Download Evolution of Vertebrate Circulatory System

Everest II: The Climb
PROLOGUE
Dominic Alexis was waiting his turn to use the airplane bathroom when he got his first
glimpse of Mount Everest.
Standing there in the narrow aisle of the 747, he froze, gawking out the rounded
porthole in the emergency door. To the north rose the jagged icy spires of the
Himalayas, the highest mountain range on the face of the Earth. And right in the heart of
it, the giant among giants - barely lower than the cruising altitude of the plane - Everest.
There should be trumpets, he thought reverently. A fanfare. Fireworks.
Norman "Tilt" Crowley came up behind Dominic and hip-checked him out of the way.
"Man, this airline stinks! What do you have to do to get a bag of peanuts?"
Wordlessly, Dominic pointed out the window at the unmistakable silhouette.
Tilt peered through the porthole. "Big deal - Mount Everest. What, you thought they
were going to move it before we got here?"
But for all his attitude, Tilt stayed riveted to the spot, fascinated by the sight of the big
mountain that the Nepalese called Jongmalungma - goddess, mother of the world.
An announcement came from the cockpit. "On our left, we see Mount Everest." It was
repeated in several other languages.
There was a rush for the left side of the plane. For most of the passengers, this was the
closest they would come to the top of the world. But Dominic and Tilt were part of
SummitQuest, the youngest expedition ever to attempt the planet's highest peak. For
them, the massive profile of Everest was the shape of things to come.
Sammi Moon shut off her Walkman and rushed over to join them at the porthole. "How
is it? Extreme, right?" She spotted the mountain. "It's beautiful!"
"You paint it; I'll climb it," put in Tilt. "That lump of rock is going to make me famous."
"We have to wake Perry," said Dominic. "He should see this."
The fourth member of their team, Perry Noonan, was in his seat, fast asleep.
"Are you kidding?" snorted Tilt. "He's so scared of Everest that he can't even face the
picture in the in-flight magazine! He'd take one look out the window and wet his pants!"
Dominic's eyes never left the mountain. "You've got to be crazy not to be a little bit
scared."
"I'm just amped," said Sammi. "I can't believe we're really on our way!"
They squinted through the clouds, trying to discern the summit - the object of years of
climbing and months of preparation.
What Dominic, Tilt, Sammi, and Perry could not know was that the mist-obscured peak
was more than a goal. For one of the four team members, it would be a final resting
place.
Everest III: The Summit
PROLOGUE
The wind pounced on them above twenty-five thousand feet.
As the youngest expedition in Everest history scrambled up the Geneva Spur, the
onslaught began - overpowering gusts that threatened to pluck the climbers off the
mountain and hurl them into space.
Amazingly, this was nothing new to them. The winds are fierce and unpredictable high
on Everest in the infamous Death Zone, and this was the second time the team had
stood atop the Spur, a mammoth club of decaying black rock. Their last summit bid had
been scuttled when they'd been called away to perform a daring high-altitude rescue.
For two long weeks, SummitQuest had waited at Base Camp, begging fate for the
weather to offer them a second chance at the peak.
Now they had it. And, as team leader Cap Cicero put it, "We're not going to let a little
breeze get in our way."
Clad in full-body windsuits, oxygen masks, and goggles, they looked like something out
of a science fiction movie. This was fitting, since the pinnacle of the world was as
inhospitable a place as any alien planet.
Bent double into the teeth of the gale, they slogged on, gasping bottled oxygen, moving
slowly, but always moving. At extreme altitude, the mere effort of putting one foot in
front of the other is the equivalent of pushing a boulder up a steep hill. It takes massive
reserves of strength and will. But mostly it takes the ability to fight through pain.
A sudden howling blast drove thirteen-year-old Dominic Alexis back a step. Cicero
reached out a hand to steady his youngest and smallest climber. Then he guided the
boy into line behind him in an effort to shelter him from the worst of the wind.
Cicero's confident carriage belied an inner concern: If the blow's this bad here, it's
bound to be murderous higher up.
Normally, conditions like this would have sent a team back to Base Camp to wait for
better weather. But it was the twenty-first of May, very late in the climbing season. Any
day, Everest's summer monsoon could begin, effectively shutting down the mountain.
They climbed now because they could not be sure they would get another chance.
The team leader had no way of knowing that summer would come late that year. Nor
could he have foreseen that, before Everest slipped into the monsoon, it would claim
the life of one of his young climbers.
Understanding the causes of and responses to global warming requires
interdisciplinary cooperation between social and natural scientists. The
theory behind global warming has been understood by climatologists since
at least the 1980s, but only in the new millennium, with an apparent tipping
point in 2005, has the mounting empirical evidence convinced most
doubters, politicians, and the general public as well as growing sections of
business that global warming caused by human action is occurring.
DEFINITION OF GLOBAL WARMING
Global warming is understood to result from an overall, long-term increase
in the retention of the sun’s heat around Earth due to blanketing by
“greenhouse gases,” especially CO2 and methane. Emissions of CO2 have
been rising at a speed unprecedented in human history, due to accelerating
fossil fuel burning that began in the Industrial Revolution.
The effects of the resulting “climate change” are uneven and can even
produce localized cooling (if warm currents change direction). The climate
change may also initiate positive feedback in which the initial impact is
further enhanced by its own effects, for example if melting ice reduces the
reflective properties of white surfaces (the “albedo” effect) or if melting
tundra releases frozen methane, leading to further warming. Debate
continues about which manifestations are due to long-term climate change
and which to normal climate variability.
SPEEDING UP THE PROCESS
Global warming involves an unprecedented speeding up of the rate of
change in natural processes, which now converges with the (previously
much faster) rate of change in human societies, leading to a crisis of
adaptation. Most authoritative scientific bodies predict that on present
trends a point of no return could come within ten years, and that the world
needs to cut emissions by 50 percent by mid twenty-first century.
It was natural scientists who first discovered and raised global warming as
a political problem. This makes many of the global warming concerns
unique. “Science becomes the author of issues that dominate the political
agenda and become the sources of political conflict” (Stehr 2001, p. 85).
Perhaps for this reason, many social scientists, particularly sociologists,
wary of trusting the truth claims of natural science but knowing themselves
lacking the expertise to judge their validity, have avoided saying much
about global warming and its possible consequences. Even sociologists
such as Ulrich Beck and Anthony Giddens, who see “risk” as a key
attribute of advanced modernity, have said little about climate change.
For practical purposes, it can no longer be assumed that nature is a stable,
well understood, background constant and thus social scientists do not
need direct knowledge about its changes. Any discussion of likely social,
economic, and political futures will have to heed what natural scientists say
about the likely impacts of climate change.
GROWING EVIDENCE OF GLOBAL WARMING
While originally eccentric, global warming was placed firmly on the agenda
in 1985, at a conference in Austria of eighty-nine climate researchers
participating as individuals from twenty-three countries. The researchers
forecast substantial warming, unambiguously attributable to human
activities.
Since that conference the researchers’ position has guided targeted
empirical research, leading to supporting (and increasingly dire) evidence,
resolving anomalies and winning near unanimous peer endorsement.
Skeptics have been confounded and reduced to a handful, some
discredited by revelations of dubious funding from fossil fuel industries.
Just before the end of the twentieth century, American researchers
released ice-thickness data, gathered by nuclear submarines. The data
showed that over the previous forty years the ice depth in all regions of the
Arctic Ocean had declined by approximately 40 percent.
Five yearly aerial photographs show the ice cover on the Arctic Ocean at a
record low, with a loss of 50 cubic kilometers annually and glacier retreat
doubling to 12 kilometers a year. In September 2005 the National
Aeronautics and Space Administration (NASA) doubled its estimates of the
volume of melted fresh water flowing into the North Atlantic, reducing
salinity and thus potentially threatening the conveyor that drives the Gulf
Stream. Temperate mussels have been found in Arctic waters, and news
broadcasts in 2005 and 2006 have repeatedly shown scenes of Inuit and
polar bears (recently listed as endangered) cut off from their hunting
grounds as the ice bridges melt.
In 2001 the Intergovernmental Panel on Climate Change (IPCC), the
United Nation’s scientific panel on climate change, had predicted that
Antarctica would not contribute significantly to sea level rise this century.
The massive west Antarctic ice sheet was assumed to be stable. However,
in June 2005 a British Antarctic survey reported measurements of the
glaciers on this ice sheet shrinking. In October 2005 glaciologists reported
that the edges of the Antarctic ice sheets were crumbling at an
unprecedented rate and, in one area, glaciers were discharging ice three
times faster than a decade earlier.
In 2005 an eight-year European study drilling Antarctic ice cores to
measure the past composition of the atmosphere reported that CO2 levels
were at least 30 percent higher than at any time in the last 65,000 years.
The speed of the rise in CO2 was unprecedented, from 280 parts per
million (ppm) before the Industrial Revolution to 388 ppm in 2006. Early in
2007 the Norwegian Polar Institute reported acceleration to a new level of
390 ppm. In January 2006 a British Antarctic survey, analyzing CO2 in
crevasse ice in the Antarctic Peninsula, found levels of CO2 higher than at
any time in the previous 800,000 years.
In April 2005 a NASA Goddard Institute oceanic study reported that the
earth was holding on to more solar energy than it was emitting into space.
The Institute’s director said: “This energy imbalance is the ‘smoking gun’
that we have been looking for” (Columbia 2005).
The second IPCC report in 1996 had predicted a maximum temperature
rise of 3.5 degrees Fahrenheit by the end of the twenty-first century. The
third report, in 2001, predicted a maximum rise of 5.8 degrees Fahrenheit
by the end of the twenty-first century. In October 2006 Austrian
glaciologists reported in Geophysical Research Letters (Kaser et al.) that
almost all the world’s glaciers had been shrinking since the 1940s, and the
shrinking rate had increased since 2001. None of the glaciers (contrary to
skeptics) was growing. Melting glaciers could pose threats to the water
supply of major South American cities and is already manifest in the
appearance of many new lakes in Bhutan.
In January 2007 global average land and sea temperatures were the
highest ever recorded for this month; in February 2007 the IPCC Fourth
Report, expressing greater certainty and worse fears than the previous
one, made headlines around the world. In 1995 few scientists believed the
effects of global warming were already manifest, but by 2005 few scientists
doubted it and in 2007 few politicians were willing to appear skeptical.
Although rising temperatures; melting tundra, ice and glaciers; droughts;
extreme storms; stressed coral reefs; changing geographical range of
plants, animals, and diseases; and sinking atolls may conceivably all be
results of many temporary climate variations, their cumulative impact is
hard to refute.
ADULTERATION OF FOOD
ADULTERATION OF FOOD. "Adulteration" is a legal term meaning that a food product fails to
meet federal or state standards. Adulteration usually refers to noncompliance with health or
safety standards as determined, in the United States, by the Food and Drug Administration
(FDA) and the U.S. Department of Agriculture (USDA).
