Biology 100/101
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What is
Biology? |
Expectations and
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| biology | life | prediction |
| adapt (v.) vs adaptation (n.) |
hypothesis | homeostasis |
| scientific method | theory | metabolism |
The study of the living world.
Modern biology encompasses all levels of organization and interaction:
among organic molecules
among organelles within a cell
among cells in an organ
among the organ systems in an organism
between organisms and the abiotic environment
among individuals in a population
among species in a biological community
Knowing the facts of biology without an understanding of the relationships among these levels of organization is insufficient to understand the biological world.
How do I know that you are living?
Life is defined in terms of qualities that the living uniquely share:
Life is organized
in sequences of increasing complexity (structures within structures)
the basic unit of life is the cell
levels of biological organization are hierarchical from cells - organisms - communities - biosphere
Life requires energy
the natural tendency of matter is towards disorder (i.e., entropy or randomness)
living systems acquire and use energy to maintain their highly organized state
metabolism: the biochemical reactions that acquire and use energy
Living things must maintain an internal constancy
this requires a separation from the non-living world
for metabolic processes to function normally, living things need to keep themselves stable in temperature, moisture level, chemistry, etc.
homeostasis: the ability to maintain internal constancy (i.e., to stay the same)
Living things grow, develop, and reproduce
vital if a population of organisms is to survive more than one generation
"Instructions" for growth and development are encoded in genes
Living things react to environmental change - Irritibility - (an individual reacts to its environment)
reaction may be immediate as in a reaction to extreme heat, or longer as in a change in leaf color in response to day length, but certainly within the lifetime of the individual.
behavior - move towards or away from stimuli
change in metabolism
change in development
Living things adapt (evolutionary change in a population over many generations)
an inherited characteristic or behavior enables an individual to live and reproduce with greater success than other members of their population in a given environment
these adaptations/modifications become more frequent in the population over several generations
Science is a process for answering our questions about the natural world.
Get together with 1 or 2 other people near you.
Write down one observation concerning the male and female pheasants on the screen.
Male and female ring-necked pheasants
Write down a hypothesis that EXPLAINS why the different sexes of pheasant look different.
Suggest a means of TESTING your hypothesis
The scientific method of investigation involves making a series of inquiries by observing, questioning, reasoning, predicting, testing, interpreting, and concluding. However, because these inquiries spawn new ideas and raise new questions, the scientific method is a cycle of inquiry, not a simple linear process of investigation.
Steps in the cycle:
Make observations, ask questions, and consult prior knowledge
After synthesizing this information, formulate a hypothesis - a tentative EXPLANATION of the observed facts (i.e., this is how I think the natural world works)
Make a prediction based on the hypothesis. The prediction is often phrased in conjunction with the hypothesis as an "If........then....." statement.
IF - state your hypothesis- THEN - state your prediction
NOTE that I am asking you to separate the hypothesis from the prediction. Think of the hypothesis as an explanation of an observed phenomenon.
Design an experiment or observation to test the hypothesis
controlled experiments can be done in a laboratory or the "field"
experiments can be purely observational
experiments can be conducted using computer models
Collect and interpret data
Draw conclusions
-these conclusions either refute or support the
hypothesis
Conclusions and further observations will probably suggest other questions, hypotheses, and experiments
Try this virtual lab experiment from the Hoefnagels Text Book web site. Directions
A scientist believes that the natural world is a physical reality, but that we can only construct a conceptual view of that reality based upon observation and experimentation.
Each of us has our own view of the natural world that is viewed through the lens of our previous experience and knowledge.
Science strives to be objective, and is founded in the belief that events can be explained fully by natural causes. Conversely, explanations based in supernatural causes are not considered to be scientific. Rocks of Ages: Science and Religion in the Fullness of Life, By Steven Jay Gould
Scientific explanations of phenomena observed in the natural world are called hypotheses (singular: hypothesis).
Scientific hypotheses must be testable and falsifiable. If the hypothesis is incorrect it can be tested by experimentation and/or observation and proved to be false.
Experimentation and observations can increase our confidence that a hypothesis is a correct explanation of a phenomenon, but can never absolutely prove a hypothesis to be true.
Once a hypothesis has been supported by many experiments and/or observations it is considered by the community of scientists to be a theory. (Note that this is very different from the common use of the word, meaning an opinion or a guess.)
The conclusions of science are subject to change. New studies, which might utilize new techniques and equipment, may produce new information that leads to the conclusion that previously accepted theories need to be modified or changed entirely.
Great science is replaced by greater science.