Increased atmospheric concentrations of carbon dioxide (CO2 )

Since it is an inference type question we need to be 100% sure that what we infer will occur given the passage.

It can be inferred from the passage that increased atmospheric carbon dioxide

a) can decrease the nutritional content of plants. Clearly mentioned in second para
b) increases the rate at which most plants grow. Most is a red flag making statement extreme as the passage does not mention "most" plants
c) will lead to increased agricultural production. "Will lead" is too strong and we cannot predict the future.
d) is the biggest threat to global nutrition that the world faces today. Non-sensical there could be other bigger threats
e) will cause millions of people to become zinc deficient by 2050. Again "will cause" is too strong

Hope it is clear.

Best,
Gladi

OE Question 2

This specific question requires that you first understand what nonscientists are arguing and then that you look beyond that information to understand the flaw in that argument. Since the question asks about the nonscientists mentioned in paragraph 1, it's helpful to first think about what those nonscientists believe. Paragraph 1 states that they believe that because increased atmospheric CO2
can have a fertilizing effect on crops, that rising levels of CO2
will increase production in crops preventing food shortages and decreasing malnutrition.

To understand what the author thinks those people fail to consider, you then need to look at the next paragraph. (The word "however" at the beginning of that paragraph is a great indication of a shift occurring.) The next two sentences state that faster growth comes at the cost of nutritional content. This best matches answer choice (B): these nonscientists don't take into account that there might be phenomena that prevent this increased growth from actually affecting malnutrition.

Among the other answers, (A) can be eliminated because the ratio of edible to nonedible material isn't discussed, and (C) can be eliminated because distribution isn't discussed. (D) can also be eliminated because it is too specific: the author doesn't directly make any claims about water availability's effects, and (E) can be eliminated because there is no claim made that these two growth rates would differ.


OE Question 3

For this question, you should go straight to the answer choices, looking for the proposed inference that is guaranteed to be true based on the information provided in the text.

Choice (A) can be eliminated because the author doesn't give enough support to justify this inference. While it is possible that the number of people with a zinc deficiency wouldn't increase, it's also just as possible that a country could have a population boom, leading to famine and therefore more people with zinc deficiency. Both of these scenarios are allowed by the text.

Choice (B) can be eliminated as well since it runs counter to the information provided. While it's certainly possible, there is no evidence that crops will do anything other than what is described in the text.

Choice (C) is close, but isn't guaranteed. The passage says that increased yields will occur "provided" that farmers can get enough water and nutrients to plants, but doesn't state one way or the other whether this is actually possible.

Choice (D) is correct. The author states that "an additional" 175 million people could become zinc deficient, making it possible to infer that at least a few people worldwide are currently zinc deficient.

Choice (E) can be eliminated because you are told that the majority of micronutrients come from plant sources, but the word "majority" doesn't rule out the existence of alternative sources.
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Please explain question 2 and 3.

Q3 - It is written -'Additional million people will suffer from zinc deficiency' so it can be inferred that some people already suffer from zinc deficiency. Hence option D.
Which option did you chose?

Q2 - Non scientists say increase of CO2 is good. But research says that increase of CO2 is not good because it decreases nutritional content of crops. hence global malnutrition.
Earlier non scientists didn't consider this association/relationship of increase in CO2 and malnutrition.
Therefore option B.

Please give Kudos if I were helpful.
Thanks!

What is wrong with B in question 4 ? Please guide.



Regards
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OE Question #4

As with any inference question, your goal should be to consider each answer and whether the inference provided is guaranteed by the passage. For these questions it can be difficult to anticipate what inference the question will make, so your strategy of attack should be to just dive in and consider each answer choice independently.

Choice (A) is a valid inference. If increased carbon dioxide can cause zinc deficiency in plants, then since zinc is a type of nutrient, increased carbon dioxide can also cause general nutrient deficiency. Note also the appearance of the word "can" - a much easier level of proof than "will" or "always."

Choice (B) is not a valid inference because it's stated that the fertilizing effect occurs "on certain crops" but doesn't state what proportion of plants is affected. The presence of the word "most" here sets the burden of proof at a high level - it's not enough for "some" plants to be affected, you need to be able to prove that it's more than 50%, and evidence just doesn't exist for that level of proof.

Choice (C) can be eliminated because the passage states that increased agricultural production will only occur if farmers can provide adequate nutrients and water, something that isn't guaranteed by this question.

Choice (D) can be eliminated through lack of evidence. While nutrient deficiencies are an issue, there is indication as to the relative importance of this issue.

Choice (E) can be eliminated for reasons similar to choice (E). While it is possible that the outcome described will occur, any number of events could prevent (E) from occurring (better technology, a meteor strike, etc).
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for most passages, understanding main idea and structure of the passages are hard and answering the questions which is based on understanding the main ideas is easy. for some passage such as this one, understanding the main idea is easy but answering the questions is hard. the focus of this passage is the infering. though the passage is easy to understand, the questions are hard and require a high lever of infering. realizing which information is correct and which information is probably correct is key to success on answering the hard questions from the easy passage.

GMATNinja, VeritasKarishma,

Could you please suggest the strategy to answer question1 of the passage?

GMATNinja

I'd like to learn the same. Could anybody please shed some light on how to to tackle this question? I picked E but realised that "without any" is too strong/unjustified

Thank you

3/4 in about 7:45. Got the last question wrong. Why can't we infer that increased CO2 leads to an increase in the rate in which plants grow? A is inferrable from the 2nd paragraph but why about B? To quote: "research on the nutritional content of crops grown at Free Air CO2
Enrichment - or FACE - sites suggests that while crops may grow more quickly in elevated concentrations of carbon dioxide"

Any thoughts would be welcomed. I'd be happy to share my logic on the first three questions.

Can anyone explain question no 1 .

I marked E for Q1. Please explain why the answer is C.

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