BIO122
HISTOLOGY OF CELL AND TISSUE
CHAPTER 2: SCIENTIFIC METHODS
RAR 2018
Chapter 2: Scientific Methods
• Course outline
2.0 SCIENTIFIC METHODS
2.1. DISCOVERY BASED SCIENCE (Inductive Method)
2.2. THE HYPOTHETICO-DEDUCTIVE METHOD (Deductive Method)
2.3. EXPERIMENTAL ANALYSIS (Dependent/Independent variables)
2.4. UNITS OF MEASUREMENT AND CONVERSIONS (SI Units)
2.4.1. Length (km, m, cm, mm, µm, nm)
2.4.2. Mass (kg, g, mg, µg)
2.4.3. Volume (L, mL, µL, cm3, mm3)
2.4.4. Temperature (°C, °F)
At the end of the study, student should be able to state and define concepts and principles in biology
Chapter 2: Scientific Methods
• The word science is derived from Latin and means “to
know”
• Scientific process includes making observations, forming
logical hypotheses, and testing them
• Scientific method = A series of ordered steps or guidelines
that scientists use in their work.
• The heart of science is inquiry.
• Inquiry is the search for information and explanation.
• Biologists use two main types of scientific inquiry:
• 1. Discovery science
• 2. Hypothesis-based science
Chapter 2: Scientific Methods
HYPOTHESIS-BASED
DISCOVERY SCIENCE
SCIENCE
• Inquiry that describes • Inquiry that asks specific
natural structures and questions and involves
processes using the proposing and
observation and analysis testing of hypothetical
of data explanations, or
hypotheses
• Involve inductive
reasoning • Involve deductive
reasoning
Chapter 2: Scientific Methods
2.1. Discovery Based Science
(Inductive Method)
• Describes natural structures and processes using
observation and analysis of data
• Observation = the use of senses (Touch, Taste,
Smell, Sight, Hearing ) to gather information,
either directly or indirectly with the help of tools
such as microscope.
• Data = Recorded observations or items of
information.
• Data can be divided into two:
• Recorded descriptions
QUALITATIVE • Example: Jane Goodall’s
DATA observations on chimpanzee
behavior
• Recorded measurements
QUANTITATIVE • Example: Data organized into
DATA tables and graphs
QUALITATIVE
DATA
QUANTITATIVE
DATA
Chapter 2: Scientific Methods
2.2. The Hypothetico-deductive
Method (Deductive Method)
• Inquiry that asks questions and involves the
proposing and testing of hypothetical explanations,
or hypotheses
• A hypothesis is a testable explanation for an
observation
or a tentative answer to a specific question
• A scientific hypothesis leads to predictions that can
be tested by experimentation.
Chapter 2: Scientific Methods
2.2. The Hypothetico-deductive
Method (Deductive Method)
• For example: your flashlight does not work
• Observation: Your flashlight doesn’t work
• Question: Why doesn’t your flashlight work?
• Hypothesis 1: The batteries are dead
• Hypothesis 2: The bulb is burnt out
• Both these hypotheses are testable
Observations
Question
Hypothesis #1: Hypothesis #2:
Dead batteries Burnt-out bulb
Prediction: Prediction:
Replacing batteries Replacing bulb
will fix problem will fix problem
Test of prediction Test of prediction
Test falsifies hypothesis Test does not falsify hypothesis
Observations
Question
Hypothesis #1: Hypothesis #2:
Dead batteries Burnt-out bulb
Hypothesis #1: Hypothesis #2:
Dead batteries Burnt-out bulb
Prediction: Prediction:
Replacing batteries Replacing bulb
will fix problem will fix problem
Test of prediction Test of prediction
Test falsifies hypothesis Test does not falsify hypothesis
Chapter 2: Scientific Methods
2.2. The Hypothetico-deductive
Method (Deductive Method)
• Hypothesis-based science often makes use of two or
more alternative hypotheses
• Failure to falsify a hypothesis does not prove that
hypothesis
• For example, you replace your flashlight bulb, and it now
works; this supports the hypothesis that your bulb was burnt
out, but does not prove it (perhaps the first bulb was
inserted incorrectly)
Chapter 2: Scientific Methods
2.2. The Hypothetico-deductive
Method (Deductive Method)
• A hypothesis must be testable and falsifiable
• For example, a hypothesis that ghosts fooled with
the flashlight cannot be tested
• Supernatural and religious explanations are outside
the bounds of science
Chapter 2: Scientific Methods
2.2. The Hypothetico-deductive
Method (Deductive Method)
• Science is systematic.
