I.THE STUDY OF LIFE
A. Themes Of Biology
1. Primordial Earth
a. Formation of first life form on Earth dates back to approx. 3.5
Billion years ago.
b. Organism – a living thing.
c. Single-celled organisms were the only form of life on Earth for
several million years after genesis.
d. Cellular organisms gradually changed through time and lead to
Earth’s current diversity.
2. Biology – the science of life or all living things. Includes…
a. Microscopic structure of single cells;
b. Interactions between millions of species
c. History of individual organisms;
d. Collective history of life on Earth.
3. Cell Structure and Function
a. The cell is the basic unit of life; all organisms are made of and
develop from cells.
b. Unicellular Organisms – composed of only one cell.
c. Multicellular Organisms – composed of more than one cell.
d. All cells are surrounded by a membrane and contain genetic
information to help carry out internal processes.
e. New cells produced by unicellular organisms are identical to
the parent cell.
f. Differentiation – the process by which cells become different
each other as they grow to perform different tasks.
4. Stability and Homeostasis
a. Internal conditions such as food, water, and temperature need
to be controlled within an organism.
b. The average temperature of the human body is around 37 C
(98.6 F).
c. Homeostasis – a stable level of internal conditions that is found
in all living things) including unicellular organisms.
1. The Harp Seal utilizes the shape of its body, fat, and
circulatory system to survive in freezing water.
5. Reproduction and Inheritance
a. Reproduction – the process by which organisms produce new
organisms like themselves.
b. DNA – hereditary information. Deoxyribonucleic Acid.
1. In Multicellular organisms, DNA is enclosed within a
structure of membrane.
2. In Unicellular organisms, DNA exists as a loop.
c. Gene – short segment of DNA. Contains the instructions for
development of a single trait.
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d. The DNA in every cell in your body is exactly identical.
e. Sexual Reproduction
1. Half of the female genome as well as half of the male
genome combine to form a single cell (fertilized egg).
2. The cell divides repeatedly.
3. The new organism is made of cells containing
hereditary information from both parents.
f. Asexual Reproduction
1. A bacteria splits in two and hereditary information is
not combined.
2. The spider plant splits off vines to form offspring.
3. Each new cell is identical to the parent in every way.
6. Evolution – change over generations.
a. Natural Selection – organisms with more favorable traits will
be more successful at reproduction.
1. Driven by competition for resources.
7. Interdependence of Organisms
a. Ecology – the interactions of organisms between one another
and their environment.
b. Ecosystem – environmental community.
8. Matter, Energy, and Organization
a. Photosynthesis – the process by which plants capture energy
from the sun and convert it to chemical food.
b. Autotrophs – organisms that make their own food.
c. Heterotrophs – organisms that get food from the outside
environment.
B.The World Of Biology
1. All organisms share certain features universal to all living things.
a. Cells – all living things are composed of cells.
b. Organization – living things are highly organized at the
molecular and cellular scale.
c. Energy Use (Metabolism) – the sum of all the chemical
processes that occur in an organism.
1. Greek metabole; i.e. to change
d. Homeostasis – all living things maintain stable conditions.
e. Growth – living and many nonliving things grow.
f. Reproduction – all species can reproduce.
2. The Living World
a. A gram of fertile soil may contain more than 2.5 Billon
unicellular organisms.
C.Scientific Methods
1. Observing
a. In 1976, a deadly pathogen appeared in the Congo. Doctors
observed symptoms and recorded locations of occurrences to
determine the cause.
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2. Asking A Question
a. All scientific investigations begin with one or more questions.
b. Questions are important to the scientific process as they
determine what aspects need to be investigated further and pick
out possible areas of further concern.
1. How is the disease transmitted?
2. Do all victims die?
3. What is the disease causing agent?
3. Collecting Data – the longest phase of a scientific investigation.
a. Data – any and all information that scientists gather in trying to
answer their questions.
b. Important aspects of collecting data include:
1. Observing
i. It is the observations of something unusual that
raises the first question in a scientific
investigation.
ii. Observation – typically employs one or more of
the five senses to perceive objects or events.
2. Measuring
i. Things are often measured in numbers.
ii. In Zaire, scientists recorded data including the
number of people who displayed symptoms of
the disease, among other key figures.
3. Sampling
i. Sampling – the technique of using a sample to
represent an entire population.
ii. Samples must be large and random.
iii. In Zaire, scientists took hundreds of blood
samples from both infected and healthy people.
