Download Chapter 1: What is Life?

Chapter 1: Exploring Life
• Hierarchy, levels of biological
structure
• Properties of life (at least 7)
• Evolution, Unity and Diversity
• Scientific Method
Life’s Hierarchical Order
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Biosphere
Ecosystem
Community
Population
Organism
Organs
Tissues
Cells
Atoms
Emergent properties
Biosphere: all the environments of Earth that support
life
 Ecosystem: All the living and nonliving components of
a particular environment
 Community: All the living organisms in an ecosystem
 Population: an interacting group of individuals of one
species
 Organism: An individual living entity
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Living organisms and their
environments form
interconnecting webs
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Producers-photosynthetic
organisms-use energy from
the sun to produce food
Consumers are ultimately
dependent on producers for
food
Decomposers break down
dead organic material, which
is recycled
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The dynamics of an ecosystem include two
major processes:
The cycling of chemical nutrients
 The one-way flow of energy, entering as sunlight and
leaving as heat
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LE 1-2
Sun
Air
Inflow
of
light
energy
O2
CO2
CO2
Chemical
energy
Producers
Cycling of
chemical
nutrients
Consumers
Decomposers
H2 O
cycling
Ecosystem
Soil
Loss
of
heat
energy
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Cells are the structural and
functional units of life
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Cells perform all functions
necessary for life
Regulate their internal environment
 Take in and use energy
 Respond to the local environment
 Develop and maintain their complex
organization
 Divide to form new cells
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Two basic types of cells: prokaryotes and
eukaryotes
Prokaryotes are smaller and less complex than
eukaryotes and lack a nucleus and other membrane
bound organelles
 Eukaryotes are generally larger and more complex
and contain a nucleus and other organelles
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EVOLUTION, UNITY, AND
DIVERSITY
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The unity of life: All forms of life have
common features
Characteristics of Living Things
Characteristic
Examples
Living things are made up of units called
cells.
Living things reproduce.
Living things obtain and use materials and
energy (TAKE IN NUTRIENTS)
Many microorganisms consist of only a single cell.
Animals and trees are multicellular.
Maple trees reproduce sexually. A hydra can
reproduce asexually by budding. (SEED TO PLANT)
Flies produce flies. Dogs produce dogs. Seeds from
maple trees produce maple trees.
Flies begin life as eggs, then become maggots, and
then become adult flies. (Caterpillar to Butterfly)
Plants obtain their energy from sunlight. Animals
obtain their energy from the food they eat.
Living things respond to their environment
Leaves and stems of plants grow toward light.
Living things maintain a stable internal
environment.
Despite changes in the temperature of the
environment, a robin maintains a constant body
temperature.
Taken as a group, living things change
over time. (Evolve)
Plants that live in the desert survive because they have
become adapted to the conditions of the desert.
Living things are based on a universal
genetic code.
Living things grow and develop.
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The diversity of life can be arranged into
three domains
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Scientists have identified about 1.8 million
species-particular types of organisms
Taxonomy classifies species into a hierarchy
of increasingly broad groups
Taxonomy
Domains of Life (3)
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1. Bacteria
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2. Archaea
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(prokaryotes, most
ancient)
(prokaryotes, extreme )
3. Eukarya
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(eukaryotes = protists,
plants, animals, fungi)
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Evolution explains the unity and diversity of life
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Charles Darwin proposed the theory of evolution by
natural selection
Species evolved from ancestors through "descent with
modification"
 Natural selection occurs as heritable variations are
exposed to environmental factors that favor the
reproductive success of some individuals over others
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The product of natural selection is adaptation
LE 1-6b
Population with varied inherited traits
Elimination of individuals with certain traits
Reproduction of survivors
THE PROCESS OF SCIENCE
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Scientists use two main approaches to learn
about nature
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Discovery science
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Primarily describes nature through verifiable
observations and measurements
Hypothesis-driven science
Attempts to explain nature by studying questions
drawn from observations made during "discovery
science"
 Hypothesis: a tentative answer to a problem or
question that is being asked
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Steps in the Scientific
Method
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Observation
Hypothesis
Experiment
Data/Results
Conclusion
What are the main
components of conducting an
experiment?
Think about this…
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Let’s say that Brad has a pimple. He
wonders what will get rid of it. He’s heard
that putting toothpaste on the zit will get rid
of it. He’s also heard that lemon juice will
get rid of it. He decides to rub his face
with lemon juice and toothpaste. The next
morning his pimple is gone. But which
thing cured him? The toothpaste or the
lemon juice?
The Answer?
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How many of you think it was the
toothpaste? Raise your hand.
How many of you think it was the lemon
juice? Raise your hand.
The truth is….
THERE IS NO WAY FOR YOU TO KNOW
FOR SURE!!!
Every Good Experiment Has
Three Things!
1)
2)
3)
Independent variable
Dependent variable
Control
So What Are These?
Variable
Change
Able to
Variable: A factor that can
change in an experiment.
Every experiment has two –
one is the cause, the other is
the effect.
Cause and Effect
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Does crushing a sugar cube effect the
rate at which the sugar dissolves in the
water?
What is the cause and what is the effect?
Crushing the sugar cube
is what we predict will
be the cause.
Crushing
the sugar
cube will
effect how
long it
takes to
dissolve.
This is called the
Independent
Variable.
The time it takes
to dissolve is
what we will see
the effect on.
This is called the
Dependent
Variable.
Independent variable
The variable being
tested in an
experiment.
(“I”choose)
Dependent variable
The variable we predict
will be effected.
(‘Depends on what I
choose’)
Experiment Title: Does the age of a person gets
married effect their chances of getting a divorce?
IV- Age
DV- Chances of
divorce
Experiment Title: Is there are relationship between
the weather and how students behave?
IV- weather
DV- behavior
What is the Purpose of a
Control?
 Controls
are NOT being
tested
 Controls are used for
COMPARISON
Practice with Controls
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Does fertilizer affect plant height?
 Independent Variable: FERTILIZER
 Dependent Variable: PLANT HEIGHT
How can we be sure that the fertilizer is effecting the
plant height?
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Control: A plant that does not contain fertilizer
Remember: To be a Valid
Experiment:
Two groups are required --the control & experimental
groups
 There should be only one
variable
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THE MISSION…
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Ms. Nakamura is in need of a group of students
who will help her create a garden.
Unfortunately she does not have that much
knowledge in the germination of seeds and has
asked the help of her brilliant AP Biology
students to help her decide what seeds to use
and what time of factors might influence the
seeds’ maturation/growth.