A question about a study tests what you can conclude from the groups and their results. Start by naming each group and what it showed, tracking any results that come at different stages. Then ask how the results at each stage relate to one another. If several things change together, the study can't show which one caused the result. Predict the smallest conclusion that fits all the findings, because a conclusion must account for every relevant result.
Hints
- Hint 1
Start with the two milkweed growing conditions and track what happened to the butterflies that fed on each type.
- Hint 2
Compare larval mass gain with adult survival. Do both results point in the same direction for monarchs that ate the high- plants?
- Hint 3
Connect the adult survival test to what it mimicked. What might its result mean if the same pattern occurred during migration?
Step-by-step
Follow the results across life stages
Step 1Name the feeding groups
The scientists compared milkweed grown under ambient atmospheric conditions with milkweed grown under elevated . Larvae were then fed one milkweed type or the other. What should the conclusion connect? It should connect the plants’ growing conditions to what happened to the butterflies, so we need to follow both feeding groups through the study.
- Step 2
Follow both life stages
Does faster larval growth lead to better adult survival? Larvae on high- milkweed gained mass more rapidly during the larval stage, yet fewer of the resulting adults survived the migration-like test. The early gain came with a later cost. So improve monarch fitness overall turns the result around, because rapid growth didn't lead to better survival in this test.
- Step 3
Separate results from causes
The high- plants developed thicker leaves and contained markedly lower levels of cardenolides. Can the comparison show which change caused faster growth? Both leaf features changed together, so neither was tested on its own. That rules out leaf structure matters more than cardenolide levels, because the study can't tell which mattered more for mass gain.
- Step 4
Keep the final claim cautious
What can lower survival tell us beyond the laboratory? The test mimicked the energetic demands of long-distance migration, so the result suggests a possible migration risk even though the study didn't count monarchs in the wild. Calling it a laboratory artifact would need evidence the passage doesn't give. Fewer surviving adults could mean fewer monarchs later, so may ultimately decrease monarch population sizes names that risk while also mentioning the early growth benefit. Choice D.