Question 159·Hard·Command of Evidence
While surveying red maple (Acer rubrum) populations along a mountain slope, ecologist Maria Delgado observed that trees growing at the highest elevations produce far fewer seeds than those at lower elevations, yet each of the high-elevation seeds is, on average, significantly larger. Delgado hypothesized that limited pollinator activity at higher elevations reduces the likelihood that the trees’ flowers will be fertilized, so the trees compensate by allocating more resources to every fertilized ovule, increasing the chance that any given seed will successfully germinate.
Which additional observation, if true, would most directly challenge Delgado’s hypothesis?
For SAT Reading questions that ask which statement would "most directly support" or "most directly challenge" a hypothesis, first restate the hypothesis in simple cause-and-effect terms and identify its key assumption(s). Then, go through the choices and quickly label each one as (a) supporting, (b) neutral/irrelevant, or (c) contradicting that key assumption. Eliminate options that merely add background detail, introduce side factors, or even strengthen the hypothesis. Choose the answer that most clearly conflicts with the core claim the author is making, especially when it overturns a necessary condition (like a claimed difference between two locations or groups).
Hints
Pinpoint the core cause in the hypothesis
Focus on why Delgado thinks there are fewer but larger seeds at high elevations. What does she say is happening with pollinators and fertilization?
Think about what would undermine that cause
If the hypothesis says "X causes Y," then evidence that X is not actually different between the situations being compared will strongly weaken the hypothesis. Ask yourself: what is X here?
Separate support from contradiction
Some answers may show that large seeds are helpful or that high elevations are stressful; those would tend to support or be consistent with her idea. Look for the option that conflicts with the specific claim about pollinator activity at different elevations.
Look closely at comparisons between elevations
Pay special attention to any choice that directly compares high and low elevations in terms of pollinator visits, not just seed size or soil conditions.
Step-by-step Explanation
Restate the hypothesis in your own words
First, simplify what Delgado is claiming:
- At high elevations there are fewer pollinator visits, so fewer flowers get fertilized.
- Because fewer ovules are fertilized, the tree can put more resources into each fertilized ovule, making fewer but larger seeds.
- Larger seeds are assumed to have a better chance of germinating successfully.
So the key causal chain is: low pollinator activity → fewer fertilized flowers → fewer but larger seeds.
Understand what it means to "most directly challenge" a hypothesis
To challenge a hypothesis, an observation should contradict or seriously undermine a key part of that hypothesis.
Ask yourself:
- What must be true for her explanation to work?
- If that thing is shown to be false, would her idea fall apart?
Here, the central assumption is that pollinator activity is lower at high elevations and that this difference in pollination is what explains the seed pattern.
Test each choice against the key assumption
Now compare each answer to the hypothesis:
- Some choices might support her idea (showing that large seeds do better, or that conditions at high elevation are harsh).
- Some might talk about other factors (like soil nutrients) that could offer an alternative explanation.
- Only one will directly contradict the claim that high elevations have reduced pollinator activity or that this reduction explains the seed pattern.
Eliminate any option that either supports the hypothesis or is mostly about something other than pollinator activity at high vs. low elevations.
Identify the observation that directly contradicts the hypothesis
The hypothesis depends on reduced pollinator activity at high elevations. If data show that the number of pollinator visits per tree at high elevations is about the same as at low elevations, then her main explanation—that fewer seeds result from limited pollination—can’t be right.
Therefore, the observation stating that direct surveys show that the number of pollinator visits per tree at high elevations is roughly equal to the number at low elevations most directly challenges Delgado’s hypothesis.