Transcript Quiz 1

Quiz 1
1. What type of cell contains a nucleus, prokaryotic or
eukaryotic?
2. Give an example of a two organisms that are connected in life.
One should be the producer and one should be the
consumer. Specify which is which.
3. A scientist notices that every spring the population of red
and orange beetles in the forest decreases but the
population shows a steep rise every fall as soon as the
leaves change. Come up with a hypothesis for why this
happens.
4. T/F Natural selection ensures that the organism that is least
adapted to its environment will live to pass on its genes.
Fig. 1-1
Ch 1
Introduction: Themes in the Study
of Biology
I. Biology is complex
II. Grouping system
III.Darwin and natural selection
IV.How to study science
(experimental design)
Theme: New properties emerge at each level in the
biological hierarchy
• Life can be studied at different levels from
molecules to the entire living planet
• The study of life can be divided into different
levels of biological organization
• Biology is complex so it has to be organized in
order to study it efficiently
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Fig. 1-4l
Atoms
Molecules
Fig. 1-4k
1 µm
Organelles
Fig. 1-4j
10 µm
Cell
Cells
Fig. 1-4i
Tissues
50 µm
Fig. 1-4h
Organs and
organ systems
Fig. 1-4g
Organisms
Fig. 1-4f
Populations
Fig. 1-4e
Communities
Fig. 1-4d
Ecosystems
Fig. 1-4c
The biosphere
Within the world (our biosphere)there are
inordinate amounts of living organisms
• Approximately 1.8 million species have been
identified and named to date, and thousands
more are identified each year
• Estimates of the total number of species that
actually exist range from 10 million to over 100
million
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Biosphere
Ecosystem
Florida coast
Community
All organisms on
the Florida coast
Population
Group of brown
pelicans
Organism
Brown pelican
Organism
Brown pelican
Spinal cord
Nerve
Organ system
Nervous system
Brain
Organ
Brain
Tissue
Nervous tissue
Atom
Cell
Nerve cell
Nucleus
Organelle
Nucleus
Molecule
DNA
What is a prokaryote or a
eukaryote?
• Prokaryotic cell:
– Lacks a nucleus
– is much simpler and usually much smaller
than a eukaryotic cell
– Ex. – bacteria
• Eukaryotic cell:
– Subdivided by internal membranes into
different functional compartments
– Including the nucleus
– Ex. Your cells are eukaryotic
Prokaryotic cell
DNA
(no nucleus)
Membrane
Nucleus
(contains DNA)
Organelles
Eukaryotic cell
Domain Eukarya
Domain Bacteria
Bacteria (multiple kingdoms)
Protists (multiple kingdoms)
Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
Domain Archaea
Archaea (multiple kingdoms)
(a) DOMAIN BACTERIA
Estimated that your body houses
100 trillion bacteria
Infect us, help us digest, some
never even bother us
(b) DOMAIN ARCHAEA
The vast majority have never
been studied in the laboratory,
many aspects closely related to
eukaryotes
(c) DOMAIN EUKARYA
Everything else
Protists
Kingdom
Plantae
Kingdom Fungi
Kingdom Animalia
However . . .
There are common features in
all of life
The unity of life: All forms of life have common
features
•
is the genetic (hereditary) material
of all cells
– A gene is a discrete unit of DNA
– The chemical structure of DNA accounts for
its function
– The diversity of life results from differences
in DNA structure from individual to individual
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Nucleus
DNA
Nucleotide
Cell
(a) DNA double helix
(b) Single strand of DNA
EVOLUTION, THE CORE
THEME OF BIOLOGY
So life is very diverse with many
different species. How have all of these
species come about?
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Contributors to Science
In 1859, Charles Darwin published On the
Origin of Species by Means of Natural
Selection
–The book accomplished two things
–Presented evidence to support the idea of evolution
–Proposed a mechanism for evolution called natural
selection
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5 year route of the Beagle
Charles Darwin
Link
1.6 Evolution explains the unity and diversity of
life

was inferred by connecting two
observations
 Individuals within a population inherit different
characteristics; populations are diverse; not everybody
looks acts or is made the same
 A particular population of individuals produces more
offspring than are needed
 Sea Turtles “Planet Earth”
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1.6 Evolution explains the unity and diversity of
life

