Are there places on Earth that
we haven’t yet explored?
YES!!!!
Inaccessible Indonesian cloud forest
“The more we learn about nature, the more we
realize we have yet to learn.”
What is Biology?
The scientific study of life
Why study it? Where do you fit in?
About 20 species become extinct every minute in rainforests alone.
The current rate of extinctions is about 1,00 times faster that normal.
Human activities are responsible for this accelerated rate of
extinction.
We, as human, are intimately connected to the world around us.
When we change the Earth, we change life on Earth.
Biology and Scientific Inquiry
If you accept information without question, you
allow someone else to think for you.
Critical thinking means judging information
before accepting it. This allows you to move
beyond the content of information and to look for
underlying assumptions, evaluate supporting
statements, and think of possible alternatives.
How can you begin to think
critically?
Be aware of what you intend to learn from new information.
Be conscious of bias or underlying agendas in books, lectures,
or online.
Decide whether ideas are based upon opinion or evidence.
Question authority figures respectfully.
Consider what you want to believe and realize that those biases
influence your learning.
The Scope and Limits of
Science: What Science Does
There are many ways to think about the natural world.
Science, the systematic study of nature, is one way.
It helps us to be objective about our observations of
nature, in art because of its limitations.
We limit science to a subset of the world: only that which
is observable.
The Scope and Limits of Science:
What Science Does Not Do
Science does not answer questions like “Why do I exist?” Answers to questions such as this
are subjective. They depend upon personal experiences and mental connections that shape
our consciousness. This is not to say that subjective answers are not valuable, but just that
they can vary from one person to the next or one society to the next.
Science also does not address the supernatural (anything beyond nature).These things are
not directly observable and so are not considered science.
In fact, scientists may cause controversy when they discover a natural explanation for
something that was thought to be supernatural.
Copernicus and the center of the universe
In addition, exploring a traditional view of the natural world from a scientific perspective
might be misinterpreted as questioning morality even though the two are not the same. As a
group, scientists are no less moral, less lawful, or less spiritual than anyone else. However,
their work follows a particular standard: Their explanations must be testable in ways that
others can repeat.
How Science Works
Science helps us to communicate our experiences without bias, similar to a universal
language.
Consider this list of common research practices:
Observe some aspect of nature.
Frame a question about your observation.
Read what others have discovered concerning the subject then propose a hypothesis (a
testable answer) to your question.
Using your hypothesis as a guide, make a prediction ( a condition that should exist if the
hypothesis is not wrong). (“If” is the hypothesis, “then” is the prediction.)
Devise ways to test the accuracy of the prediction by conducting experiments or gathering
information. Tests may be performed on a model (similar system) is testing an object or event
directly is not possible.
Assess the results of the experiments. Data that confirm the prediction are evidence in support
of the hypothesis. Data that disprove the prediction are evidence that they hypothesis may be
flawed.
Report all the steps of your work, along with any conclusions you drew, to the scientific
community.
How Science Works
These steps are commonly referred to as The Scientific Method.
These are common practices that scientists may use, but every
scientist does not always follow every single step in this list,
especially in Biology. There are different ways to do research.
No matter which steps a scientist does use and which ones he
or she leaves for others to do, scientists do NOT accept
information simply because someone says it is true. They
evaluate supporting evidence and find alternative explanations.
They think CRITICALLY.
Theory vs. Law
When a hypothesis has not been disproven even after
years of tests, if it is consistent with all of the evidence
gathered to date, and if it has helped us to make
successful predictions about other phenomena, it is
considered a scientific theory.
A law of nature describes a phenomenon that has been
observed to occur in every circumstance without fail, but
for which we currently do not have a complete scientific
explanation. It refers to the fact that we know that
something happens and how it happens, but we don’t
know why it happens.
The Power of Experiments
Experiments are used to test predictions that flow from a hypothesis.
Experiments are usually designed to determine the effects of a single
variable.
Since biological systems are complex, with many interacting variables, it
can be difficult to study one variable separately from others. Therefore
biology researchers often test two groups of individuals sisde by side.
An experimental group is a group of individuals that have a certain
characterisitic or receive a special treatment. This group is tested
alongside a control group.
A control group is identical to the experimental group except for one
variable, the variable being tested (the independent variable).
Any differences between these two groups indicates the effect of
changing the variable ( the independent variable).
Olestra Experiment
Group 1: 500 individuals who ate 13 oz. of regular potato
chips during a movie
Group 2: 500 individuals who ate 13 oz of potato chips
containing Olestra (a fat replacement used for flavoring)
during a movie
Results: 89% of people eating Olestra chips reported
having cramps after the movie.
93% of people eating regular chips reported having
cramps after the movie.
Olestra Experiment
What question were the researchers trying to
answer?
