective lens! Remember, the eye piece will always be 10x. Anytime you multiply a number by 10, all you have to do is add one zero. Example: If the objective lens of a microscope is 30x. The total magnification is 10 x 30 = 300. Preparing a Wet-Mount Slide: Please remember that bubbles are our enemy in microscopy! The most important step is to place the cover slip at a 45 degree angle. This prevents bubbles from becoming trapped with your specimen. I. Types of a Microscope: For each of the following pictures, words, or phrases indicate if it refers to a dissecting microscope (D), scanning electron microscope (S), transmission electron microscope (T), or light microscope (L) in the corresponding blanks. Uses Light Can be used to view viruses Produces a 2-D cross section Used primarily during dissections Can be used to view individual living cells Requires gold plating Used to view the parts of the eye
I am a type of microscope that produces a 3-D image by plating an item in gold and having high energy particles bounce off of it. What type of microscope am I? 2 I am a type of microscope that produces a 3-D image, but you can view individual cells by using me. I am mainly used during dissections. What type of microscope am I? I am a type of microscope that produces a 2-D image of living cells. What type of microscope am I? I am a type of microscope that produces a 2-D image by using a thin slice of a specimen by passing an electron beam through it. What type of microscope am I? Biology Objective #3: Experimental Design The Scientific Method is a process that guides the search for answers to a particular question. The scientific method is composed of 5 sequential steps. These steps are listed below: State the problem (Observation) Hypothesis Prediction Controlled Experiment Conclusion (Theory) A HYPOTHESIS is a possible explanation or tentative answer to the question being investigated. In other words, a hypothesis is a best guess at the answer to the question. A Controlled Experiment must meet all the components of PROPER EXPERIMENTAL DESIGN. The components of proper experimental design as listed below: The experiment must avoid bias The experiment must be repeatable. The experiment must have a proper CONTROL. In order for an experiment to be controlled, two groups must be present. The scientist must have a control group and an experimental group. A CONTROL GROUP is the group in the experiment that does not receive the variable or treatment. This is the group that you leave alone! The control group serves as our basis of comparison. An EXPERIMENTAL GROUP receives the variable or treatment. The results (data) gathered from the experimental group are then compared to the control group. II. The variable or treatment in an experiment is referred to as the INDEPENDENT VARIABLE. The independent variable is the thing that the scientist changed. The DEPENDENT VARIABLE is what the scientist is measuring. Remember, a good experiment will only have one manipulated (independent) variable. Parts of an Experiment 1) Experiment: A student investigates if listening to classical music can improve your memory IV: DV:
2) Sort the following steps of the scientific method in order by placing a 1-5 next to each step: 3 Draw a conclusion Controlled Experiment Make a Hypothesis State a Problem Make a Prediction 3) A good experiment should have independent variable(s). 4) Analyze the experiment below before answering questions 4-17: Superman and Batman are arguing about which muscle cream makes them look stronger in their spandex outfits. They decide to conduct an experiment to find out. For one month, they give 50 men, ages 18-25 Superman Cream; 50 other men of the same age get Batman Cream; and 50 other men of the same age et no cream at all. After one month, they measure each man s increase in muscle mass to see who was right. a. What is the independent variable? b. What is the dependent variable? c. What is/are the experimental group(s)? d. What is the control group? e. List at least 3 constants from the experiment: 5) Matching: Read through each of the following terms and place the letter of the corresponding definition in the blank provided. 9. Independent Variable 10. Hypothesis 11. Dependent Variable 12. Constants 13. Controlled Experiment 14. Theory 15. Scientific Method A. The effect the scientist measures in an experiment B. An educated guess C. The process scientists use to solve problems D. An explanation supported by lots of evidence E. Things that stay the same throughout an experiment F. A fair test of a scientific question G. What the scientists manipulates in an experiment
III. Graphing 4 Directions: Label the graph below using the following terms: Directions: Look over the data chart below. Use this information to answer the questions about the chart and to create a graph. Oxygen can be generated by the reaction of Hydrogen Peroxide with Manganese Dioxide. 2H 2 O 2 + MnO 2 2H 2 O + Mn + 2O 2 A chemistry class sets up nine test tubes and places different masses of MnO2 in each test tube. An equal amount of H2O2 is added to each test tube and the volume of gas produced is measured each minute for five minutes. The data from the experiment is:
5 1. What volume of O2 did tube #3 produce between the second and fourth minutes? 2. How much O2 is produced in tube #5 during the first two minutes? 3. How much oxygen did tubes 7 and 8 produce together during the third minute? 4. What volume of oxygen gas, in liters, was produced during this procedure 5. What is the independent variable? 6. What is the dependent variable? 7. Graph the data for tubes #1 and #3 using the graphing paper on the back of your homework.
6 III. Metric System Directions: Using the metric system ladder above answer the following questions. 1) 68598 mm = dkm 2) 5.087 hm = cm 3) 678 km dcm 4) 7 cm = hm 5) 0.000987 m = mm IV. Extra Credit: Activity 1: Practice Labeling the Parts of a Microscope
Activity 2: Practice Calculating Magnification 7 On this compound microscope, the eyepiece has a magnification of 10X. The low-powered objective lens has a magnification of 10X. The medium-powered objective lens has a magnification of 20X. The high-powered objective lens has a magnification of 40X. Find the TOTAL MAGNIFICATION of each objective. 15. Low-powered objective X = OBJECTIVE EYEPIECE TOTAL magnification magnification magnification 16. Medium-powered objective X = OBJECTIVE EYEPIECE TOTAL magnification magnification magnification 17. High-powered objective X = OBJECTIVE EYEPIECE TOTAL magnification magnification magnification 18. A student wants to view cells under the compound microscope at total magnification of 400X. If the eyepiece is 10X, what power lens should the student use? 19. A student views cells under a microscope at a total magnification of 1000X. If the lens has a magnification of 100X, what power magnification is the eyepiece?