Honors Biology
Unit 1: Introduction to Biology
How to Define Life
• Living Things Are Organized
• Living Things Acquire Materials and
Energy
• Living Things Respond
• Living Things Reproduce and Develop
• Living Things Have Adaptations
Living Things Are Organized
• Organization of living systems begins with the
cell
– cells are made of molecules that contain
atoms.
• Cells combine to form a tissue (e.g., nervous
tissue).
• Different tissues combine to make up organs
(e.g., the brain).
• Organs work together as organ systems (e.g.,
the brain, spinal cord, etc.)
• Individual multicellular organisms may
have many organ systems.
• A species in a particular area (e.g., gray
squirrels, an oak forest) constitutes a
population.
• The populations inhabiting an area at the
same time make up a community.
• A community plus its physical environment
constitutes an ecosystem.
Living Things Acquire Materials
and Energy
• Maintaining organization and carrying on life requires
outside sources of energy.
• Food provides nutrient molecules used as building blocks
or for energy.
• Energy is the capacity to do work; it takes work to
maintain organization of the cell and organism.
• Metabolism is all chemical reactions that occur in a cell.
• Ultimate source of energy for nearly all life on Earth is the
sun through photosynthesis.
• Organisms must maintain homeostasis or keep
themselves stable in temperature, moisture level,
acidity, etc. by physiology and behavior.
Living Things Respond
• A stimulus often results in movements of
plant or animal, but the resulting action is
called a response whether movement is
involved or not.
• Ability to respond helps organism survive.
• All of the responses to environment
together constitute behavior of organism.
Living Things Reproduce and
Develop
• Reproduction is the ability of an organism to
copy itself.
• Bacteria, protozoa, etc. simply split into two by
binary fission.
• Multicellular organisms may pair sperm with
egg; resulting in an immature individual,
which develops to become the adult.
• Organisms develop as result of blueprint of
instructions encoded in their genes.
• Genes are made of long molecules of DNA that
specify how the organism is ordered.
Living Things Have Adaptations
• Adaptations are modifications that make an
organism suited to its way of life. They may be
structural, physiological, or behavioral. NEVER
just acclimating or getting used to new
conditions
• Natural selection is the process by which
species become modified over time. (Causes
adaptations)
– In natural selection, members may inherit a
genetic change that makes them better suited
to a particular environment.
– Consequently, these members are more
likely to produce more surviving offspring.
• A species is a group of interbreeding
individuals.
• All living things share the same basic
characteristics: cells, DNA, etc.
• This unity suggests all organisms
descended from common ancestor -the
first cell.
• Adaptations to different ways of life explain
diversity of life forms.
How the Biosphere is Organized
• Populations
– Populations within a community interact among
themselves and with the physical and chemical
environments, forming an ecosystem.
• All ecosystems together make up the biosphere, the
thin
layer of life that encircles the earth.
– Food relationships form a major part of interaction
between populations.
• Large ecosystems keeps cycling raw materials (e.g.,
water and nitrogen)
• In contrast, energy flows through an ecosystem and is
eventually lost as heat.
• A constant supply of solar energy is required for an
ecosystem and for life to exist.
The Human Population
• Human populations tend to modify existing
ecosystems for own purposes.
• Fewer natural cycles are able to function adequately
to sustain human populations.
– For example, rain forests: absorb carbon dioxide
– keep temperatures lower
– lessen acid rain
• Preservation of biodiversity (variety of populations) is
extremely important to a normally functioning planet.
How Living Things are Classified
• Taxonomy and Scientific Names
– Taxonomy is the discipline of identifying and
classifying organisms.
• Scientific name is binomial (2 words)
– Scientific name of a species –
• underlined if handwritten
• italics if typed
• I expect you to do this automatically ALL YEAR
– contains two parts
• first name is genus (FIRST LETTER
CAPITALIZED)
• second name is a specific epithet of organism.
• Classification uses 8 taxons: species, genus, family,
order, class, phylum/division, kingdom, and domain.
