Measuring Small Volumes and Mixing Solutions

What do we do in biology?

• measure

• calculate

• use correct scientific units

What can we measure in biology?

• length

• mass

• weight

• volume

• density

• temp

How do we measure?

using the metric system

Metric system

internationally standardized system of measurements used in science

Length

• kilometer (km)

• meter (m)

• centimeter (cm)

• millimeter (mm)

Converting lengths

• 1 km = 1000 m

• 1 m = 100 cm

• 1 cm = 10 mm

Body temperature

• celsius = 37 degrees

• fahrenheit = 98 degrees

Volume

• liter (L)

• milliliter (mL)

• microliter (uL)

Converting volumes

• 1 L = 1000 mL

• 1 ml = 1000 uL

• 1 uL = 1000 nL

What does the first stop on the plunger on a micropipette do?

draws up the liquid

What does the second stop on the plunger on a micropipette do?

expels the liquid

What should you never do when using a micropipette?

• use it w/o a disposable tip attached

• exceed upper/lower volume limits of the pipette

• turn pipette upside down

Mass

• kilogram (kg)

• gram (g)

• milligram (mg)

• microgram (ug)

Converting masses

• 1 kg = 1000 g

• 1 g = 1000 mg

• 1 mg = 1000 ug

Mass definition

measures amount of MATTER in an object

Weight definition

measures attraction BETWEEN 2 OBJECTS due to gravity

Tare

zeroing out the balance so it reads 0g to get a clear reading of the mass

Tips for using a balance

• make sure its clean and stable

• use weighing boat/weighing paper

Scientific notation definition

a way of expressing numbers that are too large or too small to be written in decimal form

Ex.) write in decimal form: 1.6 × 10^-6

0.0000016 g

• negative exponent = move RIGHT

Ex. write in scientific notation: 40141900000000 km

4.01419 × 10^13 km

• positive exponent = move LEFT

Accuracy

refers to the closeness of a measured value to a STANDARD or known value

Precision

refers to the closeness of 2 or more measurements to EACH OTHER