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.
Fleas are difficult to squish
because they have
I Sclerites
II Tough spines
III Resilin in their joints
When her grandmother’s health began to deteriorate in the
fall of 1994, Mary would make the drive from Washington, DC to Winchester every
few days.
She hated highway driving, finding it ugly and monotonous. She
preferred to take meandering back roads to her grandmother’s hospital. When she
drove through the rocky town of Harpers Ferry, the beauty of the rough waters
churning at the intersection of the Shenandoah and Potomac rivers always
captivated her.
Toward the end of her journey, Mary had to get on highway
81. It was here that she discovered a surprising bit of beauty during one of
her trips. Along the median of the highway, there was a long stretch of
wildflowers. They were thin and delicate and purple, and swayed in the wind as
if whispering poems to each other.
The first time she saw the flowers, Mary was seized by an uncontrollable
urge to pull over on the highway and yank a bunch from the soil. She carried
them into her grandmother’s room when she arrived at the hospital and placed
them in a water pitcher by her bed. For a moment her grandmother seemed more
lucid than usual. She thanked Mary for the flowers, commented on their beauty
and asked where she had gotten them. Mary was overjoyed by the ability of the
flowers to wake something up inside her ailing grandmother.
Afterwards, Mary began carrying scissors in the car during
her trips to visit her grandmother. She would quickly glide onto the shoulder,
jump out of the car, and clip a bunch of flowers. Each time Mary placed the
flowers in the pitcher, her grandmother’s eyes would light up and they would
have a splendid conversation.
One morning in late October, Mary got a call that her
grandmother had taken a turn for the worse. Mary was in such a hurry to get to
her grandmother that she sped past her flower spot. She decided to turn around
head several miles back, and cut a bunch. Mary arrived at the hospital to find her
grandmother very weak and unresponsive. She placed flowers in the pitcher and
sat down. She felt a squeeze on her fingers. It was the last conversation they
had.
Which best describes what the act of stopping for flowers on
the side of the highway became for Mary?
Arrowheads, which are ancient
hunting tools, are often themselves ‘hunted’ for their interesting value both
as artifacts and as art. Some of the oldest arrowheads in the United States
date back 12,000 years. They are not very difficult to find. You need only to
walk with downcast eyes in a field that has been recently tilled for the spring
planting season, and you might find one.
Arrowheads are tiny stones or pieces
of wood, bone, or metal which have been sharpened in order to create a tipped
weapon used in hunting. The material is honed to an edge, usually in a
triangular fashion, and is brought to a deadly tip. On the edge opposite the
tip is a flared tail. Though designs vary depending on the region, purpose, and
era of the arrowhead’s origin, the tails serve the same purpose. The tail of
the arrowhead is meant to be strapped onto a shaft, which is a straight wooden
piece such as a spear or an arrow. When combined, the arrowhead point and the
shaft become a lethal projectile weapon to be thrown by arm or shot with a bow
at prey.
Indian arrowheads are important
artifacts that give archeologists (scientists who study past human societies)
clues about the lives of Native Americans. By analyzing an arrowhead’s shape,
they can determine the advancement of tool technologies among certain Native
American groups. By determining the origin of the arrowhead material (bone,
rock, wood, or metal), they can trace the patterns of travel and trade of the
hunters. By examine the location of the arrowheads, archeologists can map out
hunting grounds and other social patterns.
Arrowheads are commonly found
along riverbanks or near creek beds because animals drawn to natural water sources
to sustain life were regularly found drinking along the banks. For this reason,
riverbeds were a prime hunting ground for the Native Americans. Now, dry and
active riverbeds are prime hunting grounds for arrowhead collectors.
Indian arrowheads are tiny pieces
of history that fit in the palm of your hand. They are diary entries in the
life of a hunter. They are museum pieces that hide in the dirt. They are
symbolic of the eternal struggle between life and death.
As it is used in paragraph 2,
which is the best antonym for
honed
The
history of civilization shows how man always has to choose between making the
right and wrong use of the discoveries science. This has never been more true
than in our own age. In a brief period amazing discoveries have been made and
applied to practical purpose.
It
would be ungrateful not to recognized how immense are the boons which science
has given to mankind. It has brought within the reach of multitudes benefits
and advantages which only a short time ago were the privilege of the few. It
has shown how malnutrition, hunger and disease can be overcome. It has not only
lengthened life but it has depended its quality. Fields of the work of science
the ordinary and fuller life than was ever possible to his grandparents.
What
on the whole, has science doe mankind?
When we are young, we learn that
tigers and sharks are dangerous animals. We might be scared of them because
they are big and powerful. As we get older, however, we learn that sometimes
the most dangerous animals are also the smallest animals. In fact, the animal
that kills the most people every year is one that you have probably killed
yourself many times: the mosquito.
While it may seem that all
mosquitoes are biters, this is not actually the case. Male mosquitoes eat plant
nectar. One the other hand, female mosquitoes feed on animal blood. They need
this blood to live and produce eggs. When a female mosquito bites a human
being, it transmits a small amount of saliva into the blood. The saliva may or
may not contain a deadly disease. The result of the bite can be as minor as an
itchy bump or as serious as death.
Because a mosquito can bite many
people in the course of its life, it can carry diseases from one person to
another very easily. Two of the most deadly diseases carried by mosquitoes are
malaria and yellow fever. More than 700 million people become sick from these
diseases every year. At least 2 million of these people will die from these
diseases.
Many scientists are working on
safer and better ways to kill mosquitoes, but so far, there is no sure way to
protect everyone in the world from their deadly bites. Mosquito nests can be
placed over beds to protect people against being bitten. These nets help people
stay safe at night, but they do not kill any mosquitoes. Mosquitoes have many
natural enemies like bats, birds, dragonflies, and certain kinds of fish.
Bringing more of these animals into places where mosquitoes live might help to
cut down the amount of mosquitoes in that area. This is a natural solution, but
is does not always work very well. Mosquitoes can also be killed with poisons
or sprays. Even though these sprays kill mosquitoes, they may also harm other
plants or animals.
Although mosquitoes may not seem
as scary as larger, more powerful animals, they are far more dangerous to human
beings. But things are changing. It is highly likely that one day scientists
will find a way to keep everyone safe from mosquitoes and the diseases they
carry.
In paragraph 2 the author writes, “This
saliva may or may not contain a deadly disease.” The purpose of this statement
is to
