PrepTest 122
Passage
Passage walkthrough
Topic: Science
Paragraph 1
- Paragraph note
- Background on corn/maize; Question about it; Answer previewed
- Views, minor Meta-Structures, and the author's attitude
- Corn/Maize - Reshapes cultures; primary reason = productivity
- Question - Why so productive?
- Answer - Biochemistry has found one
Paragraph 2
- Paragraph note
- Process of plants making carbs; limit to productivity (Problem)
- Views, minor Meta-Structures, and the author's attitude
- Process - Photosynthesis - Split water, release oxygen, use carbon dioxide
- Rubisco is key enzyme
- Problem - When oxygen levels high, it gets in the way of rubisco working
Paragraph 3
- Paragraph note
- Some plants have found Solution to limit
- Views, minor Meta-Structures, and the author's attitude
- Lots of science
- Split oxygen (and other gases) from cells with rubisco
- Carbon dioxide changed to C-4, which can enter cells with rubisco
- Called C-4 photosynthesis
- List - Sugar cane, rice, maize - all on list of most productive crops
Main Point: Maize’s very high productivity is the reason it has the power to transform cultures, and it’s high productivity is due to C-4 photosynthesis.
Key Lines?Lines 10-11 - Why maize is important
Lines 15-16 - A question
Lines 16-18 - An answer is previewed
Lines 28-30 - An important part of a process
Lines 30-35 - A problem
Lines 36-38 - A solution, and an answer, all rolled into one!
Lines 45-47 - More details on solution/answer
Lines 57-61 - More details on (and a name for) the solution/answer
Meta-Structure?Question/Answer - Sometimes, the LSAT makes it a bit easy to identify a Meta-Structure. Here, the passage presents a question - question mark and all! - at the end of Paragraph 1 (Lines 15-16). It asks why maize and some similar crops are so relatively productive. And immediately after, it tells us that it’s going to dive into an answer (Lines 16-18), for maize at least (“underlying maize’s impressive productivity”). When a passage falls into a Question/Answer Meta-Structure, the Author’s answer (or her opinion on a key answer) serves as the main point. Here, the Author spends the first half of Paragraph 2 talking about the general process plants use to create carbs and the second half talking about a problem that limits productivity. She then dives into what’s different about maize that allows it to be so highly productive in Paragraph 3, resolving that problem and providing an answer to the question - maize uses a C-4 photosynthesis process to split oxygen from rubisco, allowing it to be more productive. This is the Author’s answer to the question that kicked off the argument in the passage, so it should make up the main point, as summarized above.
Problem/Solution - The end of Paragraph 2 introduces a problem that limits plant productivity - too much oxygen interferes with rubisco, slowing down the key enzyme that allows plants to make carbs (Lines 30-35). The Author then discusses the biochemistry behind how maize (and similar crops) solve this problem, allowing them to be particularly productive - they segregate the oxygen from the rubisco using a process known as C-4 photosynthesis (Lines 45-47; Lines 57-61). When a passage falls into a Problem/Solution Meta-Structure, the Author’s solution serves as the main point. In this passage, the solution to the problem also constitutes the answer to the main question of the passage, reinforcing it as the main point, which is reflected in our summary, above. Note that capturing essentially the same idea in two Meta-Structures isn’t a problem - it just means that we can look for language reflecting either in big picture questions!
List - The passage lists three crops that use C-4 photosynthesis and are among the most productive crops in Lines 59-61. This reflects the question asked at the beginning, which referred to “maize and a few similar crops.” This is a very limited list, though, so it’s likely to - at most - be the focus of a single question. That said, be careful of not falling for a trap here. It’d be easy to think that these other crops are a part of the main point since they’re referenced in the question, but look at the Author’s answer in Lines 16-18 - it discusses only maize, so our main point could reference these crops, but it doesn’t have to.
Last Thoughts?Wow...that’s a lot of science. When there’s this much science, we are going to get some questions that require us to digest it and repeat some details in the answer choices. However, there’s no way you can possibly actually remember all this stuff after reading, so make sure that your notes are strong enough that you can quickly find the relevant information. Things like causal chains or processes (how photosynthesis works, Lines 20-27; C-4 photosynthesis, starting in Line 50), elements that are noted as important (rubisco, Lines 28-30), and problems (Line 30 introduces one with “Unfortunately”) are some of the things to know where they’re located. You will go back to check your answers against these sections, so you might as well have a “Table of Contents” or “Index” for where to find them.
Question prompt
Why the credited answer is right
Credited answer: D
The notes below walk through why it fits the stem and how to eliminate the rest.
Question Type
Strategy Overview
Answer Anticipation
Answer choices
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AIt indicates why certain Remaining source text redacted.
Why choice A is not credited
(A) (Lines 30-35) The buildup of oxygen due to atmospheric conditions is a part of the limitation that prevents some plants from being as productive as maize. The phrase in question is a part of the “key” to the process that addresses this problem, so it doesn’t help to indicate why the problem develops!
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BIt supports the claim Remaining source text redacted.
Why choice B is not credited
(B) (Lines 34-35) The discussion of the limitation is in Paragraph 2, not the first half of Paragraph 3, and there’s no indication that atmospheric gases other than oxygen create a problem for rubisco or photosynthesis!
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CIt supports the conclusion Remaining source text redacted.
Why choice C is not credited
(C) (Lines 45-47) The C-4 process isn’t different in the gases that are used in the process but rather where the gases are located in the cell that’s engaged in photosynthesis. As the passage states, the key to the process is the separation of gases and rubisco, not the use of different gases!
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DIt explains why carbon Remaining source text redacted.
Why choice D matches the stem
(D) (Lines 45-47; Lines 54-57) The Author establishes excess oxygen as a problem for photosynthesis, which makes her mention of other atmospheric gases here a bit weird - if they’re not a problem, why mention them? Because, as we later learn, that excludes carbon dioxide, which is necessary for plants to make carbs. So how do the plants get around this? They convert the gaseous carbon dioxide to C-4, which can then meet up with the rubisco. In short, the Author mentions that other atmospheric gases are excluded from the areas with rubisco so that it makes sense why she’s explaining why one of them needs to be converted in order to reach the rubisco. This answer captures that, so this is the correct answer.
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EIt advances a broader Remaining source text redacted.
Why choice E is not credited
(E) (Lines 45-47) The Author says that C-4 works by excluding oxygen from rubisco cells - not by keeping oxygen levels constant. Even if oxygen fluctuates, it shouldn’t be an issue since that oxygen is in a different area of the leaf.
What this tests
Discussion
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Explanation 3 replies
Started by avif