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Chapter 1
BIOLOGY
Biology is the branch of science that deals with living organisms and vital processes.
Life can be defined in terms of the characteristics of organisms.
CHARACTERISTICS OF LIVING ORGANISMS
1. Organisms are composed of cells.
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M. Schleiden (1838) and T. Schwann (1839).
Cells are the units of structure and function.
Unicellular and multicellular.
2. Organisms grow by increasing the size and/or the number of cells.
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Development refers to all the changes that occur throughout the lifetime of an
organism.
3. Metabolic processes occur continuously in living organisms.
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Metabolism is the sum of all the chemical reactions that occur in cells.
Chemical processes are carefully regulated to maintain a balanced steady state,
homeostasis.
4. Movement, although not necessarily locomotion, is characteristic of living organisms.
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Locomotion is the ability to move from place to place.
Amoeboid movements, cilia, flagella, organs (e.g. legs, fins).
Sessile organisms do not move from place to place.
5. Organisms respond to stimuli.
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Stimulus is a physical or chemical change in the environment that elicits a
response, e.g. changes in temperature, pressure, color, sound, light, etc.
6. Organisms reproduce.
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Sexual and asexual reproduction.
Passing the traits (genes) of the parents.
7. Populations of organisms evolve and become adapted to their environment.
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Populations are groups of organisms of the same species that live in the same
area.
Adaptations are traits that enhance an organism's ability to survive in a particular
habitat.
INFORMATION
Precise instructions regulate life processes.
These instructions are coded and delivered in the form of chemical substances and
electrical impulses.
1. DNA transmits information from one generation to the next.
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Genes are functional units of DNA that regulate a particular function of the cell.
Genes occupy a specific locus in the chromosome.
They are the units of inheritance.
They control the structure and function of the cell.
2. Hormones are chemical messengers that transmit information and messages.
3.Nervous system transmits information by means of electrical impulses and chemicals.
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Neurotransmitters.
4. Organisms communicate by means of color, sounds, actions and other behavior.
EVOLUTION
Evolution is process by which populations of organisms change over time.
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Response to the environmental changes.
Mutations: changes in the DNA structure.
Natural selection is the mechanism by which evolution occurs.
It favors organisms with certain traits that allow them to survive and reproduce.
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Individuals of a population vary from one another.
Many offsprings are produced than will survive and reproduce.
There is competition between the members of the population for needed
resources.
Those best adapted survive and reproduce.
The environment exerts a selective pressure on populations of organisms.
BIOLOGICAL LEVELS OF ORGANIZATION
Biological organization is hierarchical.
Emergent properties are characteristics not found at lower levels.
E. g. density is a characteristic of populations absent in individuals; organs are absent in
tissues.
Atoms  molecules  macromolecules  cells  tissues  organs  organ
systems  organisms  populations  community  ecosystem  biosphere
SPECIES: Organisms of the same kind that are genetically very similar and can breed
in the wild or without human interference, and produce live, fertile offspring.
POPULATION: A population consists of all the members of a species living in a given
area at the same time.
BIOLOGICAL COMMUNITY: A biological community is made of all of the populations
of organisms living in a particular area.
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The functioning of a community is based on energy transformations.
ECOSYSTEM: An ecosystem is made of the biological community and its physical, nonliving environment.
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Biotic and abiotic components
Biosphere refers to that part of the Earth planet that is inhabited by organisms.
Ecology studies the interaction between organisms and their biotic and abiotic
environment.
TAXONOMY
Taxonomy is the science of classifying organisms.
The species is basic unit of classification.
Groups of closely related species form a genus.
Nomenclature is the system used in naming organisms.
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Binomial system is used in biology.
The genus name and the specific epithet are used to name the different
species.
System designed by Carolus Linnaeus in 18th. century.
Taxonomic classification is hierarchical: each level consists of groups of the previous
lower level.
Species  genus  family  order  class  phylum (division)  kingdom
Taxonomists are not in agreement about the composition of the different taxonomic
groups or taxa (singular taxon).
Your book recognizes six kingdoms. Five kingdoms are most often recognized at
present.
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Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia.
ENERGY FLOW
The sun is the ultimate sources of energy for the Earth's ecosystems: warmth and light.
A few ecosystems are based on energy derived from inorganic substances and the
earth molten interior.
Photosynthesis transforms radiant energy from the sun into chemical energy.
water + carbon dioxide + energy (light)  sugar + oxygen
Energy used by organisms comes from the breakdown of food.
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Autotrophs produce their own food through photosynthesis: producers.
Heterotrophs they consume food made by other organisms: consumers.
Cellular respiration breaks down food and releases energy through two processes:
aerobic and anaerobic (fermentation).
Sugar + oxygen  water + carbon dioxide + energy
Decomposers are heterotrophs that feed on dead organic matter.
SCIENTIFIC METHOD
Scientific method is the process that outlines a series of steps used to answer
questions.
Deductive reasoning begins with supplied information called premises, and draws
conclusions on the basis of that information.
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It discovers relationships between facts.
Inductive reasoning begins with observations and draws conclusions: general
principle.
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What do all these facts have in common?
From many examples to all possible examples: inductive leap.
1. Make observations and ask critical questions.
- Curiosity.
2. Formulate hypothesis:
- A hypothesis is an educated guess proposed as a tentative answer to a specific
question or problem.
3. Predictions are logical consequences of the hypothesis.
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Make a prediction that can be tested.
4. Test the prediction: controlled experimentation.
- Control group: in a controlled experiment, the groups in which all variables are
held constant.
5. Collect data.
6. Interpret data.
7. Draw conclusions.
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Hypothesis supported or not.