Scientific Theories in Biology
• Ultimate goal of science is to understand the natural
world in scientific theories, conceptual schemes
supported by a broad range of data.
• The four basic theories of biology are:
– Cell theory: all organisms are made of cells.
– Biogenesis theory: life only comes from life.
– Evolution theory: living things have a common ancestor
and are
adapted.
– Gene Theory: organisms contain coded information that
determines their form and behavior.
• The terms "law" and "principle" are used for fairly narrow,
mathematically based concepts. (Theories are broader and
include more lines of factual evidence)
The Process of Science
• Science is one way humans understand the
natural world.
• Science investigation is limited to questions that
can be studied by direct or indirect observations.
• An observable event is called a phenomenon.
• Formulating a hypothesis involves using what is
already known and predicting what will happen if
a variable is changed
• Science considers testable hypotheses
investigated either in the laboratory or in a field
setting.
Experimental Design
• Controlled experiments have a control group
that does not experience the tested variable;
this eliminates the possibility results are due
to nonidentifiable chance events.
• The experimental group(s) is the group that
does experience the factor or variable being
tested
• A valid experimental design includes multiple
trials or a large experimental group. This is
referred to as an adequate sample size.
• Data are the results of experiments. (Datum is
singular form)
• Data are careful measurements (quantitative
data) or descriptions (qualitative data).
• Careful records must be kept so other
researchers can repeat the experiment.
(Repeatability)
• By analysis of results, a researcher comes to
a conclusion.
• Results can falsify or show a hypothesis to be
untrue; some think of science as what is left
after alternative hypotheses have been
rejected.
– Note that the rejection of a hypothesis is NEVER
bad or wrong. Most lab work is set up to falsify
hypothesis, called a null hypothesis
– A hypothesis is never PROVEN; it can be
supported by data
Peer Review
• Science findings are reported in peer reviewed scientific journals so
results are available to the research community.
– process is called peer review: research papers must be critiqued
by several experts in the field before publication
– scientific journals that utilize peer review (also called refereed
journals) contain research that has been through a rigorous
process; this process is in place so that only the most credible
research is published
– After publication, other scientists try to poke holes in the
research, which eventually refines the research by modification
based on new information
• Claims made originally in the popular press or media that have not
gone through the process of peer review can be viewed as merely
speculation or anecdotal evidence that may not be reliable
A Laboratory Investigation
• Some investigations are held in a laboratory
where conditions can be kept constant.
• A variable is a factor that can cause an
observable change. Some standardized tests just
use the term “factor” to mean “variable”
• The independent variable is the step that is
deliberately manipulated as specified in the
procedure.
• A dependent variable is component of an
experiment that changes due to the
experimental variable; these are the results
that are measured at the end of an experiment
An Observational Investigation
• Some investigations are based on
observations rather than
experimentation. May also be called
descriptive research
• The science steps previously listed still
apply.
• When you participate in citizen science
research, you are a contributor to
descriptive science
The Scientific Method
• Scientific method refers to a set of
outlined procedures.
• Actual science research may not follow
this rigid outline and may involve
chance (e.g., Alexander Fleming's
discovery of penicillin).
