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Learn when to notify your instructor of unsafe conditions in the lab and how measurement practice impacts accuracy and precision.
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Bell Ringer #11 Feb 13, 2012 In many classrooms, lab exercises are performed by small groups of students. The students are supervised by a teacher who monitors each group’s progress periodically. When should you notify your instructor of unsafe conditions in the lab? A immediately B after the lab period C after your data has been collected D when the instructor comes by your station
Lab Equipment SI Units
Jan consistently read the volume of liquids as shown. How would this practice impact her work? • Her measurements would lack precision. • Her measurements would be very accurate. • Her measurements would be too high. • Her measurements would be too low for less dense liquids.
10. Which measurement units best describe the size relationship of cells to organs? A centimeters to meters B meters to millimeters C millimeters to micrometers D micrometers to centimeters
Experimental Design Scientific Method Hypothesis Independent v. Dependent
Harvester ants often strip a bush of all of its leaves. Some people believe this helps the plant grow thicker, healthier stems. In an experiment, a student stripped off all the leaves from a set of plants. In a second set of identical plants, the student allowed ants to strip off the plants’ leaves. In order to improve this experimental design, it is most important to add a set of plants — • of a different species • with its leaves left intact • exposed to a different ant species • that are dormant Bell Ringer #29 March 27th, 2012
A biology class wanted to develop a research project to predict the effects of a new highway on wildflower species found in the Piedmont region of Virginia. The class could best conduct such a study by sampling flowers found in the highway construction area — • during the time highway construction is taking place • both before and after highway construction is completed • immediately after highway construction is finished • one year before highway construction begins
56. Anita is studying the factors that affect seed growth. She wants to test whether soaking seeds in water affects the sprouting process. Which should Anita measure to get the most useful results? A growth of 100 soaked seeds at a given temperature B growth of 100 regular seeds at different temperatures C growth of 50 soaked and 50 regular seeds at a given temperature D growth of 50 soaked and 50 regular seeds at different temperatures
People long ago believed that maggots came from meat. In the late 1600s, Francesco Redi made the hypothesis that maggots came from flies rather than from meat. Which of these experimental designs could be used to test Redi’s hypothesis?
A biology class of 24 students decides to measure the height of each student and then calculate the average height for the class. Which of these is a possible source of error in this activity? • The number of males and females in the class • The difference in the ages of the students in the class • The total number of students in the class • The accuracy of making and recording measurements
49. Molly grew four bean plants in pots with the same soil and provided each with an equal amount of light. She gave each plant different amounts of the reactants involved in photosynthesis. She then measured the amount of gas produced by each plant and their increase in height over a few weeks. An independent variable in Molly’s experiment is the amount of A water given to each plant B height gained by each plant C oxygen produced by each plant D carbon dioxide produced by each plant Bell Ringer #22 March 2nd, 2012
Astudent wanted to look at plant growth in five different soil samples. He planted the same type of seeds in identical containers and left them together in full sunlight. He gave each plant the same amount of water and charted the growth of each plant stem. What is the independent variable in this experiment? • Seeds • Soil • Light • Container Bell Ringer #32 April 2nd, 2012