Definition of Adulterated Food
The Federal Food, Drug, and Cosmetic (FD&C) Act (1938) provides that food is "adulterated" if
it meets any one of the following criteria: (1) it bears or contains any "poisonous or deleterious
substance" which may render it injurious to health; (2) it bears or contains any added poisonous
or added deleterious substance (other than a pesticide residue, food additive, color additive, or
new animal drug, which are covered by separate provisions) that is unsafe; (3) its container is
composed, in whole or in part, of any poisonous or deleterious substance which may render the
contents injurious to health; or (4) it bears or contains a pesticide chemical residue that is
unsafe. (Note: The Environmental Protection Agency [EPA] establishes tolerances for pesticide
residues in foods, which are enforced by the FDA.)
Food also meets the definition of adulteration if: (5) it is, or it bears or contains, an unsafe food
additive; (6) it is, or it bears or contains, an unsafe new animal drug; (7) it is, or it bears or
contains, an unsafe color additive; (8) it consists, in whole or in part, of "any filthy, putrid, or
decomposed substance" or is otherwise unfit for food; or (9) it has been prepared, packed, or
held under unsanitary conditions (insect, rodent, or bird infestation) whereby it may have
become contaminated with filth or rendered injurious to health.
Further, food is considered adulterated if: (10) it has been irradiated and the irradiation
processing was not done in conformity with a regulation permitting irradiation of the food in
question (Note: FDA has approved irradiation of a number of foods, including refrigerated or
frozen uncooked meat, fresh or frozen uncooked poultry, and seeds for sprouting [21 C.F.R.
Part 179].); (11) it contains a dietary ingredient that presents a significant or unreasonable risk
of illness or injury under the conditions of use recommended in labeling (for example, foods or
dietary supplements containing aristolochic acids, which have been linked to kidney failure,
have been banned.); (12) a valuable constituent has been omitted in whole or in part or
replaced with another substance; damage or inferiority has been concealed in any manner; or a
substance has been added to increase the product's bulk or weight, reduce its quality or
strength, or make it appear of greater value than it is (this is "economic adulteration"); or (13) it
is offered for import into the United States and is a food that has previously been refused
admission, unless the person reoffering the food establishes that it is in compliance with U.S.
law [21 U.S.C. § 342].
The Federal Meat Inspection Act and the Poultry Products Inspection Act contain similar
provisions for meat and poultry products. [21 U.S.C. § 453(g), 601(m).
Poisonous or Deleterious Substances
Generally, if a food contains a poisonous or deleterious substance that may render it injurious to
health, it is adulterated. For example, apple cider contaminated with E. coli O157:H7 and Brie
cheese contaminated with Listeria monocytogenes are adulterated. There are two exceptions to
this general rule. First, if the poisonous substance is inherent or naturally occurring and its
quantity in the food does not ordinarily render it injurious to health, the food will not be
considered adulterated. Thus, a food that contains a natural toxin at very low levels that would
not ordinarily be harmful (for instance, small amounts of amygdalin in apricot kernels) is not
adulterated.
Second, if the poisonous or deleterious substance is unavoidable and is within an established
tolerance, regulatory limit, or action level, the food will not be deemed to be adulterated.
Tolerances and regulatory limits are thresholds above which a food will be considered
adulterated. They are binding on FDA, the food industry, and the courts. Action levels are limits
at or above which FDA may regard food as adulterated. They are not binding on FDA. FDA has
established numerous action levels (for example, one part per million methyl mercury in fish),
which are set forth in its booklet Action Levels for Poisonous or Deleterious Substances in
Human Food and Animal Feed.
If a food contains a poisonous substance in excess of a tolerance, regulatory limit, or action
level, mixing it with "clean" food to reduce the level of contamination is not allowed. The
deliberate mixing of adulterated food with good food renders the finished product adulterated
(FDA, Compliance Policy Guide [CPG § 555.200]).
Filth and Foreign Matter
Filth and extraneous material include any objectionable substances in foods, such as foreign
matter (for example, glass, metal, plastic, wood, stones, sand, cigarette butts), undesirable parts
of the raw plant material (such as stems, pits in pitted olives, pieces of shell in canned oysters),
and filth (namely, mold, rot, insect and rodent parts, excreta, decomposition). Under a strict
reading of the FD&C Act, any amount of filth in a food would render it adulterated. FDA
regulations, however, authorize the agency to issue Defect Action Levels (DALs) for natural,
unavoidable defects that at low levels do not pose a human health hazard [21 C.F.R. §
110.110]. These DALs are advisory only; they do not have the force of law and do not bind FDA.
DALs are set forth in FDA's Compliance Policy Guides and are compiled in the FDA and Center
for Food Safety and Applied Nutrition (CFSAN) Defect Action Level Handbook.
In most cases, DALs are food-specific and defect-specific. For example, the DAL for insect
fragments in peanut butter is an average of thirty or more insect fragments per 100 grams (g)
[CPG § 570.300]. In the case of hard or sharp foreign objects, the DAL, which is based on the
size of the object and the likelihood it will pose a risk of choking or injury, applies to all foods
(see CPG § 555.425).
Economic Adulteration
A food is adulterated if it omits a valuable constituent or substitutes another substance, in whole
or in part, for a valuable constituent (for instance, olive oil diluted with tea tree oil); conceals
damage or inferiority in any manner (such as fresh fruit with food coloring on its surface to
conceal defects); or any substance has been added to it or packed with it to increase its bulk or
weight, reduce its quality or strength, or make it appear bigger or of greater value than it is (for
example, scallops to which water has been added to make them heavier).
Microbiological Contamination and Adulteration
The fact that a food is contaminated with pathogens (harmful microorganisms such as bacteria,
viruses, or protozoa) may, or may not, render it adulterated. Generally, for ready-to-eat foods,
the presence of pathogens will render the food adulterated. For example, the presence of
Salmonella on fresh fruits or vegetables or in ready-to-eat meat or poultry products (such as
luncheon meats) will render those products adulterated.
For meat and poultry products, which are regulated by USDA, the rules are more complicated.
Ready-to-eat meat and poultry products contaminated with pathogens, such as Salmonella or
Listeria monocytogenes, are adulterated. (Note that hotdogs are considered ready-to-eat
products.) For raw meat or poultry products, the presence of pathogens will not always render a
product adulterated (because raw meat and poultry products are intended to be cooked, and
proper cooking should kill pathogens). Raw poultry contaminated with Salmonella is not
adulterated. However, USDA's Food Safety and Inspection Service (FSIS) has ruled that raw
meat or poultry products contaminated with E. coli O157:H7 are adulterated. This is because
normal cooking methods may not reduce E. coli O157:H7 below infectious levels. E. coli
O157:H7 is the only pathogen that is considered an adulterant when present in raw meat or
poultry products.
Medicine, Socialized
BIBLIOGRAPHY
The American Heritage Dictionary (4th ed., 2001) defines socialized medicine as “a system for
providing medical and hospital care for all at a nominal cost by means of government
regulation.” This leaves room for considerable craftsmanship in the construction of socialist
systems. Indeed existing socialized medical systems in, for example, Great Britain, Cuba,
Finland, and Switzerland conform to this definition, but are far from monolithic.
Because every aspect of a socialized health care industry is controlled and provided by the
government—most doctors, nurses, medics, and administrators are government employees—
the system, such as the National Health Service (NHS) in Britain, determines where, when, and
how services are provided. Of course citizens may seek care outside the system, in the private
sector.
Socialized medical systems are designed to eliminate the insurance industry and marginalize
profit while providing health care for all. According to many recent studies, socialized systems
outperform free-market profit-driven systems in terms of availability, quality, and cost of care. In
addition a report from the Johns Hopkins University Bloomberg School of Public Health stated
that the United Kingdom’s socialized medical system outperforms the U.S. system in patientreported perceptions (Blendon, Schoen, DesRoches, et al. 2003). In other words, the people
with direct experiences report greater satisfaction with their health services under a socialized
system than they do in a free-market system. These results must be considered along with the
fact that the U.S. per capita health care expenditures ($4,887) are nearly triple those in the
United Kingdom ($1,992). In the year 2000 the United States spent 44 percent more on health
care than Switzerland, the nation with the next highest per capita health care costs.
Nevertheless, Americans had fewer physician visits, and hospital stays were shorter compared
with those in most other industrialized nations. The study suggests that the difference in
spending is caused mostly by higher prices for health care goods and services in the United
States.
The British system is probably the most instructive example for Americans to evaluate because
of the similarities in economy and government structure between the two nations. According to
the NHS Web site, the system “was set up on the 5th July 1948 to provide healthcare for all
citizens, based on need, not the ability to pay” (National Health Service 2007). Originally
conceived as a response to the massive casualties of World War II (1939–1945), the system
survives and continues to evolve in the early twenty-first century. The NHS is funded by
taxpayers and managed by the Department of Health, which sets overall policy on health
issues. Individual patients are assigned a primary care center (with doctors, dentists, optician,
pharmacist, and a walk-in center) managed by a primary care trust (PCT). The NHS explains its
system of referrals this way: “If a health problem cannot be sorted out through primary care, or
there is an emergency, the next stop is hospital. If you need hospital treatment, a general
practitioner will normally arrange it for you” (National Health Service 2007).
The PCTs are responsible for planning secondary care. They look at the health needs of the
local community and develop plans to set priorities locally. They then decide which secondary
care services to commission to meet people’s needs and work closely with the providers of the
secondary care services to agree about delivering those services.
The NHS may be the world’s most sophisticated socialized medical system, but the modern
world’s first such system was established by the former Soviet Union in the 1920s. Whereas the
NHS demonstrates that socialized medicine can exist within a capitalist economy, the failures of
Soviet medicine demonstrated how corruption within a society can distort any system. China,
Cuba, Sweden, and most of Scandinavia have successful and completely socialized health care
systems.
Life expectancy and infant mortality rates are two of the best indicators of overall health.
Average life expectancy in Great Britain was 77.4 years in 1998; in comparison, life expectancy
for the U.S. population reached 76.9 years in 2000. Infant mortality in Finland is below 4
percent; in the United States it is 7 percent. Health services are available to all in Finland,
regardless of their financial situations.
Single-payer systems such as Medicare are not socialized medicine. In socialized systems the
government owns, operates, and provides every aspect of the health care services. Although it
is true that in a single-payer system the government collects and disperses the capital for
services rendered, its decision-making responsibilities end there. Even without socialized
medicine’s additional powers to limit corporate profits, studies by the U.S. General Accounting
Office and the Congressional Budget Office show that single-payer universal health care would
save $100 to $200 billion dollars per year while covering every currently uninsured American
and increasing health care benefits to those already insured (U.S. Government Accounting
Office 1991; Congressional Budget Office 1993).
Outside of the United States, health care in the twenty-first century is increasingly seen as a
basic human right that deserves to be protected and provided at an affordable fee to all citizens
of civilized societies. This idea—that medical procedures and health care in general should not
be subject to or motivated by market forces— is one that, in the late twentieth century, evolved
back into favor only after repeated experiments with the capitalization of health care led to
systematic and catastrophic failures, resulting in grotesque profits on the supply side contrasted
with the suffering of millions of disenfranchised patients on the demand side of the equation.
