A study question asking why two groups differ tests whether you can work out a likely reason from their results. Start by naming each group and what it showed, then compare the conditions around them. A condition shared by both groups can't explain their difference, so look for a condition that changed along with the result. Predict a reason that makes no extra claims, because a likely reason isn't a proven cause. Wrong choices often make claims about things the study never tested.
Hints
- Hint 1
Compare the two habitats and their noise levels. What differed besides the frogs' call pitch?
- Hint 2
Hertz measures frequency, so higher numbers mean higher pitches. Think about how the pitch of the traffic noise relates to the change in the urban calls.
Step-by-step
Compare the calls and the noise
Step 1Identify the repeated difference
The urban males consistently produced calls about 300 hertz higher than forest males of the same frog species. What needs explaining? The blank asks for the most likely reason for this repeated shift toward higher pitch in urban ponds.
- Step 2
Connect the pitch change to the setting
What differed between the settings that might explain the calls? Traffic noise peaks below 500 hertz, while the forests were nearly silent at night. Hertz measures sound frequency, so higher numbers mean higher pitches. Raising a call's pitch could help it stand apart from low-pitched traffic noise, giving us a possible benefit of the urban pitch change.
- Step 3
Draw the likely explanation
Does this suggest an evolutionary response, a change over generations that helps frogs in their surroundings? The question asks what is most likely, not for proof of how the change developed. Higher-pitched calls could be easier to hear over low-pitched traffic, so this choice explains a possible benefit of the urban shift. Choice D.