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Unit 1: Biology
Objectives: I can …
• Explain the goals of science and the function of scientific
instruments
• List the characteristics of life
• Distinguish between sexual and asexual reproduction
and the significance of each
• Evaluate the relationship between adaptation and
evolution
• Differentiate between the dependent & independent
variable and also the control group & the experimental
group, quantitative & qualitative data, etc. in a controlled
experiment.
• Design a controlled experiment accurately using the
scientific method
• Use a microscope accurately and identify its parts
• Compare/contrast the advantages and disadvantages of
using each type of microscope
• Accurately collect data using the metric system
Vocabulary:
Biology, Anatomy, Physiology, Morphology, Taxonomy,
Phylogeny, Botany, Zoology, Ecology, Genetics, unicellular,
multicellular, cell, tissues, organs, homeostasis, autotrophs,
heterotrophs, herbivores, omnivores, carnivores, natural
selection, “survival of the fittest”, zygote, divergent &
convergent evolution , analogous, homologous, scientific
sample, qualitative data, quantitative data, milli, centi, kilo,
scientific method, hypothesis, controlled experiment,
independent (manipulated) variable, dependent (responding)
variable, control group, experimental group, operational
definition, Inference, theory, law, magnification, resolution,
Darwin, natural selection, objective lens, ocular lens, stage,
turret, diaphragm
Biology
Bio - “life”
-ology = “the study of”
Biology is the study of both unicellular and multicellular
organisms and includes several subcategories such as:
Anatomy - the study of structure (Literally “to cut apart”)
Physiology - the study of function
Morphology - outer shape or appearance; used in taxonomy.
Taxonomy - classification of organisms according to their
“relatedness”
Phylogeny - ancestry/evolutionary history of organisms
Genetics - the study of inheritance
Botany - the study of plants
Zoology - the study of animals
Ecology - study of interactions between organisms and their
environment
AND MANY MORE
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Characteristics of Life
All living things are composed of one (unicellular) or more
cells (multicellular - allows “specialization” of cells). Cell =
basic unit of life and contains the “genetic code”
Living things are organized at both the cellular level
(organelles have specific tasks) and the multicellular level:
cells -> tissues -> organs -> organ systems And they can
maintain their internal conditions (homeostasis)
Living things respond to their environment
Grow by cell division and/or enlargement
Have the potential to reproduce
Use energy for growth and maintenance
– Autotrophs - make their own food (Ex: plants photosynthesize)
– Heterotrophs - eat other organisms
• Herbivores - eat mostly plants
• Omnivores - eat plants and animals
• Carnivores - eat mostly meat
• Adapt to their environment and as a species, may evolve
Is movement a characteristic of all life?
NO !!!!!!
All areas of biology believe in evolution - the theory that
species change over time as they adapt to their
environment.
Charles Darwin proposed that natural selection, or “survival of
the fittest” occurred when organisms with the “right” traits
(adaptations) survived to reproduce.
Organisms can reproduce through either:
1) Sexual reproduction - genetic information in egg and sperm
combine to form a zygote. Sexual reproduction increases
genetic variability in a population.
2) Asexual reproduction - an organism simply divides into two.
Offspring are genetically identical (clones) to parents.
How might the consequences of being infected by ONE sexually
reproducing organism differ from ONE that asexually reproduces?
An asexual organism could create 1000’s of offspring over time. Without a
partner, sexually reproducing organisms can’t multiply.
To better study groups of organisms, scientists often classify
them into related groups (taxonomy). Initially this was done
by their morphology (shape/outer appearance). But
evolutionary adaptations can fool us:
1) Homologous organs - physical features look quite different
but developed from similar structures. This is known as
divergent evolution. (Ex: a bat’s wing, a whale’s flipper, and
a human hand.)
2) Analogous organs - features look similar but came from
quite different structures. This is called convergent
evolution. (Ex: a butterfly wing and a bird wing, a panda’s
“thumb” and a human thumb)
To study large populations of organisms, scientists may
use smaller groups. This is known as scientific sampling.
This is similar to surveys where a smaller number of people
are asked their opinion to determine how the overall
population feels about an issue.
Understanding populations of organisms also requires
observing those organisms. Observations may be qualitative
(ex: color, texture - non-numerical qualities) or quantitative,
numerical data (ex: 5 cm tall, 110 grams).
Worldwide, the metric system (similar to the Systeme
Internationale, SI system)is most commonly used for
collecting numerical data. It is based on multiples of 10.
Base units: distance - meter, mass - gram, volume - liter
Prefixes: milli- 1/1000th (.001), centi- 1/100th (.01),
deci- 1/10th (.1), deka - 10, hecto- 100, kilo- 1000
The scientific method is usually followed during
experiments. It includes:
1) Problem statement /question (Ex: How fast do E. coli
bacteria reproduce at 10 degrees Celsius?)
