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War On Words: NYC Dept. Of Education Wants 50 ‘Forbidden’ Words Banned From
Standardized Tests
Words that suggest wealth are excluded because they could make kids jealous. “Poverty” is also on
the forbidden list. That’s something Sy Fliegal with the Center for Educational Innovation calls
ridiculous.
“The Petersons take a vacation for five days in their Mercedes … so what? You think our kids are
going to be offended because they don’t have a Mercedes? You think our kids are going to say ‘I’m
offended; how could they ask me a question about a Mercedes? I don’t have a Mercedes!’” Fliegal
said.
Here is the complete list of words that could be banned:
Abuse (physical, sexual, emotional, or psychological), Alcohol (beer and liquor),
tobacco, or drugs, Birthday celebrations (and birthdays)
Cancer (and other diseases)
Catastrophes/disasters (tsunamis and hurricanes), Children dealing with serious issues,
Cigarettes (and other smoking paraphernalia)
Crime
Death and disease, Divorce, Evolution, Expensive gifts, vacations, and prizes,
Halloween, Homelessness, Homes with swimming pools, Hunting
Junk food, Loss of employment, Nuclear weapons, Occult topics (i.e. fortune-telling),
Politics, Pornography, Poverty, Religion
Religious holidays and festivals (including but not limited to Christmas, Yom Kippur,
and Ramadan)
Running away, Sex, Slavery, Terrorism, Violence, War and bloodshed, Weapons
(guns, knives, etc.), Witchcraft, sorcery, etc.
© Cengage Learning 2015
Biology
Concepts and Applications | 9e
Starr | Evers | Starr
Chapter 18
Life’s Origin and Early Evolution
© Cengage Learning 2015
© Cengage Learning 2015
Which of these groups are more
closely related?
a) jellyfish, starfish, swordfish
b) human, cat, manatee
© Cengage Learning 2015
18.1 What Was The Building Material For
Earth’s First Life?
• Conditions on early Earth
– Earth formed about 4.6 billion years ago
– Early atmosphere contained little or no
oxygen
– Presence of water
– Volcanic eruptions were common
– Constant hail of meteorites
© Cengage Learning 2015
What Was The Building Material For
Earth’s First Life?
• Formation of simple organic compounds
– All life consists of:
• Amino acids
• Fatty acids
• Nucleotides
• Simple sugars
© Cengage Learning 2015
What Was The Building Material For
Earth’s First Life?
• Where did the subunits of the first life
come from?
• There are several possibilities:
– Lightning-fueled atmospheric reactions
– Reactions at deep-sea hydrothermal vents
– Meteorites from space
© Cengage Learning 2015
What Was The Building Material For
Earth’s First Life?
• Hydrothermal vents
– Deep underwater openings in ocean where
mineral-rich water heated by geothermal
energy streams out
• Reactions in the hot, mineral-rich water near deepsea hydrothermal vents also produce organic
building blocks
• Simulated experiments combining hot water with
carbon monoxide (CO), potassium cyanide (KCN),
and metal ions formed amino acids
© Cengage Learning 2015
What Was The Building Material For
Earth’s First Life?
• Miller-Urey experiment
– 1953, Stanley Miller and Harold Urey showed
that reactions in Earth’s early atmosphere
could have produced building blocks for the
first life
– Indirect evidence that organic compounds
self-assemble spontaneously under
conditions like those in Earth’s early
atmosphere
© Cengage Learning 2015
“Atmosphere”
CH4
Water vapor
NH3
H2
Electrode
Condenser
Cold water
Cooled water
containing organic
molecules
H2O
Stanley Miller re-creating
his 1953 experiment
Abiogenesis
© Cengage Learning 2015
“Sea”
Sample for
chemical analysis
Miller and Urey’s experiment
Figure 15.4
A
C5H5N5
G
T
C
© Cengage Learning 2015
18.2 What Steps Led to the Formation of
the First Cells?
• Similarities in structure, metabolism, and
replication among all life indicate descent
from a common cellular ancestor
– Experiments demonstrate how traits and
processes seen in all living cells could have
begun with physical and chemical reactions
among non-living collections of molecules
© Cengage Learning 2015
Precambrian
Common ancestor to
all present-day life
Origin of
Earth
4,500
© Cengage Learning 2015
Earth cool enough
for crust to solidify
4,000
Oldest prokaryotic fossils
3,500
Millions of years ago
3,000
Atmospheric oxygen
begins to appear due
to photosynthetic
prokaryotes
2,500
Figure 15.1a
What Steps Led to the Formation of the
First Cells?
