Reading Comprehension

PT122 · S3 · P4 · Q26 Maize

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Every culture that has adopted the cultivation of maize—also known as corn—has been radically changed by it.

Topic

How maize (corn) and some similar crops became so important and productive due to a unique photosynthesis process.

Framework

Answer / Explain

Main Point

The incredible productivity of maize and some other crops, which has had major impacts on societies, is due to a special adaptation in their photosynthesis process called C-4 photosynthesis, which prevents oxygen from interfering with sugar production. Most Valuable Sentence: The first sentence of paragraph 3: The last paragraph as a whole reveals the explanation for maize's productivity.

P1: The Transformative Impact of Maize

Maize (corn) has radically changed every society that adopted it, dramatically boosting food production and even supporting population growth. The reason for its influence is how productive it is compared to other crops, but the passage sets up a question: why is it so much more productive?

P2: The Biological Challenge of Photosynthesis

This paragraph explains some basics of plant photosynthesis and introduces a problem: in most plants, a key enzyme called rubisco can be interfered with by oxygen, which messes up how efficiently plants make food (sugar) from sunlight and carbon dioxide.

P3: The C-4 Photosynthesis Solution

Certain plants, like maize, have evolved a special way to avoid this problem. In these plants, the process is split up in a way that keeps oxygen away from rubisco. Carbon dioxide gets turned into a special molecule called C-4, which is then used in sugar production. This process—C-4 photosynthesis—explains why crops like maize, sugar cane, and rice can produce so much food.

26.

The author of the passage would be most likely to agree with which one of the following statements?

Maize’s impressive productivity cannot be
Reversed Causality
This is a strongly worded idea and it seems to reverse the idea in the 1st paragraph where the author says, "The primary reason for this plant's profound influence is its sheer productivity". That would suggest the author might say that, "Maize's profound cultural influence cannot be understood without an appreciation of its impressive productivity."
1% picked this
Maize is an example of
Contradicted: oxygen not released
We're told in the 2nd paragraph that, "all plants split water into its constituent elements, hydrogen and oxygen. They use the resultant hydrogen to form one of the molecules they need for energy, but the oxygen is released into the atmosphere." Maize is an example of a plant in which the oxygen released doesn't interact somewhat with rubisco.
5% picked this
Maize’s high yields are due
Out of Scope
Out of Scope: large quantities of rubisco We're only told that C-4 plants have high yields because they keep the oxygen from competitively binding with the rubisco. We're never told that they produce an abnormally large quantity of rubisco.
6% picked this
Until maize was introduced to
Out of Scope: lacked techniques
We have no basis for saying that Europeans could cultivate C-4 plants. In fact, given that rice is a C-4 plant, our outside knowledge would probably suggest that Europeans were already cultivating rice before coming to North America. Maize might just have been a plant that was endemic to North America, so Europeans didn't grow it until they arrived in North America because they didn't have any contact with the plant / didn't have any seeds to plant, not because they didn't have techniques to grow it.
2% picked this
Correct
Maize’s C-4 photosynthesis is an
Why this is right
This is a good example of a correct answer that doesn't map to one particular support sentence, but is a very reasonable claim that our author would almost surely endorse. We know that the author thinks it's an effective evolutionary adaptation: Modern biochemistry has revealed the physical mechanism underlying maize's impressive productivity. That physical mechanism is an evolutionary adaptation, as the start of the final paragraph tells us: Some plants (C-4) have evolved a photosynthetic mechanism that prevents oxygen from impairing photosynthesis. And we know from the first few sentences of the passage that maize has benefited humans. .... leading to such developments as the adoption of agrarian and in some cases urban lifestyles, and much of the explosion of European populations after the fifteenth century was driven by the introduction of maize together with another crop from the Americas, potatoes.
Skill tested: Author Opinion · how this choice captures the passage's function is the move to repeat next time.
85% picked this

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