2) Gathering background information (Ex: According to
Smith & Jones, E. coli can double in numbers in 15
minutes at 15 degrees Celsius.)
3) Forming a hypothesis. This must be TESTABLE to be
useful. A hypothesis is an educated guess as to what will
likely happen based on your background research. (Ex:
If E. coli doubles in number in 15 minutes at 15o C
(Smith & Jones), then it will probably take 30 minutes to
double in number at 10 degrees because bacteria
populations do not grow as fast at low temperatures
(Jason & Kline).
4) Experimenting and experimental design - This is often done
as a controlled experiment. Here, only a single variable
(variation from “normal”) is tested in an experimental group.
A control group, where nothing has changed (everything is
“normal”, or “standard”) is used as a comparison. (Ex: Two
groups of E.coli bacteria are exposed to the same amount of
light, heat, etc., but the experimental group gets 10 minutes
of radiation exposure each day and the control group does
not.)
In this example, the variable that the scientist “manipulated”
was the exposure to radiation. This is the independent
(manipulated) variable. Whether or not the bacteria died or
grew, or ??? due to the radiation exposure, is known as the
dependent (responding) variable. The independent variable
and the expected outcome (dependent variable) should
always be stated in the experimental design. An operational
definition should also be given if needed. Ex: growth means
an increase in number of bacteria, or growth means an
increase in size of individual bacteria)
The experimental design should give a clear step by step
account of how to conduct the experiment and also
describe the size of the sample population used (Ex: 10
colonies of bacteria will be used in the control group and
10 colonies in the experimental group) and other factors
such as gender, age, etc, when applicable.
5) Data collection - Both qualitative and quantitative
observations are made. Quantitative data may be put in
graphs, charts, etc. However, it is important to use the
right type of graph for the data! How might qualitative
data be quantified?
6) Analysis and Conclusion - This is made based on the data
collected. It should briefly summarize the data and how it
either supported or refuted the hypothesis. “Sources of
Error” should be included here. (Ex: Since only 2 bacterial
colonies were used in this experiment, the sample size was
too small to generalize the findings to all bacteria exposed
to radiation.) Beware of making inferences, stay strictly with
what was actually observed (seen, heard, smelled, etc)
Inferences are assumptions (Ex: I hear yelling in hall - I
infer there must be a fight)
7) Sharing of the experimental findings - the experimental
design should be reproducible so that other people can
review the findings and re-create the experiment to either
support the findings or find flaws with them (refute them).
This may lead to new discoveries!
If a hypothesis is found true over & over again and it pertains
to natural phenomenon, it may become a theory. This is a
well-tested explanation that “unifies a range of
observations.” Theories that hold true may become “laws”.
One of the many tools used by biologists is the microscope.
Microscope parts:
Ocular lens (eyepiece) - magnifies (usually 10x)
Objective lenses - each lens has a different magnification. The
shortest lens magnifies the least. These usually ride on a
turret (revolving nosepiece)
Diaphragm - adjusts the amount of light
Stage - flat platform to place slides
Coarse adjustment - used for main focus. Do NOT use on
high power.
Fine adjustment - used to focus on higher powers
Note: Always put object into focus on low power ( shortest
objective) first, then work up to medium, readjusting focus if
needed, then high if needed.
Energy source - we use light microscopes but other sources of
energy, like electrons can be used. Because both an
ocular and objective lens are used, it’s called a compound
light microscope.
Total magnification can be found by multiplying the power
of the ocular lens by the power of the objective lens in
place.
Ocular lens x Objective = Total magnification
10
x
10
= 100
10
x
40
= 400
10
x
100 = 1000
Resolution is different than magnification. It’s the clarity or
ability to show distinct detail.
(Ex: Two dots close together - if seen as 2 separate dots,
the resolution is better than if seen as 1 dot.)
Electron Microscopes
Electrons are bounced off the object to create an image.
This increases magnification many times greater than is
possible with compound light microscopes.
1) Scanning Electron Microscope (S.E.M.) - shows surface
of object in 3 dimensions.
2) Transmission Electron Microscope (T.E.M.) - greatly
magnifies thin sections of material.
3) Scanning Tunneling E. M. (STEM) - has the highest
magnification of all. Magnifies up to 100 million times.
(Can even see DNA) Uses computer to create image.
Electron Microscope Advantages:
1) Magnification of 300,000x or more
2) Very high resolution
Disadvantages of Electron Microscopes:
1) Very expensive
2) S.E.M. requires thin coating of gold over objects.
3) T.E.M. requires skilled person to cut super thin section
(often use a laser knife)
4) Requires a vacuum chamber within microscope. Dust
inside scope would completely block view.
5) Except for STEM, can only view dead organisms
Of course many other instruments are used by
biologists, such as a special blender to break cells apart
(cell fractionation) and separate their parts or a
centrifuge to spin blood, separating the liquid plasma
from the solid cells.