What was their independent variable?
What was their dependent variable?
What were some of their constant variables?
Which group was their control group?
Which group was their experimental group?
Butterflies and Birds
Experiment
Researchers made two observations
When a peacock butterfly rests, it folds its wings
so that only the dark underside shows.
When the butterfly sees a predator approaching, it
repeatedly flicks its paired forewings and hind
wings open and closed. As the forewing slides
over the hind wing, a hissing sound and a series of
clicks are produced.
Birds and Butterflies
Experiment
The researchers asked a question:
“Why does a peacock butterfly flick its wings?”
They then came up with two hypotheses:
Although wing-flicking probably attracts predatory birds, it also
exposes brilliant spots that resemble owl eyes. Anything that
resembles owl eyes is known to startle small, butterfly-eating birds,
so exposing the wing spots might scare off the predators.
The hissing and clicking sounds produced when the the peacock
butterfly rubs the sections of its wings together may deter
predatory birds.
Birds and Butterflies
Experiment
The researchers then made two predictions:
IF brilliant wing spots of peacock butterflies deter predatory
birds, THEN individuals with no wing spots will be more likely
to get eaten by predatory birds than individuals with wing
spots.
IF the sounds that peacock butterflies produce deter
predatory birds, THEN individuals that do not make the
sounds will be more likely to be eaten by predatory birds than
individuals that make the sounds.
Birds and Butterflies
Experiment
To test their predictions, the researchers conducted an
experiment.
They painted the wing spots of some butterflies black, cut
off the sound making part of the hindwing of other
butterflies, and did both to a third group. They then put
each butterfly into a large cage with a hungry predator
and watched the pair for thirty minutes.
Birds and Butterflies
Experiment
Results of the experiment:
Wing Spots
Wing Sound
Total Number
of Butterflies
Number Eaten Number
survived
Spots
Sound
9
0
9 (100%)
No spots
Sound
10
5
5 (50%)
Spots
No sound
8
0
8 (100%)
No spots
No sound
10
8
2 (20%)
Birds and Butterflies
Experiment
What conclusion did the researchers come to?
Sampling Error
Because researchers can rarely observe all individuals of a group,
they often have to look at subsets of an area, a population, event, or
some other aspect of nature. They test the subset, then use their
results to make generalizations to the entire population. However,
generalizing results from a subset to an entire population is risky
since that subset may not represent the whole population.
Therefore, scientists have to consider sampling error when reporting
their results. Sampling size is represented on a graph with error bars.
Sampling error is the difference between the results from a subset
and results from the whole. It is used most often when sample size is
small. Beginning an experiment with a large sample size or repeating
an experiment many times can minimize sampling error.
Sampling error
Probability
Sample size is also important in probability.
For example, if you flip a coin, there is a 50% chance that it will land on
heads and a 50% chance that it will land on tails.
If you flip the coin ten times only (small sample size) and get that is
landed on heads only 3 times (30% probability of landing on heads), this
isn’t representative of the true probability of the coin landing on heads.
However, if you flipped the coin 1,000 times (large sample size), you
would most probably find that your results would more accurately reflect
the true probability of the coin landing on heads (50%) or on tails (50%)
Scientists will refer to their experimental results as statistically
significant. This simply means that the results that they observed and
recorded were unlikely to have happened just by chance. It means that
the results have been rigorously statistically analyzed and that there is a
very low probability (< 5%) that the results have been skewed by
sampling error.
Levels of Organization of Life
Levels of Organization of Life
ATOMS: the basic building blocks of all matter
MOLECULES: Atoms join to form molecules. The molucules of lfie are made only by living
cells. These are carbohydrates, lipids, proteins, and nucleic acids. The same atoms make up
both living and non-living things. The unique properties of life emerge as certain kinds of
molecules become organized into cells.
CELL: The smallest unit of life that can survive and reproduce on its own, given information in
its DNA, energy, and raw materials.
ORGANISM: An individual that consists of one or more cells. In larger organisms, these cells
may be organized into tissues (groups of similar cells that have the same function), organs, and
organ systems.
POPULATION: A group of the same type of individuals (or species) living in a given area.
COMMUNITY: Consists of all population of all species in a given area.
ECOSYSTEM: Communities interacting with their environment.
BIOSPHERE: Most inclusive level- includes all regions of Earth’s crust, waters, and
atmosphere in which organisms live.
Life is more than just the
sum of its parts.
Some emergent property occurs at each
successive level of life’s organization.
An emergent property is a characteristic of a
system that does not appear in any of a system’s
component parts.
For example, the emergent property- lifeappears first at the level of the cell.
So, what is life, really?
Even though life is not easy to define since it has
always been and always is changing, we can
determine if something is alive by considering
the characteristics of life.
