1. C, D, and E are quickly able to be removed from contention due to being patently incorrect. Between A and B, maize and oats are never compared to the effect on wheat in the passage, so A is incorrect as well. By elimination, B must be correct, even if the passage doesn't specify it needing to be surplus (a fact that would make B possible to be incorrect via another answer being "more correct," something the GRE generally doesn't do).

2. EXCEPT means we are looking for an answer that is either too absolute or clearly false. "would have been ensured" is an absolute, so we will start with assuming its the correct answer and decide quickly if the other ones sound agreeable. A,B, and C we can see are fine pretty quickly just from having read the passage. A because the Malthus limit hasn't been reached, B being a weak comment that is supported by the passage, and C also being a weak comment supported by the passage. D, while similar to E, is effectively a weaker way of saying it while not specifying GE. Therefore, we agree with our initial assumption that that answer is E.

3. This requires either understanding the passage as a whole, which constantly talks about food vs population issues, or knowing what a geometric vs an arithmetic ratio means. Regardless, we come to the conclusion that Malthus believed that populations would increase faster than food supply would, leading to problems. The only answer that coincides with this idea is D.

4. Even if you don't know what the word precipitous means, or what a precipice is, you can still figure out from context that it is a modifier of the word "decline." Even without knowing the word, you should be able to narrow it down to being either a gradual decline or a sharp decline. While you would still effectively be guessing, you can further narrow the answer down to being "sharp" by the fact that the passage refers to it as a DIRE PREDICTION. Therefore, if you know the word precipice, precipitous, or even dire (with further context clues) you should be able to get to the answer of E, sharp.

According to the passage, which of the following is true about Haber nitrogen? (Detail Question Type)

A) Haber nitrogen is more effective at increasing the yield of wheat crops than that of maize or oat crops. - Inconsistent. Efficiency is not stated in the passage.
B) Undesired effects can result from the application of surplus quantities of Haber nitrogen. Stated in last sentence of 3rd para.
C) Haber nitrogen was the first non-naturally occurring substance to be applied to crops as fertilizer. - out of scope.
D) Haber nitrogen may not be effective if applied at an improper time in wheat’s growth cycle. - Inconsistent. Efficiency is not stated in the passage.
E) Farmers were quick to adopt Haber nitrogen because it made their - I think the Answer choice is incomplete. However, Farmers did not used nitrogen widely. - Opposite.

The passage implies all of the following EXCEPT (Inference Question Type)

A) world food production has kept pace with world population growth. Yes. All paragraphs indicates this.
B) technological innovation is one factor that allowed for an increase in crop production. Yes. passage indicates this.
C) farmers are not the only group that has opposed artificial efforts to increase crop yield. Yes, "environmental movement" - last para suggests that people were against this.
D) the Malthusian limit might well have been reached if new methods to increase crop production had not been found. Last line of first para suggests this.
E) a Malthusian disaster would have been ensured if it were not for the invention of genetic engineering. This cannot be inferred as Malthus Doctrine is not related with genetic engineering.

Which of the following, if true, would best represent Malthus’ contention in the first paragraph? (Inference Question Type)

“population increases in a geometric ratio, while the means of subsistence increases in an arithmetic ratio.” - Meaning that population increases more than crops.

A) By 2040 the world’s population increases marginally, and food production keeps pace with demand.
B) By 2040 the world’s population decreases marginally, and food production outstrips demand.
C) By 2040 the world’s population remains unchanged, and food production declines slightly.
D) By 2040 the world’s population has significantly increased, and food production has increased slightly.
E) By 2040 the world’s population has significantly decreased, and food production has decreased slightly.

Only option D clears this.

Which of the following most nearly means the word precipitous, as used in context? (Vocabulary Question Type)

precipitous - steep or sudden change.

A) anticipated
B) deliberate
C) gradual
D) risky
E) sharp

Only option E makes sense.