• Science organize and often quantify knowledge.
• Science is not mysterious as anyone who understands its
rules and procedures can take on its challenges.
• Two types of systematic thought processes:
1. Deductive Reasoning (also called, the “if…then” logic)
2. Inductive Reasoning
Deductive Inductive
Reasoning Reasoning
Use general Use specific
observation to observation to
make specific make general
conclusion conclusion
Helps discover Helps organize data into
relationships manageable categories
by answering this
among known question: ‘What do all
facts facts have in common?’
Chapter 2: Scientific Methods
Deductive Reasoning Inductive Reasoning
• Premise 1: All birds have • Premise 1: Sparrows are
wings birds with wings and can
• Premise 2: Sparrows are fly
birds • Premise 2: Robins, eagles,
• Conclusion: Sparrows hawks, and pigeons are
have wings birds with wings and can
fly
• Conclusion: All birds have
wings and can fly
General Specific
Specific General
Chapter 2: Scientific Methods
• Scientific method = A series of ordered steps or
guidelines that scientists use in their work.
• The scientific method is an idealized process of
inquiry
• Hypothesis-based science is based on the
“textbook” scientific method but rarely follows all
the ordered steps
SCIENTIFIC METHOD SONG
Copyright © 2012 Have Fun Teaching, LLC
song from: http://www.havefunteaching.com/science-songs/scientific-method-song
First you make an observation of the world around
Take notes and record all the things that you found
Then you ask a simple question something that you want to learn
Then you form a hypothesis to explain what you observed
Then you make a prediction about how it's gonna go
Do a test with a control and variable
Then you analyze the data and draw a conclusion
Do the scientific method to avoid all confusion
Make an observation
Ask a question
Form a hypothesis
And make a prediction
Do a test or experimentation
Analyze data and draw a conclusion
Scientific Method
SCIENTIFIC METHOD PROCESS
OBSERVATION
QUESTION
HYPOTHESIS
PREDICTION
EXPERIMENT
RESULTS
CONCLUSION
SCIENTIFIC DEFINITION
METHOD
1. OBSERVATION - The use of senses (Touch, Taste, Smell, Sight,
Hearing) to gather information
2. QUESTION - A question about the observation
3. HYPOTHESIS -A testable explanation for an observation
-An ‘educated guess’
4. PREDICTION -Make assumptions on the results of experiment
-‘If….then’ statement
5. EXPERIMENT - Conduct a study and test the prediction
6. RESULTS - Analyze the data from the experiment
7. CONCLUSION - Hypothesis is accepted or rejected?
OBSERVATION
exp: my car cannot start
ASK QUESTIONS
exp: why my car cannot start?
HYPOTHESIS
exp: My car cannot start because of its damaged engine
PREDICTION
exp: if i change the engine of my car, then my car can start
TEST PREDICTION (EXPERIMENT)
exp: change the old engine of the car with a new one
RESULTS
exp: my car can be started
CONCLUSION
exp: hypothesis is accepted
Observation Shrimp color is similar to that of algae they feed upon
Ask critical questions Is the shrimp color related to the color of the algae?
Develop hypothesis Shrimp color is derived from pigments in the algae.
Make a prediction than can be If diet is changed, shrimp will develop different color.
tested
Perform experiments to test the Control group shrimp eat usual algae.
prediction Experimental group shrimp are fed different algae.
