The Nature of Biology
Module 1: How to Define Life
How do you design an experiment?
A. Problem/Purpose
1. The question the lab will answer
2. Identifies the independent and dependent
variables
a. Independent variable – the factor the scientist changes
from group to group
b. Dependent variable – the factor the scientist measures
to see the effect of the independent variable
Variables and Controls Videoclip
How do you design an experiment?
B. Research/Background
Information
1. Lets the reader learn about the
topic
2. Helps the scientist develop an
educated hypothesis
C. Hypothesis
1. An educated prediction
2. Can be tested, proven false, and
agrees with previous research
How do you design an experiment?
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D. Procedure/Experiment
1. Steps must be precise and detailed
2. Has one control group
a. Normal conditions or absence of independent variable
b. Used for comparison
3. Experimental group(s) have only one changing
variable (which is the independent variable)
How do you design an experiment?
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E. Observations/Data
1. Must be objective.
a. Good Example: The bacterial colony is yellow.
b. Bad Example: The bacterial colony is nasty.
2. Use measurements whenever possible.
a. Good Example: There are 50 bacterial colonies.
b. Bad Example: There are a whole bunch of colonies.
How do you design an experiment?
E. Observations/Data
4. Do not draw conclusions in the data section of
the report.
a. Good Example: There are bacteria and fungal colonies
in the shoe section.
b. Bad Example: The shoe was really dirty and so it was
the most contaminated and grew a lot of stuff.
5. Should be organized.
a. May use a graph, table, or drawing(s).
b. Always include units of measurement and a title.
How do you design an experiment?
F. Analysis/Conclusions
1. Answers the purpose
question.
2. Accepts or rejects the
hypothesis.
3. Explains what can be
inferred from the data.
How do we know it is “good science”?
A. Scientific knowledge must be shared,
which allows other scientists to repeat
and verify the work of others (peer
review).
A. Scientific knowledge is tentative.
1. Theories are the most logical explanation based
on current evidence, become stronger as more
evidence is gathered, and give us a basis for
prediction.
2. Laws are universal generalizations that are
virtually unchanging.
How do you know something is alive?
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A. Biology means the study of (-ology) all
life (bio-) and includes many branches.
B. Biologists organize living things into
kingdoms. There are currently six
kingdoms
Kingdom
Example
Archaebacteria
Extremophile bacteria
Eubacteria
Typical bacteria
Protista
Seaweed, Amoeba, Slime Mold
Fungi
Yeast, Mushrooms
Plantae
Moss, Fern, Holly, Oak tree
Animalia
, Fish, Birds, Frogs, Humans
How do you know something is alive?
B.
Characteristics of Life - Alive! Videoclip
1. Organization (The level of complexity)
a.
Organism
Organ System
Organs
Tissues
Cells
Molecules
Atoms / Elements
Meet the Elements - They Might Be Giants
How do you know something is alive?
b. All living things
need six essential
elements (atoms):
Carbon, Hydrogen,
Nitrogen, Oxygen,
Phosphorus,
Sulfur (CHNOPS)
c. All living things
are made of cells.
b. One-celled
organism –
unicellular
c. Many-celled
organism multicellular
electron
neutron
proton
How do you know something is alive?
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2. Energy Use
a. Organisms need energy
constantly to build molecules
(synthesis) and cells and to
break down (digest) substances
(such as breaking down food for
nutrition)
b. Organisms must transport
nutrients to be used in cellular
respiration to produce energy.
c. An organisms’ chemical
reactions are called its
metabolism
How do you know something is alive?
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3. Reproduction
a. Organisms must
replace themselves
so the entire species
will survive.
b. May be asexual
(only one individual
contributes genetic
material) or sexual
(two individuals
contribute genes).
How do you know something is alive?
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4. Growth and Development
a. Growth – to increase in size. Increases the number of
cells of a multicellular organism.
b. Development – change that takes place in structure and
function of an organism during its life cycle.
Example: Embryo becomes a fetus
How do you know something is alive?
5. Respond to Stimuli
a. A quick, nonpermanent change
b. Stimulus – any
condition that causes
an organism to react.
Example – A loud noise (stimulus)
causes your dog to run under
the bed (response).
How do you know something is alive?
6.
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Adjust to
Environment
a.Homeostasis - the
regulation of an
organism’s internal
environment to
maintain conditions
suitable for life
Ex: Getting rid of
wastes by excretion
How do you know something is alive?
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b. An adaptation is an
inherited structure,
behavior, or internal
process that enables
organisms to better
survive an
environment.
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Ex: Gills on a fish
Life Processes: STERNGRR
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Synthesis – making materials
Transport – moving materials
Excretion – getting rid of wastes
Respiration – gas exchange AND production of
energy (ATP)
Nutrition – gaining and using energy from food
Growth and Development – getting bigger
and/or changing
Regulation – controlling internal processes
Reproduction – producing new cells or new
organisms
What technology allows biologists
to study microscopic life?
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A. Compound Light
Microscope
1. Has two lenses –
ocular (eyepiece)
and objective
2. In order to be viewed,
specimen must be
thin (so the light may
shine through the
specimen) and
placed on a slide.
3. Specimen may be
stained to better see
structures
What technology allows biologists to
study microscopic life?
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B. Electron Microscope
1.
2.
Eye of an ant
Uses electrons to produce an image
Types:
a. Scanning Electron Microscope (SEM)
i. Sends a beam of electrons
across the object’s surface
ii. Produces a 3-D image
b. Transmission Electron Microscope
(TEM)
i. Designed to look at structures
inside a cell
ii. Capable of greatest
magnification
What technology allows biologists to
study microscopic life?
C. Limitations of microscopes
1. Magnification is limited by the strength of the
lens.
a. Calculating magnification:
Ocular lens x objective lens = total magnification
b. Example:
Ocular (10x) x objective (40x) = 400x
2. As magnification increases
resolution/(sharpness) decreases.