Chapter 1 Notes
1.1
Goal of Science – to investigate and understand the natural world, to explain
events in the natural world, & to use those explanations to make useful predictions
that can be tested. Its power has definite limits.
3 features that make science different from other subject areas –
 Deals only with the natural world
 Collect & organize information in a careful, orderly way looking for patterns
& connections between events
 Propose explanations that can be tested by examining evidence
Observations usually involve the 5 senses—sight, smell, taste, hearing & touch
There are 2 main categories of data (the information obtained through an
observation) –
 Quantitative – observation that involves numbers
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Qualitative – observation that is descriptive
Scientists use data to draw a valid conclusion.
An inference is a logical interpretation based on prior knowledge or experience.
A hypothesis is a proposed scientific explanation for a set of observations.
Performing controlled experiments tests some hypotheses. Gathering more data
tests others. A hypothesis is only useful if it can be tested. It should be tested by
an experiment in which only one variable is changed at a time. 3 sources that
hypothesis may arise from are
 Prior knowledge
 Logical inference
 Imaginative guesses
A theory is a broad comprehensive statement about what is believed based on
facts, scientific laws, inferences, & experiments, and may tie together several
hypotheses. Ex: homeostasis, cell theory
Scientific Method
 Formulate useable questions that can be solved through experimentation
 Research topic – make qualitative & quantitative observations
 Hypothesis – if…then, statement
 Experiment – develop & follow a procedure, the outcome must be measurable
 Collect, interpret & analyze data – tables, graphs, pictures
 Draw conclusions – statement that validates or rejects hypothesis
 Communicate results – peer review (allows for other scientists to check
their work)
Parts of an experiment –
 Independent variable – I AM changing/manipulated variable – factor that a
scientist purposely changes
 Dependent variable – responding variable – factor that is measured for
change
 Control group – no treatment group, exposed to all the same conditions
(constants) as the experimental group except for the variable being tested
 Experimental group – the groups that are being manipulated and compared to
the control group
Spontaneous generation – hypothesis (disproved) stating that life could arise from
nonliving matter
Cell fractionation – technique in which cells are broken into pieces & the different
cell parts are separated
Why must you have a control group? So you know which variable is responsible for
change.
If one cannot perform an experiment a field study is an option. This is usually the
option in wild animal studies. Scientists identify as many relevant variables as
possible so as to control them.
1.2
Biological Levels of Organization
 Molecules – groups of atoms, smallest unit of most chemical compounds
 Cells – smallest functional unit of life
 Tissue – group of cells working together
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Organism – individual living thing
Population – group of organisms of one type that live in the same area
Community – groups of species that live within a geographical location
Ecosystem – community and its nonliving surroundings
Biosphere – the part of the Earth that contains all ecosystems
Biology –science that seeks to understand the living world
Cell – collection of living matter enclosed by a barrier that separates the cell from
its surroundings; basic unit of all forms of life
Cell culture – group of cells grown in a nutrient solution from a single original cell
Sexual reproduction – process by which two cells from different parents unite to
produce the first cell of a new organism
Asexual reproduction – process by which a single parent reproduces by itself
Metabolism – set of chemical reactions through which an organism builds up or
breaks down materials as it carries out its life processes
Homeostasis – process by which organisms maintain a relatively stable internal
environment
Evolve – change in a kind of organism over time
1.3
What makes something living? – Characteristics of life
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Made up of cells (unicellular – bacteria, protists) (multicellular – plants,
fungi, animals)
Can reproduce (asexual – copy themselves to make new cells, ex: budding)
(sexual – making sperm & egg)
Able to obtain & use materials and energy-metabolism (all chemical reactions
carried out by the body, build up & break down molecules)
Able to develop & grow – follow a pattern of development
Respond to environmental stimuli – responsiveness (ex: reflexes)
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Unified by a universal genetic code – DNA (pass traits to offspring via genes
in each generation) - heredity
Able to maintain a stable internal environment – homeostasis (ex: body
temperature-sweating, shivering, pH, hydration, blood pressure, pulse)
Taken as a group, living things change over time – evolve (survival of the
fittest)
Autotrophic – self-feeding organism
Abiotic – non-living factors
Heterotrophic – other-feeding
Natural selection – favorable traits
Stimulus – a signal to which an organism responds (ex: light & temperature)
1.4
Microscopes –
 Light microscopes – produce magnified images by focusing visible light rays
 Electron microscopes - produce magnified images by focusing beams of
electrons
 Compound light microscopes – allow light to pass through the specimen and
use 2 lenses to form an image
Metric system– decimal system of measurement based on certain physical
standards and scaled on multiples of 10
KHDBDCM –
Kilo
Kyle Hates Dates Because Dates Cost Money
Hecto
Deka
Meter
Deci
Centi
Milli
.1
.01
.001

Base
Unit
1,000
100
10
1
Practice using the metric system
Light Microscope