When two experiments sit in one passage, find the one factor that changed and treat everything else as the same. That single difference is usually the answer. Research-summaries passages do this on purpose, in research summaries.
One variable at a time
Experiment 1 used 10°C. Experiment 2 used 20°C. Same species, same time, same measurement. The independent variable is temperature, in independent and dependent variables. A true control is the no-treatment version, in the control group.
Look at the named experiment's figure, not the other one, in the right figure and the right interval.
The bottom line
Isolate the difference. If both setups match except one setting, that setting caused any change in the results.
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