Socialized medicine is an egalitarian system that addresses these iniquities.
germs
The media is increasingly filled with reports about outbreaks of SARS, AIDS,
ebola, hanta virus, anthrax, polio, and mad cow disease. The rapid spread of these
diseases and the concerns that arise from the media attention raise questions about how to
best educate the public to be able to make informed decisions about their health, travel
and family safety. The purpose of this study is to document what students of different
ages and their teachers know about viruses and bacteria and to examine how this
knowledge compares to that of experts.
Research in the area of students' conceptual understandings of biological science
phenomena has become increasingly prevalent over the past two decades emphasizing the
shift away from rote learning in science. Studies have investigated the ideas and
reasoning students have about the cell (Flores, Tovar & Gallegos, 2003), the human
circulatory system (Arnaudin & Mintzes, 1985), mammals, (Markham, Mintzes & Jones,
1994), and biotechnology (Dawson & Schibeci 2003; Dori, Tal, & Tsaushu, 2003).
These studies and others have found that students and adults can have drastically
Electronic Journal of Science Education, Vol. 9, No. 1, September 2004
different ideas about science concepts compared to the models held by the scientific
community. Disparity between students, adults and experts within a specific field of
inquiry are often associated with the development of preconceptions (also called naïve
conceptions, misconceptions, alternative conceptions or personal theories) by the learner
during interactions with physical, social, and cultural environments. Students begin
developing these early concepts about natural phenomenon prior to formal instruction
(Driver, 1987) and enter school with individual explanations and understandings about
the science concepts they are taught. The personal theories held by children emerge as
they try to understand and explain the experiences they confront in their environment.
These working theories may, or may not, be consistent with current scientific
explanations but are nevertheless resistant to change. Research has shown that students
may hold original intuitive concepts simultaneously with new formal science concepts
(Hewson & Hewson, 1992; Scott, 1992; Strike & Posner, 1985).
As individuals move from novice knowledge to expert knowledge they move
from holding disconnected information to a system of connected knowledge bound by
larger principles (Chi et al., 1981). Ericsson and Charness (1994) maintain that expert
knowledge is more than an accumulation of facts but instead is structured to facilitate
problem solving. For science educators, the challenge arises when students learn factual
knowledge without developing the connections that move them along the continuum to
principle-guided knowledge like that held by experts. When scientific knowledge
conflicts with intuitive naïve knowledge the challenge is even greater.
Although research on children's development of science concepts has greatly
expanded in recent years, most studies have focused on concepts related to the physical
Electronic Journal of Science Education, Vol. 9, No. 1, September 2004
sciences and there are only a limited number of studies of biological systems. According
to Benchmarks for Science Literacy (American Association for the Advancement of
Science, 1993), there has been little research on germs and one of the few studies by
Nagy (1953) examining elementary school children's ideas about germs is "an admittedly
dated study [which is] still cited by many authors" (American Association for the
Advancement of Science, 1993, p. 345). There is a distinct lack of research in the area of
the human body in general, and more specifically the effect of microorganisms on human
health as well as the role of microorganisms in the environment.
Children's Conceptions of Germs
Research into children's conceptions of germs and illness has focused primarily
on interview and test data. Few studies regarded children's physical representations of
germs as insightful. However, Nagy's (1953) research on how children represent germs
showed clear distinctions between age groups, consistent with Piaget's developmental
stages. When children were asked to draw pictures of germs, more than half of the
children between the ages of 5 and 7 were unable to draw a germ. The remaining children
drew abstract figures such as dots to represent germs. Children ages 8 to 11 represented
germs in one of three forms: germs, animals such as insects or scenes such as a garbage
dump. When the elements of the drawings were analyzed three distinguishing categories
emerged: animals, abstract figures, or a combination of both. The use of abstract figures
seemed to decrease with age as animal representations increased.
Adults’ Conceptions of Germs
As research in the area of causative agents associated with illness has increased,
the focus on adult conceptions and personal theories continues to be minimal. The studies
Electronic Journal of Science Education, Vol. 9, No. 1, September 2004
in the area of biology which primarily focus on the young seem to make the assumption
that children will eventually reach a point of scientific understanding in adulthood.
However, very few studies have explored what adults actually know about the effects of
microorganisms on the body; therefore the similarities and differences between adults’
and children’s conceptions are not clear. In studies on children’s understandings of
biology it is believed that young children are able to access naïve theories on the subject
“which are constrained in ways quite similar to adult versions” (Rosser, 1994).
This study adds to the conceptual development literature through an examination
of elementary, middle and high school students' knowledge of germs. In response to the
lack of research on adult and expert conceptions, teachers and science professionals have
been included in this research. In this study the concepts of children, adolescents, and
adults are examined in order to provide a broad spectrum of ages that allows for the
examination of how knowledge of microorganisms differs by age and experience.
This study seeks to answer the following research question: How does knowledge
in the domain of germs1 held by students, teachers, and science professionals differ?
I CAN READ
Why is the sky blue?
Light is a kind of energy that can travel through space. Light from the sun or a light bulb
looks white, but it is really a mixture of many colors. The colors in white light are red,
orange, yellow, green, blue and violet. You can see these colors when you look at a rainbow
in the sky.
The sky is filled with air. Air is a mixture of tiny gas molecules and small bits of
solid stuff, like dust.
As sunlight goes through the air, it bumps into the molecules and dust. When
light hits a gas molecule, it may bounce off in a different direction. Some colors
of light, like red and orange, pass straight through the air. But most of the blue
light bounces off in all directions. In this way, the blue light gets scattered all
around the sky.
When you look up, some of this blue light reaches your eyes from all over the
sky. Since you see blue light from everywhere overhead, the sky looks blue.
In space, there is no air. Because there is nothing for the light to bounce off, it
just goes straight. None of the light gets scattered, and the "sky" looks dark and
black.
PROJECTS TO DO TOGETHER
SAFETY NOTE: Please read all instructions completely before starting. Observe all safety
precautions.
PROJECT 1 - Split light into a spectrum
What you need:
a small mirror, a piece of white paper or cardboard, water
a large shallow bowl, pan, or plastic shoebox
a window with direct sunlight coming in, or a sunny day outdoor
What to do:
1. Fill the bowl or pan about 2/3 full of water. Place it on a table or the floor, directly in the
sunlight. (Note: the direct sunlight is important for this experiment to work right.)
2. Hold the mirror under water, facing towards the sun. Hold the paper above and in front of the
mirror. Adjust the positions of the paper and mirror until the reflected light shines on the paper.
Observe the colored spectrum.
What happened: The water and mirror acted like a prism, splitting the light into the colors of the
spectrum. (When light passes from one medium to another, for example from air to water, its speed and
direction change. [This is called refraction, and will be discussed in a future issue.] The different colors of
light are affected differently. Violet light slows the most, and bends the most. Red light slows and bends
the least. The different colors of light are spread out and separated, and we can see the spectrum.)
PROJECT 2 - Sky in a jar
What you need:
a clear, straight-sided drinking glass, or clear plastic or glass jar
water, milk, measuring spoons, flashlight
a darkened room
What to do:
1.
2.
3.
4.
Fill the glass or jar about 2/3 full of water (about 8 - 12 oz. or 250 - 400 ml)
Add 1/2 to 1 teaspoon (2 - 5 ml) milk and stir.
Take the glass and flashlight into a darkened room.
Hold the flashlight above the surface of the water and observe the water in the glass from the
side. It should have a slight bluish tint. Now, hold the flashlight to the side of the glass and look
through the water directly at the light. The water should have a slightly reddish tint. Put the
flashlight under the glass and look down into the water from the top. It should have a deeper
reddish tint.
What happened: The small particles of milk suspended in the water scattered the light from the
flashlight, like the dust particles and molecules in the air scatter sunlight. When the light shines in the
top of the glass, the water looks blue because you see blue light scattered to the side. When you look
through the water directly at the light, it appears red because some of the blue was removed by
scattering.
PROJECT 3 -Mixing colors
You need:
a pencil, scissors, white cardboard or heavy white paper
crayons or markers, a ruler
a small bowl or a large cup (3 - 4 inch, or 7 - 10 cm diameter rim)
a paper cup
What to do:
1. Use the bowl to trace a circle onto a piece of white cardboard and cut it out. With the ruler,
divide it into six approximately equal sections.
2. Color the six sections with the colors of the spectrum as shown. Try to color as smoothly and
evenly as possible.
3. Poke a hole through the middle of the circle and push the pencil part of the way through.
4. Poke a hole in the bottom of the paper cup, a little bit larger than the diameter of the pencil.
Turn the cup upside down on a piece of paper, and put the pencil through so the point rests on
the paper on a table. Adjust the color wheel's position on the pencil so that it is about 1/2 inch
(1 - 2 cm) above the cup.
5. Spin the pencil quickly and observe the color wheel. Adjust as necessary so that the pencil and
wheel spin easily.
What happened: The colors on the wheel are the main colors in white light. When the wheel spins fast
enough, the colors all appear to blend together, and the wheel looks white. Try experimenting with
different color combinations.
HOW DO ANIMALS SPEND THE WINTER?
The weather gets colder, days get shorter and leaves turn color and fall off the trees. Soon, winter
is here. Snow covers the ground. People live in warm houses and wear heavy coats outside. Our
food comes from the grocery store. But what happens to the animals?
MIGRATE
Animals do many different, amazing things to get through the winter. Some of them "migrate."
This means they travel to other places where the weather is warmer or they can find food.
Many birds migrate in the fall. Because the trip can be dangerous, some travel in large flocks.
For example, geese fly in noisy, "V"-shaped groups. Other kinds of birds fly alone.
How do they know when it is time to leave for the winter? Scientists are still studying this. Many
see migration as part of a yearly cycle of changes a bird goes through. The cycle is controlled by
changes in the amount of daylight and the weather.
Birds can fly very long distances. For example, the Arctic tern nests close to the North Pole in
the summer. In autumn, it flys south all the way to Antarctica. Each spring it returns north again.
Most birds migrate shorter distances. But how do they find their way to the same place each
year? Birds seem to navigate like sailors once did, using the sun, moon and stars for direction.
They also seem to have a compass in their brain for using the Earth's magnetic field.
Other animals migrate, too. There are a few mammals, like some bats, caribou and elk, and
whales that travel in search of food each winter. Many fish migrate. They may swim south, or
move into deeper, warmer water.
Insects also migrate. Some butterflies and moths fly very long distances. For example, Monarch
butterflies spend the summer in Canada and the Northern U.S. They migrate as far south as
Mexico for the winter. Most migrating insects go much shorter distances. Many, like termites
and Japanese beetles, move downward into the soil. Earthworms also move down, some as far as
six feet below the surface.
ADAPT
Some animals remain and stay active in the winter. They must adapt to the changing weather.
Many make changes in their behavior or bodies. To keep warm, animals may grow new, thicker
fur in the fall. On weasels and snowshoe rabbits, the new fur is white to help them hide in the
snow.
Food is hard to find in the winter. Some animals, like squirrels, mice and beavers, gather extra
food in the fall and store it to eat later. Some, like rabbits and deer, spend winter looking for
moss, twigs, bark and leaves to eat. Other animals eat different kinds of food as the seasons
change. The red fox eats fruit and insects in the spring, summer and fall. In the winter, it can not
find these things, so instead it eats small rodents.
