UNIT 1 – Science of Biology
NOTES
•This is “THEORY”
•“PRACTICAL” is the lab
•Be ready to make the connections between
the two.
Topic 1A: Characteristics of Living Things
BIOLOGY– The study of life
Living things are known as organisms.
The living world and the non-living world are mixed.
As you look out the window here at school or as you
investigate any environment you will find a mixture
of the two. How can we identify something as an
organism?
For each of the items listed below state a reason that
makes it living or non-living:
Clouds
Mushrooms
Worm
Fire
Automobile
What characteristics do all living things
share?
1. Living things are made up of units
called cells
•Some organisms are made of only one
cell and some are made of trillions of
cells.
•Cells are small self-contained units of
living material that are separated from
the surroundings by a barrier.
Unicellular – organism made
of only one cell
Multicellular – organism
made of more than one cell.
In complex multicellular
organisms such as humans,
many different types of cells
work together to perform the
functions needed by the
organism.
2. Living things reproduce:
Reproduction is the life process that
provides for continuation of the
species. An individual will not die if it
does not reproduce but the species will
end if no members reproduce.
Terms to know:
Sexual reproduction- requires cells
from 2 parents to create a new
individual different from each
parent. Common in multicellular
organisms (trees, birds etc.)
Asexual reproduction – requires
only one parent. Offspring is
identical to parent.
3. The traits of living things are
determined by the genetic code:
When organisms reproduce they pass
on genetic information in the form of
DNA to the offspring.
• In sexually reproducing organisms the
offspring obtain a mixture of genetic
information from each parent.
• In asexually reproducing organism the
offspring have identical genetic
information to the parent
4. Living things grow and develop.
Every organism has its own life-cycle – a
pattern of growth and change that occurs over
the organisms lifetime.
5. Living things obtain and use materials and
energy.
Examples
• Oxygen and sugar are needed by organisms
to make energy.
• Food is needed to help build the body
Chemical reactions take place in the body to convert the
materials from the environment into forms usable by the
organism.
Metabolism is the collection of all the reaction that take
place within an organism.
Examples of Metabolic
Reactions:
•Building Cells
•Breaking down cells
•Converting oxygen and
glucose to energy and carbon
dioxide.
6. Living things respond to their environment.
Organisms live in a constantly changing
environment.
Examples:
Light, temperature and amount of water change
from day to day and season to season. Plants
and animals must respond to these changes or
they will die.
7. Living things maintain and a stable
internal environment.
The steady state (balance) inside an organisms
body is known as HOMEOSTASIS.
While the environment outside changes an
organism must be able to keep conditions
inside mostly the constant. If homeostasis is
disturbed the organism will become sick and
will die if the balance is not fixed.
8. Taken as a group, living things change
over time
Life has
changed
significantly
over the
history of the
earth. The
process of
this change is
known as
evolution.
Topic 1B: The Scientific Process
What is Science?
Science comes from a
Latin word which means
“to know”
Therefore, Science is a way of
knowing….
It is what we use to answer a question
about the natural world
Science is all about
inquiry. People ask
questions about nature
and what they observe
and then actively seek
to find answers.
The process of finding answers is
known as the Scientific Method.
The scientific method has brought us the
technology we enjoy today.
These inventions are not the result of any one
discovery but the total knowledge collected
over centuries of scientific inquiry.
The steps of the Scientific Method?
1-Define the problem (What’s the
Question)
What are you trying to find out?
What just happened?
Why does it do that?
Write 2 questions about the
natural world which you have
wondered about?
Examples of questions:
Why do pigeons bob their
heads when they walk?
Why do leaves turn color in
the fall?
2-Formulate a Hypothesis
Hypothesis- A possible
explanation for an observation
that can be tested.
Example: Pigeons bob their
heads because it helps them
see better.
3-Testing the HypothesisExperimentation
Finding a procedure to either verify or
disprove the hypothesis
Hypothesis is accepted only when
predicted effects are observed and
repeatable
A. Experiment design is critical to make
experiment and hypothesis accepted
Controlled Experiment- Situation is set up more
than once to test your hypothesis
•Variable- A single factor in the experiment is
changed to see if this has an effect on the results
•Control group- One group in the experiment
where no change is made.
