Fleas are perfectly designed by
nature to feast on anything containing blood. Like a shark in the water or a
wolf in the woods, fleas are ideally equipped to do what they do, making them
very difficult to defeat. The bodies of these tiny parasites are extremely
hardy and well-suited for their job.
A flea has a very hard exoskeleton,
which means the body is covered by a tough, tile-like plate called a sclerite.
Because of these plates, fleas are almost impossible to squish. The
exoskeletons of fleas are also waterproof of fleas are also waterproof and shock
resistant, and therefore fleas are highly resistant to the sprays and chemicals
used to kill them.
Little spines are attached to his
plate. The spine the flea scurries through an animal’s fur in – search of
grooming pet tries to pull a flea off through the hair coat, these spines will
extend and stick to the fur like Velcro.
Fleas are some of the best jumpers
in the natural world. A flea can jump seven inches, or 150 times its own
length, either vertically or horizontally. An equivalent jump for a person
would be 555 feet, the height of the Washington Monument. Fleas can jump 30,000
times in a row without stopping, and they are able to accelerate through the
air at an incredibly high rate – a rate which is over ten times what humans can
withstand in an airplane.
Fleas have very long rear legs with
huge thigh muscles and multiple joints. When they get ready to jump. They fold their
long legs up and crouch like a runner on a staring block. Several of their
joints contain a protein called resilin, which helps catapult fleas into the
air as they jump, similar to the way a rubber band provides momentum to a
slingshot. Outward facing claws on the bottom of their legs grip anything they
touch when they land.
The adult female flea mates after
her first blood meal and begins producing eggs in just 1 to 2 days. One flea
can lay up to 50 eggs in one day and over 2,000 in her lifetime. Flea eggs can
be seen with the naked eye, but they are about the size of a grain of salt. Shortly
after being laid, the eggs begin to transform into cocoons. In the cocoon
state, fleas are fully developed adults, and will hatch immediately if
conditions are favorable. Fleas can detect warmth, movement, and carbon dioxide
in exhaled breath, and these three factors stimulate them to emerge as new
adults. If the flea does not detect appropriate conditions, it can remain
dormant in the cocoon state for extended periods. Under ideal conditions, the
entire life cycle may only take 3 weeks, so in no time at all, pets and homes
can become infested.
Because of these characteristics,
fleas are intimidating opponents. The best way to control fleas, therefore, is
to take steps to prevent an infestation from ever occurring.
According to the passage, fleas are
able to jump
I with a high rate of acceleration
II up and down and from side to side
III because the blood they eat
contains resilin
On January 3, 1961, nine days after
Christmas, Richard Legg, John Byrnes, and Richard McKinley were killed in a
remote desert in eastern Idaho. Their deaths occurred when a nuclear reactor
exploded at a top-secret base in the National Reactor Testing Station (NRTS).
Official reports state that the explosion and subsequent reactor meltdown
resulted from the improper retraction of the control rod. When questioned about
the events that occurred there, officials were very reticent. The whole affair,
in fact, was discussed much, and seemed to disappear with time.
In order to grasp the mysterious
nature of the NRTS catastrophe, it help to know a bit about how nuclear
reactors work. After all, the generation of nuclear energy may strike many as
an esoteric process. However, given its relative simplicity, the way in which
the NRTS reactor functions is widely comprehensible. In this particular kind of
reactor, a cluster of nine-ton uranium fuel rods are positioned lengthwise
around a central control rod. The reaction begins with the slow removal of the
control ro, which starts a controlled nuclear reaction and begins to heat the
water in the reactor. This heat generates steam, which builds pressure inside
the tank. As pressure builds, the steam looks for a place to escape. The only
place this steam is able to escape is through the turbine. As it passes through
the turbine on its way out of the tank, it turns the giant fan blades and
produces energy.
On the morning of January 3, after
the machine had been shut down for the holidays, the three men arrived at the
station to restart the reactor. The control rod needed to be pulled out only
four inches to be reconnected to the automated driver. However, records
indicate that Byrnes yanked it out 23 inches, over five times the distance
necessary. In milliseconds the reactor exploded. Legg was impaled on the
ceiling; he would be discovered last. It took one week and a lead-shielded
crane to remove his body. Even in full protective gear, workers were only able
to work a minute at a time. The three men are buried in lead-lined coffins
under concrete in New York, Michigan, and Arlington Cemetery, Virginia.
The investigation took nearly two
years to complete. Did Byrnes have a dark motive? Or was it simply an accident?
Did he know how precarious the procedure was? Other operators were questioned
as to whether they knew the consequences of pulling the control rod out so far.
They responded “Of course! We often talked about what we would do if we were at
a radar station and the Russians came.
“We’d yank it out.”
Official reports are oddly
ambiguous, but what they do not explain, gossip does. Rumors had it that there
was tension between the men because Byrnes suspected the other two of being
involved with his young wife. There is little doubt than he, like the other
operators, knew exactly what would happen when he yanked the control rod.
According to the paragraph 2,
which of the following is directly responsible for energy production?