Animals may find winter shelter in holes in trees or logs, under rocks or leaves, or underground.
Some mice even build tunnels through the snow. To try to stay warm, animals like squirrels and
mice may huddle close together.
Certain spiders and insects may stay active if they live in frost-free areas and can find food to
eat. There are a few insects, like the winter stone fly, crane fly, and snow fleas, that are normally
active in winter. Also, some fish stay active in cold water during the winter.
HIBERNATE
Some animals "hibernate" for part or all of the winter. This is a special, very deep sleep. The
animal's body temperature drops, and its heartbeat and breathing slow down. It uses very little
energy. In the fall, these animals get ready for winter by eating extra food and storing it as body
fat. They use this fat for energy while hibernating. Some also store food like nuts or acorns to eat
later in the winter. Bears, skunks, chipmunks, and some bats hibernate.
AND MORE
Cold-blooded animals like fish, frogs, snakes and turtles have no way to keep warm during the
winter. Snakes and many other reptiles find shelter in holes or burrows, and spend the winter
inactive, or dormant. This is similar to hibernation.
Water makes a good shelter for many animals. When the weather gets cold, they move to the
bottom of lakes and ponds. There, frogs, turtles and many fish hide under rocks, logs or fallen
leaves. They may even bury themselves in the mud. They become dormant. Cold water holds
more oxygen than warm water, and the frogs and turtles can breath by absorbing it through their
skin.
Insects look for winter shelter in holes in the ground, under the bark of trees, deep inside rotting
logs or in any small crack they can find. One of the most interesting places is in a gall. A gall is a
swelling on a plant. It is caused by certain insects, fungi or bacteria. They make a chemical that
affects the plant's growth in a small area, forming a lump. The gall becomes its maker's home
and food source.
Every type of insect has its own life cycle, which is the way it grows and changes. Different
insects spend the winter in different stages of their lives. Many insects spend the winter dormant,
or in "diapause." Diapause is like hibernation. It is a time when growth and development stop.
The insect's heartbeat, breathing and temperature drop. Some insects spend the winter as wormlike larvae. Others spend the winter as pupae. (This is a time when insects change from one form
to another.) Other insects die after laying eggs in the fall. The eggs hatch into new insects in the
spring and everything begins all over again.
The man on the street would probably cite coins and bills as a definition of money.
But the balance on his checkbook is probably also viewed as many, even though the
bank does not have cash to match. A traveler check would also has as many. What
about bank checks? And IOUs? Gold? The family silver? A mortgage?
Most people believe that there is a underlying value to coins and bills. But at the same
time they are familiar with inflation, as well as the inability to exchange their cash for
gold at the central bank.
Money is confidence - a belief that you can reuse the tool for future purchases.
There are numerous myths about the origins of money. The concept of money is often
confused with coinage. Coins are a relatively modern form of money. Their first
appearance was probably among the Lydians, in Asia Minor in the 7th century BC.
And whether these coins were used as money in the modern sense has also been
questioned.
To determine the earliest use of money, we need to define what we mean by money.
We will return to this issue shortly. But with any reasonable definition the first use of
money is as old as human civilization. The early Persians deposited their grain in state
or church grainaries. The receipts of deposit were then used as methods of payment in
the economies. Thus, banks were invented before coins. Ancient Egypt had a similar
system, but instead of receipts they used orders of withdrawal - thus making their
system very close to that of modern checks. In fact, during Alexander the great’s
period, the grainaries were linked together, making checks in the 3rd century BC more
convenient than British checks in the 1980s. The Egyptians had in fact invented the
first giro system.
However, money is older than written history. Recent anthropological and linguistic
research indicates that not only is money very old, but it’s origin has little to do with
trading, thus contradicting another common myth. Rather, money was first used in a
social setting. Probably at first as a method of punishment. Dowries were probably
also an early use. These early origins have left their traces in our language - as in “pay
one’s dues”.
Early stone age man began the use of precious metals as money. Until the invention of
coins, metals were weighed to determine their value. Counting is of course more
practical, the first standardized ingots appeared around 2200 BC. Other commonplace
objects were subsequently used in the abstract sense, for example miniature axes,
nails, swords, etc.
Full standardization arrived with coins, approximately 700 BC. The first printed
money appeared in China, around 800 AD. The first severe inflation was in the 11th
century AD. The Mongols adapted the bank note system in the 13th century, which
Marco Polo wrote about. The Mongol bank notes were “legal tender”, I.e. it was a
capital offense to refuse them as payment. By the late 1400s, centuries of inflation
found eliminated printed bank notes in China. They were reinvented in Europe in the
wake 17th century.
The lower image is of the Greek Drachma, which had a constant value from the 6th
century BC to the 2nd century BC, and became standard coinage in much of Asia and
Europe.
We have become accustomed to living in a stable monetary system. We’ve inherited
this stability from the economists who analyzed World War II. Keynes predicted in
1919 that the unequal terms of the Versailles treaty would cause hardship in years to
come. The resulting inflation from the high war payments forced upon Germany
caused the german currency to drop in value from 14 per U.S. dollar in 1919 to 4
trillion at the end of the german depression in 1923. By wiping out the assets of the
middle class (which were generally financial), it eliminated it’s moderating influence.
Another recent example is Germany after the War. The West Zone and the East Zone
shared a currency beginning in 1945. The Soviets also got printing plates, and using
them within weeks were able to extra hundreds of millions of dollars worth of goods.
RM were stopped as form of payment to troops, and cigarettes became the common
currency. A new currency, the deutschemark was introduced. On that day, the soviet
military blockaded Berlin.
These were just two examples of the impact of currency politics on human history.
They are sufficiently distant to be fairly well understood, yet sufficiently recent for
their true significance to be clear also. Human history is literally full of such interplay
of money and civilization.
This lesson is not lost on the leaders of today. The technology and politics of money
has the ability to change the balance of power, between nations as well as between
classes. The advent of radically new technologies for monetary transactions will
literally affect the lives of billions, as well as creating and destroying fortunes. This
will effectively block any radical changes to our current monetary systems within the
foreseeable feature.
In May 1975 Whitfield Diffie and Martin Hellman conceived of what is today called
public-key cryptography. They published their ideas in November of the next year.
Public-key cryptography is the breakthrough that has become the basis for essentially
every secure protocol suggested since.
The problem that Diffie and Hellman addressed was that of key management.
Designing secure algorithms for encryption was fairly well understood. The problem
was handling the keys. Prior to Diffie and Hellman, two parties who wished to
communicate securely would have to exchange keys in some manner. Typically this
would be done either through a trusted third party, or via a separate secure channel.
Both methods had drawbacks.
What Diffie and Hellman proposed was to use the concept of one-way functions. A
one-way function in this context is one that is significantly more difficult to calculate
in one direction than the other.
The slide shows the RSA algorithm, developed by Rivest, Shamir, and Adleman in
1977. By combining the difficulty of factoring a prime number with the ease of
generating large prime numbers (using a probabilistic algorithm), a key could be split
into a public and a private part.
Factoring primes is an old problem. Probably the first algorithm was by Eratosthenes
(c.276 - 194 BC), a remarkable man who, other than having been librarian at the
famous Alexandrian library, calculated the earth’s circumference with an error of
16.5%. It is generally believed that factoring will remain a very difficult problem,
although there is no proof of this yet. 666*v

MEMO
RE: Check Cashing / Deposit Policies
TO: All Staff
Please follow these instructions when cashing or depositing checks from our
students.









Check cashing by customers is limited to $500.
Two pieces of identification are required, one of which must be a valid driver's
license.
All checks must be signed on the reverse side at the moment of presentation.
Out-of-state checks are only accepted from residents.
International checks may not be cashed. They must first be deposited and can
be drawn on after a minimum of 14 days.
Direct bank deposits and formal reporting procedures are available.
Payments received must always be deposited intact. Never make disbursements
from payments received.
Never send coin or currency through the mail. Bring it to Accounting Services
and obtain a receipt from the cashier. Come before 2 o'clock, so that we can
include it with that day's bank deposit.
Checks and money orders should be restrictively endorsed with these words as
soon as you receive them:
Smither Brothers Language School
15 Whitehead Street
Olympia, WA 98501
Check Your Understanding

What is the limit on cashed checks?
_____

How many piece of identification are required?
_____

When must the checks be signed?
_____

In order to cash an out-of-state check what must you be?
_____

How long do students have to wait for international checks?
_____

What mustn't be sent through the mail?
_____
The Amazing Human Body
The human body contains a number of awe-inspiring and complex systems. Each one
of these systems consists of vital parts that demonstrate incredible coordination as they
accomplish important bodily functions. The amazing design is hard to miss… not just
within each system, but also between systems, in the way the different human body
systems interact with each other. Dive in and see for yourself!
Body Systems: A concise and clear overview of the systems in the human body
The Human Body: Quick facts about the human body systems, written for children.
CIRCULATORY SYSTEM
The circulatory system makes the blood circulate through the human body. It serves its
purpose of supplying the body with nutrients, oxygen, and hormones, and taking out of
the body wastes such as carbon dioxide and ammonia. The circulatory system is further
classified into: systemic circulation, coronary (heart-related) circulation, and pulmonary
(lungs) circulation.
SYSTEMIC CIRCULATION: This is the largest part of the circulatory system. Its
purpose is to supply oxygen and nutrients to the tissues other than those of the lungs
and the heart. It consists of three types of vessels:
1.
Arteries (which carry blood from the heart to the rest of the body),
2.
Veins (which carry blood from the lungs and the rest of the body back to the
heart), and
3.
Capillaries which connect the former two.
In the capillaries, the blood absorbs carbon dioxide and other waste that the body needs
to expel from the tissues. Likewise, in the capillaries, the oxygen and other nutrients that
the body needs, diffuse out of the blood.
CORONARY CIRCULATION: The heart pumps the blood which circulates throughout
the body and thus supplies the necessary oxygen and food to the tissues. The coronary
circulation is the part that gives these provisions to the heart tissues.
PULMONARY CIRCULATION: Inhaled oxygen is absorbed into the blood through the
process of diffusion in the lungs. Similarly, carbon dioxide present in the blood is
transferred back into the lungs. Both of these processes take place through diffusion in
the lungs. The part of the lungs where diffusion takes place is called alveoli.
Circulatory System: A great resource for understanding interactions of the circulatory
system with other systems of the body.
Cardiovascular System: Topics to explore for those who want to take care of their
circulatory system (also known as the cardiovascular system).
Carbon Dioxide Transport: The chemistry of releasing carbon dioxide and bringing in
oxygen.
How the Body Works: An activity which will help you learn about the important parts of
the lungs.
INTEGUMENTARY SYSTEM
The main purpose of the integumentary system is to protect the body by providing the
ability to feel things and by helping maintain a suitable body temperature. Its main parts
are:
1.
Skin,
2.
Hair
3.
Nails
The skin itself is further divided into two major layers: the epidermis (outer) and the
dermis (inner). New cells are formed at the bottom of the outer layer, epidermis, which
gradually move up towards the top. As newer cells move up, the oldest cells at the very
top die. It is these dead cells that form the part of the skin that is visible to the naked
eye.
