The extinction of the dinosaurs – thought to be caused by an asteroid

1. What is the central theme of the passage?

A. The role of mantle plumes in the extinction of dinosaurs
=> It is only discussed in one of the paras, not the passage as a whole

B. Unanticipated effects of mantle plume activity
=> It was not unanticipated, the scientists did some thorough research.

C. Earth science theories that explain the extinction of dinosaurs
=>Same as A

D. The formation and consequences of mantle plumes
=>CORRECT. The passage discusses its formation, eruptions, and effects over the surroundings and earth

E. Contrasting views of earth scientists on the mantle plume phenomenon
=> The views are not contrasting. The contrast is nowhere discussed.

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2. The author mentions ‘two extinction events’ in line 11 most probably in order to

A. support Dr. Kerr’s view that mantle plumes have a significant effect on the course of evolution, especially the predominance of mammals and the origin of humankind
=> No, the events are mentioned to show the cause of Extinctions but Dr. Kerr's view talks about evolution. Doesn't support each other

B. undermine the evidence offered by Professor Keller’s study of mantle plume eruptions
=>Doesn't undermine, instead the study has been used to conclude the statement of two extinction events

C. highlight the devastating effects that mantle plume activities can have on the earth’s environment
=> It is a devastating effect of the mantle plume activity but not the most probable reason for mentioning it there because Extinction has already been mentioned in the one para back to this.

D. question the assertion that mantle plumes were responsible for the eruptions that caused devastating environmental impact
=> It doesn't question, it supports.

E. strengthen the theory that asteroid impact was not the primary reason for the extinction of species in the past
=> CORRECT. Yes, if Mantle plume activity was the reason for the 2 two extinction events, then it means asteroid impact was not. Hence it correctly strengthens the theory.

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3. According to the passage, each of the following statements about mantle plume activity is true, EXCEPT:

A. It is caused due to the heat from the earth’s mantle bubbling up, similar to the functioning of a lava lamp
=> "Likened to the actions of a lava lamp, the mantle's heat causes it" - mentioned here

B. During mantle plume eruptions, magma is spewed over hundreds of kilometres on the earth’s surface
=>=> "spew magma over the earth's surface and across an area of some 1,000 kilometres diameter." - mentioned here

C. Several ‘hotspots’ of volcanic activity across the globe give rise to mantle plume eruptions
=> CORRECT. The passage says that "hotspots" are the remnant of the Mantle plume eruptions, not caused by it.

D. It is an eruption that originates between the earth’s crust and its core and lasts for one or two million years
=>=> "'mantle plume' – a huge volcanic eruption from deep within the earth's mantle, the region between the crust and the core of the earth" - mentioned here

E. The massive deluge of lava, ashes, and gas during mantle plume eruptions can have significant effects on climate and evolution
=>=> "The massive outpouring of lava, ashes, and gas can have significant effects on climate and have the potential to dictate the course of evolution" - mentioned here

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4. It can be inferred from the passage that Professor Keller and team would be most likely to agree that which of the following is a possible outcome of mantle plume activity

A. The extinction of a species other than dinosaurs
=> CORRECT. "a similar eruption under the Indian Ocean several million years before the extinction of the dinosaurs had a similarly devastating impact on the environment" - This states that mantle plume activity could be the cause for other species' extinction as well as because of similar devastating impact

B. The asteroid impact that happened 65 million years ago
=> No, they researched on mantle plume activity but didn't find any evidence on asteroid impact

C. The formation of microfossil assemblages on the ocean floor
=> Keller's findings are based on microfossil assemblages but no info on if they were an outcome of mantle plume activity. They could have always there but had traces of plumes when eruptions occurred and passed over them.

D. The fundamental reshaping of the earth’s surface
=> This is Dr. Kerr's views, not Keller's views

E. The recent bouts of volcanic activity that the earth’s ‘hotspots’ have seen
=> Not relevant to Keller's research

PS: All OEs are already posted above.

Hello, I would like to pose a question that maybe, just maybe, may seem stupid, but a thoughtful and serious answer might not seem so stupid. I am aware that under the premise that it should be impossible, or perhaps not, a planet cannot in a short space of time increase its "gravity" due to an external event (I could have a hypothesis in this regard, of course not verified , but very interesting). So, I throw the following question; -
What could have happened, if life on earth 80-65 million years ago had faced a temporary increase (1 year, 10 million years ...?) In gravity of 0.3 / 0.4g?

I apologize for my English
Regards.

4 mins all correct, moderate passage imo, 650 level, happy to help if needed !

Answering this question just for the sake of fun and also because I am happy today since I did well in this 700 lvl RC after many days of effort

What could have happened, if life on earth 80-65 million years ago had faced a temporary increase (1 year, 10 million years ...?) In gravity of 0.3 / 0.4g?

I am not an expert but I do have a deep interest in physics. From my humble understanding, I believe the if and when the earth would have had suddenly experienced a gravity increase of 0.3/0.4g - we are talking about 30% to 40% increase here btw - the first and very important evolutionary changes that we would have seen, IF WE ARE TALKING ABOUT A CHANCE WHERE MAMMALS STILL SURVIVE THIS CHANGE, would be the changes in the bone density of the vertebrates. The bone density would be higher than what it is now. Also, our circulatory system would have been stronger because our heart and blood vessels would have required way more effort to counter gravity so as to flow the blood throughout the body.

In terms of architecture, our whole engineering and hydraulic systems would have had developed in a whole new concept because the early humans would have to find way stronger materials to build a strong enough bridge to sustain the bare minimum weight of the vehicles or even to build a simple house. Finding such rare and stronger materials would have had big implications on the world trade and economy and everything related to geo-politics and balance of power that we see today would have had been very different from what we can imagine.

Another thing to take into consideration is that our atmosphere would have been way denser, which can be good in some ways. However, the pollution caused by us would have impacted us in a way stronger manner than the manner in which we are facing today. For this reason, either our lungs would have had given up and we would have been on the verge of extinction or we would have adapted an evolutionary change in terms of respiration. (of course, if this gravity increase event happens for a longer time).

This event would have taken a huge toll on floods and devastation as well. The moon would be much closer due to an increase in the gravity of the earth and this change would have initiated a sudden change in tidal waves, making them much stronger and fearsome. Lots of regions would have faced sudden floods and tsunamis. There would be a total collapse of ecological systems and the earth would have seen unprecedented chaos of devastation.

These are some of the obvious effects that the earth would have had to encounter if it would have faced the scenario mentioned in your question. In short, everything is in perfect balance and in the perfect numerical amount on our planet so as to sustain life. Tip anything towards the extremes and life will cease to exist in the way it is existing now.

I hope I have satiated your hunger for the answer