• Origin of metabolism
– Proteins that speed metabolic reactions might
have first formed when amino acids stuck to
clay, then bonded under the heat of the sun
– Metabolism may have begun in rocks near
deep-sea hydrothermal vents when iron
sulfide in the rocks donated electrons to
dissolved carbon monoxide
© Cengage Learning 2015
What Steps Led to the Formation of the
First Cells?
• Protocells
– May have preceded cells
– Membrane-like structures and vesicles form
when proteins or lipids are mixed with water
– Membranous sacs that contain interacting
organic molecules; hypothesized to have
formed prior to the earliest life forms
– Origin of the cell membrane
© Cengage Learning 2015
18.3 What Do We Know About Early Cells?
• Early divergence separated bacteria from
ancestors of archaeans and eukaryotes
– An oxygen-releasing, noncyclic pathway of
photosynthesis evolved in one bacterial
lineage, cyanobacteria
– 2.5 billion years ago, oxygen released by
cyanobacteria began to accumulate in Earth’s
sea and air
– Cyanobacteria changed Earth’s atmosphere
© Cengage Learning 2015
18.4 How Did Increasing Oxygen Affect
Early Life?
• Evidence of early eukaryotes
– Biomarker
• Molecule produced only by a specific type of cell
• A molecular signature
– Oldest widely accepted eukaryote microfossils
date to about 1.8 billion years ago
© Cengage Learning 2015
1 Billion
• How many millions make a Billion?
• If a volcano erupts every 1,000 years, how
many times will it erupt in a million years?
• If a volcano erupts every 1,000 years, how
many times will it erupt in a billion years
• How old will you be when you get to your
Billionth second in life?
• 1,000,000,000
60 seconds per minute X
60 minutes per hour X 24 hours in a day X
356.25 days per year = 31.68 years
© Cengage Learning 2015
How Did Increasing Oxygen Affect Early
Life?
• Effects of increasing oxygen
– Interferes with self-assembly of complex
organic compounds
– Prevented evolution of new life from non-living
molecules
– Presence of oxygen gave organisms that
thrived in aerobic conditions an advantage
– Formation of an ozone layer in the upper
atmosphere protected Earth’s surface from
high levels of solar ultraviolet (UV) radiation
© Cengage Learning 2015
18.5 How Did Eukaryotic Organelles
Arise?
• Scientists study modern cells to test
hypotheses about how organelles evolved
in the past
– By one hypothesis, internal membranes
typical of eukaryotic cells may have evolved
through infoldings of plasma membrane of
prokaryotic ancestors
– Existence of some bacteria with internal
membranes supports this hypothesis
© Cengage Learning 2015
How Did Eukaryotic Organelles Arise?
• Origin of mitochondria and chloroplasts
– Endosymbiont hypothesis
• Mitochondria and chloroplasts resemble bacteria
• One species lives and reproduces inside another
• Over generations, host and guest cells come to
depend upon one another for essential metabolic
processes
© Cengage Learning 2015
Plasma
membrane
Photosynthetic
prokaryote
DNA
Cytoplasm
Membrane
infolding
(Some cells)
Endosymbiosis
Endoplasmic
reticulum
Nucleus
Ancestral
prokaryote
Aerobic
heterotrophic
prokaryote
Chloroplast
Mitochondrion
Nuclear
envelope
Photosynthetic
eukaryotic cell
Cell with nucleus and
endomembrane system
(a) Origin of the endomembrane system
© Cengage Learning 2015
(b) Origin of mitochondria and chloroplasts
Figure 15.20
18.6 What Happened During the
Precambrian?
• Precambrian
– Encompasses almost all of Earth’s history
– From 4.6 billion years ago to Cambrian (542
mya)
– Life arose and diversified
– By the close of this period, bacteria, archaea,
and eukaryotes lived in the sea
© Cengage Learning 2015
18.7 Life in Extreme Habitats
• Astrobiologists study properties of the
ancient Earth that allowed life to arise,
survive, and diversify
– Astrobiology
• The scientific study of life’s origin and distribution
in the universe
• Presence of cells in deserts and deep
below Earth’s surface suggests life may
exist in similar settings on other planets
© Cengage Learning 2015
Biology
Concepts and Applications | 9e
Starr | Evers | Starr
Chapter 19
Viruses, Bacteria, and Archaea
© Cengage Learning 2015
© Cengage Learning 2015
19.1 What Are Viruses?
• Viruses: noncellular infectious agents
– Consists of a protein coat around a core of
DNA or RNA
• The coat is enveloped in a bit of plasma
membrane derived from a previous host
– Replicates only in a host cell
– A virus is far smaller than any cell
– Has no ribosomes or other metabolic
machinery
© Cengage Learning 2015
19.2 How Do Viruses Affect Human
Health?
