The Mertic System--Answer Key

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Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 11 THE METRIC SYSTEM Objectives 1. Convert measurements between different metric units. • kilo (k) = 1000 x base unit • base unit = 1 x base unit • centi (c) = 0.01 x base unit • milli (m) = 0.001 x base unit • micro (μ) = 0.000001 x base unit • nano (n) = 0.000000001 x base unit 2. Determine what metric units to use when measuring mass, volume, temperature, and length. 3. Accurately measure mass, volume, and length. 4. Determine average body temperature, typical room temperature, and freezing and boiling points of water (in Celsius). 5. Collect data and construct graphical representations of data using a line graph. Case Study: “Island Adventure ” You are a budding marine biologist. This summer you applied to go on a month-long expedition to explore local marine life on an island in the South Pacific. In the acceptance letter, you are reminded that all measurements made during this trip must be in metric units. As you research different units, you learn that the metric system is the standard system of measurement in most of the world and in all scientific fields. In this lab, you will review the different units of scientific measurement, and practice converting among them. Metric Conversions The metric system is a system of measurements that uses the base units of meter for length, liter for volume, and gram for mass. The metric units are: • Length or distance = meter (m) • Mass = gram (g) ● Volume = liter (L) All units of length in the metric system are derived from meter as the base unit. Conversion between units of length in the metric system are based on factors of ten and moving the decimal point to the right or to the left. The units to the right of the base unit are smaller than the base unit. As we move to the right, each unit is 10 times smaller or

Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 12 one-tenth of the unit to its left. The units to the left of the base unit are bigger than the base unit. As we move to the left, each unit is 10 times greater than the unit to its right. A prefix is a group of letters added before the base unit. The prefix “centi-“ means one hundredth. A centimeter is one hundredth of a meter. The prefix ‘kilo’ is a thousand times the base unit. Conversion between units of length in the metric system involves moving the decimal point to the right or to the left. The prefixes have the same meanings whether they are attached to the units of length (meter), mass (gram), or volume (liter). The table below contains ways to help you to convert among the different units you will be working with in lab ( Table 1 ). Meter (m), liter (L), and gram (g) are defined as “base units” and thus do not use a prefix. The prefixes are in increments (powers) of ten. As you move to the right of the base unit, the subdivisions become 10x smaller, and those to the left of the base unit become 10x larger. To make a measurement into a smaller unit, move the decimal to the right. This effectively makes the number larger. Similarly, measurement values get larger as you move to the left. To help you remember the order of units on the table you can use the following mnemonic. “King Henry Doesn’t Usually Drink Chocolate Milk” King is kilo, Henry is hecto, Doesn’t is deca, Usually is the base unit, Drink is deci, Chocolate is centi, and Milk is milli Table 1: Prefixes for the metric system units of measurements King Henry Doesn’t Usually Drink Chocolate Milk Kilo (k_) Hecto (h-) Deca/Deka (da_) Base Unit Deci (d_) Centi (c_) Milli (m_) 0.001 km 0.01 hm 0.1 dam 1 meter 10 dm 100 cm 1,000 mm 1,000 times larger than the base unit 100 times larger than base unit 10 times larger than base unit Base unit 10 times smaller than base unit 100 times smaller than base unit 1,000 times smaller than base unit When moving to the RIGHT, move the decimal point to the RIGHT When moving to the LEFT, move the decimal point to the LEFT

Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 13 Example 1: 1.0 centimeter (cm) equals how many millimeters (mm)? On a metric ruler, centimeters (cm) are indicated with whole numbers. The smaller lines between each centimeter represent millimeters (mm). One way observe this is to count the number of small lines from the start of the ruler to 1.0 cm ( Figure 1 ). You should count ten little lines. Another way to do this conversion is to look at the chart and see how many columns are between the two units. To move from centimeters (cm) to millimeters (mm) you need to move one column to the right. This will equal moving the decimal one place to the right: 1.0 cm = 10 mm (Table 1). Example 2: 1.0 meter (m) equals how many millimeters (mm)? Millimeter (mm) is three columns to the right of a meter (m). For every column that you count, move the decimal place in the same direction the same number of places. To convert meters to millimeters you move three columns to the right. To convert 1.0 meter (m) to millimeters (mm) you will move the decimal three places to the right. Each time you move the decimal, add a zero to the number. Thus, 1.0 m = 1,000 mm Example 3: 1.0 meter (m) equals how many kilometers (km)? Consider the units in this example: for perspective, the length of the body is typically measured in meters (m) while the length between cities is measured in kilometers (km). Kilometers (km) are larger units than meters (m). Therefore, 1.0 meter (m) would be a fraction of a kilometer (km). The number of kilometers in one meter will therefore be a very small number. Figure 1: A centimeter ruler with millimeter markings cm 1 2 10 mm 1 cm Milli (m_) Centi (c_) 10 mm 1 cm 1 jump Figure 2: Conversion chart for metric units. Milk Chocolate Drink Usually Milli (m_) Centi (c_) Deci (d_) Base Unit 1,000 mm 100 cm 10 dm 1 meter 1 When moving to the RIGHT move the decimal point to the RIGHT 2 3 1 m = ? mm 1 m = 1 . 0 . 0 . 0 . 1 2 3 1 m = 1,000 mm Usually Doesn’t Henry King Base Unit Deca/Deka (da_) Hecto (h_) Kilo (k_) 1 meter 0.1 dam 0.01 hm 0.001 km When moving to the LEFT move the decimal point to the LEFT 3 2 1 1 m = ? km 1 m = .0 .0 .1 . 3 2 1 1 m = 0.001 km

