Invitation to Biology Chapter 1. 1.1 Impacts/Issues: The Secret Life of Earth Biology The...
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Transcript of Invitation to Biology Chapter 1. 1.1 Impacts/Issues: The Secret Life of Earth Biology The...
Invitation to Biology
Chapter 1
1.1 Impacts/Issues:The Secret Life of Earth
Biology • The systematic study of life
We have encountered only a fraction of the organisms that live on Earth• Scientists constantly discover new species• Extinction rates are accelerating
Video: Lost worlds and other wonders
Exploring New Guinea
A rare golden-mantled tree kangaroo
1.2 Life’s Levels of Organization
The building blocks (atoms) that make up all living things are the same ones that make up all nonliving things
The unique properties of life emerge as certain kinds of molecules become organized into cells
Life’s Levels of Organization
Atom• Fundamental building block of all matter
Molecule• An association of two or more atoms
Cell• Smallest unit of life
Organism• An individual; consists of one or more cells
Life’s Levels of Organization
Population• Group of individuals of a species in a given area
Community• All populations of all species in a given area
Ecosystem• A community interacting with its environment
Biosphere• All regions of Earth that hold life
Nature and Life
Nature• Everything in the universe, except what humans
have manufactured
Emergent property• A characteristic of a system that does not appear
in any of a system’s component parts
Levels of Organization in Nature
3
Fig. 1-2, p. 5
2
8
17
6
45
Animation: Life’s levels of organization
Active Figure: Levels of organization
1.3 Overview of Life’s Unity
All living things have similar characteristics• Require energy and nutrients• Sense and respond to change• Reproduce with the help of DNA
Energy Sustains Life’s Organization
One-way flow of energy through the biosphere and cycling of nutrients among organisms sustain life’s organization
Energy• The capacity to do work
Nutrient• Substance that is necessary for survival, but that
an organism can’t make for itself
Organisms and Energy Sources
Producers• Organisms that make their own food using
energy and simple raw materials from the environment
• Example: plants
Consumers• Organisms that get energy and carbon by feeding
on tissues, wastes, or remains of other organisms• Example: animals
Energy Flow and Material Cycling
Fig. 1-3a, p. 6
Fig. 1-3a, p. 6
sunlight energy A Producers harvest energy
from the environment. Some of that energy flows from producers to consumers.
PRODUCERSplants and other
self-feeding organisms
B Nutrients that become incorporated
into the cells of producers and consumers are
eventually released by decomposition. Some
cycle back to producers.
CONSUMERSanimals, most fungi,
many protists, bacteria
C All energy that enters the world of life eventually flows out of it, mainly as heat.
Fig. 1-3a, p. 6
sunlight energy A Producers harvest energy
from the environment. Some of that energy flows from producers to consumers.
PRODUCERSplants and other
self-feeding organisms
CONSUMERSanimals, most fungi,
many protists, bacteria
C All energy that enters the world of life eventually flows out of it, mainly as heat. Stepped Art
B Nutrients that become incorporated
into the cells of producers and consumers are
eventually released by decomposition. Some
cycle back to producers.
Fig. 1-3b, p. 6
Animation: One-way energy flow and materials cycling
Organisms Sense and Respond to Change
Organisms sense and respond to change to keep conditions in their internal environment within a range that favors cell survival (homeostasis)
Homeostasis• Set of processes by which an organism keeps its
internal conditions within tolerable ranges
Receptor• Molecule or structure that responds to a stimulus
Response to Stimuli
Organisms Grow, Develop and Reproduce
Organisms grow, develop, and reproduce based on information encoded in DNA, which they inherit from their parents
Growth• Increase in size, volume, and number of cells in
multicelled species
Development• Multistep process by which the first cell of a new
individual becomes a multicelled adult
Organisms Grow, Develop and Reproduce
Reproduction• Process by which parents produce offspring
Inheritance• Transmission of DNA from parents to offspring
DNA (Deoxyribonucleic acid)• Molecule that carries hereditary information about
traits
1.4 Introduction to Life’s Diversity
The millions of species on Earth vary greatly in details of body form and function
Each species is given a unique two-part name that includes genus and species names
Species• A type of organism
Genus• Group of species that share a unique set of traits
Classification Systems
Classification systems group species according to traits and organize information about species
One system sorts all organisms into one of three domains: Bacteria, Archaea, and Eukarya
The eukaryotes include plants, protists, fungi and animals
Life’s Diversity: Three-Domain Classification System
Fig. 1-5, p. 8
Bacteria Archaea
Eukarya
Animation: Life’s diversity
Prokaryotes
Prokaryotes• Single celled organisms in which DNA is not
contained in a nucleus
Bacterium• A member of the prokaryotic domain Bacteria
Archaeans• A member of the prokaryotic domain Archaea
Eukaryotes
Eukaryotes• Organisms whose cells typically have a nucleus
Fungus• Eukaryotic consumer that obtains nutrients by
digestion and absorption outside the body
Protists• Eukaryotes that are not plants, animals, or fungi
