Question 48·Hard·Inferences
When environmental stress such as rising sea temperature forces reef-building corals to expel the symbiotic algae that supply much of their energy, the corals typically turn stark white—a phenomenon known as bleaching. Marine biologist Tia Rodríguez and colleagues recently documented several reef sites in which bleached corals nonetheless appeared vividly colored. Laboratory analysis revealed that the corals had produced high concentrations of fluorescent pigments that masked the characteristic whitening but did not restore the lost algae or the corals’ ability to photosynthesize efficiently. These findings suggest that _____
Which choice most logically completes the text?
For “These findings suggest that” inference questions, paraphrase the study’s key result and then state the broader implication in cautious terms. Prefer answers about what observers can and cannot conclude (limits of visual cues, measurement issues) and eliminate choices that add unstated mechanisms (recovery, increased resilience) or make claims stronger than the evidence.
Hints
Locate the key contrast in the passage
Focus on what the fluorescent pigments change (appearance) and what they do not change (algae and efficient photosynthesis).
Think about appearance vs. reality
If a coral can look colorful while still being bleached, what might that imply about judging reef health just by looking?
Aim for a cautious, study-based implication
The best completion should be a reasonable conclusion drawn from the findings, not a claim about recovery or reduced stress that the study didn’t show.
Watch for unsupported leaps
Eliminate choices that assume pigments restore function, reduce stress, or occur only under certain conditions—unless the passage states that.
Step-by-step Explanation
Understand what bleaching and pigments do
First, restate the key science facts:
- When corals bleach, they lose the symbiotic algae that provide much of their energy, and they turn stark white.
- At some sites, bleached corals instead appeared vividly colored.
- Lab analysis showed these colors came from high concentrations of fluorescent pigments.
- Crucially, these pigments did not bring back the algae or restore efficient photosynthesis.
So the corals looked colorful, but they were still missing their main energy source and were not functioning normally.
Infer what problem this creates for observers
Ask: If corals can be badly stressed but still look vivid and colorful, what problem might that create for people checking reef health?
An observer might assume “colorful = healthy,” even though the lab results show the corals are still bleached and not photosynthesizing efficiently. This creates a mismatch between appearance and true condition.
Decide what the findings "suggest" in general terms
Because the sentence begins with “These findings suggest that…,” the correct completion should be a broader implication of the study:
- Color alone can be misleading.
- Some stressed/bleached corals may not look stark white.
- Therefore, visual impressions may fail to capture the real extent of physiological stress.
Match the inference to the answer choices
Compare each option to what the study shows:
- “Fluorescent pigments are a sign that bleached corals are regaining the algae needed for efficient photosynthesis.” This conflicts with the lab finding that pigments did not restore algae or efficient photosynthesis.
- “Reefs with many vividly colored corals are likely experiencing less environmental stress…” The passage never links vivid coloration to lower stress; it suggests the opposite risk (stress can be hidden).
- “Fluorescent pigments make bleaching easier to detect because they appear only in stressed corals.” The passage doesn’t claim pigments occur only in stressed corals, and it emphasizes that pigments can mask the usual whitening.
- “Using visual inspection alone may significantly underestimate the extent of stress in a coral reef.” This directly matches the implication that corals can look vivid even while still bleached and impaired.
Therefore, the correct answer is: using visual inspection alone may significantly underestimate the extent of stress in a coral reef.