CSAT Solved Papers/ 2025/Q52
2025 CSAT — Q52
Passage
It is hard to predict how changes in the climate and the atmosphere’s chemistry will affect the prevalence and virulence of agricultural diseases. But there is a risk that such changes will make some plant infections more common in all climatic zones, perhaps catastrophically so. Part of the problem is that centuries of selective breeding have refined the genomes of most high-value crops. They are spectacular at growing in today’s conditions but genetic variations that are not immediately useful to them have been bred out. This is good for yields but bad for coping with changes. A minor disease or even an unknown one could suddenly rampage through a genetically honed crop.
With reference to the above passage, the following assumptions have been made:
I. Global climate change can result in the migration of several plant diseases to new areas.
II. Scientific understanding of the wild relatives of our present crops would enable us to strengthen food security.
Which of the above assumptions is/are valid?
Thinking pathway
Locate. This is a valid-assumption question, so find the premise the argument rests on. The passage’s worry is built on the risk that climate change will “make some plant infections more common in all climatic zones” — i.e. diseases reaching areas they didn’t before. That risk premise is Statement I.
Test (the negation test). Negate I — suppose climate change does not spread infections to new zones — and the passage’s central risk evaporates. So I is load-bearing: valid. Statement II proposes studying wild relatives to strengthen food security. The passage mentions that useful genetic variation has been “bred out,” but it never suggests that understanding wild relatives is the route to food security. Negate II — the argument is untouched. II is not assumed.
Eliminate by anatomy. (b) and (c) admit II, a claim the passage never actually makes — a plausible scientific remedy (study wild relatives) that the passage never raises. (d) wrongly rejects I, the risk premise the whole passage rests on. The transferable rule: a remedy that “sounds like a good idea given the problem” is not an assumption unless the passage actually leans on it. Key: (a).
Evidence in the text
Statement I: “there is a risk that such changes will make some plant infections more common in all climatic zones” — the passage’s risk premise is that climate change spreads infections across zones (I). Statement II: the passage notes that useful genetic variation has been “bred out,” but it never says studying the WILD RELATIVES of crops would strengthen food security — that remedy is not in the text.
Worked rationale
Statement I. The passage’s argument is grounded in the risk that climate change “will make some plant infections more common in all climatic zones.” That diseases can spread to new areas is exactly the premise the worry rests on. Negate I and the passage’s risk disappears. I is valid.
Statement II. The passage observes that genetic variation has been bred out of high-value crops, but it nowhere claims that scientific understanding of wild relatives would strengthen food security. That is a remedy supplied from outside. Negating II changes nothing. II is invalid (out of scope).
Answer: (a) I only.
Why the other options miss
- B a claim the passage never actually makes: selects the “study wild relatives” remedy the passage never proposes and misses the disease-spread risk premise (I).
- C half right, half wrong: takes I correctly but admits the unsupported II.
- D a step the text doesn’t license: over-rejects; misses that the passage’s risk rests on infections spreading to new zones (I).
Specialist insight
II is the tempting “solution” distractor: the passage shows a genetic-uniformity problem, so a reader reaches for the obvious fix — restore variation by studying wild relatives. But that fix is the reader’s idea, not the passage’s premise. The valid assumption is the risk the argument is built on (diseases spreading with climate change), not the remedy a clever reader proposes for the problem the passage raises.
II is a reader-supplied "study wild relatives" remedy the passage never proposes; the real assumption is climate-driven disease spread — (a).