The Science of Biology
Chapter 1
1-1 What is the goal of
Science?
• Investigate and understand nature
• Explain events in nature
• Use those explanations to make useful
predictions
What is Science?
• An organized way of using evidence to
learn about the natural world
• Body of knowledge that scientists have
built up after years of using this
process
The Scientific Method
1)
2)
3)
4)
5)
Stating Problem/Observations
Hypothesis
Experimentation
Data collection and analysis
Conclusion
a.
b.
c.
d.
e.
Answer to problem
Validity (restate data)
Prove/Disprove hypothesis
Errors
Improvements
Observations
*using the senses to gather/collect data
Quantitative
-observations based on
numbers or
quantities
Qualitative
-observations based on
description
Ex.Counting/measuring
7 birds, 14 miles, 200
people
Ex. Color/texture
blue neck, large teeth,
soft cushion
Objective vs. Subjective
Observations
• Objective-without a predetermined
point of view, unbiased
• Subjective-with a predetermined point
of view, biased (dangerous-Jews
inferior to Germans)
Hypothesis
• A possible answer to a scientific
question or an explanation for a series
of observations.
Ex. Use hypothesis to discover how infected
disease was contracted:
-spread by human contact?
-spread through insect bites?
-spread through contaminated air/water/food?
**All of these are then tested to find the correct
explanation.
Experimentation
•
•
Controlled steps used to test the
hypothesis
Controlled Experiment-only 1 variable
is changed and all others are kept
unchanged, or controlled.
Variables
• Independent/Manipulated: the one that
is deliberately changed/tested (only 1);
on X axis.
• Dependent/Responding: the one that is
measured and changes in RESPONSE to
the independent variable; on Y axis.
• Controls: those that remain
constant/unchanged
Data Collection and Analysis
• Clear, precise, and objective
– Displayed in table/graph
• Understanding and making sense of
observations
– What does your data tell you about the
experiment?
Conclusion
• Analyzing data brings you to a final
decision/conclusion
• Evidence found supports or refutes
hypothesiswill test correct or wrong
Role of Experiments
• Procedures used to study a phenomenon
under known conditions
• Allows you to predict what will happen if a
hypothesis is not wrong
• Can never prove a hypothesis 100%
correct
Experimental Design
• Control group
– A standard for comparison
– Identical to experimental group except no
independent variable present
• Experimental group
– Independent variable present and being
tested
Draw samples from some aspect of nature
CONTROL GROUP
The variable being
tested is absent
EXPERIMENTAL GROUP
The variable being
tested is present
Compile results
Compile results
Compare and analyze the test results
Report on experimental design, test results,
and conclusions drawn from results
1-2 Spontaneous Generation
Belief that living things arose from non-living
things
Examples:
Maggots come from
meat
Mice from wheat
Beetles from cow
dung
Their Explanation…
**Gods, witchcraft,
mythology, devil
Francesco Redi and Spontaneous Generation
Section 1-2
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.
PROCEDURE
Uncovered jars
Controlled Variables:
jars, type of meat,
location, temperature,
time
Covered jars
Several
days pass
Independent Variables:
gauze covering that
keeps flies away from
meat
Dependent Variable:
whether maggots
Maggots appear
No maggots appear
appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous
generation of maggots did not occur.
What is Redi’s Conclusion?
• Spontaneous generation does not occur.
The Return of Spontaneous Generation
Anton van Leeuwenhoek – uses a microscope to
find tiny organisms swimming in pond water.
“animalcules”
John Needham (mid 1700’s) performs an
experiment that refutes Redi
Lazzaro Spallanzani – improves Needham’s
experiment
Figure 1-10 Spallanzani’s Experiment
Section 1-2
What are the
controlled
variables?
What are the
independent
variables?
Gravy is boiled.
Flask is
open.
Gravy is teeming
with microorganisms.
Gravy is boiled.
Flask is
sealed.
Gravy is free of
microorganisms.
What are the dependent variables?
Controlled variables: Gravy,
flask, heat
Independent variables: sealed
flask
Dependent variables:
presence/absence of
microorganisms
The debate continues
In the 1800’s some believe the air
contained a “life force” perpetuating the
belief of spontaneous generation.
Louis Pasteur –1864, his experiment finally
disproved spontaneous generation
Figure 1-11 Pasteur’s Experiment
Section 1-2
Broth is boiled.
Broth is free of
microorganisms
for a year.
Curved neck
is removed.
Broth is
teeming with
microorganisms.
Figure 1-11 Pasteur’s Experiment
Broth is boiled.
