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Chapter 1
The Science of
Biology
What were your first questions?
WHY?
What?
How?
What is Science?
Science asks the same questions you did as
a young child.
What is that?
Why does it do what it does?
How does that happen?
What happens if …?
Science (knowledge) is a
process that investigates and
attempts to understand and
explain events in nature.
Goal of Science
Provide natural explanations for events
in the natural world.
Give examples of this
Use explanations to understand
patterns in nature and to make useful
predictions about natural events
Give examples of this
Since Science is a process, how do we
go about doing “Science”?
The Scientific Method of course!!
1.
2.
3.
4.
5.
6.
7.
Ask a question based on an observation
Do some research or infer
Propose a hypothesis
Conduct a controlled experiment
Collect data and make observations
Analyze data
Draw a conclusion
Observing and Asking Questions
– Scientific investigations begin with observation,
the act of noticing and describing events or
processes in a careful, orderly way.
– Researchers observed that marsh grass grows
taller in some places than others.
– A question is formed: Why do marsh grasses
grow to different heights in different places?
Inferring & Forming a Hypothesis
– Through observations and research,
scientists form inferences, or logical
interpretations based on what is already
known.
– These lead to a hypothesis, or a scientific
explanation for a set of observations that
can be tested in ways that support or reject
it.
–
What kind of hypothesis could be made
concerning the marsh grass growth?
– Researchers inferred that something limits
grass growth in some places. Based on their
knowledge of salt marshes, they hypothesized
that marsh grass growth is limited by available
nitrogen.
Design a Controlled Experiment
• Design an experiment that keeps track of
various factors that can change, or variables
– Only one variable is changed at a time
• Manipulative or Independent variable
– The variable that is observed and that changes
in response to the independent variable is
called the dependent variable (also called the
responding variable).
– All other variables should be kept unchanged,
or controlled
• Controlled variable
For the marsh grass experiment, identify
each of the following variables:
• Manipulative or independent variable
–
Nitrogen fertilizer is added to the soil
• Control variables
–
Similar plant density, soil, plant type, sunlight,
amount of water, temperature…
• Dependent or responding variable
–
The rate at which the grass grows or its height.
Control and Experimental Groups
An experiment typically has two groups:
1. An experimental group contains the
independent variable
2. A control group is exposed to the same
conditions as the experimental group except
for one independent variable.
How will scientists keep track of experimental observations
and then analyze the results?
• Collecting Data
– Quantitative data
• Numbers
– How many blades of grass were found per meter?
– How high, wide, long…was the grass?
– How much nitrogen was found in the blades of grass?
– Qualitative
• Describe
– Which way did the grass grow?
– What color was the grass?
– Where there any other plants growing around it?
Recording the data
How is data recorded?
 Use charts, photos,
drawings or graphs
This graph shows how
grass height changed
over time.
What might have been a source of error in this experiment?
The larger the sample size, the more reliably
researchers can analyze variation and
evaluate differences between experimental
and control groups.
What conclusion could be drawn from the data collected?
Use experimental data as evidence to support,
refute, or revise the hypothesis being tested,
and to draw a valid conclusion.
Marsh grasses grew taller than controls by
adding nitrogen.
What if our hypothesis is not
supported in our experiment?
– Close but no cigar.
• Reevaluated and
revised the original
hypothesis
• Make new
predictions
• Redesign the
experiment
Do you know where bees come from?
Recipe for Bees
1. Kill a bull during the first thaw of winter
2. Build a shed
3. Place the dead bull on branches and
herbs inside the shed
4. Wait for summer. The decaying body of
the bull produces bees
Words from a Roman poet about 2000 years ago
Spontaneous Generation
Life arises from non-living matter or just suddenly
appear.
Abiogenisis
Meat grows maggots
Corn produces rats
Bread breeds mold
So what do you think of this
theory?
How are new living organisms produced?
1. Question is stated Where do flies come from?
2. Now we need to form a hypothesis
1. Francesco Redi (1668)
Hypothesis: Flies lay small eggs on meat
that become maggots
Set up a controlled experiment to test his
hypothesis
Analysis: Found that by keeping
flies away from meat, no maggots
appear
Conclusion: Maggots are the result
of flies laying tiny eggs on
meat that develop into
maggots
Variables
1. Controlled variable:
Jar, meat, location, temperature, time
2. Independent or Manipulative variable:
Gauze covering the meat jars
3. Dependant (responding) variable:
Whether maggots appear
Lazzaro Spallanzani 1776
• Designed experiment to show that
life did not arise spontaneously from
food
– Inferred that food spoils due to microbes
in the food.
