priyanshu14
jeffn
Scientists studying climate change have found that global warming not only increases the temperature of the planet but also leads, on average, to an earlier arrival of the spring season and a later arrival of the autumn season. Though some argue that this effect on the seasons is advantageous because it increases the length of the summer growing season, leaders of the World Wildlife Fund fear that many animal species will not be able to adapt to the altered season lengths and will thus soon face extinction.
Which of the following, if true, provides the best evidence in support of the view held by the leaders of the World Wildlife Fund?
A. When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets.
B. As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows.
C. Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely.
D. The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.
E. As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species.
Dear
VeritasKarishma GMATNinja bb generis Bunuel egmat RaviSreerama,
I have doubt in option A and D
Option A- Possibility 1: Mammals will need to find alternate source of food. If food is not available then it will lead to extinction of mammals
Possibility 2: If food is available, then Mammals will survive
Option D- Possibility 1: If metamorphosis is earlier and the time is insufficient for young ones of rodents and birds to feed, then it will cause extinction of many species of rodents and birds
Possibility 2: if metamorphosis is delayed, then extinction wont happen.
So, in both option A and D, there is possibility of extinction and possibility of no extinction.
But answer is D, please suggest.
Thanks in advance for support
WWF fears that many animal species will not be able to adapt to the altered season lengths and will thus soon face extinction.
We need to strengthen that many animal species will not be able to adapt to the altered season lengths and hence become extinct.
A. When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets.
With earlier spring, animals will emerge from hibernation earlier and will have to find alternative food sources to supplement their diets. This does not indicate that they will not be able to adapt to the altered season lengths. They might be able to find alternative food sources. This option tells us that altered season lengths brings in a problem for animals but doesn't say that it is likely that they will not be able to manage it.
B. As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows.
How do the altered season lengths impact, this doesn't say.
C. Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely.
This says that altered season lengths may impact humans. Irrelevant.
D. The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.
Caterpillars morph into butterflies on arrival of spring (seasonal changes trigger it). If spring arrives early, they will turn into butterflies early. The young of many species feed EXCLUSIVELY on caterpillars. With the availability of caterpillars reducing to a shorter time, it is likely that the young of many species will not survive and may lead to extinction. Provides much better support.
E. As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species.
Again, temp increase is said to endanger animal species. Impact of change in season lengths is indirect.
Answer (D)