• Viral diseases
– Pathogens: disease-causing agents
– Usually produce mild symptoms persist in
body for long periods
– Can be latent and then reawaken
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• Common viral diseases
– Nonenveloped viruses:
• Adenoviruses (colds)
• Viral gastroenteritis (stomach flu)
• Human papillomavirus (genital warts, cervical
cancer)
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• Enveloped viruses
– Herpes viruses (cold sores, genital herpes,
infectious mononucleosis, chicken pox)
– Influenza (flu)
– Mumps, measles, and German measles
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• Emerging viral diseases
– Changes to viral genomes as a result of
mutation or gene exchanges can alter the
properties of a viral disease
– A disease that was previously unknown, is
new to humans, or has recently begun
spreading to a new region
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• West nile fever
– An enveloped RNA virus that replicates in
birds
– Mosquitoes carry the virus from host to host
(the vector for this virus)
– Attacks the nervous system and can be fatal
– An endemic disease throughout the
continental United States
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• Ebola hemorrhagic fever
– Ebola virus is highly contagious to humans
– Symptoms include fever, muscle pain, and
massive internal bleeding
– Death rate is 90 percent
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• Viral recombination
– Viruses have genomes that can mutate
– RNA viruses can mutate quickly
– Viral genomes can also exchange genes
when two viruses infect a host at the same
time
© Cengage Learning 2015
How Do Viruses Affect Human Health?
• Viral recombination
– Avian influenza H5N1 (bird flu) occasionally
infects people who are in contact with birds,
and has a high mortality rate
– Influenza H1N1 (swine flu) first appeared in
2009, can cause severe respiratory
symptoms, and is easily transmitted
© Cengage Learning 2015
How important is long-distance travel in spread of
epidemics?
November 5, 2014
When modeling the spread of epidemics, such as the Ebola outbreak, scientists must take into account the longdistance hops now possible with international air travel. But how important are such long-distance jumps? A new
model by biophysicists shows that how common long-range jumps are makes a big difference in the dispersal of a
disease, that is, whether you get slow, rippling versus rapid metastatic spread.
Yet knowing how to predict the spread of these epidemics is still uncertain, because the complicated models used
are not fully understood, says a UC Berkeley biophysicist.
Using a very simple model of disease spread, Oskar Hallatschek, assistant professor of physics, proved that one
common assumption is actually wrong. Most models have taken for granted that if disease vectors, such as
humans, have any chance of "jumping" outside the initial outbreak area -- by plane or train, for example -- the
outbreak quickly metastasizes into an epidemic.
Hallatschek and co-author Daniel Fisher of Stanford University found instead that if the chance of long-distance
dispersal is low enough, the disease spreads quite slowly, like a wave rippling out from the initial outbreak. This
type of spread was common centuries ago when humans rarely traveled. The Black Death spread through 14thcentury Europe as a wave, for example.
But if the chance of jumping is above a threshold level -- which is often the situation today with frequent air travel the diseases can generate enough satellite outbreaks to spread like wildfire. And the greater the chance that
people can hop around the globe, the faster the spread.
"With our simple model, we clearly show that one of the key factors that controls the spread of infection is how
common long-range jumps are in the dispersal of a disease," said Hallatschek, who is the William H. McAdams
Chair in physics and a member of the UC Berkeley arm of the California Institute for Quantitative Biosciences
(QB3). "And what matters most are the rare cases of extremely long jumps, the individuals who take plane trips to
distant places and potentially spread the disease."
This new understanding of a simple computer model of disease spread will help epidemiologists understand the
more complex models now used to predict the spread of epidemics, he said, but also help scientists understand
the spread of cancer metastases, genetic mutations in animal or human populations, invasive species, wildfires
and even rumors.
© Cengage Learning 2015
19.4 How Are Bacteria and Archaea
Similar?
• Bacteria and archaea
– Prokaryotes
– Small, structurally simple and single-celled
– Three cell shapes
• Coccus (spherical)
• Bacillus (rod-shaped)
• Spirillum (spiral)
© Cengage Learning 2015
How Are Bacteria and Archaea Similar?
• Prokaryotic traits
– Ribosomes distributed in the cytoplasm
– Asexual reproduction by binary fission
– Capacity for gene exchange among existing
cells through conjugation, transduction, and
transformation
© Cengage Learning 2015
19.5 What Are Some Major Bacterial
Lineages?
• Bacteria are widespread, abundant, and
diverse
– Most either harmless or beneficial
• Many bacteria have essential ecological
roles:
– Decomposers
– Cycle nutrients
– Form partnerships with other species
© Cengage Learning 2015
19.6 How Do Bacteria Affect Human
Health?
• Normal flora
– Normally harmless or beneficial
microorganisms that typically live in or on a
body
• Some endospore-forming bacteria make
deadly toxins:
– Bacillus anthracis: anthrax
– Clostridium tetani: tetanus
– C. botulinum: botulism
© Cengage Learning 2015
How Do Bacteria Affect Human Health?