• Took 2 flasks with broth in them
– Boils on but leaves it open
– Boils the other but has it closed
Results – Only the closed one
prevented growth
What was wrong with what
Spallanzani assumed?
No air
Everyone knows that every living thing needs air to
live
Whose experiment solved Spallanzi’s air problem?
Louis Pasteur - 1859
Tested Spallanzani’s work by using a
curved neck flask to prevent microbes from
entering flask but would let air in
Microbes collecting in bend
Boiled broth in control and experimental flasks.
Result: No growth in curved neck flask.
Pasteur’s broth in the curved necked flask
stayed sterile for years until he tilted it and
the airflow carried the microbes into the broth
Conclusion
Contamination is due to microbes in the air.
Spontaneous generation theory died here!!
Biogenesis is born!!
All living things come from other living
things.
Identify some scientific theories you have
knowledge of.
1.
2.
3.
Big Bang
Evolution
Relativity
A theory is a well-tested explanation for a
range of phenomena.
A law is a concise, specific description of how
some aspect of the natural world is
expected to behave in a certain situation
such as the Gas laws
What is Biology?
Biology is the study
of living things and
how they interact
with each other.
What are the characteristics of living things?
You and your partner are to brainstorm
and ask yourselves the following.
•
All living things have…
•
All living things need…
•
All living things can…
•
All living things must…
What makes a living thing different from
the desk you are sitting in?
• After you have brainstormed and edited
your list, write them down on the chart
on the next slide.
• When told to do so, go to each station
in the back of the room, observe the
specimen and check off if it has the
characteristics you wrote down.
Specimen
1
Trait
1
2
3
4
5
6
7
8
9
10
2
3
4
5
6
7
8
9
10
What makes something living?
Characteristics of Life
All living things…
1. …are made up of cells.
Unicellular or Multicellular.
2…need a constant flow of energy.
Necessary for Metabolism
All the chemical processes
taking place in the organism
including those that are needed
for growth and those that are
needed to break down
molecules (such as digestion)
Some such as plants and some
bacteria, make their own food
from raw materials
(Autotrophic)
Others such as animals, need to
process organic matter to
obtain energy. (Heterotrophic)
3… maintain a stable, internal environment by
responding to stimuli.
Maintain an internal steady state –
Homeostasis.
Stimulus – anything that causes an
organism to react/respond
Examples:
• Increased heart rate when stressed
• Goosebumps and shivering.
• Pupillary response to light and darkness
– Let’s give this one a try
4. …Evolve
…as a group
• Evolution is a
change in a species
over time
• Results from an
species ability to
adapt to changing
conditions and
reproduce.
5…grow and develop.
Your very first baby picture
Process occurs by adding on more cells by cell
division (making more cells of the same kind)
and cell differentiation (cells becoming different to
suit their various functions).
Red blood cell
Easily flow through
capillaries
White blood cell
Change shape to
squeeze through
intracellular spaces
Nerve cells
Like a wire to
conduct electrical
impulses
6...can reproduce.
Adding on more cells or reproducing
another organism
Passing on of genetic information (DNA
and genes)
Not a necessary life process but
needed for the continuation of the
species.
Sexual (involves the fusion of two cells)
Asexual (involves only 1 cell dividing)
reproduction.
7. …all living things are based on
a universal genetic code
• DNA
It doesn’t matter if the
DNA of a bacterium or a
human is analyzed, we
all have the same 4
bases (ATCG) making
up our DNA.
Measurements in Science
SI Measurements (Standard Increments)
aka: The Metric System
Unit
Abbreviation
Length
Meters
m
Mass
Gram
g
Volume
Liter
l
Time
Second
s
Temperature Celsius
`C
Kelvin
`K
Density
Mass/Volume g/l or g/cm3
Symbols of measurement
Prefixes
kilo
deci
centi
milli
micro
Abbrevation
k
d
c
m
u
Factor of base unit
1,000
.1 or 1/10
.01 or 1/100
.001 or 1/1000
.000001 or 1/1,000,000
Metric Conversions
Kilo
Hecto
Deka
Meter
Deci
Centi
Milli
Micro
Liter
Gram
Convert:
5L = ______ml
1.025cm = _______ m
.035um = ______ mm 2.5mm = ______um
7.2g = _____kg
.017g = ______mg
1. A recipe calls for 300ml of water. You add
0.25 L. Have you put in too much, too little
or the right amount?
