314 Biology: Appendix E: Measurements

textbook page 893

Scientists measure: Systeme Internationale d’ Unites – International System of Units

Modified SI used in France and is common system used throughout the world today.

** **

**Four units:**

Meter – length

Kilogram – mass

Kelvin temperature

Second – time

All other units are derived from the above units.

Some of the units will be used in the experiments we do in class.

** **

**Length:**

1 kilometer ( km ) = 1000 meters

1 hectometer ( hm ) = 100 meters

1 dekameter ( dkm ) = 10 meters

1 meter ( m )

1 decimeter ( dm ) = 0.1 meter

1 centimeter ( cm 0 = 0.01 meter

1 millimeter ( mm ) = 0.001 meter

1 micrometer ( m m ) = 0.000001 meter

1 nanometer ( nm ) = 0.000000001 meter

- The meter is basic unit for length.

- Increments of increasing or decreasing by power of 10.

- Most frequently used is cm.

- Area = length x length = squared length

- cm x cm = cm
^{2}, used in lab setting

- hectometer x hectometer = 10,000 m
^{2 }, also known as a hectare

** **

Mass:

1 kilogram ( kg ) = 1000 grams

1 hectogram ( hg ) = grams

1 dekagram ( dkg ) = grams

1 gram ( g )

1 decigram ( dg ) = grams

1 centigram ( cg ) = grams

1 milligram ( mg ) = grams

1 microgram ( m g ) = grams

1 nanogram ( ng ) = grams

- Like the meter, mass is based on the gram.

- Mass increases or decreases by the power of 10.

- Lab measures are usually in kg, g, cg, mg.

**Volume:**

1 kiloliter ( kL ) = 1000 liters

1 hectoliter ( hL ) = 100 liters

1 dekaliter ( dkL ) = liters

1 liter ( L )

1 deciliter ( dL ) = liter

1 centiliter ( cL ) = liter

1 milliter ( mL ) = liter

- SI units of volume = L x W x H = meter cubed ( m
^{3}) is the standard unit.

- Not officially part of SI, liters used to measure volume of liquids.

- 1000 liters in 1 meter cubed
- 1 L = 0.001 m
^{3} - 1 mL = 1 cm
^{3}, used in the lab. Glassware marked for mL or L

** **

Temperature:

- degrees Celsius used in this course. Which are equal to kelvins.
- 0
^{0}C = freezing point of water - 100
^{0}C = boiling point of water - Fahrenheit scale still used in the U.S.
- 32 degrees F = freezing point of water
- 212 degrees F = boiling point of water

Molarity ( M ) – measures the concentration of a dissolved substance in a solution.

High molarity indicates high concentration