The Characteristics of Life
Biology
Ms. Haut
Biology


Study of life
Biologists recognize that all living things
share certain characteristics
Characteristics of Life
1.
Order


All living things
made of one or
more cells
Cells are the smallest
unit capable of all
life functions
Life at Its Many
Levels

Biologists
explore life at
levels ranging
from the
biosphere to the
molecules that
make up cells.
Figure 1.3
2.
Regulation

Maintenance of
stable internal
conditions despite
changes in external
conditions
(Homeostasis)
homestudy.ihea.com/wildlifeID/0
43jackrabbit.htm
Characteristics of Life
Characteristics of Life
3.
Growth and
Development


DNA directs pattern
of growth and
development
Pattern of growth
characteristic of
species
www.antarcticlife.com/.../emperor-penguin.html
Characteristics of Life
4.
Energy Utilization
 Sum of all chemical
reactions carried out
in an organism
(Metabolism)
 All energy originates
from the sun
 Plants convert solar
energy into sugar
 Animal use/store
energy in own
tissues
Characteristics of Life
5.
Response to the Environment


Organisms have evolved to
live and interact with other
organisms (Interdependence)
Ecology is the study of
interactions of living
organisms with one another
and their environment


Food webs
Respond to stimuli

Each organism interacts continuously with its
environment.


Both organism and environment are affected by the
interactions.
The dynamics of any ecosystem depend on two
processes:


Cycling of nutrients
Flow of energy
Figure 1.4
6.
Reproduction


Process of making more
of one’s own kind
No organism lives
forever; necessary part of
living
Heredity


Passing of traits from
parent(s) to offspring
Genes are inherited from
parent(s)
www.blue-room.com/animals/rosie/
Characteristics of Life
Characteristics of Life
7.
Evolution



Change over time
New species (group
of genetically similar
organisms that can
produce fertile
offspring) can
develop over time if
enough changes
occur
Natural selection—
survival of the fittest
Figure 1.11
Graphs and Graphing Data
Pre-AP Biology
Ms. Haut
Experimental Variables
•
Variable: A factor in an experiment.
–
Independent variable: The factor that is
different between groups. The topic of interest
in an experiment.
•
•
Has two or more levels.
Levels can be numbers (age, weight, etc.) or
categories (gender, color, etc.)
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Experimental Variables
 Variable: A factor
in an experiment.
 Independent
variable: The factor that is
different between groups. The topic of interest
in an experiment.

On graphs, the
independent variable
always goes on the
X-axis.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Experimental Variables
 Variable: A factor
in an experiment.
 Dependent
variable: The factor being
measured in the experiment.
 Almost always numerical

On graphs, the
dependent variable is
always on the Y-axis.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Types of Graphs

Two common types of graphs:
Biology Test Scores
Bar graphs
100%
80%
Score

60%
40%
20%
0%
Boys
Girls
Gender
Absences vs. Scores
Line graphs
Test Score

90
80
70
60
50
0
1
2
3
4
5
Absences
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
6
7
8+
Types of Graphs
Score
Bar graphs are used when the independent
variable has categories.
Biology Test Scores
Boys/girls
100%
80%
Adults/children
60%
40%
Salt water/distilled water
20%
/tap water
0%
Boys
Girls
Etc.
Gender
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Types of Graphs
graphs are used when the independent
variable has numbers.
Hours of television watched
Absences vs. Scores
Age (in years)
90
80
Calories eaten per day
70
Etc.
Test Score
Line
60
50
0
1
2
3
4
5
6
Absences
Both
line graphs and bar graphs show the relationship between
independent variables and dependent variables.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
7
8+
Making a Graph
1)
Choose a scale
for each axis
that includes
all values.
Number your
gridlines
evenly.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Making a Graph
2)
Label both axes,
including units.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Making a Graph
3)
Plot each data
point and
connect your
dots with a
line.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
Making a Graph
4)
Give your
graph a
descriptive
title.
Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.
The Scientific Process
Pre-AP Biology
Ms. Haut
The Process of Science

The word science is derived from a Latin verb
meaning “to know.”


Science is a way of knowing.
Science developed from people’s curiosity about
themselves and the world around them.
Hypothesis-Driven Science

As a formal process of inquiry, the scientific
method consists of a series of steps.

The key element of the scientific method is
hypothesis-driven science.
Scientific Method



Observations
Question
Hypothesis






Prediction
Experiment
Data
Conclusion
Retest
Communicate Results
Observation

You observe something in the material
world, using your senses or machines
which are basically extensions of those
senses.
AH—Look at this!
Question


You ask a question about what you observe.
State the problem or question.
http://upload.wikimedia.org/wikipedia/commons/thumb/9/9c/Surface_Tension_01.jpg/800px-Surface_Tension_01.jpg
Hypothesis


A testable statement about your observation
Based on research


You should be able to give reasons for why
you chose your hypothesis
If/then… statement

Deductive reasoning is used in testing
hypotheses


If a hypothesis is
supported, and we test it,
then we can expect a
particular outcome
Case study: flashlight
failure
Figure 1.19
Experiment

You figure out a way to test whether the
hypothesis is supported.




Control group– nothing changed
Experimental group – one variable changed
The outcome must be measurable
(quantifiable).
Record and analyze data.

Biologists developed a hypothesis regarding
mimicry in snakes.


If an animal has certain color patterns, then it will not
be preyed upon.
They tested the hypothesis by making artificial snakes
and observing how often they were attacked by
predators.
Figure 1.20
This is an example of a controlled
experiment.


Such an experiment is designed to compare an
experimental group with a control group.
Ideally, a control group and an experimental
group differ in only one variable.
Figure 1.21
Analyze Results




You do the experiment
using the method you
came up with and record
the results.
Create data tables, graphs
to represent data
Perform calculations that
will determine what
results mean (averages,
percentages, totals)
Identify possible sources
of errors
Table 1. Percent of total attacks on different
colored artificial snakes.
Draw Conclusions

You state whether
your hypothesis was
supported or not and
try to explain your
results.
Table 1. Percent of total attacks on different
colored artificial snakes.
Retest

In order to verify the results, experiments
must be retested.
Communicate Results

Share results with science community
http://ez002.k12.sd.us/scientific_method01.gif
The Culture of Science
Figure 1.22

Scientists build on what has been learned from
earlier research.


They pay close attention to contemporary scientists
working on the same problem.
Both cooperation and competition characterize
the scientific culture.

Scientists check the conclusions of others by
attempting to repeat experiments.
Evolution Connection: Theories in
Science

What is a scientific theory, and how is it different
from a hypothesis?


A theory is much broader in scope than a hypothesis.
Theories only become widely accepted in science if
they are supported by an accumulation of extensive and
varied evidence.