Unit 1: What is
Biology
I. What is Biology?
A. Biology – study of life, of all living things
1. Many branches: biochemistry, cell biology,
genetics, evolutionary theory, microbiology,
botany, zoology, et.
B. Six (6) Major Themes in Biology
1. Cell Structure & Function
a) Unicellular – organisms made of one cell
b) Multicellular – organisms made of more than one
cell
2. Stability & Homeostasis
a) Homeostasis – a level of stable internal
environment in cells/living things
3. Reproduction & Inheritance
a) Sexual Reproduction – DNA from 2 parts or 2
organisms is combined
b) Asexual Reproduction – DNA is not combined,
rather an organism copies its DNA and splits
4. Evolution
a) Evolution – how organisms change and come to
exist
b) Natural Selection – “survival of the fittest”; drives
evolution
5. Interdependence of Organisms
6. Matter, Energy, & Organization
a) Organisms obtain, use, & transfer energy &
matter
b) Autotrophs – organisms that can make their own
food to obtain energy
c) Heterotrophs – orgnanisms that cannot make
their own food, but must take it in for energy
C. Characteristics of Life
1. Made of units called cells.
•
•
Prokaryote Cell – cell that lacks a true nucleus
and true organelles
Eukaryote Cell – cell that has a true nucleus and
true organelles
2. Reproduce
3. Based on a universal genetic code
4. Grow & develop
5. Obtain and use materials, and energy
• Metabolism (Energy use) – sum of all
chemical reactions in an organism
6. Respond to external environment
7. Homeostasis – maintain a stable internal
environment
8. As a group, living things change over time
II. Spontaneous Generation vs.
Biogenesis
A. Spontaneous Generation – early theory
that nonliving material could give rise to
living organisms
B. Francesco Redi - In 1668, tested the theory of
spontaneous generation, specifically that maggots
come from rotting meat.
Control Group
- Placed raw meat in an
open jar
- In a few weeks, maggots
were on the meat
- Flies layed eggs on meat,
maggots are fly larva
Experimental Group
- placed meat in a jar
covered with netting
- in a few weeks, maggots
were on the netting
- flies could smell meat,
but only lay eggs on netting
3rd Experiment by Redi
- Placed meat in a sealed jar
- Maggots never appeared
- Flies could not smell the meat
Redi’s Experiment
C. Lazzaro Spallanzani – 1768, microscopes
have been invented & microorganisms are known
to exist; tests the spontaneous generation of
microorganisms.
Control Group
Experimental Group
- Boiled broth to sterilize - boiled broth
- Left flask open to air
- sealed flask immediately
- in several days, broth - in several days, broth remains
was cloudy
clear
Spallanzani’s Experiment
D. Louis Pasteur – 1862
1. Many refused to give up their belief in
spontaneous generation. They argued that
life required a “vital force”, and that
Spallanzani killed this force and prevented it
from entering by sealing the flask.
2. Pasteur completely disproved spontaneous
generation and the idea of a “vital force”.
Pasteur cont.
3. Pasteur boiled broth in a flask with a curved
neck. This allowed him to sterilize the broth
and leave in open for the “vital force”. After
1 year, the broth remained clear and sterile.
FSGPT – Discuss and write down
similarities and differences between the
three scientists experiments.
E. Biogenesis – current, accepted theory
that living organisms can only arise from
preexisting living organisms.
III. Scientific Method
Steps:
A.Observing & Asking Questions
1. Observation – act of noting or
perceiving objects or events by using
the senses
B. Formulating a Hypothesis
1. Hypothesis – possible explanation that
can be tested by observation or
experimentation.
C. Perform an Experiment
1. Experiment – carried out under
controlled conditions to test a
hypothesis.
A. Control Group – group used as a
comparison; results are known
B. Experimental Group – identical to control
group except for one factor, making the
outcome unknown.
i. Independent Variable – the factor that is
different in the experimental group
ii. Dependent Variable – During the
experiment, this is what is being
observed or measured
2. Example: FSGPT
Hypothesis – adding food coloring to a
white flower’s water will change the
flower’s color
Control Group Experimental Group Independent Variable Dependent Variable -
D. Analyzing Results – complete
calculations, plot data, summarize
observations, etc.
E. Draw Conclusions & Verify Results
1. Draw conclusions that explain experimental
results.
2. Verify conclusions by repeating experiments
& checking other scientists results.
F. Scientific Theories – highly tested,
generally accepted principle that explains
a vast number of observations and
experimental data
– Hypothesis = specific, testable prediction for
a limited set of conditions
– Theory = general explanation for a broad
range of data