U1S4
Tools and Measurement
Tools, Measurement, and Safety
• Objectives
I Can:
Give three examples of how life scientists use
computers and technology.
Describe three tools life scientists use to
observe organisms.
Explain the importance of the International
System of Units, and give four examples of SI
units.
Tools, Measurement, and Safety
• Would you use a hammer to tighten a bolt on a bicycle?
You probably wouldn’t. To be successful in many tasks, you
need the correct tools.
• Life scientists use various tools to help them in their work.
These tools are used to make observations and to gather,
store, and analyze information. Choosing and using tools
properly are important parts of scientific work.
Computers and Technology
• The application of science for practical purposes is called
technology. By using technology, life scientists are able to
find information and solve problems in new ways. New
technology allows scientists to get information that wasn’t
available previously.
Tools, Measurement, and Safety
• Since the first electronic computer was built in
1946, improvements in technology have made
computers more powerful and easier to use.
Computers can be used to create graphs, solve
complex equations, and analyze data.
Computers also help scientists share data and
ideas with each other and publish reports
about their research.
STOP! On page 16, answer:
• What do life scientists use tools for?
• When was the first electronic computer built?
• How do scientists use computers?
Tools, Measurement, and Safety
Tools for Seeing
• It’s difficult to make accurate observations of things
that cannot be seen. When the first microscopes
were invented, scientists were able to see into a
whole new world. Today, the workings of tiny cells
and organisms are well understood. New tools and
technologies allow us to see inside organisms in new
ways. For example, the images shown in Figure 1
were created by sending electro magnetic waves
through human bodies.
Tools, Measurement, and Safety
Figure 1 The image on the left is a computerized axial
tomography scan (CAT scan). The image on the right was
made with magnetic resonance imagery (MRI).
Tools, Measurement, and Safety
Compound Light Microscope
• The compound light microscope is a common tool in
a life science laboratory. A compound light
microscope is an instrument that magnifies small
objects so that they can be seen easily. It has three
main parts—a tube with two or more lenses, a stage,
and a light. Items viewed through a compound
microscope may be colored with special dyes to
make them more visible. Items are placed on the
stage so that the light passes through them. The
lenses at each end of the tube magnify the image.
Tools, Measurement, and Safety
Electron Microscopes
• Not all microscopes use light. In electron microscopes, tiny
particles called electrons are used to produce magnified
images. The images produced are clearer and more detailed
than those made by light microscopes. However, living things
cannot be viewed with electron microscopes because the
preparation process kills them. There are two kinds of
electron microscopes used in life science—the transmission
electron microscope (TEM) and the scanning electron
microscope (SEM). Figure 2 shows each kind of microscope,
describes the specialized purpose of each, and shows an
example of the images each can produce.
Tools, Measurement, and Safety
STOP!
• A scientist wants to look at a living cell.
Should the scientist use a compound light
microscope or electron microscope? Explain
your answer on page 16.
Tools, Measurement, and Safety
Measurement
• The ability to make reliable measurements is an
important skill in science. But different standards of
measurement have developed throughout the world.
Ancient measurement units were based on parts of
the body, such as the foot, or on objects, such as
grains of wheat. Such systems were not very reliable.
Even as better standards were developed, they
varied from country to country.
Tools, Measurement, and Safety
The International System of Units
• In the late 1700s, the French Academy of Sciences began to
form a global measurement system now known as the
International System of Units (also called SI, or Système
International d’Unités). Today, most scientists and almost all
countries use this system. One advantage of using SI
measurements is that it helps scientists share and compare
their observations and results.
• Another advantage of SI units is that almost all units are based
on the number 10, which makes conversions from one unit to
another easier. Table 1 contains commonly used SI units for
length, volume, mass, and temperature. Notice how the prefix
of each SI unit relates to a base unit.
Stop
• Galileo Dialog and Test
– What is SI?
Tools, Measurement, and Safety
Length
• How long is an ant? A life scientist would
probably use millimeters (mm) to describe an
ant’s length. If you divide 1 m into 1,000 parts,
each part equals 1 mm. So, 1 mm is onethousandth of a meter. Although millimeters
seem small, some organisms and structures
are so tiny that even smaller units—
micrometers (µm) or nanometers (nm)—must
be used.
Tools, Measurement, and Safety
Area
• How much paper would you need to cover your
desktop? To answer this question, you must find
the area of the desk. Area is a measure of how
much surface an object has. Area can be
calculated from measurements such as length
and width. Area is stated in square units, such as
square meters (m2), square centimeters (cm2),
and square kilometers (km2).
Tools, Measurement, and Safety
Volume
• How many books will fit into a backpack? The answer
depends on the volume of the backpack and the volume of
each book. Volume is a measure of the size of something in
three-dimensional space.
• The volume of a liquid is most often described in liters (L).
Liters are based on the meter. A cubic meter (1 m3) is equal to
1,000 L. So 1,000 L will fit into a box measuring 1 m on each
side. A milliliter (mL) will fit into a box that is 1 cm on each
side. So, 1 mL = 1 cm3. Graduated cylinders are used to
measure the volume of liquids, as shown in Figure 3.
Tools, Measurement, and Safety
Figure 3 A rock added to a graduated cylinder raised the level of water
from 70 mL to 80 mL of water. Because the rock displaced 10 mL of water
and because 1 mL = 1 cm3, the volume of the rock is 10 cm3.
Tools, Measurement, and Safety
• The volume of a solid object is given in cubic
units, such as cubic meters (m3), cubic
centimeters (cm3), or cubic milli-meters
(mm3). To find the volume of a box-shaped
object, multiply the object’s length by its
width and height. As Figure 3 shows, the
volume of an irregularly shaped object is
found by measuring the volume of liquid that
the object displaces
Tools, Measurement, and Safety
Mass
• How much matter is in an apple? Mass is a measure
of the amount of matter in an object. The kilogram
(kg) is the basic unit for mass. The mass of a very
large object is described in kilograms or metric tons.
A metric ton equals 1,000 kg. The mass of a small
object may be described in grams (g). A kilogram
equals 1,000 g; therefore, a gram is one-thousandth
of a kilogram. A medium-sized apple has a mass of
about 100 g. Mass can be measured by using a
balance.
Tools, Measurement, and Safety
Temperature
• How much should food be heated to kill any bacteria in the
food? To answer this question, a life scientist would measure
the temperature at which bacteria die. Temperature is a
measure of how hot or cold something is. Temperature is
actually an indication of the amount of energy within matter.
You are probably used to describing temperature in degrees
Fahrenheit (ºF). Scientists commonly use degrees Celsius (ºC),
although the kelvin (K) is the official SI base unit for
temperature. You will use degrees Celsius in this book. The
thermometer in Figure 4 shows how two of these scales
compare.
Tools, Measurement, and Safety
Figure 4 Water freezes at 0ºC and boils at 100ºC. Your normal body
temperature is 37ºC, which is equal to 98.6ºF.
STOP!
• What SI units are used for volume?
• What are three different units for measuring
temperature?
Tools, Measurement, and Safety
• Section Summary
• Life scientists use computers to collect, store, organize,
analyze, and share data.
• Life scientists commonly use light microscopes and electron
microscopes to make observations of things that are too small
to be seen without help. Electromagnetic waves are also used
in other ways to create images.
• The International System of Units (SI) is a simple and reliable
system of measurement that is used by most scientists.
• Section Review
• To answer questions online, click here.