4. Organizing Data
i. Organizing involves placing data in a logical
order, such as a graph, chart, table, or map.
ii. Flowcharts are also commonly used (Figure 114, Pg. 16)
4. Hypothesizing
a. Hypothesis – a suggested explanation for what has been
observed or recorded. A hypothesis can be tested.
b. Steps involves in hypothesizing:
1. Forming A Hypothesis
i. Cause-and-effect relationships can never be
assumed in an investigation.
ii. A statement is testable if evidence can be
collected that does or does not support it.
iii. A hypothesis can never be proved true beyond
all doubt.
2. Predicting
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i. Prediction – states the results that will be
obtained from testing a hypothesis.
ii. A prediction must always take the form of an if
then statement.
5. Experimenting
a. Experiment – the process of testing a hypothesis or prediction
by gathering data under controlled conditions.
b. Aspects of experimenting:
1. Conducting A Controlled Experiment
i. Controlled Experiment – based on a comparison
of a control group with an experimental group.
ii. The control group and experimental group
are designed to be exactly the same except for
one factor called the independent variable.
iii. Dependant Variable – driven by or results from
the Independent variable.
2. Analyzing Data
i. Analyzing data is the process of determining
whether data are reliable and support a
hypothesis.
ii. Scientists may use statistics to determine
relationships between variables.
6. Drawing Conclusions
a. Steps of drawing a conclusion:
1. Modeling
i. Model – an explanation supported by data.
ii. Scientists can use models to generate new
hypotheses or predictions.
2. Inferring
i. Inference – a conclusion made on the basis of
facts or premises rather than on direct
observations.
ii. Unlike a hypothesis, an inference is not directly
testable.
3. Forming A Theory
i. Theory – a broad and comprehensive statement
of what is thought to be true. A theory is
supported by considerable evidence and may tie
together several related hypotheses.
D. Section 4 – Microscopy And Measurement
1. Microscope – an instrument that produces an enlarged image of an
object.
2. Magnification – the increase of an object’s apparent size.
3. Resolution – the power to show details. Microscopes vary in power.
4. Compound Light Microscope (LM) – a lighter microscope used to
examine small organisms and cells. The specimen must be transparent.
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1. Stage – where the slide holding the specimen is placed.
2. Objective Lens – a variety of lenses through which
light passes through after the specimen. Objective
lenses enlarge the image of the specimen.
3. Ocular Lens – the lens in the in the eyepiece where the
image is magnified further.
4. Nosepiece – a rotating piece holding the objective
lenses in place.
5. Power Of Magnification – the factor of enlargement. A
typical light microscope produces an image 40 times
the actual size of the specimen.
6. Computing The Power Of Magnification
i. The standard ocular lens magnifies 10x.
ii. The power of the strongest objective lens is
multiplied by the power of the ocular lens to get
the total power of the microscope.
5. Electron Microscope – a powerful microscope in which a beam of
electrons produces an enlarged image of the specimen.
a. Beyond 2,000x, the image of a specimen becomes blurry due to
the physical characteristics of light; therefore, another method
must be used.
b. Types of Electron Microscopes:
1. Transmission Electron Microscope (TEM) – transmits
a beam of electrons through a thinly sliced specimen.
TEM can magnify up to 200,000 times but cannot be
used to view living specimens.
2. Scanning Electron Microscope (SEM) – generates 3-D
images. The SEM operates by bouncing electrons off
an intact, metal-coated specimen. SEM can magnify up
to 100,000 times. Like the TEM, SEM cannot be used
to view living organisms.
6. Measurement In Science
a. The official name of the measurement system is Systèm
International d’Unités (Internal System of Measurements),
commonly called SI.
b. Base Units – fundamental base units that describe length, mass,
time, and other quantities.
c. The Seven Fundamental Base Units:
1. Meter (m) – length
2. Kilogram (kg) – mass
3. Second (s) – time
4. Ampere (A) – electric current
5. Kelvin (K) – thermodynamic temperature
6. Mole (mol) – amount of substance
7. Candela (cd) – luminous intensity
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d. Derived Unit – produced by the mathematical relationship
between two base or two derived units.
e. SI Derived Units:
1. Square Meter (m2) – area
2. Cubic Meter (m3) – volume
3. Kilogram per Cubic Meter (kg/m3) – mass density
4. Cubic Meter per Kilogram (m3/kg) – specific volume
5. Degree Celsius (0C) – Celsius temperature
f. There are other units accepted for use with SI, concerning units
of time, volume, and mass including hours, days, and metric
ton.