Introduction
to Math Topics in Biology
Units
and Scientific Notation
Introduction:
Data is usually acquired via
measurement. (mass, volume, length,
temperature, pressure, pH, …)
Most of the time scientific data
are expressed in units of the modern metric system, which is also called the
International System (SI) of Units. Metric
units are often referred to as SI units. In
the metric system the basic units are the gram (g) for mass, the meter (m) for
length, and the liter (l or L) for volume.
Objectives:
-
Define the terms used in this lab: precision, accuracy, significant
figures, meter, gram, liter.
Preparation
– To Do Before class:
Metric
Units:
In the metric system the basic units are the gram (g) for
mass, the meter (m) for length, and the liter (l or L) for volume.
Prefixes
and Abbreviations:
| Multiplier |
Prefix |
Abbreviation |
Example |
| 109 |
giga-
|
G
|
Gigabyte 109 bytes
(information storage)
|
| 106
|
Mega-
|
M |
M
|
| 103
|
kilo-
|
k
|
kilogram [kg] (a
measure of mass)
|
| 10-1
|
deci-
|
d
|
d
|
| 10-2 |
centi-
|
c
|
centimeter [cm] (10
mm – length)
|
| 10-3 |
milli-
|
m
|
milliliter
|
| 10-6
|
micro- |
µ |
microliter[µl]
(10-6 liter – volume) |
| 10-9
|
nano- |
n
|
nanometer [nm] (wavelegth
of light)
|
| 10-12
|
pico-
|
p
|
p
|
450
nm = ________ m Light
with a wavelength of 450 nm appears “blue” to most humans.
20
µl = ________ l (or L) You
will load 20 µl of DNA into each “lane” of a gel for electorphoresis.
2.54
cm = ________ m One
inch is equal to 2.54 cm.
Activity:
Using different equipment in you
will measure the following volumes of fluid:
1 liter, 500 ml, 5 ml, 1 ml, 100 µl, 20 µl, and 2 µl.
Compare these different volumes and discuss the similar differences
between units of mass and length. Why
is the concept of “order of magnitude” important?
Exercise
1: Conversion
Using the scientific measurement
information in your textbook convert the data below from centimeters to inches
|
Age
(yr)
|
Near-point
accommodation
(cm)
|
Near-point
accommodation
(inches)
|
| 10 |
7.5
|
|
| 20 |
9.0
|
|
| 30 |
11.5
|
|
| 40 |
17.2
|
|
| 50 |
52.5
|
|
| 60 |
83.3
|
|
Represent the following in decimal or scientific notation.
|
1 nm = ____________ m
|
10 mg = ____________ g
|
| 1 cm = ____________mm |
50 µg = ____________mg |
| 1 mm = ____________ nm
|
7.5 µm = ____________ m
|
| 1 µm = ____________ mm
|
1 mm = ____________ µm
|
| 1 µl = ____________ l
|
0.5 nm = ____________ mm
|
| 1 ml = ____________ l
|
1 l = ____________ µl
|
Exercise
2: Scientific Notation
Represent the numbers below in
scientific notation.
| 0.00015 g =
_________________ g |
0.00015 g =
_________________ mg |
| 70,000 g = _________________g |
70,000g = _________________kg |
| 15,000 m = _________________
m |
15,000 m = _________________
km |
| 0.000015 m =
_________________ m |
0.0000015 m =
_________________ µm
|
| 0.0000007 m =
_________________ m |
0.0000015 m =
_________________ nm
|
| 0.00002 l =
_________________ l |
0. 00002 l =
_________________ µl |
| 0.002 l = _________________
l |
0.002 l = _________________
ml |