2. The goal of science is to investigate and
understand nature, to explain events in nature,
and to use those explanations to make useful
predictions.
Science – an organized way of using evidence
to learn about the natural world
3. Observation – involves using one or more of the
senses – Which are?
sight
hearing
touch
smell
taste
4. Data – information gathered from
observation.
Two types of observation –
Quantitative – involves numbers. Examples?
Qualitative – involves characteristics that
cannot be easily measured or counted.
Examples?
5. Inference – a logical interpretation based on
prior knowledge and experience.
Hypothesis – a possible explanation for a set of
observations or an answer to scientific
questions.
*It can be useful ONLY if it can be tested.
6. 5 Steps
1) Stating the Problem– Identify a problem to
solve.
2) Forming a Hypothesis- Example – Life can arise
from not living matter or spontaneous generation.
(Maggots appear on meat)
Hypothesis formulated by Francesco Redi in
1600s – Flies produce maggots.
7. 3) Setting Up a Controlled Experiment- Factors that
can be changed in an experiment are called
variables. Examples:
temperature, light, time
*A hypothesis should be tested by an experiment
in which only one variable is changed at a time. All
other variables should be kept unchanged, or
controlled.
Why? If multiple variables are changed, one would
not be able to tell which variable is
responsible for the observed results
8. Manipulated variable – the variable that is
purposely changed. (independent v.)
Responding variable – the variable that changes
as a result of the manipulated variable.
(dependent v.)
9.
10.
11. 4) Recording and Analyzing Results
5) Drawing a Conclusion
Hypothesis accepted or rejected?
If accepted, the test can repeated again for validity.
If rejected, the experiment can be altered.
To make results more valid:
(1) – Repeat the experiment
(2) - Increase sample size
12. Experiments can be retested (like Redi’s)
and/or improved with further investigation.
Examples – Needham, Spallazani, and Pasteur
In 1700s, microorganisms were discovered by
Anton van Leeuwenhoek.
13. Needham and Spallazani’s Work
Both scientists proved existing
Filled with
microorganisms organisms are produced only by
existing organisms.
14. Pasteur proved that spontaneous generation
was incorrect; he said that all living things
come from other living things.
His work was different than Needham and
Spallazani’s because he involved air.
15. Tube uncut –
microorganisms not
present. Tube cut –
microorganisms present
An experiment was finally revised over
a 200 year period.
16. Theory – applies to well-tested explanation
that unifies a broad range of observation.
- starts off initially as hypothesis but then
becomes so well supported.
17. Characteristics of Living things
1) Living things are made up of units called
cells.
Cell – collection of living matter enclosed by a
barrier that separates the cell from its
surroundings.
Two types of organisms – multicellular and
unicellular
18. 2) Living things reproduce.
Two types of reproduction:
sexual reproduction – involves two different parents
(multicellular organisms)
asexual reproduction – involves only one
parent
(unicellular organisms)
19. 3) Living things are based on a universal
genetic code.
DNA - the genetic code that determines the
inherited traits of every organism on Earth
4) Living things grow and develop.
20. 5) Living things obtain and use materials and
energy.
Metabolism – combination of chemical
reactions in which an organism builds up or
breaks down materials as it carries out its life
processes
- Energy needed to live
21. 6) Living things respond to their environment.
Organisms live in constantly changing
environments.
7) Living things maintain a stable internal
environment.
Homeostasis – process by which organisms keep
their internal conditions relatively stable (breathing)
- if disrupted in major way, organisms will not
survive
22. 8) Living things evolve, or change over time.
Branches of Biology
The many levels at which life can be studied include
molecules, cells, organisms, populations of a single
organism, communities of populations living in the
same area, and the biosphere.
23. Most scientists use the metric system when
collecting data and performing experiments.
Metric system – decimal system of
measurement whose units are based on
certain physical standards
scaled on multiples of 10.
24.
25. Microscopes –devices that produce magnified
images of structures that are too small to see
with the unaided eye.
Light microscopes produce
magnified images by focusing
visible light rays. Electron
microscopes produce magnified
images by focusing beams of
electrons.
26. Cell Culture – group of cells that develop from a
single original cell.
Purpose – To test cell responses under controlled
conditions and to study interactions between cells.
27. Cell fractionation – a
technique in which cell parts
(organelles) can be
separated.
