A finding question tests whether a study’s results would support a claim with linked causes and effects. Put the claim into a few words, then split it into its links. Predict what each link would look like in the groups being compared. A cause comes before its effect, so use the starting measurements and later results to check the order. Results can share the claim’s topic without showing the full chain.
Hints
- Hint 1
Go back to Morales’s first sentence and split her claim into two links. What changes in the water, and what is that change supposed to do for shell-forming organisms?
- Hint 2
Use the month before installation to check the coves’ starting pH. Why did the team need readings from both before and after adding kelp?
- Hint 3
Trace the order of the pH and shell-growth changes. Which change would need to come first for Morales’s explanation to work?
Step-by-step
Trace both links in order
Step 1Split the claim into two links
Morales says kelp can lessen local ocean acidity (raise pH) and thereby improve the calcification of shell-forming organisms, so support must show both parts. What are the links? Kelp should raise pH, which should help mussels build shells. Shell-thickness growth is the team’s measure of how much shell the mussels build.
- Step 2
Check when the pH gap began
Weekly pH records cover one month before the kelp was installed and six months afterward. What would show that adding kelp changed pH? We’d need a new pH advantage after installation. In the outcome where the difference remained about the same, the gap began before the kelp was added, so it doesn’t support kelp raising pH.
- Step 3
Test shell growth and its timing
The researchers measured shell thickness monthly, so compare growth, not starting thickness. What would show that higher pH helped shell building? Faster growth would need to follow the pH rise, because a cause comes before its effect. The outcome with the same average shell-thickness growth misses this link despite starting with thicker shells. In the outcome with growth several weeks before any pH difference, faster growth starts before the pH change, so that change can’t explain the earlier growth advantage.
- Step 4
Find the full chain in order
The outcome with growth after the pH values diverged starts with similar pH and shell thickness. After installation, the kelp cove’s pH becomes about 0.15 units higher than the control’s, and its mussels then show 18 percent greater shell-thickness growth. Kelp is followed by higher pH and then faster shell growth. Choice D.