Result Experimental shrimp remain same Experimental shrimp develop
color as control shrimp. different color from control
shrimp
Interpretation and Food does not affect shrimp color. Food effects shrimp color.
conclusion
Hypothesis is not supported Hypothesis is supported
Results may Develop
suggest further theory
experiments
Principle
Spontaneous Generation Theory : Most living organisms arose
directly from inanimate materials
Observation : Flies arose directly from decayed meat that covered
with maggots – the larval stage of flies
Question : Where is the origin of maggots?
Hypothesis : Maggots arose only from eggs deposited by flies
and not from meat.
Prediction : If this hypothesis is correct, the meat without flies
will not have any maggots
Experiment : 2 sets of 4 vessels were prepared. 1 set was sealed
and 1 set was exposed to the air
Result : The decaying meat in each of the open vessel was teeming
with maggots. The meat in the sealed vessel had no maggots
Chapter 2: Scientific Methods
• Course outline
2.0 SCIENTIFIC METHODS
2.1. DISCOVERY BASED SCIENCE (Inductive Method)
2.2. THE HYPOTHETICO-DEDUCTIVE METHOD (Deductive Method)
2.3. EXPERIMENTAL ANALYSIS (Dependent/Independent variables)
2.4. UNITS OF MEASUREMENT AND CONVERSIONS (SI Units)
2.4.1. Length (km, m, cm, mm, µm, nm)
2.4.2. Mass (kg, g, mg, µg)
2.4.3. Volume (L, mL, µL, cm3, mm3)
2.4.4. Temperature (°C, °F)
At the end of the study, student should be able to state and define concepts and principles in biology
Chapter 2: Scientific Methods
2.3. Experimental Analysis
(Dependent/Independent Variables)
*Variable = factor that is likely to change in an experiment.
• variable that is changed in a scientific experiment to test
INDEPENDENT the effects on the dependent variable
VARIABLE • Variable that “stands alone”
DEPENDENT • variable being tested in a scientific experiment.
VARIABLE • Variable that ‘depends on other variables’
CONTROL • Variable that is kept constant throughout the experiment
VARIABLE • Variable that ‘does not change’
Chapter 2: Scientific Methods
Example: A scientist wants to see if the brightness of light
has any effect on a moth being attracted to the light.
• Independent variable: Brightness of light
• Dependent variable: How the moth reacts to the different
brightness levels of light
• Control variable: Type of moth used
Experimental Controls and Repeatability
• A controlled experiment compares an experimental
group with a control group
• Experimental group = the group being tested
• Control group = the group that is not tested and used
to compare with experimental group
• A controlled experiment means that control groups are
used to cancel the effects of unwanted variables
A Case Study in Scientific Inquiry: Investigating Mimicry in
Snake Populations
• In mimicry
• A harmless species resembles a harmful species
Flower fly
(non-stinging)
Honeybee
(stinging)
Case study on mimicry in king
snake
• In this case study
• Mimicry in king snakes is examined
• The hypothesis predicts that predators in non–coral snake
areas will attack king snakes more frequently than will
predators that live where coral snakes are present
Scarlet king snake
Key
Range of scarlet king snake
Range of eastern color snake
North
Carolina
South
Carolina
Eastern coral snake
Scarlet king snake
Field Experiments with Artificial Snakes
• To test this mimicry hypothesis