Melanin is the substance that gives our skin its color—the darker the skin, the more
melanin it has.
Your Skin: A detailed article about the skin layers, and the skin’s relationship to
temperature.
How the Body Works: An activity which will help you learn about the different parts of
the skin.
NERVOUS SYSTEM
The nervous system allows the different parts of the body to communicate with each
other. Its major parts are the brain, the spinal cord, and the nerves that branch out of it
to the rest of the body. The brain tells the rest of the human body what to do. It is
connected to other body parts via a network of nerves. Messages are relayed to the
brain by sensory nerves; and then, the brain’s decision on how to react is conveyed
back to the relevant body parts, again by nerves.
The Nervous System: A short movie (less than 4 minutes) explaining how the nervous
system works.
The Brain and Nervous System: A multi-view, interactive diagram of the brain.
Nervous System: About the break up (parts) and the breakdown (problems) of the
nervous system.
Neurons are the nerve cells.
IMMUNE AND LYMPHATIC SYSTEM
The purpose of the lymphatic system is to drain out unwanted fluids from the tissues
and foreign bodies (such as bacteria) that could cause infections. It consists of vessels
called lymphatic vessels, the lymph nodes, and the spleen. Unwanted germs are
transported to the lymph nodes where white blood cells destroy them or otherwise
isolate them so that they cannot infect the body. Blood passing through the spleen gets
filtered in the sense that the white blood cells remove them from the blood stream
The Spleen and the Lymphatic System: Lots of great info about the lymphatic system
(focuses mostly on the spleen)
Lymphatic System: Nice concise and clear summary of the immune system and the
challenges it faces.
While Blood Cells: Battling Blood Cells: Ample detail about white blood cells.
Lymphatic System and Immunity: A technical description of the lymphatic system,
including general defences, specific defences, antibodies, organ-transplants, and
allergies.
Spleen Diseases: The spleen’s location, function, and what can happen if the spleen is
removed or damaged.
SKELETAL SYSTEM
The skeletal system gives the human body a structure, assists the muscles in
movement, and even acts as a shield for some organs such as the heart, brain, and
lungs. It consists of over 200 bones.
Cross-Section of a Bone: An interactive diagram describing different parts of a bone.
Full Skeletal System Description: A general overview of the system including the
function of ligaments, tendons, fused bones, axial, and appendicular skeleton.
MUSCULAR SYSTEM
The muscular system is designed to allow movement, both external and internal. The
muscular system consists of muscles which are made up of elastic tissues. Muscles can
relax; and they can tighten. They pull; they even push.
Your Muscles: A description of the different types of muscles.
Muscular System: A brief description of the Muscular System with a labelled diagram of
major skeletal muscles.
Alcohol and its effect on Muscles: Discusses what harm alcohol can have on your
muscles.
Healthy Muscles Matter: About muscles and exercise.
OTHER MAJOR SYSTEMS
Other major systems of the human body include the digestive system, the endocrine
system, the respiratory system, and the reproductive system.
CONCLUSION
Science has allowed us to learn a great deal about the complex, and yet so wellcoordinated human body. This article is just the tip of the iceberg; a great wealth of
information is available for those who want to explore further.
Read more:
http://www.startlocal.com.au/articles/educational_human_body.html#ixzz2LRP4YNO2
Circulatory System
Introduction
The circulatory system consists of blood, a heart, and blood vessels.
Functions of the Circulatory System
The circulatory system functions with other body systems to provide the following:
Transport of materials:
Gasses transported: Oxygen is transported from the lungs to the cells. CO2 (a waste) is
transported from the cells to the lungs.
Transport other nutrients to cells - For example, glucose, a simple sugar used to produce ATP, is
transported throughout the body by the circulatory system. Immediately after digestion, glucose
is transported to the liver. The liver maintains a constant level of glucose in the blood.
Transport other wastes from cells - For example, ammonia is produced as a result of protein
digestion. It is transported to the liver where it is converted to less toxic urea. Urea is then
transported to the kidneys for excretion in the urine.
Transport hormones - Numerous hormones that help maintain constant internal conditions are
transported by the circulatory system.
Contains cells that fight infection
Helps stabilize the pH and ionic concentration of the body fluids.
It helps maintain body temperature by transporting heat. This is particularly important in
homeothermic animals such as birds and mammals.
Large Animals
Small animals may not need a circulatory system because the interior cells are close to the
surface. Oxygen absorbed from the environment by surface cells can diffuse to interior cells.
Wastes produced by interior cells move a short distance to the surface and diffuse into the
environment.
Most invertebrates and all vertebrates have interior cells that are too far from the body surface to
exchange substances efficiently. They require a circulatory system.
A circulatory system is not needed in small, flat, or porous animals because they have a high
surface-to-volume ratio and can obtain sufficient absorption directly through their skin.
Gas Exchange and Transport in Invertebrates
Only coelomate animals have a circulatory system.
The choanocytes of sponges use cilia to move water through pores in the sides so that water
brings each of the cells all of the nutrients necessary for survival.
Cnidarians have a gastrovascular cavity that provides inner cells with exposure to water. They
are only two cell layers thick, so that all cells are exposed to the water for nutrient and gas
exchange.
Flatworms also have a gastrovascular cavity to provide for internal cells. Their small size and
flattened shape gives them a higher surface-to-volume ratio for better absorption from the
environment.
Fluid contained within the body cavity of pseudocoelomate animals functions to transport
nutrients and wastes but these animals do not have a heart or blood vessels.
Echinoderms have gills on the surface of their skin for gas exchange. Nutrients are distributed by
coelomic fluid. Amoeboid cells within the coelomic cavity transport some wastes. The water
vascular system functions to operate the tube feet.
Open Circulatory System
In an open circulatory system, blood is pumped from the heart through blood vessels but then it
leaves the blood vessels and enters body cavities, where the organs are bathed in blood, or
sinuses (spaces) within the organs.
Blood flows slowly in an open circulatory system because there is no blood pressure after the
blood leaves the blood vessels. The animal must move its muscles to move the blood within the
spaces.
In a closed system, blood remains within blood vessels, pressure is high, and blood is therefore
pumped faster.
Arthropods and most mollusks (except cephalopods: nautilus, squid, octopus) have an open
circulatory system.
Insects
The coelom of insects has been reduced to a cavity that carries blood (hemolymph). It is called a
hemocoel..
dorsal heart --> aorta --> hemocoel
Ostia (openings in the heart) close when heart contracts. When heart relaxes, the ostia open and
blood is sucked into openings.
The blood of insects is colorless because it lacks respiratory pigments; it functions to carry
nutrients, not gases.
Animals with open circulatory systems generally have limited activity due to limitations in the
oxygen delivery capability of the system. Insects are able to be active because gas exchange is
via a tracheal system.
Closed Circulatory System
In a closed circulatory system, blood is not free in a cavity; it is contained within blood vessels.
Valves prevent the backflow of blood within the blood vessels.
This type of circulatory system is found in vertebrates and several invertebrates including
annelids, squids and octopuses.
The blood of animals with a closed circulatory system usually contains cells and plasma (liquid).
The blood cells of vertebrates contain hemoglobin.
Earthworms
Earthworms have a dorsal and ventral blood vessel that runs the length of the animal. Branches
from these vessels are found in each segment.
There are five vessels that pump blood from the dorsal vessel to the ventral vessel.
Earthworms have red blood (due to the pigment hemoglobin) but they have no cells. Hemoglobin
binds with oxygen to carry it to the tissues.
Evolution of Vertebrate Circulatory System
Chambers of the Heart
Vertebrate hearts contain muscular chambers called atria (sing. atrium) and ventricles.
Contraction of the chamber forces blood out. Blood flows in one direction due to valves that
prevent backflow.
The atrium functions to receive blood that is returning to the heart. When it contracts, blood is
pumped into the ventricle.
The ventricle is the main pumping chamber of the heart. When it contracts, blood is pumped
away from the heart to the body, lungs, or gills.
Circulatory System of Fish
In the diagrams that follow, arrows represent the direction of blood flow in blood vessels
(arteries and veins). Blood pressure is represented by the thickness of the arrows. Thick arrows
indicate high blood pressure. Blood that is rich in oxygen is represented by red arrows. Blue
arrows represent blood that is low in oxygen after it has passed through the body tissues.
Fish have a two-chambered heart with one atrium (A) and one ventricle (V).
The gills contain many capillaries for gas exchange, so the blood pressure is low after going
through the gills. Low-pressure blood from the gills then goes directly to the body, which also
has a large number of capillaries. The activity level of fish is limited due to the low rate of blood
flow to the body.
Circulatory System of Amphibians
Amphibians have a 3-chambered heart with two atria and one ventricle.
Blood from the lungs (pulmonary flow) goes to the left atrium. Blood from the body (systemic
flow) goes to the right atrium.
Both atria empty into the ventricle where some mixing occurs.
The advantage of this system is that there is high pressure in vessels that lead to both the lungs
and body.
Circulatory System of Some Reptiles
In most reptiles, the ventricle is partially divided. This reduces mixing of oxygenated and
unoxygenated blood in the ventricle. The partial division of the ventricle is represented by a
dashed line below.
Circulatory System of Crocodilians, Birds, and Mammals
Birds and mammals (also crocodilians) have a four-chambered heart which acts as two separate
pumps. After passing through the body, blood is pumped under high pressure to the lungs. Upon
returning from the lungs, it is pumped under high pressure to the body. The high rate of oxygenrich blood flow through the body enables birds and mammals to maintain high activity levels.
Blood Vessels
heart --> arteries --> arterioles --> capillaries --> venules --> veins --> heart
Arteries
Arteries carry blood away from heart.
Arteries have a thick, elastic layer to allow stretching and absorb pressure. The wall stretches and
recoils in response to pumping, thus peaks in pressure are absorbed.
The arteries maintain pressure in the circulatory system much like a balloon maintains pressure
on the air within it. The arteries therefore act as pressure reservoirs by maintaining (storing)
pressure.
The elastic layer is surrounded by circular muscle to control the diameter and thus the rate of
blood flow. An outer layer of connective tissue provides strength.
Arterioles
Smooth muscle surrounding the arteries and arterioles controls the distribution of blood. For
example, blood vessels dilate when O2 levels decrease or wastes accumulate. This allows more
blood into an area to bring oxygen and nutrients or remove wastes.
Capillaries
The smallest blood vessels are capillaries. They are typically less than 1 mm long. The diameter
is so small that red blood cells travel single file.
The total length of capillaries on one person is over 50,000 miles. This would go around the
earth twice.
Not all of the capillary beds are open at one time because all of them would hold 1.4 times the
total blood volume of the all the blood in the body. Vasodilation and vasoconstriction refer to
the dilation and constriction of blood vessels. The diameter is controlled by neural and endocrine
controls. Sphincter muscles control the flow of blood to the capillaries.
The total cross-sectional area of the capillaries is greater than that of the arteries or veins, so the
rate of blood flow (velocity) is lowest in the capillaries. Blood pressure is highest in the arteries
but is considerably reduced as it flows through the capillaries. It is lowest in the veins.
