measurement and data collection

PRE-AP BIOLOGY

Measurement and Data Collection

Bellwork

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You are making a 10% gelatin solution by adding 10 g of gelatin to 100 mL of water and heating to 70oC. What measurement tools would you use to make this solution?

Be ready to share

Objectives

Define the international system of unitsCalculate conversions between metric units Identify scientific tools in the laboratory used

for measurement

Purpose

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• Your experimental results will not mean very much if you don’t have a way to attach numbers or non-opinion descriptions to them.

• The numbers collected must be expressed in units that have the same meaning world-wide

• Scientists have developed tools to assist in data collection

• Proper organization of the data allows the scientist to determine what the data really means.

International System of Units-Metric System

Scientists use the metric or SI systems of units for the measurement of physical quantities-length, volume, and mass

This system of measurement is used world-wide

The metric system is a decimal system of measurement that is scaled on multiples of 10

Prefixes are used in front of the units to indicate powers of ten

Metric System

Measurement Base Unit Symbol

Mass gram g

Length meter m

Volume liter L

Metric Prefixes

Prefix Symbol Power Prefix Symbol Power

tera- T 1012 deci- d 10-1

giga- G 109 centi- c 10-2

mega- M 106 milli- m 10-3

kilo- k 103 micro- 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 Always convert to base units first

Ex. To convert cmkm must first convert cm to m then to km

Make conversions using the prefix definition Ex. Use the conversion 1 cm = 102 m rather than 1 m = 100 cm

Example

Conversion of 6.5 km to m Start with what?

Why do I need to learn this method?

You need to fill your swimming pool with your garden hose. The hose releases 1L of water per minute. Your pool holds 1000 kLof water. How long will it take to fill your pool?

Can you answer this by moving the decimal point?

Example

Conversion of 6.5 km to m

Practice Problem-complete on note-taker

435 mL L

Practice Problem-complete on note-taker

5.39 g mg

Measurement tools used in Biology

Reading a Meter Stick

Meter Stick – major scale division represent centimeters

Each cm is further divided into minor scale divisions-0.1 cm or 1 mm divisions

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 numbers– Minor scale divisions

between the numbers

• Read the volume at the bottom of the meniscus

Use of balance for determining massIn this class, an electronic balance will be used for measuring mass

Zero the balance by hitting the Tare button before each measurement

Place object on stainless steel tray

Read the value for massIf you get the tray dirty,

please clean it off

Closure Activity

Name two measurement tools discussed in the notes today and explain how they are used in measurement.

Measurement Lab

Constructing well organized Data Tables

Example of a Good Data Table-

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Date Height in cm of plant

Appearance of leaves

4/5/11 10 Leaves are green and there are 2 areas of light green new leaves

4/6/11 10 All leaves are green and there are 3 areas of light green new growth

4/7/11 11 The plant has 3 areas with light green leaves. The leaves appear to be larger

4/8/11 13 Plant is more spread out and has 5 areas of light green leaves

4/9/11 16 Plant has 5 areas of light green leaves

Effect of fertilizer on plants

TThinkhink-P-Pairair-S-SharehareExamine the example data

table. Write down key characteristics of a data table on your note-taker.

Share with a partner3

Data table characteristics

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• Title• Clear labels• Dates• Column/row labels• Units are included• Easy to view• Straight lines• All data can be displayed

PROPERTY OF PIMA COUNTY JTED, 2010 24

Minute Paper- think back to Minute Paper- think back to the bellworkthe bellworkYou have one minute to write down qualitative and quantitative data in the form of a data table that you might take on the new species of plant

Be prepared to share.