2. You are told that you need a jar with a
volume of at least 150cm3. The label on the
jar you find says 0.16L. Can you use it?
Remember that 1cm3 = 1ml.
Lab Safety
• Contracts must be signed and returned
to me immediately.
• All Science students must complete the
Safety contract before entering into the
lab
• Any student who does not have a lab
safety contract signed will not be
allowed to conduct labs.
The right tool is
Where babies
what is important really come from
Used to measure
out a volume of a
liquid
Theory that life
came from nonliving things
Disproved the
Vessel to hold and
above using the
heat a liquid
gauze covered jar
Our method
The Way we do
things here
Measure this
Method used to
solve problems
Where the heating
test tube should
be pointed
Basic units of
measure for
Volume
An educated
guess
Watch it or the
Safety Police will They're a What?
get you
If on fire, what
should be done
What shouldn't be
Where to go if
Basic units of
on top of a
you get chemicals
measure for mass
heating test tube
in your eyes
Life is a Wonderful
Thing
Studies animals
Non-essential to the
individual's life
characteristic
Studies plants
Type of
reproduction found
in amoeba and hydra
Also disproved it
What should be
Instrument used to
Three conditions
using the sealed What the above is on your eyes if How tall are you
Studies bacteria Keeping the body in
pick up small
when goggles
boiled flasks of
based on
you are heating a
in meters
and viruses
a balanced state
specimens
would be worn
gravy
test tube
Device used to
Father of
Looks at how
Your 5 senses Where all the lab
How many
What to do if you
observe small
Microbiology who
living things
allows you to do safety equipment milliliters are in a break a piece of
Building up process
specimens (not
disproves this
interact with their
this
are in the room
liter
glassware
microscopic ones)
theory
environment
How you should
Special type of
Measures the mass
Keep these out of be dressed when
flask used by the
of an object
the above
doing a lab with
above
an open flame
What part of a
meter is a cm?
Where all
Studies how traits
glassware should are passed from
be on your lab one generation to
tables
the next
What was the big
difference
Caution should
Used on top of a
between
The final answer
always be
glass slide with a
Spallanzani's
to your problem exercised when
wet mount
work and
working with this
Pasteur's
What does um
stand for?
The fact that you are
How to pull out an Studies the form getting scared about
electrical cord
of the human
taking this test
from the socket
body
means that you are
…
The last thing you
should always do
after performing a
lab
1cm3 = ______
What to use when
Studies how
handling
living things are
something hot
classified
What units a
Life comes from
graduated cylinder
life
measures in
That which
changes in an
experiment
Breaking down
process
All the chemical
reactions in an
organism
The right tool is
Where babies
what is important really come from
Our method
The Way we do
things here
Measure this
Watch it or the
Safety Police will They're a What?
get you
Life is a Wonderful
Thing
Graduated
cylinder
Spontaneous
generation
Scientific method
Away from all
people in lab
ml
Screamed that
you are on fire,
stop, drop and
roll and someone
will bring a fire
blanket
Beaker or flask
Redi
Hypothesis
A stopper
g
eye wash station
Botony
Asexual
Forceps
Spallanzani
Basic research
and prior
knowledge
Goggles
</= 2m
Chemicals,
heating
something,
glassware
Microbiology
Homeostasis
Hand lens
Pasteur
Observations
On the side of the
room
1000ml in a m
Let the teacher
know. Do not
touch it
Ecology
Anabolism
Balance
Swan necked
flask
Opinions and
inferences
Hair tied back and
sleeves rolled up
1/100 or 100th
Away from the
edge of your table
Genetics
Catabolism
Cover slip
Pasteur allowed
oxygen to get in
Conclusion
Chemicals
micrometer
Gently unplug by
the plug, not the
cord
Anatomy
Irritability
ml
Biogenesis
Variables
Clean up
everything and
put all away
1ml
Test tube holders,
tongs or mitts
Taxonomy
Metabolism
Zoology
Reproduction