Begin with:

OBSERVATIONS

• the process of gathering INFORMATION about events or processes in a CAREFUL, ORDERLY way.

• Observations generally involve using the SENSES, particularly sight and hearing.

• The information gathered is called DATA (datum – singular)

• Scientist may use DATA to make INFERENCES

• An inference is A LOGICAL INTERPRETATION based on PRIOR knowledge or EXPERIENCE.

Science is made up of FACTS, THEORIES and LAWS.

FACTS• are based on experiments are careful

OBSERVATIONS THEORIES • are scientific explanations developed by using

both OBSERVATIONS and FACTS that people already know about the world.

• Theories CHANGE as new EVIDENCE arises and may eventually bec

• ome SCIENTIFIC LAWS. A SCIENTIFIC LAW • results only when MANY scientist REPEATEDLY

reach the SAME CONCLUSIONS.

The technique for scientific inquiry used is known as the SCIENTIFIC METHOD.The scientific method solves problems

in a LOGICAL and ORGANIZED way.

The first step is to find a PROBLEM TO SOLVE

• This requires a great deal of RESEARCH.

The second step is to STATE A HYPOTHESIS

• This is an INTELLECTUAL PREDICTION of the POSSIBLE OUTCOME of an experiment or a solution to the problem.

The third step is to DESIGN a CONTROLLED experiment that tests the HYPOTHESIS

There must be TWO groups that are needed for this type of experiment:

• A) The CONTROL group contains ALL the parts of the experiment EXCEPT the one EXPERIMENTAL FACTOR being TESTED

• B) The EXPERIMENTAL group contains all the factors of the control group PLUS the one factor that is being tested. This is also called the variable group.

The CONTROL GROUP • acts as a REFERENCE point or measuring stick

to compare with the EXPERIMENTAL group. • Any difference between the two groups can

only be due to the one EXPERIMENTAL factor that is being tested.

• Sometimes the control group BLIND. This means that the members of the CONTROL group do not realize that they are not even part of the experimental group.

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There are two types of variables.

1. The INDEPENDENT variable • is always UNDER YOUR CONTROL • On a graph, you would plot this

data on the X-AXIS • YOU can SET the LEVEL of this

factor at whatever you wish. • Example: the amount of fertilizer

given to a plant.

2. The DEPENDENT variable • relies upon the parameters set by

the INDEPENDENT variable. • On a graph, you would plot this

data on the Y- AXIS.• Example: the height the plant will

grow is dependent upon the amount of fertilizer it is given. So the change in height would be the dependent variable.

4. The fourth step is to REVIEW THE RESULTS 5. The fifth step is to DRAW CONCLUSIONS • No assumptions can be made past the one

and only experimental factor that is being tested. Just the facts that have been observed may be used as part of the conclusion.

6. The last step is to communicate the results with others.

• This can be done over the Internet, in a scientific journal or by some other means. It is very important to communicate results because as you know research is one of the most important parts of conducting an experiment.

Improper Scientific Procedures

•         The data are based on SMALL samples•         The experiment was inadequately

CONTROLLED•         Fact and OPINION are intermingled•         Adequate EVIDENCE is not cited•         Conclusions are based on FAULTY,

INCOMPLETE or MISLEADING use of numbers

•         The conclusions do not follow logically from the evidence given.

Test Yourself"Try To Test For Plant Growth Using

Various Light Colors"

• It is important to realize what specific colors of light plants prefer, especially if you have a green house or an aquarium.

• Fill in the information in the blank space to test for plant growth.

• Remember you need a control group and experimental (variable) group to test your hypothesis. Note the difference between the independent and dependent variables.

• You can assume both groups are using genetically identical plants.

Hypothesis:

Red will increase the growth of plants

Please note how this is a statement. It is NOT a question.

Also note how the hypothesis PREDICTS the outcome of the experiment.

Independent/

Dependent

Factor Experimental Group

Control

Other variable Amount of Water (ml) Other variable Temperature (Co) Other variable Soil Type (sand, potting)

Dependent Change in Growth (cm) Should see increase

Should grow to normal

height

Other variable Fertilizer (grams)

Type: standard, special)

Independent Color of Light

(ROYGBIV)Red White

Other variable Carbon Dioxide Levels(ppm)

Should see increase

Should grow to normal level

Other variable Length of Light

Exposure (hrs. of light)

Data should be organized in a logical manner. One good way to do that is to collect your data in a “Data Table”. There are certain guidelines that are followed. 1. Always have a TITLE• A good way to format a title is:• “The Effect of the Independent Variable on

the Dependent Variable in/on Name of the Organism.”

•  (Hint: whenever possible, use the SCIENTIFIC NAME for the organism. Remember, the scientific name is the genus and species of that organism.)

2. The INDEPENDENT variable is always the LEFT-most variable.

3. Include units of measure in the subheading for your independent variable. Ex.: mls (milliliters), gms (grams), Co (temperature).

4. The DEPENDENT variable will always be the right-most column/columns.

5. Include units of measure in the subheading for your dependent variable.

The Effect of Moisture on the Movement of Arion subfuscus

  Amount of Water (mls) 

Movement of Arion subfuscus

(mm)

0 0.5

0.5 1.2 

1.0 2.2 

2.0 0

Example:

Guidelines for Graphing

1. Always have a TITLE for your graph.2. The INDEPENDENT variable is always on the X-

AXIS. 3. In the axis label, always include the Units of

Measure.4. The DEPENDENT variable is always on the Y-AXIS. 5. In the axis label, always include the Units of

Measure6. There MUST always be a STARTING value for BOTH

the X & Y axis.7. Increments (spacing between the numbers) MUST

always be the SAME (equal intervals). This applies to both axis.

