Biology 143

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Chapter 1. The science of Biology


1. Properties of life
2. Science
a. Scientific Reasoning/method
b. Experimental controls
3. Intro to Evolution
a. Charles Darwin
b. Malthus
c. Natural selection
d. Examples of evolution
4. Evidence for evolution


Biology: Scientific study of living organisms and how they evolved.

Science: Knowledge derived from observation and experimentation carried out to determine the principles underlying what is being studied.

Hypothesis: A suggested explanation that accounts for the observations

Experiment: Test of a hypothesis

Variable: An influencing factor

Theory: A proposed explanation for some natural phenomenon, often based on a general principle. In Science, a theory is on solid ground, well tested, and widely accepted. An accepted principle or body of knowledge.

Control experiment: An experiment where the variable in question is left unaltered

Evolution: Operation of natural laws that produce change over time. The process of change in living organisms.

Natural selection: Differential reproduction under natural conditions. Differential contribution of genotypes to the gene pool of the next generation under natural conditions.

Characteristics of life:
1. Order: All organisms consist of one or more cells with highly ordered structure. Atoms to molecules to organelles to cells and cells to tissues to organs to organisms to populations to species to community to ecosystem 2. Sensitivity: All organisms respond to stimuli.

3. Growth, Development, and Reproduction: All organisms are capable of growing and reproducing. Reproduction is carried out using hereditary molecules (DNA, RNA) ensuring the offspring are the same species. 4. Regulation: All organisms have internal mechanism that coordinates the organism internal functions. 5. Homeostasis: All organisms maintain constant internal conditions different from their environment. 6. Evolutionary Adaptation: All organisms are subject to evolutionary forces

Scientific Method:
Inductive reasoning vs. deductive reasoning:
1. Inductive reasoning: Using specific observations to construct general scientific principles 2. Deductive reasoning: Using general principles of predict specific results.

Both are used in science, deductive reasoning is used to test the validity of general principles. Inductive reasoning is used to come up with the underlying explanations

Observations ( Hypothesis ( Experiment

Basic Scientific method

1. Observations
a. Some phenomenon is observed
2. Formation of a hypothesis
a. The hypothesis is a potential explanation for the observations b. The hypothesis needs to be testable
3. Experimentation
a. Design a controlled experiment to test the hypothesis b. In a controlled experiment only one variable is manipulated. c. Only changing one variable ensures that any changed can be attributed to the variable 4. Results

a. Support hypothesis
b. Do not support hypothesis

Hopefully the scientist publishes results in a good journal.

Theory: Scientific usage vs. popular usage

In science, when a concept is called a “theory”, it is a well accepted, well tested, ex theory of gravity, or theory of evolution.

In popular usage, a “theory” is basically a guess; ex I have a theory that Colonel mustard committed the murder with the candlestick.

In science a hypothesis becomes a theory only after lots of rigorous experimental confirmation.

Darwin and Evolution:

Charles Darwin (1809-1882) was an English naturalist who after years of observation wrote a very famous book. The book had the rather long title of:

On the Origins of species by means of Natural Selection, or the preservation of favored races in the struggle for life.

Often this...
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