Interstitial fluid
The exchange of substances between blood and the body cells occurs in the capillaries.
Capillaries are specialized for exchange of substances with the interstitial fluid. No cell in the
body is more than 100 micrometers from a capillary. This is the thickness of four sheets of paper.
Interstitial fluid surrounds and bathes the cells. This fluid is continually being replaced by fresh
fluid from blood in the circulatory system.
Body cells take up nutrients from the interstitial fluid and empty wastes into it.
By maintaining a constant pH and ionic concentration of the blood, the pH and ionic
concentration of the interstitial fluid is also stabilized.
Although fluid leaves and returns to the capillaries, blood cells and large proteins remain in the
capillaries.
At the arterial end of capillaries (the left side of the diagram below), blood pressure forces fluid
out and into the surrounding tissues. As blood moves through the capillary, the blood pressure
decreases so that near the veinule end, less is leaking into the surrounding tissues.
As blood flows through the capillary and fluid moves out, the blood that remains behind
becomes more concentrated. The osmotic pressure in the capillary is therefore greater near the
veinule end and results in an increase in the amount of fluid moving into the capillary near this
end.
The arrows on the diagram above represent the movement of blood into and out of the capillary.
Long and thick arrows are used to represent a large amount of fluid movement. The total amount
of movement out of the capillary is approximately equal to the amount of movement into the
capillary. Notice that more blood tends to leave the capillary near the arteriole end and more
tends to enter it near the veinule end.
The lymphatic capillaries collect excess fluid in the tissues.
Venules
Capillaries merge to form venules and venules merge into veins.
Venules can constrict due to the contraction of smooth muscle. When they are constricted there
is more fluid loss in the capillaries due to increased pressure.
Veins
The diameter of veins is greater than that of arteries.
The blood pressure in the veins is low so valves in veins help prevent backflow.
The contraction of skeletal muscle during normal body movements squeezes the veins and assists
with moving blood back to the heart.
The vena cava returns blood to the right atrium of the heart from the body. In the right atrium,
the blood pressure is close to 0.
Varicose veins develop when the valves weaken.
Veins act as blood reservoirs because they contain 50% to 60% of the blood volume.
Smooth muscle in the walls of veins can expand or contract to adjust the flow volume returning
to the heart and make more blood available when needed.
Portal Veins
Portal veins connect one capillary bed with another.
The hepatic portal vein connects capillary beds in the digestive tract with capillary beds in the
liver.
Human Circulation
Chambers of the heart
The heart is actually two separate pumps. The left side pumps blood to the body (systemic
circulation) and the right side pumps blood to the lungs (pulmonary circulation). Each side has
an atrium and a ventricle. See the diagram below
The atria function to receive blood when they are relaxed and to fill the ventricles when they
contract.
The ventricles function to pump blood to the body (left ventricle) or to the lungs (right ventricle).
Valves
Valves allow blood to flow through in one direction but not the other. They prevent backflow.
Atrioventricular valves (diagram above) are located between the atria and the ventricles. They
are held in place by fibers called chordae tendinae. The left atrioventricular valve is often called
the bicuspid or mitral valve; the right one is also called the tricuspid valve.
The semilunar valves (diagram above) are between the ventricles and the attached vessels.
The heartbeat sound is produced by the valves closing.
Below: The structure of the mammalian heart is summarized using a model.
Click on the images to view an enlargement.
Cardiac cycle
As the atria relax and fill, the ventricles are also relaxed.
When the atria contract, the pressure forces the atrioventricular valves open and blood in the
atria is pumped into the ventricles.
The ventricles then contract, forcing the atrioventricular valves closed. The pulmonary artery
carries blood from the right ventricle to the lungs. The aorta carries blood from the left ventricle
to the body.
Electrical stimulation
The heart does not require outside stimulation.
The sinoatrial (SA) node is a bit of nervous tissue that serves as the cardiac pacemaker.
Stimulation from this node causes both of the atria to contract at the same time because the
muscle tissue conducts the stimulation rapidly.
The contraction doesn't spread to the ventricles because the atria and ventricles are separated by
connective tissue.
As a wave of stimulation (depolarization) spreads across the atria resulting in their contraction,
another bit of nervous tissue called the atrioventricular (AV) node also becomes stimulated
(depolarized). It conducts the action potential slowly to the ventricles. The slow speed is due to
the small diameter of the neurons within the node.
The slow speed of conduction within the AV node ensures that the ventricles contract after the
atria contract..
The bundle of His then transmits impulse rapidly from the AV node to the ventricles.
Nervous Control
Details of nervous control of the cardiac cycle are in the chapter on the nervous system.
Coronary circulation
Coronary arteries supply the heart muscles with blood.
They have a very small diameter and may become blocked, producing a heart attack.
Blood Pressure
The units of measurement are millimeters of mercury (mm Hg). For example, 120 mm Hg/80
mm Hg is considered to be normal blood pressure.
The top number is referred to as the systolic pressure; the bottom number is the diastolic
pressure.
Hypertension - High Blood Pressure
High blood pressure is associated with cardiovascular disease.
In males under 45 years, pressures greater than 130/90 are considered to be high. In males over
45 years, pressures greater than 140 /95 are high.
Blood
Human blood has two parts, liquid (plasma) and cells.
Plasma
Plasma contains dissolved gasses, nutrients, wastes, salts, and proteins.
Salts and proteins buffer the pH so that it is approximately 7.4 and they maintain osmotic
pressure.
Plasma proteins also assist in transporting large organic molecules. For example, lipoproteins
carry cholesterol and albumin carries bilirubin (produced from the breakdown of hemoglobin
when old blood cells are destroyed).
Cells
Red Blood Cells (Erythrocytes)
Red blood cells are biconcave disks filled with hemoglobin.
Red blood cells are continuously produced in the red marrow of the skull, ribs, vertebrae, and
ends of the long bones. The nucleus of the cell disappears as it matures.
Mammalian red blood cells loose their nucleus as they mature. As a consequence, human red
blood cells have a life span of approximately 120 days. Other vertebrates have nucleated red
blood cells. Phagocytic cells in the liver and spleen remove old cells.
Anemia occurs when there are insufficient numbers of red blood cells or the cells lack sufficient
hemoglobin.
White Blood Cells
White blood cells are covered in the chapter on the immune system.
Blood Clotting
Damaged tissue produces spasms of the smooth muscle and these spasms stop the blood flow for
a few minutes.
Platelets are fragments of larger cells produced in the bone marrow that assist in forming a clot.
They adhere to exposed collagen in damaged blood vessels. This causes some to rupture and
release substances that attract more platelets. Platelets and damaged tissue release substances that
cause a blood protein called fibrinogen to be converted to fibrin. Fibrin forms a mesh-like
structure that traps blood cells and platelets. The resulting plug that forms seals the leak.
Details of Blood Clot Formation
When tissue damage occurs, muscles begin to spasm, which temporarily reduces blood flow to
the area. Blood flow is also reduced when platelets in the blood adhere to the damaged tissue.
Blood clotting is initiated when platelets and damaged tissue secrete prothrombin activator.
The platelets and damaged tissue release a clotting factor called prothrombin activator.
Prothrombin activator and calcium ions catalyze the conversion of prothrombin to thrombin
which then catalyzes the conversion of fibrinogen to fibrin threads.
Fibrin threads are sticky and trap more platelets, further sealing the leak.
Review Activity
Be able to list the following structures in the order that blood would pass through them. Begin
with the vena cava.
Blood Vessels
aorta
pulmonary artery
pulmonary vein
vena cava
Chambers of the Heart
left atrium
left ventricle
right atrium
right ventricle
Valves
left atrioventricular valve (mitral valve)
left semilunar valve
right atrioventricular valve
right semilunar valve
Organs receiving the blood
body
lungs
Tracking a Hurricane
To monitor and track the development and movement of a hurricane, meteorologists rely on
remote sensing by satellites, as well as data gathered by specially equipped aircraft. On the
ground, Regional Specialized Meteorological Centers, a network of global centers designated
by the World Meteorological Organization, are charged with tracking and notifying the public
about extreme weather.
Weather satellites use different sensors to gather different types of information about hurricanes.
They track visible clouds and air circulation patterns, while radar measures rain, wind speeds and
precipitation. Infrared sensors also detect vital temperature differences within the storm, as well
as cloud heights.
The Hurricane Hunters are members of the 53rd Weather Reconnaissance Squadron/403rd
Wing, based at Keesler Air Force Base in Biloxi, Miss. Since 1965, the Hurricane Hunters team
has used the C-130 Hercules, a very sturdy turboprop plane to fly into tropical storms and
hurricanes. The only difference between this plane and the cargo version is the specialized,
highly sensitive weather equipment installed on the WC-130. The team can cover up to five
storm missions per day, anywhere from the mid-Atlantic to Hawaii.
The Hurricane Hunters gather information about wind speeds, rainfall and barometric pressures
within the storm. They then relay this information back to the National Hurricane Center in
Miami, Fla. If you're curious about these foolhardy pilots, read Why would someone fly an
airplane into a hurricane?
Meteorologists take all the storm data they receive and use it to create computer forecast
models. Based on a great deal of current and past statistical data, these virtual storms allow
scientists to forecast a hurricane's path and changes in intensity well in advance of landfall. With
this data, governments and news agencies ideally can warn residents of coastal areas and greatly
reduce the loss of life during a hurricane.
Long-term forecasting now allows meteorologists to predict how many hurricanes will take place
in an upcoming season and to study trends and patterns in global climate.
Hurricane Names
While personifying a massive, destructive force certainly makes for a jazzier headline, the
practice of naming hurricanes originated with meteorologists, not media outlets. Often more than
one tropical storm is active at the same time, so what better way to tell them apart than by
naming them?
For several hundred years, residents of the West Indies often named hurricanes after the Catholic
saint's day on which the storm made landfall. If a storm arrived on the anniversary of a previous
storm, a number was assigned. For example, Hurricane San Felipe struck Puerto Rico on Sept.
13, 1876. Another storm struck Puerto Rico on the same day in 1928, so this storm was named
Hurricane San Felipe the Second.
During World War II, weather officials only gave hurricanes masculine names. These names
closely followed radio code names for letters of the alphabet. This system, like the West Indian
saints system, drew from a limited naming pool. In the early 1950s, weather services began
naming storms alphabetically and with only feminine names. By the late 1970s, this practice was
replaced with the equal opportunity system of alternating masculine and feminine names. The
World Meteorological Organization (WMO) continues this practice to this day.
The first hurricane of the season is given a name starting with the letter A, the second with the
letter B and so on. As the storms affect varying portions of the globe, the naming lists draw from
different cultures and nationalities.
Hurricanes in the Pacific Ocean are assigned a different set of names than Atlantic storms. For
example, the first hurricane of the 2001 hurricane season was a Pacific Ocean storm near
Acapulco, Mexico, named Adolf. The first Atlantic storm of the 2001 season was named Allison.
A list of names through 2011 is available from the National Hurricane Center.