Characteristics of a well designed experiment:
• The sample size is large enough to draw a valid
conclusion about the hypothesis
• Only one significant variable is tested through the
experiment.
• A control group is present
• Conclusions must be based on measurable
quantities or clear criteria and not subject to opinion
of the observer.
The dependent variable is the one
that changes is response to the
other variable.
The independent variable is the one
that causes the change the other
variable.
In investigating questions where one factor
(variable) is dependent on another, phrase
the tests as:
The effect of ___________________ on
___________________________.
Or
______________________________
depends on _____________________
Example
The effect of rain amount on oak
tree growth.
The growth of the tree depends on
the amount of rain. Therefore we
call the growth of the tree the
dependent variable and the
amount of rain the independent
variable.
In the relationships below circle the
dependent variable and underline the
independent variable. (look for things that can be
measured)
1. People gain weight based on the
amount of calories they take in.
2. The amount of sunlight available
influences how fast a tomato will ripen.
3. The amount of television watched
by children impacts attention span
In general the dependent variable is plotted on the yaxis and the independent variable is plotted on the xaxis.
Example: Hypothesis – The more time a student spends
thinking before blurting out, the less time they spend in the
Assistant Principals office.
Time in AP office
Fill in the dependent and independent variables on the axes
below:
Time spent thinking before
speaking
B. Measuring Variables
i. International System Units
Measurement Base Unit Basic Tools
Length
Meter
Mass
Gram
Balance/Scale
Liter
Seconds
Graduated Cylinder
Volume
Time
Temperature
Celsius or
Kelvin
Ruler
Stop Watches
Thermometer
ii. The Scale of Biology
Sub-Units of metric
system used in
Biology
Tools for length
Kilo 1000 times
Centi 1/100th
Milli 1/1000th
Micro 1/1,000,000th
Nano 1/1,000,000,000
Measuring Tape
Ruler
Ruler
Light Microscope
Electron
Microscope
For each of the following organisms listed
below choose the appropriate scale of
measurement (metric) for scientists to use:
•
Kilograms
Weight of an Elephant __________________
Micrometers
• Width of a Bacteria _____________________
Celsius or Kelvin
• Temperature of a liquid ________________
Centimeters
•Length of a feather ___________________
Grams
•Weight of a feather ___________________
Meters
• Height of a person ____________________
4-Analyzing and Drawing Conclusions
I. Looking at data obtained in the
experiment(Use graphs, charts, pie graphs etc.)
II. Looking for patterns or relationships
III.Draw a conclusion about your data
(Does the data support your hypothesis or
not)
5-Reporting Observations-
Record your data and report in
detail your means experimentation
and observed results
Scientists must report all the details
because the experiment has to be
repeatable.
Practice Graph Problems
A. Baby chicks require a constant source of food. As
chicks grow, more energy is required for daily activities.
The following table gives the grams of food eaten by a
chick over a five day period.
Number of Days
Graph in packet
Food eaten (g)
0
0.0
1
2
1.0
3.2
3
6.5
4
5
10.6
15.4
A water plant placed in bright light gives off bubbles of
oxygen. In the lab, it was noticed that if the light were
placed at different distances from the plant in the
aquarium, the rate of bubbling varied. Plot a graph of
the following data.
Distance from light
10
Oxygen
Bubbles/Minute
40
20
20
30
10
50
3
6. Tying Discoveries Together
A. Theories and Laws
Theory-Explanations that apply to a broad
range of phenomena and that are supported
by experimental evidence
Scientific Law- Statement that describes
some aspect of a phenomenon that is
always true
How do you tell the difference between
a Scientific Theory and Scientific Law?
A Scientific Law relates to a single
action
•
Example: Gravity
• A Theory explains a series of related
phenomena
Example: Evolution
Cell Theory
Both theories and laws are well tested
and widely accepted.
• Parts of theories can be adapted to new
discoveries or to make them more
understood, but the overall theory will
not change.
Laws are not flexible but can be put into
simpler words.
•
Laws and Theories are different then
Hypotheses.
• Laws and theories are well tested by
experimentation.
• Hypotheses are educated guesses
based on an observation before they are
tested.
Remember: All Hypotheses are Valuable:
Even if a hypothesis (testable guess) is
false it is a valuable tool because it may
lead to further investigations.