8. No squiggly lines on the Y-axis!!!!!!!

Example of a good graph The Effect of Moisture on the Movement of Arion

subfuscus

0

0.5

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5

Amount of Water (mls)

Mo

ve

me

nt

of

Ari

on

s

ub

fus

cu

s (

mm

)

Series1

• How does a scientific theory compare with a scientific hypothesis?

• A hypothesis is a proposed scientific explanation for a set of observations, whereas a theory is a well-tested explanation that unifies a broad range of observations.

• List the steps of the scientific method. • Define the problem• Research• Formulate a hypothesis• Test the hypothesis• Observe, measure analyze, • Draw conclusions• Repeat the experiment• Report

II. Metric System • In science, measurements are expressed in

units of the metric system or the International System of Units (Systeme Internationale d'Unites), abbreviated SI.

• The metric system is a decimal system of weights and measurements. The units of the system are related by factors of ten. Prefixes in the names of the units denote the size of the units.

• Because researchers need to replicate each other’s experiments and most experiments involve measurements, scientists need a common system of measurement.

 Prefix  Meaning  Example

 *Kilo-One thousand times (103)

1 kilometer = 1,000 meters (103)

 *Centi- One-hundredth (10-2) 1 centimeter = 0.01 meter (10-2 m)

 *Milli- One-thousandth (10-3) 1 millimeter = 0.001 meter (10-3 m)

 *Micro- One-millionth (10-6)1 micrometer = 0.000001 meter (10-

6 m)

1. BASE UNITS

      Meter (m) = length       Kilogram (Kg) = mass – measured with

mechanical or electronic balances      Liter (L) = volume – measured with

pipettes, graduated cylinders, flasks, etc. Volume Equivalents 1 ml = 1 cm3 (cc)

2. TEMPERATURE

Celsius (0C)

Based on freezing point of H2O = 00C

& boiling point of H2O = 1000C

Conversion Sample Problem: Nitrogen gas is the major component of air. A sample of nitrogen gas in a glass bulb weighed 243 mg. What is this mass in SI base units of mass (kilograms)?

To complete this problem, you MUST know your prefixes

Note, however, that we can do the two conversions in one step, as follows:

0.000243 OR 2.43 x 10-4 kg

RULE: when you are given a prefix and would like to convert to another unit, start at that prefix given, count the number of prefixes away from the desired prefix and move the decimal that many places in the same direction

Sample Problem) 14.5 mm =? m

• Solution) Micro () is three places away from milli. Move the decimal three places to the right to get the answer. 14500 m

is the Greek letter mu and is used for the prefix micro or 10-6

TYPES of MICROSCOPES

• A. Simple Microscope –a magnifying glass or hand lens

B. Compound Microscope

• Produces magnification of 40x (scanning objective), 100x (low power objective) & 400x (high power objective)

• Makes it possible to observe many types of cells and small organisms.

STEPS for FOCUSING the Compound Microscope

1. Position the specimen under scanning.2. Adjust the diaphragm.3. Focus using the coarse adjustment.4. Center specimen.5. Switch to low power, position specimen

and repeat steps 2-4 in order.6. Switch to high power, position specimen, &

adjust the diaphragm.7. Focus using the fine adjustment.

MAGNIFICATION – Apparent enlargement of the specimen

TOTAL MAGNIFICATION: Power(ocular lens) X Power(objective lens) =

Total Magnification

RESOLUTION-

the quality of the compound microscope that makes it possible to see the separation between objects that are very close together in a microscope field

STAINS

allow normally invisible cell parts to be viewed under the microscope

examples:

iodine & methylene blue

Phase-Contrast Microscope

• this microscope can see details of cells without staining

Stereo Microscope (DISSECTING Microscope)

• low power microscope that gives the viewer a three dimensional image for purposes of gross dissection.

Electron Microscopes • Uses beam of electrons instead of light• Would use to observe cell organelles such as the

mitochondria and ribosomes and chromosomes

1. Transmission Electron Microscope (TEM)- has extremely high magnification, used to view cell structures (organelles), has resolving power of 0.5 nm, magnification 250,000X

2. Scanning Electron Microscope (SEM)- produces three-dimensional image, has resolving power of 500 nm

Transmission Electron

Microscope

IV. OTHER TOOLS SCIENTISTS USE for EXPERIMENTS

Graduated Cylinder

measures volume, the experimenter must read the meniscus which is the bottom of the curve within the graduated cylinder

Centrifuge

is use to separate mixtures according to densities. Materials with the greatest density are on the bottom

Would use to separate out cell organelles like ribosomes

Ultracentrifuge

• a tool used to separate cell parts according to their densities

• Video Cameras

– used to view objects in motion

• Tissue Cultures

– placing living organisms on a medium (containing nutrients & other factors so the organism can survive) outside the body

Electrophoresis• technique for separating substances made of

particles that have an electrical charge. Used to separate DNA, RNA and proteins.

• ***This procedure is used in one of our state labs. • You ARE required to understand how electrophoresis

works.

Chromatography• another separation technique used for colored

mixtures.

• Separates the out the colored pigments.

• Microdissection Apparatus

– is a small instrument used to operate on cell organelles

• Computer

– invaluable tool – used to perform complex tasks and analyze data