• Dangerous infections:
– Mycobacterium tuberculosis: tuberculosis
– Streptococcus: strep throat, “flesh-eating
bacteria”
– Staphylococcus: Antibiotic-resistant staph
infections
© Cengage Learning 2015
Biology
Concepts and Applications | 9e
Starr | Evers | Starr
Chapter 20
The Protists
© Cengage Learning 2015
© Cengage Learning 2015
© Cengage Learning 2015
20.1 What Are Protists?
• Protists
– Protists are a collection of mostly single-celled
eukaryotes
– Protists are not a natural group, but a
collection of lineages, some only distantly
related to one another
– Many have chloroplasts
© Cengage Learning 2015
What Are Protists?
© Cengage Learning 2015
What Are Protists?
• Chloroplasts evolved by endosymbiosis
– Primary endosymbiosis – bacterium enters
cell and descendants evolve into organelles
– Secondary endosymbiosis – photosynthetic
protist engulfed by a heterotrophic protist
© Cengage Learning 2015
What Are Protists?
primary
endosymbiosis
1
Eukaryotic cell
engulfs
a cyanobacterium.
© Cengage Learning 2015
The resulting
chloroplast
has two
membranes.
secondary
endosymbiosis
2
Heterotrophic protist
engulfs an autotrophic one with
chloroplasts that
evolved by primary
endosymbiosis.
The resulting
chloroplast
has four
membranes.
What Are Alveolates?
• Dinoflagellates
– Whirling aquatic heterotrophs and autotrophs
– Have cellulose plates
– Photosynthetic
– Supply reef-building corals with sugars and
oxygen
– Some dinoflagellates are bioluminescent
© Cengage Learning 2015
© Cengage Learning 2015
20.5 How Does Malaria Affect Human
Health?
• Malaria is a leading cause of human
death, killing more than 1.3 million people
every year
• Plasmodium, a single-celled
apicomplexan, causes malaria
– Mosquitoes carry Plasmodium from one
human host to another
© Cengage Learning 2015
What Are Stramenopiles?
• Brown algae
– Multicelled marine protist
– Range in size from microscopic strands to
giant kelps
– Contain the brown pigment fucoxanthin
– Source of algins, used as thickeners and
emulsifiers
© Cengage Learning 2015
20.7 Which Protists are Closest To Plants?
• Red algae
– Photosynthetic protist
– Most red algae are multicelled and marine
– Deposit cellulose in cell walls
– Store sugars as starch
– Has chloroplasts containing chlorophyll a and
red pigments called phycobilins
• Pigments allow them to capture light even in deep
waters
© Cengage Learning 2015
Which Protists are Closest To Plants?
• Green algae
– Closest relatives of land plants
• Charophyte algae (Chara): closest relatives; unlike
most other green algae, divide by cell plate
formation, and have plasmodesmata cytoplasmic
connections
– May be single cells, colonial, or multicelled
• Some multicelled algae have an alternation of
generations
© Cengage Learning 2015
Green algae
© Cengage Learning 2015
Red algae
Brown algae
Figure 15.25
– Seaweeds are classified into three different
groups, based partly on the types of pigments
present in their chloroplasts:
• Green algae
• Red algae
• Brown algae (including kelp)
© Cengage Learning 2015
Which Protists are Closest To Plants?
• Alternation of generations: the process
– The diploid gametophyte is sheetlike
• Gametes form at its edges
– Fertilization produces a diploid zygote
– The zygote develops into a diploid sporophyte
– Haploid spores form by meiosis on the
sporophyte body, and are released
– Spores germinate and develop into a new
gametophyte
© Cengage Learning 2015
20.10 Algal Blooms
• Harmful algal bloom (HAB)
– A population explosion of an aquatic protist, or
of another aquatic microorganism
– Toxins released during some algal blooms
can harm wildlife and endanger human health
• Keeping harmful algal toxins out of the human food
supply requires constant vigilance
– Nutrients in water (fertilizers, farm waste,
sewage) can cause runaway algal growth
– Sometimes called “red tides”
© Cengage Learning 2015
Pfiesteria
piscicida
Red = toxic stages, yellow = possibly toxic stages, blue = passive stages
© Cengage Learning 2015
Unicellular
protist
Gamete
Locomotor
cells
Food-synthesizing
cells
Somatic
cells
Colony
Early multicellular organism
with specialized, interdependent cells
© Cengage Learning 2015
Later organism with
gametes and somatic cells
Figure 15.26-3
Bacteria
Prokaryotes
Archaea
Protists
Eukarya
Plants
Fungi
Animals
© Cengage Learning 2015
Figure 15.UN01