Chapter 3: Measurement, Errors, Data and Unit Conversion Martin Caon Examination Questions and Answers in Basic Anatomy and Physiology Third Edition

Martin Caon Examination Questions and Answers in Basic Anatomy and Physiology Third Edition Chapter 3: Measurement, Errors, Data and Unit Conversion 3.1 Measurement and Errors 1. Say that someone’s body temperature is measured by four different devices and the resulting four measurements are given below. Which reading has an absolute error of ±0.05 °C? a. 38 °C b. 37.8 °C c. 37.85 °C d. 37.855 °C Answer is B: Absolute error is plus or minus half the smallest scale interval. Two times 0.05 = 0.1, so the smallest scale interval is 0.1 of a degree Celsius which applies to the 37.8 °C value. 2. If someone’s height is measured while the person is wearing shoes, the height will be overestimated. This type of error is known as which of the following? a. Absolute error b. Parallax error c. Calibration error d. Zeroing error Answer is D: Zeroing error because in this example, the object being measured is not aligned with the start of the measuring scale. 3. A bathroom scales displays a mass reading of 68.4 kg. Which one of the following could NOT be the true mass of the person standing on the scales? a. 68.40 kg b. 68.44 kg c. 68.47 kg d. 68.37 kg Answer is C: A reading of 68.4 (that is, stated to the nearest 0.1 kg) means that the actual value is between 68.35 and 68.44, so only 68.47 (which is closer to 68.5) is outside this range. 4. Look at the figure of a thermometer. What is the temperature reading? a. 15 °C b. 15.4 °C c. 17 °C d. 20 °C Answer is C: Every 5 scale intervals is labelled with a number, and each interval corresponds to 1 °C. As the reading is two intervals above 15: 15 + 2 = 17. 5. Look again at the figure of a thermometer. What is the absolute error of the temperature reading? a. ±0.05 °C b. ±0.5 °C c. ±1.0 °C d. ±5.0 °C Answer is B: Absolute error is plus or minus half of the smallest scale interval (which is 1 °C), half of one is 0.5. 6. On a clinical thermometer where the smallest scale interval is 0.1 °C, a person’s temperature is measured to be 37.7 °C. Which of the listed temperatures could NOT be the person’s true temperature? a. 37.72 °C b. 37.76 °C c. 37.67 °C d. 37.685 °C Answer is B: An actual value of 37.76 °C would be seen on a scale that has 0.1 as its smallest interval, as 37.8. All other values are closer to 37.7 than they are to 37.8 or to 37.6. 7. What is meant when a person’s mass is stated as 73.6 kg? a. The mass is closer to 73.6 than it is to 73.7 or 73.5. b. The mass is closer to 73.6 than to any other value. c. The mass is between 73.5 and 73.7. d. The mass is 73.6 ± 0.1 kg. Answer is A: Because the mass is stated to one decimal place, the absolute error is ±0.05. 8. Which of the following measurements is a semi-quantitative one? a. A blood pressure of 120/80 mmHg b. A blood glucose level of +++ c. A state of anxiety measure of “calm” d. The patient’s name is Tim Cruise Answer is B: The number of “+” signs indicates a level of magnitude that is semiquantitative, but there is no unit of magnitude. C is “qualitative”, while D is “nominal”. 9. A baby’s mass measurement is 3.8 ± 0.05 kg. What is the absolute error in the measurement? a. ±0.05/3.8 b. ±(0.05/3.8) × 100% c. ±0.05 kg d. 0.05 kg Answer is C: By definition, absolute error is half the smallest scale interval (0.1 in this case) above and below the measured value. 10. 1 mL of water has a mass of 1.00 g. Which of the following sets of three measurements of the mass of 1 mL of water is the most precise set? a. 0.98 g, 1.00 g, 1.02 g b. 0.99 g, 0.99 g, 0.99 g c. 1.00 g, 1.01 g, 1.02 g d. 0.99 g, 0.99 g, 1.00 g