The tsetse fly, belonging to any of

Question

The tsetse fly, belonging to any of approximately twenty species 
composing the genus Glossina, is indigenous to Africa and is found 
primarily in forests and savannahs south of the Tropic of Cancer. 
Dependent on vertebrate blood for nourishment, the tsetse fly is 
equipped with a long proboscis which is sharp enough to penetrate most 
animal skins and powerful enough to enable the tsetse to drink quantities 
of blood up to three times its own body weight.

At the same time that the tsetse drains blood, it can also transmit a 
variety of dangerous diseases. A bite from a tsetse fly can induce African 
sleeping sickness in human beings and nagana, a similar ailment, in 
domestic livestock. The agent of these diseases is the trypanosome, a 
unicellular, flagellated parasite which feeds primarily on the blood of 
vertebrates and is generally transmitted by an intermediary leech or 
insect host, such as the tsetse fly. In humans the trypanosome causes 
damage to the brain and spinal cord, leading to extreme lethargy and, 
ultimately, death; in livestock, trypanosomes destroy red blood cells, 
causing fatal anaemia.

The immune system is ill-equipped to counter trypanosomes. As the 
immune system attempts to counter disease, antibodies are produced to 
attack microbes whose antigens, surface proteins, are foreign to the 
body. However, the trypanosome is capable of disguising itself by altering 
its genetic code, thereby changing its antigen coating in resistance to 
each new antibody that evolves. This ―quick change‖ has confounded 
pathologists and made the development of effective vaccines elusive.

A controversy has been sparked between proponents of the 
elimination of the tsetse fly and African environmentalists. Those in 
favour of eradication feel that in addition to reducing disease, the 
removal of the tsetse fly will open immense tracts of land to cattle 
breeding. This, however, is precisely what the opposition fears. 
Environmentalists and conservationists dread the day when cattle and 
livestock, permitted to roam and graze freely, will uncontrollably devour 
plush African grasslands, converting them into barren desert. They argue 
that the tsetse fly must remain for the sake of the land.

With efforts to eradicate the tsetse fly largely unsuccessful, control 
may offer the only available option for the interests of both health and 
environment. Since the protozoan cannot be conquered through 
antibodies or vaccines, scientists have begun efforts to prevent the 
transmission of the trypanosome parasite by eliminating the tsetse. 
Attempts to eradicate the tsetse fly, however, have met with little 
success. Rhodesia used to combat tsetse by extensive brush cleaning, 
game shooting, and chemical attack, yet the fly persisted. Aerial pesticide 
treatments have produced inconclusive results.

The reproductive cycle of the tsetse fly is such that a larva pupates 
underground for several weeks before it emerges as an adult fly. This 
makes repetitive chemical sweeping at intermittent periods an 
inconvenient necessity. All of these methods, however, share the 
weakness of dependence on harmful chemicals, such as DDT, which 
threaten both the health of the humans who handle them and the 
environment in which their toxic residues amass.

1. All of the following statements correctly describe the relationship between 
the tsetse fly, the trypanosome, and vertebrates EXCEPT:

A. vertebrate blood provides the nourishment for the transport of 
trypanosomes. 
B. the ―bite‖ of a tsetse fly can kill vertebrates since it often injects a 
deadly chemical. 
C. both the tsetse fly and the trypanosome utilize vertebrate blood for 
nourishment. 
D. vertebrates may die after trypanosome contamination via a tsetse 
proboscis. 
E. the tse tse fly transfers the trypanosome into the vertebrates' bodies

2. In the passage, the author does NOT identify which of the following as a 
characteristic of the tsetse fly?

A. dependence upon vertebrate blood 
B. ability to transmit a fatal parasite to livestock and humans 
C. ability to alter its genetic code 
D. ability to influence the African cattle population 
E. its larva pupates for several weeks beneath the ground

3. According to African environmentalists, which of the following accurately 
describes the effect the tsetse fly has on the African grasslands?

A. If the tsetse fly population continues to exist, the African grasslands 
will turn into barren wasteland. 
B. If the tsetse fly population continues to exist, the African grasslands 
will not be able to provide sufficient food supply for African cattle and 
livestock. 
C. Destruction of the tsetse fly population will lead to the conversion of 
grasslands into desert. 
D. Destruction of the tsetse fly population will cause overgrowth of the 
African grasslands. 
E. Tse tse fly has no impact on grasslands, it only impacts vertebrates

4. What is the primary purpose of the fourth paragraph in the passage

A. to decsribe the harmful effects of the tse tse fly 
B. to argue that the proliferation of tse tse flies can lead to large scale 
deforestation of African grasslands 
C. to discuss a beneficial impact of tse tse flies 
D. to state that efforts to eradicate the tse tse flies have generally proved 
to be ineffective 
E. to discuss the reproductive cycle of a tse tse fly

anilnandyala · Answer

answers will be provided after a discussion, proviode ur answers with explanations.
1 q answer c because only tsetse uses blood for nourishment not trpyansome
2 c ability to alter its genetic code is answer because from passage 3 trypansome is capable of changing it's genetic code not insect
3 c Destruction of the tsetse fly population will lead to the conversion of 
grasslands into desert, an easy one the environmenatalists opposes destroying tsetse because cattle will sweep entire green land in the absence of tsetse
4 c to discuss a beneficial impact of tse tse flies, direct q here the passage offers advantages of tsetse

jaxis · Answer

1:B
2:C
3:C
4:D

phamduyha · Answer

Here are my answers:
1. E
2. C
3. C
4. D
What are the OAs?

anilnandyala · Answer

oa's are bccc

rite2deepti · Answer

Got 3/4 , for last one it was my careless mistake did not count the paragraphs :-(

..hope to avoid such silly mistakes on real GMAT

montani · Answer

Friends Will you provide me the electronic version of RC-99.... I believe that will be helpfull for me.

garimavyas · Answer

3/4 in exactly 7:00 min. although i dont agree with answer for the 3rd question . i think it has to be E , because tsotsobe fly has no impact on grasslands, it does not suck the blood out of grass. the fly does not eat the grass either, it only sucks the blood of vertebrates.

and option E exclusively states just that.

and option E exclusively states just that.

garimavyas · Answer

option C in q 3 clearly states that elimination of tsotsobe fly WILL lead to conversion of grasslands into deserts . this is a clear exaggeration.

anyone to counter this ?

fluke · Answer

Question states: "According to African environmentalists".

"C" would be an exaggeration if the Author, not the African environmentalists, were to conclude something based on the premise. Here, the word "will" is used to describe African environmentalists' exact thinking, which is of course an adamant hypothesis, about the effect on grassland upon eradication of tsetse flies.

Environmentalists and conservationists dread the day when cattle and 
livestock, permitted to roam and graze freely,  will  uncontrollably devour 
plush African grasslands, converting them into barren desert.

moneymike · Answer

4/4 in 8 minutes... long passage.

1. B, D and B somewhat contradict IMO and I liked D better. Passage didn't talk about bite or chemical.
2. C, trypanosome alters code, not the teste fly. 
3. C, Less teste's -> more cattle -> less grass -> desert
4. C, Explains the answer in question 3.

gijoedude · Answer

7:50.

I got

B
C
E
C.

How come the 3rd is C? I was down to C and E. But chose E because the fly has no direct impact on the grassland. The fly impacts the grassland indirectly by keeping the population of animals in check.

PS: fluke's explanation makes sense.

The tsetse fly, belonging to any of

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