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Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 14 Kilometers are three columns to the left of meters. You will therefore need to move the decimal point three places to the left. 1.0 meter (m) will thus equal 0.001 kilometers (km). The number got much smaller as you moved to the left on the chart, while the units got larger ( Figure 2 ). Conversely, as you move to the right in the chart, the numbers will get bigger and the units will get smaller, such that 1.0 km = 1,000 m. Example 4: 1.0 meter (m) equals how many micrometers (µm)? How do you convert if the prefix is not between kilometers to millimeters? Easily! You can use the following chart and follow the rule that each prefix is based on the power of ten ( Table 2 ). A meter (m) is the base unit for length and is equal to 1.0 x 10 0 which is one. Micrometers (µm) are 1.0 x 10 -6 . The exponential power tells you how many places to move the decimal and the direction. Micrometers (µm) have a negative exponent and are much smaller than meters (m) and therefore you need to move the decimal to the right six places. (1.0 m = 1,000,000 µm) Example 5 : 1.0 micrometer (µm) equals how many millimeters (mm)? Micrometer (µm) is 1.0 x 10 -6 , which means that you will move the decimal six places to the right from meters (m). Millimeter (mm) is 1.0 x 10 -3 , which means that you will move the decimal three places to the right from meters. To calculate how many places to go from micrometer to millimeter, simply subtract the exponential numbers: 6 - 3 = 3. Since you are moving from micrometers to millimeters the number will get smaller because millimeters is a larger unit. You will need to move the decimal three places to the left. (1.0 µm = 0.001 mm) Table 2: Conversion chart between metric units. Metric Unit Abbreviation Description Decimal Scientific Notation Meter m Base unit of length 1.0 m 1.0 x 10 0 Decimeter dm One-tenth of a meter 0.1 m 1.0 x 10 -1 Centimeter cm One-hundredth of a meter 0.01 m 1.0 x 10 -2 Millimeter mm One-thousandth of a meter 0.001 m 1.0 x 10 -3 Micrometer µm One-millionth of a meter 0.000001 m 1.0 x 10 -6

Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 15 Activity 1: Metric units for length Background: When learning about different species, range of length is frequently given to help properly identify a species. The following activity will describe the metric units for length and how to convert between smaller and larger metric units. Procedure: (Work individually) 1. Practice converting metric units by filling out the chart below. Use the number in bold as your starting measurement. Fill out each row based on the bolded number. (Refer to Table 1 for help.) Instructor’s initials: ________

Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun Activity 2: Measuring and estimating volume, mass, and temperature Background: Just as you practiced understanding the units for length (meters), now you will practice using the units for mass (grams) and volume (liters). We will also determine the range of temperatures in degrees Celsius (°C). Procedure: (Work in pairs)

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Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 17 7. Dump the water out of the weigh boat back into the water beaker. Place the empty weigh boat on the scale and tare the scale. Use the 2 mL volumetric pipet with a regulator to remove 2 mL of water from the beaker of water. Remember to not fill the pipet all the way to the top. Place the water into the weigh boat and weigh the 2 mL of water on the scale. Continue to weigh increments of 2 mL until you reach 10 mL in the weigh boat. Record the measurements in grams (g) in the table below. Volume of water (mL) Mass of water (g) 2 mL 2g 10 mL 10g 6 mL 6g 4g 4 mL 8 mL 8g

Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 18 11. Erlenmeyer flask and beakers are not accurate for measuring liquids. a. Measure 10 mL of water in the 25 ml Erlenmeyer flask. Pour the water into the tared empty weigh boat and weigh the 10 mL of water. After recording the weight of the water, pour it back into the water beaker. b. Measure 10 mL of water in the 50 mL beaker. Pour the water into the tared empty weigh boat and weigh the 10 mL of water. After recording the weight of the water, pour it back into the water beaker. 12. 13. 14. Mass of water from the Erlenmeyer flask ____ vairable _______________. c. Mass of water from the beaker ___ variable ________________. d. How close were these weights to your answer in question 6 above? variable

Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 19 15. Activity 3: Putting it all together Background : Time to practice your newfound skills and see if you are ready to go out on an expedition to discover a new species! Procedure : (Work in pairs) 1. Look at the sample of an unknown marine animal. 2. Record the following measurements of your unknown marine animal to the best of your ability and use the correct units. 4. When done with all the activities in lab, make sure to clean up your lab space and return all supplies used to the tray as seen in the picture on your tray and counter. Water should boil at 100°C and freeze at 0°C. How did your results in question 14 compare to the expected? If there was a difference, can you think of a reason why? variable a. Length:_______ variable ________ b. Width:________ variable ________ c. Weight:_______ variable ________ 3. Use complete sentences to describe this animal. You must include the three different measurements from question 2. Pick one additional measurement to include in your description. variable

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Bio 101 Lab Supplement The Metric System Spring 2024 Northern Virginia Community College, Loudoun 20 5. Before leaving lab, check that you have completed all items in the “ Lab Checkout ” list on the next page. You must have your instructor sign that you have completed all items on the list before leaving lab. Name: ________________________ Date: ___________________ Lab Checkout: When you finish the lab, please clean up your lab space and put away your materials neatly in the tray. Please get your instructor’s initials to check-out of lab. q Lab bench clean, washed, and dried q Glassware washed, dried, and in tray q Place the graduated cylinders on their side in the tray q Place the pennies back into the weigh boats q Trays neatly put away Instructor initials: % Completion of activities: ____________

The Mertic System--Answer Key

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