A finding question tests whether evidence backs up a proposed explanation. Read the explanation and put its cause and effect in a few words, then split it into links. If the passage gives a competing cause, ask what would tell the causes apart. Strong support should show every link in the claimed path and help rule out a competing cause that predicts the same result. Findings that share the topic may still leave the cause of the result unclear.
Hints
- Hint 1
Venn proposes an underground route for the water. Break that route into the places the water passes through.
- Hint 2
The critics offer a different reason for greater water retention. Ask what would tell the two causes apart.
- Hint 3
Return to the passage’s final sentence. Ask what would show where the juveniles’ water came from and how it reached them.
Step-by-step
Follow the water’s route
Step 1Map Venn’s route
Venn starts with water in deep, moist layers, so support needs to follow that water to the juveniles. What route does she propose? Mature roots draw it upward at night and release it into surface soil, where shallow-rooted juveniles absorb it. She calls this hydraulic redistribution, water moving through mature roots from deep soil into surface soil.
- Step 2
Separate transfer from shade
Why wouldn’t greater hydration alone settle the cause? The critics say canopy shade alone could reduce water loss, so wetter juveniles could result without any underground transfer. We need evidence of the water’s route that also tests whether shade caused the difference.
- Step 3
Find the missing links
Does each finding connect deep water to surface soil, where shallow-rooted juveniles absorb it? With roots from both age groups reaching the labeled layer, juveniles could take deep water directly. The finding with artificial covers tests whether shade caused the difference, but wetter soil and juveniles don’t reveal the water’s source or route. The greenhouse columns containing no juveniles show upward release without showing transfer to juveniles.
- Step 4
Connect deep water to juveniles
What makes the harmless tracer finding evidence that hydraulic redistribution is responsible? The tracer starts in deep soil that juvenile roots can’t reach, and it reaches surface soil and juvenile leaves by dawn only beside trees with intact mature roots. That shows deep water reaching juveniles through mature roots, rather than through the juveniles’ own roots. Shade and temperature are the same across plots, so shade can’t account for the traced transfer. Choice A.