is an editing mechanism
– This population that is diverse is then exposed to the
environment. Depending on the environment some
individuals will be selected by nature to continue to live.
This results in these individuals living long enough to
pass on these beneficial genes. The environment favors
some individuals over others.
– Over time this results in evolution of new species adapted to
particular environments
– Organisms do not evolve structures deliberately or out of
want or need
– Individuals do not evolve, they are stuck with the genes
they were born with
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1 Population with varied inherited traits
2 Elimination of individuals with certain traits
3 Reproduction of survivors
Question
 What is the difference between natural
selection and artificial selection? What is an
example of each?
Discussion Questions
With these facts about a population of
sparrows:
1. The individuals have varying
traits
2. Their traits are heritable
3. Those with better traits will
survive
Make a “tree” to describe the
evolution of a population of
sparrows after a period of time in
which 1the ants they eat begin to
live under the bark of trees. This is
followed by a period of time in
which a 2disease that affects birds
with blood type B and not blood
type G.
Discussion Questions
 Many people still dispute the theory of natural selection
because they say that it is only a “theory.” This position
misinterprets the meaning of scientific theory. How is the
scientific usage of the word theory different from the
popular usage?
THE PROCESS OF SCIENCE
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1.7 Scientists use two main approaches to learn
about nature
Two approaches are used to understand natural
causes for natural phenomena
– Discovery science—uses verifiable observations and
measurements to describe science
– Hypothesis-based science—uses the data from
discovery science to explain science
– This requires proposing and testing of hypotheses
– Hypothesis - researched, tentative answer to some question
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Examples from modern media
 Decide which article discusses hypothesis based
science and which article discusses discovery based
science.
Observations
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burned-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
Observations
How does this compare to
discovery science article?
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burned-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
What is the hypothesis in itch
the article?
Hypothesis based science can
be very complex.
Control groups and experimental groups
This is a study that was submitted to the FDA for approval of a cancer drug,
Avastin. Shown is the survival rate for patients with colorectal cancer that were
given Avastin. At the beginning all patients were alive and at the end of 30
months about 30% were alive. Would you approve this drug? Is it a good drug?
Control groups and experimental groups
This is a study that was submitted to the FDA for approval of a cancer drug.
Shown is the survival rate for patients with colorectal cancer that were given the
drug. At the beginning all patients were alive and at the end of 30 months about
30% were alive. Almost 10% more patients in the control group (not
given this drug) died after 30 months. Would you approve this drug? Is it a
good drug?
Designing Controlled Experiments
A controlled experiment compares an experimental
group (patients given Avastin) with a control group
(patients given placebo)
Ideally, only the variable of interest (the experimental
drug) differs between the control and experimental
groups
A controlled experiment means that control groups
are used to cancel the effects of unwanted variables –
age, sex, diet of patients
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Why use hypothesis based science?
The Lowdown on Gingko Biloba
Concept Review
• Gingko biloba is a popular
herbal supplement that
reportedly improves memory,
learning, and other cognitive
functions.
•Hypothesis – Ginko biloba
improves brain function
•Let’s see . . .
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The Lowdown on Gingko Biloba
Concept Review
• Researchers cannot say
exactly what gingko
biloba does, but they
have found that it effects
the brain in several ways.
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The Lowdown on Gingko Biloba
Concept Review
• Studies that examined the effect of gingko treatments on
individuals with mild to moderate mental impairment have
shown improvement of various cognitive abilities.
-However, some placebo-based studies have shown no
difference in cognitive abilities.
-Demonstrates the importance of a control group!
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The Lowdown on Gingko Biloba
Concept Review
• Few studies on gingko biloba have focused on healthy
young adults.
-Those that have showed some improvement of shortterm memory.
-Demostrates the necessity for numerous studies!
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The Lowdown on Gingko Biloba
Concept Review
• Since production of gingko biloba is unregulated, its
manufacturers have not been required to test it on animals.
-Consequently, there are few reports of its efficacy in
improving learning in animals.
-Not reproducible in other studies!
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The Lowdown on Gingko Biloba
Concept Review
• Given the available evidence, it is difficult to conclude that
gingko biloba actually improves cognitive performance.
- In fact glucose, a sugar found in everyday foods, has
been shown to improve cognitive performance. Why?
-Is Ginko Biloba actually improving cognitive
function or just making people more alert, etc?
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The Lowdown on Gingko Biloba
Concept Review
• Evidence supporting the effectiveness of gingko biloba has
been reported in some research studies.
-But there are too few studies on which to base clear
recommendations for its use.
- Many more studies are needed to confirm or deny the
value of taking this supplement
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Hypothesis based science
• Validate previous results or hypothesis
• Disprove previous results or hypothesis
• As in case of ginko, can help to understand
whether you want to ingest a potentially
hazardous/helpful agent into your body
• As a person knows more about hypothesis
science they can check fraudulent or erroneous
claims
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The Lowdown on Gingko Biloba
If you were caretaker of an Alzheimer’s patient, would you
give permission for them to participate in a study on gingko
biloba?
Strongly
Agree
A.
B.
C.
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D.
E.
Strongly
Disagree