If a hurricane inflicts significant damage, a country affected by the storm can request that the
name of the hurricane be "retired" by the WMO. A retired name can't be reissued to a tropical
storm for at least 10 years. This helps to avoid public confusion and to simplify both historical
and legal record keeping.
Hurricane History
Our modern understanding of hurricanes depends largely on a mere century's worth of scientific
study and record keeping, but the storms have been dictating the course of human history for
millennia. After all, they're a part of an atmospheric system that predates the human race by
billions of years.
While scientists are largely left to speculate about the strength of Mesozoic Era storms,
geologists have discovered evidence of Iron Age hurricanes in layers of ground sediment. When
storm surges wash over land and into lakes, they leave fans of sand behind. Scientists can carbon
date organic materials above and below the sand to determine an approximate storm date.
A team from Louisiana State University studied thousands of years worth of lake bed evidence
and discovered that, over the past 3,400 years, a dozen Category 4 or higher hurricanes hit the
area -- yet most of them occurred 1,000 years or more ago [source: Young]. Findings such as
these allow scientists to better study long-term weather patterns and possibly make better sense
of current climate trends.
As far as human records go, the ancient Mayans of South America made some of the earliest
mentions of hurricanes in their hieroglyphics. The centuries that follow are littered with accounts
of hurricanes affecting the outcomes of wars, colonization efforts and an untold number of
personal lives.
Just to name a few, hurricane activity thwarted the following sea ventures through the
destruction and scattering of ocean fleets:
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The 1274 Mongol invasion of Japan
A 1559 attempt by the Spanish to recapture Florida
The French defense of a Floridian fort, subsequently lost to the Spanish in 1565
The Spanish Armada's attack on England in 1588
A 1640 Dutch attack on Cuba
British dominance over the French in the Caribbean Islands in 1780
Today, modern meteorology prevents most hurricanes from arriving unannounced, greatly
decreasing the massive hurricane fatality rates of previous centuries. But even with advance
warning, governments and the residents of coastal areas still have to properly prepare for the
coming storms.
Meanwhile, some experts look to the future with concern. Some point to periods of intense
hurricane activity in Earth's past and worry that such trends may return. Others argue that global
warming brought on by the increased production of greenhouse gasses will lead to larger
hurricane zones and more powerful storms. After all, hurricanes thrive on warm, moist waters,
and a warmer Earth could provide more sustenance for tropical storms.
Explore the links on the next page to learn more about hurricanes and the Earth's weather,
including a story about those crazy pilots who fly their planes into hurricanes.
ORIGIN OF THE ORGANIC SOUP
For inquiries contact Arthur Stern, Professor Emeritus, Biology Department, University of
Massachusetts Amherst
Photosynthesis
Introduction
Photosynthesis evolved over three billion years ago, shortly after the appearance of the first
living organisms. The food we eat and the oxygen we breathe are both formed by plants
(including algae) through photosynthesis. The power to drive this reaction comes from sunlight
absorbed by chlorophyll in the chloroplasts of plants. At the present time, no known chemical
system can be made to serve as a substitute for this process. It has been calculated that each
CO2 molecule in the atmosphere is incorporated into a plant structure every 200 years and that
all the O2 in air is renewed by plants every 2000 years. All life depends directly or indirectly on
the sun's energy, and only plants are capable of capturing and converting this energy into
chemical energy in the form of sugar and other organic compounds. Thus, if plants should
suddenly disappear from the earth, so would we.
Our geological heritage of coal, oil, and gas also originated directly or indirectly from
photosynthesis, since these fossil fuels were all derived from the remains of living organisms.
Our stake in photosynthesis is, therefore, great, since we are not only dependent upon it for the
food we eat, but also for many of the goods and most of the energy we use.
The Site of Photosynthesis in Vascular Plants
Leaves are the major organs of photosynthesis in vascular plants. Chloroplasts are found mainly
in the mesophyll cells, the green tissue in the interior of the leaf
Diagram of a Leaf Cross Section and Structure of the Chloroplast
Chloroplasts are ellipsoidal or disc-like in shape and are between 5 - 7 micrometers in
diameter and 1 - 2 micrometers thick (1 micrometer = one millionth of a meter, 1 meter =
39 inches). There are about 36 chloroplasts in each mesophyll cell. The chloroplast is
bounded by a double membrane that encloses the stroma, a dense aqueous solution that
contains DNA, RNA, metabolites, and the enzymes associated with the conversion of
CO2 into organic matter. Membranes of the thylakoid system separate the stroma from
the thylakoids. Thylakoids are concentrated in stacks called grana. Thylakoids contain the
pigments chlorophyll a and b, carotenoid, and the enzymes associated with the oxidation
(splitting) of water (H2O) and the production of oxygen.
The Chemistry of Photosynthesis
Photosynthesis takes place in the chloroplasts of plant cells and consists of Light-Dependent and
Light-Independent reactions. The Light-Dependent reaction occurs in the thylakoids and
converts light energy into ATP and NADPH2. During this process water is split (oxidized) and
oxygen is given off.
Overview of Photosynthesis.
Light-Independent reactions (the Calvin Cycle) incorporate CO2 into sugar, the basic
food source for all organisms. Thylakoid membranes are the sites of the Light-Dependent
reactions, whereas the Calvin cycle occurs in the stroma. These reactions can be
summarized by the following equations:
A Design Flaw in Photosynthesis - Photorespiration
Since plants first moved onto land about 425 million years ago, they have been adapting to the
problems of terrestrial life, particularly the problem of dehydration. The solutions often involve
tradeoffs. An important example is the compromise between photosynthesis and the
prevention of excessive water loss from the plant. The CO2 needed for photosynthesis enters a
leaf via microscopic pores called stomata. However, the stomata are also the main avenues of
transpiration, the evaporation of water from leaves. On hot, dry days, most plants close their
stomata in order to conserve water. This response limits access to CO2, thereby reducing
photosynthetic yield. Under these conditions, CO2 concentrations in the air spaces within the
leaf begin to decrease and the concentration of oxygen released from photosynthesis begins to
increase. This favors what appears to be a wasteful process within the leaf called
photorespiration.
In most plants (about 800,000 species), CO2 is initially fixed via rubisco of the Calvin cycle into
ribulose bisphosphate. Because the product of this reaction is a three-carbon compound, 3phosphoglycerate, such plants are called C3 plants. Rice, wheat, and soybeans are among the C3
plants that are important in agriculture. On hot, dry days when their stomata close, these plants
produce less food as CO2. levels within the leaf decline. Making matters worse, rubisco can use
oxygen in place of CO2. As O2 increases, rubisco adds oxygen to RuBP instead of CO2. The
product splits, and one piece, a two-carbon compound (glycolate), is exported from the
chloroplast. Other organelles (mitochondria and peroxisomes) then break down glycolate back
to CO2. This process is called photorespiration because it occurs in the light (photo) and
consumes oxygen (respiration). However, unlike normal cellular respiration, photorespiration
generates no ATP. And unlike photosynthesis, photorespiration produces no food.
Photorespiration is probably a metabolic relic from a much earlier time when the atmosphere
had less O2 and more CO2 than it does today. When rubisco first evolved, the inability of the
enzyme's active site to exclude O2 would have made little difference. Now, it is considered to be
wasteful, since photorespiration drains away as much as 50% of the carbon fixed by the Calvin
cycle. If photorespiration could be reduced in certain plant species, without affecting
photosynthetic productivity, crop yields and food supplies would increase.
Alternative Strategies of Carbon Fixation - C4 and CAM C4 Plants
The environmental conditions that promote photorespiration are hot, bright, dry days. In these
climates, alternate modes of carbon fixation have evolved to minimize photorespiration. The
two most important of these photosynthetic adaptations are exhibited by C4 and CAM C4 plants.
C4 plants are so named because they form a four-carbon compound as the first product of the
nonlight requiring reactions of photosynthesis. Several thousand species in at least 19 families
use the C4 pathway. Agriculturally important C4 plants are sugarcane and corn, members of the
grass family.
Leaves of C4 plants contain two distinct types of photosynthetic cells: a cylinder of bundlesheath cells surrounding the vein, and mesophyll cells located outside the bundle sheath. CO2 is
initially fixed in mesophyll cells by the enzyme PEP carboxylase. A four-carbon compound is
formed (malate in this case) which conveys the fixed CO2 via plasmodesmata (protoplasmic
connections) into a bundle sheath cell where the enzymes of the Calvin cycle are located.
C4 Leaf Anatomy
In the bundle sheath cell, the malate is converted into pyruvate and CO2; the latter is now
used by rubisco and the Calvin cycle to make sugar. Compared to rubisco, the enzyme
PEP carboxylase has a much higher affinity for CO2. Thus, PEP carboxylase can fix CO2
efficiently when it is hot and dry and stomata are partially closed. Also, by pumping CO2
from the mesophyll cells into the bundle sheath, this keeps the CO2 concentration high
enough for rubisco to accept CO2 rather than O2. In this way, C4 photosynthesis
minimizes photorespiration and enhances sugar production. This adaptation is especially
advantageous in hot climates with intense sunlight and it is where C4 plants evolved and
thrive today.
A second photosynthetic adaptation to arid conditions (as found in deserts) has evolved in
succulent (water-storing) plants (including ice plants), many cacti, and representatives of other
plant families. These plants close their stomata in the day and open them during the night, just
the reverse of other plants. Closing the stomata during the day helps desert plants conserve
water, but it also prevents CO2 from entering the leaves. At night, when the stomata are open,
these plants take up CO2 and initially fix it into four-carbon compounds like malate. This mode of
carbon fixation is called crassulacean acid metabolism, or CAM, after the plant family
Crassulaceae, the succulents in which the process was first discovered. The photosynthetic cells
of CAM plants store the malate formed in the night in their vacuoles until morning, when the
stomata close. In the daytime, when the light reactions can make ATP and NADPH2 for the Calvin
cycle, CO2 is released from the malate made the night before to become fixed into sugar in the
chloroplasts.
The above diagram compares C4 and CAM C4 photosynthesis. Both adaptations are characterized
by initial fixation of CO2 into an organic acid such as malate followed by transfer of the CO2 to
the Calvin cycle. In C4 plants, such as sugarcane, these two steps are separated spatially; the two
steps take place in two cell types. In CAM C4 plants, such as pineapple, the two steps are
separated temporally (time); carbon fixation into malate occurs at night, and the Calvin cycle
functions during the day. Both C4 and CAM C4 are two evolutionary solutions to the problem of
maintaining photosynthesis with stomata partially or completely closed on hot, dry days.
However, it should be noted, that in all plants, the Calvin cycle is used to make sugar from
carbon dioxide. On a global scale, this represents a prodigious amount of sugar, about 160
billion metric tons of carbohydrate per year.
A List of C4 Plants Found in the Connecticut River Valley
Cyperaceae (sedge family)
Cyperus esclentus L.