Topic 1C: Laboratory Techniques
A. Main Techniques used in Biology
1.Centrifugation
Materials of different densities suspended in a
liquid can be separated by spinning a tube at
high speeds
2. Micro dissection
Tiny instruments that work on one cell at a time
3. Tissue Culture
Maintaining living cells of tissues outside
the body (in vitro)
4. Chromatography
A technique that separates different substances
from each other on the basis of chemical or
physical properties
5. Electrophoresis
A technique that separates proteins, nucleic
acids(DNA), and other substances with an
electric current
6. Spectrophotometry
Using light to analyze what a
substance is and how much is
present.
“Photo” means - Light
7. Staining –
A technique in which a dye is
added to make a substance
within a cell easier to observe.
8. Microscopy
The microscope is perhaps the most important tool in
the history of biology. The invention of the
microscope opened up the worlds of cells to scientists.
The two types of microscopes used in this class are
compound microscopes and dissecting microscopes.
Important Microscope Vocabulary
Magnification – enlargement of an object
100X means that the image appears
100 times bigger than the actual object.
Resolution – the ability of a microscope to
show detail (clarity, sharpness).
Compound
light
microscope:
The compound
light microscope
brings light to
your eye through
a combination of
lenses that allow
you to see small
“Micro” sized
objects in a
magnified form.
To determine magnification you multiply the
power of each lens used.
4 (objective) X 10 (eyepiece) = 40
magnification
4 x 10 = 40X
10 x 10 = 40X
10 x 40 = 400X
The best compound
microscopes can
reach a magnification
of about 2000X.
Compound light
microscopes require
light to work. The
objects observed in a
compound
microscope must be
thin enough for light
to pass through.
Images in a compound microscope appear
upside down and backwards.
Examples:
Would become
t
Would become
e
e
B. How to properly use a microscope:
1. Adjust the microscope to the low power objective
and raise the stage to top position.
2. Center the specimen over the light that is coming up
through the hole in the stage.
3. Look through the eyepiece of the microscope and
adjust light so that it is comfortable for your eyes.
4. Use coarse focus knob until object comes into view
and then use fine adjustment to get sharp focus.
5. You may then use higher power objectives with fine
adjustment knob only.
Dissecting Microscopes (also known as
Stereoscopes):
Dissecting microscopes are used
to view an image in 3D format.
Images are not inverted or upside down.
Dissecting microscopes can not magnify as well as
a compound light microscope.
C. Measuring with microscopes
The area of the slide that you see when you look
through a microscope is called the “Field of
View”.
•You need to know the size of your field of view
to estimate the size of the object.
• Use a thin metric rule to determine the size of
field of view in millimeters (mm).
• Convert millimeters to micrometers using
1 millimeters = 1000 micrometers
Quick trick: just move decimal 3 places to
the right
Practice the following
1.3 mm = 1300 micrometers
2.4 mm = 2400 micrometers
.8 mm = 800 micrometers
.25 = 250 micrometers
The symbol for a micrometer is
m
Determining field of view when you change
power:
We can use proportions to determine the field of
view when the magnification changes:
Low power
High power
=
Low field of view
High power field of view
Example:
If the diameter of the field of view on low power
(40X) is 4000 micrometers, determine the field of
view for medium power (100X)
Example:
If the diameter of the field of view on low power
(40X) is 4000 micrometers, determine the field of
view for medium power (100X)
40X
100X
=
?
4000m
ANS: 1600 m
Estimating the size of an object with field of view:
•Calculate the diameter of the field of view for the
power of magnification.
• Looking through the eyepiece, estimate how many
times the object will fit across the field of view.
• Calculate the size of the object using the formula
below.
Size of object = diameter of field of view (in m)
Number of times object fits across
• Remember to use m
EXAMPLE:
The image of the amoeba to the
left is seen under medium
power (100X) with field of view
1600 m
Calculate size of the amoeba
The amoeba would fit across the field of
view 2 times. Therefore, the approximate
length of the amoeba is 800 m or 0.8 mm.
Now “THE LAB”
Be prepared to show what you learn in the
lab on the LAB EXAM.
“DETAILS! DETAILS! DETAILS!”