The Characteristics of
Life
Living things require energy to sustain life’s
organization
• All organisms spend a lot of time acquiring energy and
nutrients. However, how they go about this task is different.
• Producers make their own food using energy and simple raw
materials they get directly from their environment. (ie. plants)
• Consumers cannot make their own food; they get energy and
nutrients indirectly by feeding on other organisms. (ie.
Animals, decomposers, etc.)
One Way Flow of Energy in Living Things
Energy is not recycled. It flows through the world of life in one
direction, from the environment to living organisms. The flow of
energy is one way because, with each energy transfer, some
energy escapes as heat. Cells can not use heat to do work.
Thus the energy that enters the world of life eventually leaves it.
The Characteristics of
Life
Living things sense and respond to change.
Living organisms sense and respond to changes both inside and
outside of its body using receptors ( a molecule or cellular structure
that responds to a specific form of stimulation).
Unless the internal environment is kept within certain ranges of
composition, temperature, etc., your body cells will die.
By sensing and adjusting to change, you an all other organisms keep
conditions in the internal environment within a range that favors cells
survival.
This condition that favors cell survival is called homeostasis (“staying
the same”) and is a defining feature of life.
The Characteristics of Life
Living things grow and reproduce.
Individuals of every natural population are alike in certain aspects of their body
form, function, and behavior but the details of such traits can take different forms
from one individual to the next. This is due to the outcome of information encoded
in DNA (deoxyribonucleic acid).
DNA is the signature molecule of life.
DNA carries information that guides growth (increases in cell size, number, and
volume) and development ( process by which the first cell of a new individual
becomes a multi-celled adult.
Only multi-celled species undergo development, but all organisms inherit DNA
from parents.
Inheritance refers to the transmission of DNA from parents to offspring.
Inheritance occurs by the process of reproduction.
Both inheritance and reproduction are hallmark features of life.
Life’s Diversity
Living organisms differ in their details; they show tremendous
variation in traits.
Each time a new species (kind of organism) is discovered, it is
given a two-part name. The first part of the name specifies the
genus, which is a group of species that share a unique set of
features. The second part of the name is the species name.
Individuals of a species share one or more heritable traits and
they can interbreed successfully (producing fertile offspring) if
the species is sexually reproducing
The genus and species names are always italicized and the
genus name is always capitalized.
Classification of Life’s Diversity
Classification Systems are used to organize and retrieve
information about species. Most classification systems sort
species into groups on the basis of their traits.
There are different classification systems. A very popular
system that has been used is the Five Kingdom classification
system. The five kingdoms in this system are Monera, Protista,
Fungi, Plantae, and Animalia.
A common classification system that is currently used classifies
all living things into three domains: Bacteria, Archae, and
Eukarya. Protista, Plantae, Fungi, and Animalia kingdoms are
included in the Eukarya domain, while the Monera kingdom is
subdivided into two domains: Archae and Bacteria.
Life’s Diversity: Prokaryotes
All Bacteria and Archaeans are single-celled
organisms. All are also prokaryotes, meaning that
their DNA is not contained within a nucleus (
membrane-enclosed sac that protects a cell’s DNA).
Prokaryotes are the most numerous and diverse
organisms. Different kinds are producers or
consumers and they inhabit nearly all of the
biosphere, including extreme environments such as
frozen desert rocks, boiling sulfur-clogged lakes, and
nuclear reactor waste.
Life’s Diversity: Eukaryotes
All organisms in the domain Eukarya are eukaryotes.
These organisms are those that contain a true, welldefined nucleus.
Protists are the simplest eukaryotes. Some protists are
rpoducers while others are consumers. Many are single
cells that are larger and more complex than prokaryotes.
Some are unicellular while others are multicellular.
Fungi, plants, and animals are also eukaryotes.
Eukaryotes: Fungi
Most fungi are multicellular.
Many are decomposers, and all secrete enzymes
that digest food outside the body and then
absorb the released nutrients.
Examples include yeast, mushroom
Eukaryotes: Plants
All plants are multicellular and live on land or in
freshwater. (Ex. Trees)
Most produce their own food using a process
called photosynthesis, in which the energy of the
sun is used to drive the production of sugars
from carbon dioxide and water.
Plants serve as food for most other organisms in
the biosphere.
Eukaryotes: Animals
Animals are multicellular consumers that ingest the tissues and/or juices of other
organisms.
Herbivores eat plant material. (Ex. Rabbits)
Carnivores eat meat. (Ex. Lions)
Scavengers (or detritivores) eat the remains of other organisms. (Ex. Vultures)
Parasites withdraw nutrients from the tissues of a host. (Ex. Mosquitoes)
Animals grow and develop through a series of stages that lead to the adult form.
Most animals actively move about for at least part of their lives.