Eukaryotes
Plant• Typically a multicelled, photosynthetic producer
Animal• Multicelled consumer that develops through a
series of embryonic stages and moves about during all or part of the life cycle
Animation: Three domains
1.5 The Nature of Scientific Inquiry
Critical thinking• Mental process of judging the quality of information
before deciding whether or not to accept it
The Scope and Limits of Science
Science is a way of looking at the natural world which helps us to communicate our experiences without bias by focusing only on testable ideas about observable phenomena• Science does not address the supernatural
Science• The systemic study of nature
1.6 How Science Works
Researchers make and test potentially falsifiable predictions about how the natural world works
Generally, scientific inquiry involves forming a hypothesis (testable assumption) about an observation then making and testing predictions based on the hypothesis
A hypothesis that is not consistent with the results of scientific tests is modified or discarded
Common Research Practices
1. Observe some aspect of nature
2. Frame a question about your observation
3. Propose a hypothesis (a testable explanation of the observation)
Common Research Practices
4. Make a prediction – a statement based on a hypothesis, about some condition that should exist if the hypothesis is not wrong
5. Test the accuracy of the prediction by experiments or gathering information (tests may be performed on a model)
Common Research Practices
6. Assess the results of the tests (data) to see if they support or disprove the hypothesis
7. Conclusions: Report all steps of your work and conclusions to the scientific community
Making Observations: A Field Study
A Scientific Theory
Scientific theory• A hypothesis that has not been disproven after
many years of rigorous testing• Useful for making predictions about other
phenomena
Laws of Nature
Law of nature• Generalization that describes a consistent and
universal natural phenomenon for which we do not yet have a complete scientific information
• Example: gravity
Examples of Scientific Theories
Animation: An example of the scientific method
1.7 The Power of Experiments
Natural processes are often influenced by many interacting variables
Variable• A characteristic or event that differs among
individuals
The Power of Experiments
Experiments simplify interpretations of complex biological systems by focusing on the effect of one variable at a time
Experiment• A test to support or falsify a prediction
Experimental and Control Groups
Experimental group• A group of objects or individuals that display or
are exposed to a variable under investigation
Control group• A group of objects or individuals that is identical
to an experimental group except for one variable
Potato Chips and Stomachaches
Fig. 1-7, p. 12
AOlestra® causes intestinal cramps.Hypothesis
B PredictionPeople who eat potato chips made with Olestra will be more likely to get intestinal cramps than those who eat potato chips made without Olestra.
C Experiment Control Group Experimental Group
Eats regular potato chips
Eats Olestra potato chips
D 93 of 529 people get cramps later (17.6%)
89 of 563 people get cramps later (15.8%)
Results
E ConclusionPercentages are about equal. People who eat potato chips made with Olestra are just as likely to get intestinal cramps as those who eat potato chips made without Olestra. These results do not support the hypothesis.
Results 93 of 529 people get cramps later (17.6%)
89 of 563 people get cramps later(15.8%)
Experiment Control GroupEats regularpotato chips
Experimental GroupEats Olestrapotato chips
HypothesisOlestra® causes intestinal cramps.
PredictionPeople who eat potato chips made with Olestra will be more likely to get intestinal cramps than those who eat potato chips made without Olestra
Conclusion
Percentages are about equal. People who eat potato chips made with Olestra are just as likely to get intestinal cramps as those who eat potato chips made without Olestra.These results do not support the hypothesis.
Fig. 1-10, p. 14
Stepped Art
Example: Butterflies and Birds
Question• Why does a peacock butterfly flick its wings?
Two hypotheses• Exposing wing spots scares off predators• Wing sounds scare off predators
Two predictions• Individuals without spots are eaten more often• Individuals without sounds are eaten more often
Peacock Butterfly Defenses
Experiments and Results
Four groups of butterflies were exposed to predators (birds)• Butterflies without spots• Butterflies without sounds• Butterflies without spots or sounds• Control group
Test results support both original hypotheses
Results: Peacock Butterfly Experiment
Sampling Error
Biology researchers experiment on subsets of a group, which may result in sampling error
Sampling error• Difference between results derived from testing
an entire group of events or individuals, and results derived from testing a subset of the group
Sampling Error
Fig. 1-9, p. 14
24
20
16
12
8
Win
g-f
lick
s p
er m
inu
te
4
0– spots + sound
– spots – sound
+ spots – sound
Probability
Researchers try to design experiments carefully in order to minimize sampling error
Statistically significant• Refers to a result that is statistically unlikely to
have occurred by chance
Animation: Sampling error
1.8 Impacts/Issues Revisited
Biologists constantly discover new species• Mouse lemur (Microcebus lehilahytsara),
discovered in Madagascar in 2005
Digging Into Data:Peacock Butterfly Predator Defenses