• Researchers made hundreds of fake snakes with wire covered by
plasticine resembling king snakes (experimental group) and plain
brown fake snakes (control group)
(a) Artificial king snake
(b) Brown artificial snake that has been attacked
• After a given period of time
• The researchers collected data that fit a key prediction
Key
Key
% of attacks on artificial king snakes
% of attacks on brown artificial snakes
Field site with artificial snakes
17%
In areas where coral snakes
were absent, most attacks 83%
were on artificial king snakes
X
North X X
X X XX
Carolina
South X X
Carolina X
X X
X X 16%
84%
In areas where coral
snakes were present,
most attacks were on
artificial brown snakes
Limitations of Science
MORALITY
VALUE
LIMITATIONS
OF SCIENCE
SUPERNATURAL
RELIGION
• Science cannot address some phenomena because:
• hypotheses must be testable and falsifiable
• experimental results must be repeatable
Theories in Science
Scientific Theory
• Theory = An explanation based on many hypothesis
• Is broader in scope than hypothesis
• Is supported by more evidence than hypothesis
• Often tested but never rejected
“A hypothesis that stands the test of time—often
tested and never rejected—is called a theory”
Chapter 2: Scientific Methods
• Course outline
2.0 SCIENTIFIC METHODS
2.1. DISCOVERY BASED SCIENCE (Inductive Method)
2.2. THE HYPOTHETICO-DEDUCTIVE METHOD (Deductive Method)
2.3. EXPERIMENTAL ANALYSIS (Dependent/Independent variables)
2.4. UNITS OF MEASUREMENT AND CONVERSIONS (SI Units)
2.4.1. Length (km, m, cm, mm, µm, nm)
2.4.2. Mass (kg, g, mg, µg)
2.4.3. Volume (L, mL, µL, cm3, mm3)
2.4.4. Temperature (°C, °F)
At the end of the study, student should be able to state and define concepts and principles in biology
2.4. UNITS OF MEASUREMENT AND CONVERSIONS
(SI Units)
SMALL BIG
UNIT UNIT
BIG SMALL
UNIT
x UNIT
2.4. UNITS OF MEASUREMENT AND CONVERSIONS
(SI Units)
Big to
Small
2.4. UNITS OF MEASUREMENT AND CONVERSIONS
(SI Units)
1. Length
x1000 x100 x10 x1000 x1000
km m cm mm µm nm
km m cm mm µm nm
1000 100 10 1000 1000
Examples
• LENGTH
• 2.3 cm = ___ mm
• 75 cm = ____km
• 15.2 mm = ___ µm
• 80 nm = ___ µm
• 9 µm = ___ m
Examples (length)
• 2.3 cm = 23 mm
• 75 cm = 7.5 x 10⁻4 km
Big to
• 15.2 mm = 15200 µm Small
• 80 nm = 0.08 µm
• 9 µm = 9 x 10⁻⁶ m
2.4. UNITS OF MEASUREMENT AND CONVERSIONS
(SI Units)
2. Mass
x1000 x1000 X1000000
kg g mg ng
kg g mg ng
1000 1000 1000000
Examples
• MASS
• 65.4 kg = ___ g
• 320 mg = ____ng
• 43 mg = ___ kg
• 780 ng = ___ g
Examples (mass)
• 65.4 kg = 65400 g
• 320 mg = 320 x 10⁶ ng
Big to
Small
• 43 mg = 4.3 x 10⁻⁵ kg
• 780 ng = 7.8 x 10⁻⁷ g
2.4. UNITS OF MEASUREMENT AND CONVERSIONS
(SI Units)
3. Volume
x1000 x1000000 X 1000
L mL nL cm³ mm³
L mL nL cm³ mm³
1000 1000000 1000
Examples
• VOLUME
• 90.4 L = ___ nL
• 55 nL = ____ mL
• 5 cm³ = ___ mm³
• 232 mm³ = ___ cm³
Examples (VOLUME)
• 90.4 L = 9.04 x 10¹⁰nL
• 55 nL = 5.5 x 10⁻⁵ mL
Big to
Small
• 5 cm³ = 5000 mm³
• 232 mm³ = 0.232 cm³
2.4. UNITS OF MEASUREMENT AND CONVERSIONS
(SI Units)
4. TEMPERATURE
°C °F °F = (9/5 x °C) + 32
°F °C °C = 5/9 (°F - 32)
Examples
• TEMPERATURE
• 94 °C = ___ °F
• 33 °F = ____ °C
Examples (TEMPERATURE)
• 94 °C = 201.2 °F
• 33 °F = 0.56 °C
REFERENCE
Campbell, N. A., Urry, L. A., Cain, M. L., Wasserman, S. A.,
Minorsky, P. V. and Reece, J.B. (2017). Campbell
Biology : Global Edition. New York, NY : Pearson
Education, Inc
