UPCAT Reading Comprehension practice question 8: The passage suggests that a reef struck by severe bleaching in two consecutive years would most likely
Correct answer
C. fare worse than one struck once, because recovery time was insufficient
The final paragraph identifies the shortening gap between events as the central difficulty, since recovery is slow and requires time before the next event.
Why Corals Turn White
A healthy coral is not a single organism but a partnership. The coral animal builds the limestone skeleton, while microscopic algae called zooxanthellae live inside its tissues, converting sunlight into sugars. The algae supply as much as ninety percent of the coral's energy, and they also give the reef its color.
When water temperature rises even one to two degrees Celsius above the usual summer maximum and stays there for several weeks, the partnership breaks down. The algae begin producing compounds that damage the host, and the coral expels them. What remains is translucent tissue over a white skeleton, which is why the event is called bleaching.
A bleached coral is not yet a dead coral. If temperatures fall soon enough, it can reacquire algae and recover, though it will typically grow more slowly and reproduce less for years afterward. If the heat persists, the coral starves.
The difficulty is one of interval rather than intensity. Reefs have always endured occasional hot years. What is new is the shortening gap between them, which leaves too little time for recovery before the next event begins.
The question
The passage suggests that a reef struck by severe bleaching in two consecutive years would most likely
- Option A: recover fully once cooler water returns
- Option B: develop resistance to future temperature increases
- Option C: fare worse than one struck once, because recovery time was insufficientCorrect
- Option D: lose its skeleton before losing its algae
Why C is correct
The final paragraph identifies the shortening gap between events as the central difficulty, since recovery is slow and requires time before the next event.
Why the other options are wrong
- A recover fully once cooler water returns
- Contradicts the passage, which says a recovered coral typically grows more slowly and reproduces less for years afterward.
- B develop resistance to future temperature increases
- The passage makes no such claim; it identifies the shortening gap between events as the problem.
- D lose its skeleton before losing its algae
- Reverses the mechanism. The coral expels the algae, leaving translucent tissue over the skeleton that remains.