CHAPTER OUTLINE
1.1 The Characteristics of Life
The diversity of life seems overwhelming, and yet all living things have certain characteristics in
common.
Organisms Are Organized
Organisms can be organized in a hierarchy of levels. A cell is the smallest unit of life.
Organisms Acquire Materials and Energy
Organisms need an outside source of materials and energy to maintain their organization
or carry on life’s other activities.
Organisms Reproduce
Life comes only from life.
Organisms Respond to Stimuli
Organisms respond to external stimuli, often by moving toward or away from a
stimulus.
Organisms Are Homeostatic
Homeostasis means “staying the same.” The internal environment of an organism stays
relatively constant.
Organisms Grow and Develop
Growth, recognized by an increase in the size of an organism and often in the number of
cells, is a part of development.
Organisms Have the Capacity to Adapt
Natural selection results when adaptations, which are certain features that make
organisms better suited to an environment, allow those individuals of a species to be able
to reproduce and pass on those characteristics. Evolution explains both the unity and
diversity of life.
1.2 The Classification of Organisms
Because life is so diverse, it is helpful to have a classification system to group organisms based
upon their similarities.
Domains
Domains are the largest classification category. There are three domains: Archaea,
Bacteria, and Eukarya. Archaea and Bacteria are unicellular prokaryotes, which lack
the membrane-bounded nucleus found in the cells of eukaryotes, which make up the
Eukarya.
Kingdoms
Systematists are in the process of deciding how to categorize archaea and bacteria into
kingdoms. The eukaryotes are currently classified into four kingdoms: protists, fungi,
plants, and animals.
Other Categories
The other classification categories are phylum, class, order, family, genus, and species.
Scientific Names
Taxonomy is the assignment of a binomial, or two-part name, to each species, where the
first word is the genus to which the species belongs and the second word is the species.
Scientific names are in a common language—Latin.
1.3 The Organization of the Biosphere
The organization of life extends beyond the individual to the population, community,
ecosystem, and finally the biosphere, which is the zone of air, land, and water on Earth where
living organisms are found.
The Human Species
The human species tends to modify existing ecosystems for its own purposes. Humans
depend on healthy ecosystems for food, medicines, and various raw materials.
Biodiversity
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Biodiversity encompasses the total number of species, the variability of their genes, and
the ecosystems in which they live.
1.4 The Process of Science
Biology is the scientific study of life.
Observation
Natural phenomena can be understood more fully by observing and studying them.
Hypothesis
After making observations and gathering knowledge about a phenomenon, a scientist
uses inductive reasoning to come up with a hypothesis, a tentative explanation for the
natural event.
Experiment/Further Observations
Testing a hypothesis involves either conducting an experiment or making further
observations.
Data
The results of an experiment are referred to as the data. Data should be
observable and objective, rather than subjective or based on opinion.
Conclusion
Scientists must analyze the data to reach a conclusion to determine if the hypothesis can
be supported or not.
Scientific Theory
The ultimate goal of science is to understand the natural world in terms of scientific
theories, concepts that join together well-supported and related hypotheses.
A Controlled Study
Most investigators perform controlled studies in which the experimental group receives a
treatment and the control group receives no treatment.
The Experiment
The pigeon pea plant is a legume with a high rate of atmospheric nitrogen
conversion. A hypothesis was outlined involving winter wheat and nitrogen
fertilizer.
The Results
The results lead to the conclusion that the hypothesis is not
supported.
Continuing the Experiment
The researchers modified the hypothesis to involve sustained
effects.
The Results
The results lead to the conclusion that the hypothesis was supported.
Ecological Importance of This Study
This study showed that the use of a legume improved the soil to produce a better yield
than the use of a nitrogen fertilizer over the long haul.
1.5 Science and Social Responsibility
The application of scientific knowledge for a practical purpose is called technology. Most
technologies have benefits but also drawbacks. Making value judgments is not a part of science.
Ethical and moral decisions about technology must be made by all people.
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