Gnpth wrote:
It is proposed to introduce mosquitoes into the wild with genetic alterations that destroy their disease-carrying capacity. In this way, the dangerous wild population could eventually be replaced with a harmless one without leaving room for another disease-transmitting type to flourish. One candidate gene would interfere with the mosquito’s finding mates; another would cause destruction of a disease parasite before the stage at which it could be transmitted; another would disable the mosquito’s own resistance to disease, so that it would die before transmitting the disease.
Which of the following identifies a discrepancy in the proposal above?
A.It is presupposed that the three genes would prove equally easy to isolate and insert into the cells of the mosquitoes.
B.Two of the ways of destroying disease carrying capacity in the wild would jeopardize the goal of the proposal.
C.It does not take into account positive roles that mosquitoes play in the environment, such as serving, in the larval stage, as food for fish.
D. None of the proposed alternatives would ensure that there would be fewer mosquitoes in any given area.
E. Evidence is not presented to show that each alternative method has been successfully tested on a wide scale.
Aim: destroy mosquitoes' disease-carrying capacity
Plan: Introduce mosquitoes with 3 possible genetic alterations:
- One candidate gene would interfere with the mosquito’s finding mates;
- another would cause destruction of a disease parasite before the stage at which it could be transmitted;
- another would disable the mosquito’s own resistance to disease, so that it would die before transmitting the disease.
What is the problem with the plan?
A.It is presupposed that the three genes would prove equally easy to isolate and insert into the cells of the mosquitoes.
Does the plan need them to be equally easy to isolate? No. They are just possible options. One could be easier to implement and the other harder (but perhaps better) - we don't know.
B.Two of the ways of destroying disease carrying capacity in the wild would jeopardize the goal of the proposal.
Correct.
We plan to introduce modified mosquitoes and we hope that they will replace the current ones. So they will propagate among the current ones and perhaps pass on their genes to the babies (new mosquitoes) and eventually, when current mosquitoes live out their life cycle, all mosquitoes will have the new genes.
But of the 3 proposals,
- One candidate gene would interfere with the mosquito’s finding mates;
If the introduced mosquitoes are unable to find mates, how will they replace the current population? The current population will continue mating among themselves and propagating.
- another would cause destruction of a disease parasite before the stage at which it could be transmitted;
This is good. The mosquito would kill the parasite before transmitting so the mosquito will become harmless.
- another would disable the mosquito’s own resistance to disease, so that it would die before transmitting the disease.
This again would lead to the introduced mosquitoes being weak and not resistant to disease. So they will die quickly and not be able to propagate. Then how will they replace the current population?
Hence, 2 of the 3 ways are against our goal.
C.It does not take into account positive roles that mosquitoes play in the environment, such as serving, in the larval stage, as food for fish.
Irrelevant.
D. None of the proposed alternatives would ensure that there would be fewer mosquitoes in any given area.
Irrelevant. We only want to make mosquitoes harmless.
E. Evidence is not presented to show that each alternative method has been successfully tested on a wide scale.
Evidence if out of scope for us.
Answer (B)
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