Eragrostoideae (Cloridoideae)
Cynodon dactylon (L.) Pers., Bermuda grass
Eragrostis pilosa (L.) Beauv., India love grass
Panicoideae
Andropogon scoparius Michx., little bluestem
Digitaria sangunalis(L.) Scop., crab grass
Echinochloa crus-galli(L.) Beauv., barnyard grass
Panicum capillare L., common witch grass
Setaria italica (L.) Beauv., foxtail millet
Amaranthaceae (amaranth family)
Amaranthus albus L., white pigweed
Amaranthus retroflexus L., redroot pigweed
Froelichia gracilis (Hook) Mog., froelichia
Euphorbiaceae
Euphorbia maculata L., spotted euphorbia
Portulacaceae (portulaca family)
Portulaca oleracea L., common purslane
References
Campbell, N.A. Biology, 4th ed., Menlo Park, CA: Benjamin/Cummings, 1996. Chapter
10.
Purves, W.K., Orians, G.H., Heller, H.C. and Sadava, D. Life, The Science of Biology,
5th ed.,
Sunderland, MA: Sinauer Associates, 1998. Chapter 8.
What are employers looking for?
Most employers say that they wish to employ the right person for the right job. A
recent report by Britain's independent Institute of Manpower Studies, however,
disagrees with this. The report states that most employers wish to avoid employing the
wrong person. Rather than looking for the right person, they are looking for applicants
to turn down.
The report also suggests that in Britain and in many other parts of the world, the
selection methods used to identify the right person for the job certainly do not match
up to those used to evaluate a piece of new equipment. Recruiters used three main
selection methods: interviewing, checking curriculum vitae or application forms against
predecided criteria, and examining references. Most of the recruiters consulted in this
survey stated that these selection methods were used more for "weeding out"
unsuitable candidates rather than for finding suitable ones.
Interviews were considered to be more reliable than either curriculum checks or
references from past employers. Research, however, proves otherwise. Interviewers'
decisions are often strongly influenced by their previous assessment of the written
application. Also, different recruiters interpret facts differently. One may consider
candidates who have frequently changed jobs as people with broad and useful
experience. Another will view such candidates as unreliable and unlikely to stay for long
in the new job.
Some employers place great importance on academic qualifications whereas the link
between this and success in management is not necessarily strong. Some recruiters use
handwriting as a criterion. The report states that there is little evidence to support the
validity of the latter for assessing working ability. References, also, are sometime
unreliable as they are rarely critical, whereas checks on credit and security records and
applicants' political leanings are often the opposite.
The report is more favourable towards trainability tests and those which test personality
and personal and mental skills. The report concludes by suggesting that interviewing
could become more reliable if the questions were more structured and focused on the
needs of the employing organisation.
Money matters
Hard Times
Large industrialised counties are now in a recession. What are the prospects for
economic recovery?
The three most important industrial economies in the world are, at the moment, facing
enormous problems. Germany is struggling with the cost of reunification and is in
recession. Japan is also experiencing recession and the United States has a large
budget deficit.
Forecasters and analysts face questions about the prospects of an economic recovery.
Here are some of their findings:
The election of a new president of the United States gave hope to the rest of the world.
If the US recovered, the rest of the world would face a more promising future.
However, analysts now accept that the US will only recover very slowly.
Consumer and investor confidence is still lacking. Large deficits and declining shortterm interest rates mean that there is little scope for economic stimulus.
The Japanese economy, after years of trade and budget surpluses, is in deep recession
and the growth rate has slowed down considerably. German economists have lowered
their forecasts for economic growth this year. The lowering of German interest rates
may bring some relief to other members of the European Exchange Rate Mechanism
(ERM). However, Germany's importance as Europe's largest export market may decline.
Most forecasters are predicting world growth of only one percent in 1993. Others
predict that it will only be after the completion of the GATT (General Agreement on
Tariffs and Trade) negotiations that the world economy will improve.
In some parts of the world, there are more positive signs, particularly in some Latin
American countries and in South-East Asia. Another encouraging point is that analysts
do not expect an upsurge in inflation in 1993.
Analysts says that, as long as the rate of interest stays above the rate of growth in
national income, then the ratio of debt to income will get worse. Falling interest rates
help towards overcoming this problem. They believe it may take several years before
there is real recovery. However, advances in technology and the collapse of
communism offer hope for the world economy.
Business talk
A vital factor in a company's success is good communication among its employees.
According to the book In Search of Excellence (Peters and Waterman) excellent
companies have a vast network of informal, open communication. Their staff keep in
contact with one another on an informal and formal basis. Management encourages
easy and frequent communication.
How do you rate communication within your own company? Are you happy with it or do
you think it could be improved? Perhaps some of the following factors affecting incompany communication are familiar to you?
Failing to get the message
Many managers believe they give clear instructions to their employees. In fact,
research has shown that employees very often do not realise they have been told to do
something. When managers give instructions they should endeavour to ensure that
these have been understood and interpreted correctly.
Breakdown in communication
People can have difficulty communicating with other employees of higher job status.
This "social distance" may affect how openly employees speak about their work. People
of the same rank may talk frankly to one another about how things are going. However,
they may be less honest with someone higher up in the hierarchy - for fear of
prejudicing their position in the company. For this reason employees often "filter"
information. They alter the facts to tell the boss what s/he wants to hear. One way of
reducing social distance is to cut down the ways in which employees can indicate higher
status. In Japanese companies, for example, it is usual for all staff to wear the same
uniform. Many companies have a common dining area for all staff.
The physical element
Physical surroundings and distance can affect how well people communicate. The
farther away one person is from another, the less often they communicate. Some
research has shown that when the distance is more than 10 metres, the probability of
communicating at least once a week is only 8%. This compares with 25% for people
less than 5 metres apart! The physical layout of an office should therefore be carefully
planned. Open-plan offices, for example, are designed to encourage quick and easy
communication. Some companies prefer to install escalators, rather than lifts, to
increase the chances of employees meeting face-to-face.
Selective perception
People perceive things in different ways. The world of a sender of a message is not the
same as that of the receiver. Because their knowledge and experience is different, the
sender and receiver are always on slightly different wavelengths. So the message may
get distorted.
How can good communication be fostered?
The most important thing for all managers to remember is that communication is a
two-way process. They should encourage their employees to ask questions and to react
to what the managers are saying. Feedback is vital. The most useful question a
manager can ask is "Did you understand that?"
Sales in recessions
Sales figures are often used as evidence of the general health of the economy. In a
recession, any rise in high street sales is quoted by government ministers as evidence
of the increase in consumer confidence that is the first step on the road back to
economic growth.
In free market terms, sale figures reflect the state of local market forces at any one
place and at any one time. They show the amount of a product that the public wants to
buy at the current price.
To a large extent, this is true. At times of falling sales, high street shops are forced to
reduce prices - with out-of-season sales, special offers and even "closing down" sales.
Newspapers are full of advertisements for special offers on consumer durables, cars, for
example, or computers and video recorders.
The reason for these goods being the ones that are most frequently discounted in times
of recession is that they are the most expensive in terms of their opportunity cost their relative value to buyers compared to the value of alternative goods and services
on which they may want to spend that same amount of money. If you have £X, you can
buy a CD player or go on a short holiday, but you cannot do both.
Even more important, perhaps, is the consumer's fear of his or her personal future. In
recessions come job losses, with job losses comes an increased reluctance to spend; it
is expensive luxuries such as videos that are the first items to be cut from household
budgets. People feel the need to save against the possible future loss of income. In
recessions, a greater proportion of the public's income is saved than in times of
economic growth.
The effect of all this on manufacturers can easily be seen. Falling sales lead to
production cut-backs. This results in the under-capacity of plant and machinery. Since
fixed overheads remain basically the same, other ways of cutting back on costs and
thus of reducing prices have to be found. Almost always, this is achieved through
cutting back on jobs.
But therein lies the problem. Although, for a manufacturer, cutting back on the
workforce is a relatively simple short-term solution, it is not necessarily the best longterm strategy. In certain key industries, skilled labour is hard to find - and keep. the
job market can fluctuate as erratically as the consumer market. There are fashionable
jobs and unfashionable jobs. There are glamorous jobs and jobs that nobody wants to
do. These trends are reflected in the kind of further training chosen by school leavers
and in the kinds of further education courses on offer.
Manufacturers, therefore, tend to wait longer before laying off any staff than they
would do if they were obeying market forces. To keep these workers fully occupied,
companies may have to depress prices artificially to a point lower than that demanded
by prevailing market forces, merely in order to maintain production levels.
It is almost certainly true, therefore, that there are forces at work at the time that an
economy is entering a recession that distort the real value of sales figures. It may also
be true that, on the way out of a recession, or in a boom period, the competition for
scarce labour has the same distorting effect.
Golf: safe for the environment?
Throughout Europe golf is booming. France is building golf courses faster than any
other country in Europe. The success of Bernhard Langer and Germany's recent World
Cup win have led to an upsurge in golf's popularity in that country. Sweden won the
Dunhill Cup and the World Cup in 1991 and Anders Forsbrand is currently at the top of
the European Order of Merit. Spanish golf is dominated by the twin talents of Seve
Ballesteros and Jose-Maria Olazabal, but there are several tournament winners amongst
the other Spanish professionals. Portugal has just had its first-ever European tour
winner with Daniel Silva's Jersey Open triumph.
A recent report by the English Golf Union estimated that in Great Britain alone, 700 new
golf courses would have to be built over the next ten years to satisfy current and
expected demand. As the average golf club in England has between 600 and 700
members, that means another half a million golfers joining the estimated 1.2 million
that already play regularly or occasionally.
This is all good news for golf lovers, but there are those who are not so happy. Chief
amongst these are the environmentalists. "Greens" used to refer to the area around the
holes on which golfers putted for pars, birdies and, very occasionally, eagles. Mention
the Greens today and the word refers to the people who are preventing, on ecological
grounds, the building of many courses.
The Greens' argument is that the new courses are effecting the balance of nature.
Woods, hedges, ponds and fields are being dug up or bulldozed flat to make way for
manicured fairways and sand bunkers. The birds and animals that used to live there are
being killed or forced to leave. The amount of water that the average club uses to keep
the course in good condition is reducing the amount of water available for domestic and
industrial uses. The pesticides used to control weeds and insects are sinking down to
the water table. Precious resources are being destroyed or wasted.
There may be some truth in this, but it is not the whole truth. The days are long past
when building of any kind was allowed in areas of outstanding beauty with no thought
for the environment. Planning permission, nowadays, is as strict for golf courses as it is
for any other type of development. Before any such project is given the go-ahead, the
various factors involved, social, financial and environmental, are studied. It is only
when the authorities are completely satisfied that no harm will be done to the area that
the builders are allowed to move in.
The benefits
A strong case can even be made that golf courses actually benefit the areas where they
are built. In many instances, courses are built in areas which are not areas of natural
beauty and where nature is, at best, old and tired. The new courses often rejuvenate
the area. To make holes more difficult, trees are planted, streams are diverted across
fairways and lakes are filled in around greens. Not surprisingly perhaps, given such
delightful surroundings, it is not unusual to find that, within months of a course being
completed, a whole variety of animals and birds has moved in.
Obviously, careful thought has to go into the design of the new courses. Obviously, as
few changes as possible should be made to the natural environment. Obviously, the
wild-life and the trees and woods should be protected. But this can be, and is being,
done. There is no reason why golfers and nature cannot live together in harmony.