Unit I: Intro to Biology

Part IV: Measurement &

Data Collection

Intro ?•You have just discovered a new plant species, write down what kind of information you would include in your description of the plant to help others identify the plant.

Data Collection

Two Types of Data•Qualitative:•Descriptive – use words to describe an object

•Quantitative:•Uses numbers to describe an object

•Give examples of qualitative & quantitative data for describing the Gila Monster

Mars Climate Orbiter

• https://www.youtube.com/watch?v=ZD4jPnk49PE• https://www.youtube.com/watch?v=q2L5_swAT5A

Purpose of Measurement•Experimental results have no meaning unless there are numbers or written descriptions

•As science is international, the numbers must have the same meaning world-wide

International System of Units: Metric System

•Used for measurement of physical quantities •Length•Volume •Mass•Based on a decimal system of measurement – multiples of 10•Prefixes of units indicate powers of ten•Used world-wide

Metric SystemMeasurement Base Unit Symbol

Mass gram g

Length meter m

Volume liter L

Metric PrefixesPrefix Symbol Power Prefix Symbol Powertera- T 1012 deci- d 10-1

giga- G 109 centi- c 10-2

mega- M 106 milli- m 10-3

kilo- k 103 micro- µ 10-6

hecto- h 102 nano- n 10-9

deca- da 101 pico- p 10-12

Metric Conversions•When converting between metric units, follow these rules…1. Always convert to base units first•Example: To convert cm à km, must convert cm to m then to km

2. Make conversions using the prefix definition•Example: Use the conversion 1cm = 102m rather than 1m = 100cm

Example•Conversion of 6.5km to m•Start with what??•Convert to what??

Try on your Own…•Conversion of 435mLàL•Start with what??•Convert to what??

Try on your Own…•Conversion of 5.39kgàmg•Start with what??•First, convert to what??•Then, convert to what??

Measurement Tools in Biology

Measurement Tools•Length – metric ruler•Volume -•Greater than 10mLs – graduated cylinder•Less than 10mLs – pipette•Mass – triple beam balance or electronic balance

Reading a Metric Ruler•Metric Ruler – major scale of division represents centimeters

•Each cm is further divided into minor scale divisions – millimeters (mm)

Measurement of Volume•Measures the amount of space something occupies• In biology…• Volume traditionally measured in liters (L), milliliters

(mL), or microliters (µL)• Commonly use graduated cylinders or pipettes for

measuring volume• Beaker is NOT used• Graduations are only estimates• Only use beakers for mixing solutions

Reading Volume in a Graduated Cylinder

•Graduated cylinder is marked off in equal units of volumes•Usually they are graduated in mLs•Most graduated cylinders have:• Major scale divisions – associated with whole numbers• Minor scale divisions between the numbers

• Read the volume at the bottom of the meniscus

What is the Volume?

Volume of a Solid Object•Measured by volume displacement•Volume of object = final volume – initial volume

Measurement of Mass•Mass: quantity of matter in an object

irrespective of its volume or the forces acting on it• Gravitational force has no effect on mass

• Units for mass• In biology, commonly measured in grams (g) or milligrams

(mg)

• Distinction from weight:• Measurement of gravitational force on an object• Weight changes depending on gravity

Use of Balance for Mass•In this class, you will use triple beam

balance or an electronic balance for measuring mass•For the electrical balance:•Zero the balance by hitting the tare button•Place weigh boat with object on stainless

steel tray•Read the value for mass

Use of Balance for Mass

•Never weigh a sample directly on the balance pan. Use:•Weigh paper – for solids under a gram•Weigh boat – for solids above a gram

Use of Balance for Mass•For the triple beam balance:•Make sure the TBB is balanced &

tared•Place your object on the metal tray• In this class, we will use these for

weighing larger objects•Read the value for mass

What is the Mass?1.

2.

Measuring Temperature• Thermometers measure temperature based on a

temperature scale• Three types of scales…• Fahrenheit• Freezing Temp of Water - 32oF• Boiling Temp - 212oF

• Celsius• Freezing Temp - 0oC• Boiling Temp - 100oC

• Kelvin – SI Unit of Measure• 0K – absolute zero

Converting Between oFand oC

•The following equations can be used for converting between oF and oC•oC=(5/9) x (oF-32)•oF= [(9/5) x oC] +32

Example•Conversion of 86oF to oC• Start with what??• Convert to what??

•Conversion of 12oC to oF• Start with what??• Convert to what??

Calculating Kelvin•Calculation of Kelvin:•K = oC + 273

Example•Conversion of 30oC to K•Start with what??•Convert to what??

Answer the ?s in Note Guide