Graphing
• Which type is appropriate for data
– Pie chart: when comparing parts of a whole
• Ex: all of the representative phyla in
kingdom Animalia
– Bar graph or Histogram: when comparisons
are made of discontinuous things; brands of
paper towels, states, etc. (good for qualitative
data)
– Line graph: when comparisons are made of
continuous data; change over time; change
over temperature, etc. (always quantitative)
Titles for Graphs
• Three titles must be on all graphs
– Title of graph must include a statement of the
independent and dependent variables
• Ex: The relationship of (DV) to (IV)
• If an organisms other than human is used, the
correctly written scientific name must be in title of
graph
– Both axes must have titles with units in parentheses
• Time (years) ; temperature (oC)
• If there is more than one graph in a laboratory, give it a
number before the title for easy reference
– Ex: Graph 1: The relationship of (DV) to (IV)
Placement of Variables
• Independent variable must be on
horizontal or X axis
• Dependent variable must be on vertical
or Y axis
Scaling
• Each axis must be scaled so that the data takes up as
much space as possible
• Zero must begin each axis, but if it is inappropriate for
the data, a scale break must be used
• The X and Y axes do not need to be scaled the same
• Each interval must be quantitatively equal along the axis,
unless a scale break symbol is clearly indicated
• Scoring Tip:
– The first interval on each axis (without a break) will be
used to determine your intended scale; be sure they
are all the same
– Continue your numbering to the end or slightly
beyond your data
– NEVER draw in extra graph boxes
Plotting and Key
• Make your points large enough to see
• Double check that your points are correctly
placed
• Use a different shape (and color, if possible)
for each data set
• If there is more than one data set, there must
be a key
• Outliers, data points that are way off due to an
obvious error, must be included, but circled
• If you are writing a conclusion you must
explain any outliers
Lines
• A line must be present
• Dot to dot lines may be used to show fluctuation in
data
• Lines of best fit are used to show trends in the data
– May be a [straight] line or a smooth curve
– A “line of best fit” is not the same thing as a
mathematical line, just as the “bridge of the nose”
is not the same thing as a bridge on a road
– Lines of best fit should have approximately the
same number of data points above and below the
line, omitting any outliers
Distinctions between Mathematical
and Science Graphs
• Arrows on the end of lines indicate that the line is true
for any number beyond the scope of the graph
– These are NEVER used in the life sciences, because
living things must maintain constant internal
conditions (homeostasis) or die
– Ex: Your heart rate cannot continually increase with
increasing amounts of caffeine; at some point you
will pass out or die
• This also explains why a line of best fit can be a
smooth curve in biology, but not in mathematics
– Ex: Population growth is usually “J” or “S” shaped
Tables of Data
• Title: must include IV and DV; this may
be the same as the title for the graph,
but if both are used or if more than one
table is included, the proper format is
“Table 1: The relationship between (IV)
and (DV)”
• Place the IV first, then the DV
• You may subdivide for clarity
Conclusion for a Graph
• When writing a concluding sentence for a
graph, use the following template:
• “ As the (IV) (increases/decreases/remains
constant), the (DV) (increases/decreases/
remains constant)”
• Ex: As the length of time spent preparing for
a test increases, scores on the test increase.
Writing a Testable Question
• Key : must be in the form of a question, and
it must include the IV and DV.
• Observation: Fred noticed that some
stretches of the highway had more accidents
involving deer than others.
• Testable question: If floodwaters are closer
(m) to the highway will there be more
accidents involving deer?
Writing a Testable Hypothesis
• Must include IV and DV and a prediction
about what you expect to happen
• Use this format: If the (IV) (increases/
decreases) , then the (DV) will (increase/
decrease/ remain constant)
Ex: If the distance of water to the highway is
greater, then there will be a decrease in
accidents involving deer.
System International (SI)
• If you did not learn the metric system last year
or any of the previous years; do so now.
• In general:
• King Henry Died Drinking Chocolate Milk
• The root word of the measurement unit goes
between the two “d’s” ( gram, second, liter, etc.)
• Kilo, Hecto, Deka, Root, Deci, Centi, Milli
• Unless otherwise specified, always use metric
in science classes
• Other SI prefixes used in biology:
– Micro- µ 0.000001
– Nano- n 0.000000001
– Pico- p
0.000000000001
• If you need to convert a lab measurement,
ALWAYS use dimensional analysis. All this
means is to set up the equation so that units
cancel, ending up with the unit you want on
the top at the end
• 1 g x 1 kg/ 1000g = 0.001 kg
• Always use the zero in front of the decimal
point to make the decimal more obvious
Some notes on Temperature
• Celsius is a difficult concept for most
students.
• Memorize the following:
• Freezing = 0.0 oC
• Room temperature (about) = 22.0 oC
• Human body temperature = 37.0 oC
• Boiling = 100.0 oC