Broth is free of
microorganisms
for a year.
Curved neck
is removed.
Broth is
teeming with
microorganisms.
Figure 1-11 Pasteur’s Experiment
Broth is boiled.
Broth is free of
microorganisms
for a year.
Curved neck
is removed.
Broth is
teeming with
microorganisms.
Pasteur’s Conclusions
• All living things must come from other
living things.
• Opening the jar (Redi) exposes the
contents to come in contact with
organisms in the air, just as breaking
neck of flask
• (pg.13)What improvement did Pasteur
make to Redi’s experiment?
What is a Theory?
A well tested explanation that unites many
observations (evidence builds up to make hypothesis
very well supported)
Can be proven wrong when new data
arises to refute it.
May be revised or
replaced by a more
useful explanation.
1-3 Studying Life
• What do all living things have in
common?
List 5 things that all living things do:
Is a hurricane alive?
Are flowers alive?
Is a fire alive?
Is a dragon fly alive?
Is a river alive?
Is a crowd alive?
•
•
•
•
•
•
•
•
Characteristics of Living
Things:
Made of units called cells
Reproduce
Based on universal genetic code
Grow and develop
Obtain/use materials and energy
Respond to environment
Maintain stable internal environment
Change over time
Living Things are Made of
Cells
A Cell
• Collection of living matter enclosed by
barrier separating the cell from its
surroundings.
• Smallest units of an organism that can
be considered alive.
• Small size, but highly organized and
complex.
Asexual Reproduction
New organism has a single parent
(ex. Budding hydra)
Sexual Reproduction
2 cells from different parents unite to
produce new organism
(ex. Sperm and egg)
Universal Genetic Code
**Everything living is based on this
the molecule of inheritance
Growth and Development
Required for Life…
Metabolism
-chemical reactions an
organism uses to
build up and break
down materials
-how cells acquire and
use energy to grow
and survive
(ex. Digestion, making
proteins)
Homeostasis
-keeping the internal
conditions of an
organism stable
(ex. Body temperature,
breathing, heart
rate)
Nothing Lives Without Energy
Energy = Capacity to do work
Homeostasis
• Maintenance of internal environment
within range suitable for cell activities
• Ex. pancreas maintains level of sugar in
blood by secreting hormones
Sensing and Responding
• Organisms sense changes in their
environment and make responses to them
• Receptors detect specific forms of energy
• The form of energy detected by a receptor
is a stimulus
Evolution - as a group all living
things change over time
Evolution
• Genetically based
change in a line of
descent over time
• Population
changes, not
individuals
Figure 1-21 Levels of Organization
Biosphere
The part of Earth
that contains all
ecosystems
Ecosystem
Community and
its nonliving
surroundings
Biosphere
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Community Populations that
live together in a
defined area
Hawk, snake, bison, prairie dog, grass
Population
Group of
organisms of one
type that live in
the same area
Bison herd
Figure 1-21 Levels of Organization continued
Organism
Individual living
thing
Groups of
Cells
Tissues, organs,
and organ systems
Bison
Nervous tissue
Cells
Brain
Nervous system
Smallest functional
unit of life
Nerve cell
Molecules
Groups of atoms;
smallest unit of
most chemical
compounds
Water
DNA
What are the different levels of
organization in Biology?
Smallest to Largest
Atom
• Smallest unit of an a
element that retains
the properties of that
element
Molecules - groups of atoms
Organelle
• Membrane-bound
internal compartment
for specialized
reactions
• Not found in most
prokaryotic cells
Cells - smallest functional unit of life
Tissues
Organs
Organ Systems
Organism - an individual living thing
Population - group of organisms of one
type (species) living in the same area
Community - Populations that
live together in a defined area
Ecosystem - community and its
nonliving surroundings
Biosphere - Part of the Earth that
contains all ecosystems
1-4 Tools and Procedures
Metric System-SI-International
System of Units
• To collect data and perform
experiments
• Decimal system of units scaled on
multiples of 10
• Measures: length, mass, volume, and
temperature
How can a graph help biologists
to organize this data?
Microscopes-produce magnified
images of structures too small for
naked eye
• Light Microscopeproduce magnified
images by focusing
visible light rays.
• Up to 1000 times.
• Live and dead
organisms
•
Fig. 1-25 (compound light
microscope)
• Electron Microscopesproduce magnified
images by focusing
beams of electrons.
• Form images 1000 times
more detailed than light
microscope.
•
•
•
Fig. 1-26
Only dead organisms.
Have no color. Why?