A student performed an experiment to measure the rate of photosynthesis in *Elodea* (an aquatic plant) by counting oxygen bubbles produced per minute under various light conditions. Four identical glass beakers were prepared with equal volumes of water and equal masses of *Elodea*:
- Setup 1: Exposed to a white light lamp at a distance of .
- Setup 2: Exposed to a blue light lamp at a distance of .
- Setup 3: Exposed to a red light lamp at a distance of .
- Setup 4: Placed inside a light-tight dark chamber with no light source.
Which setup served as the control group to establish a baseline rate of oxygen production in the absence of the test variable?
- ASetup 1, because white light contains all wavelengths of visible light.
- BSetup 2, because blue light is absorbed efficiently by chlorophyll.
- CSetup 3, because red light stimulates photosynthetic activity.
- Setup 4, because it measures background oxygen production without the presence of light.Cevap
Cevap
Setup 4 served as the control group because it measured oxygen output without light exposure.
Setup 4 completely removes the independent variable (light) by placing the plant in a light-tight chamber. This establishes a baseline level of oxygen production (or lack thereof) to ensure that any oxygen produced in Setups 1, 2, and 3 is directly attributable to light exposure.
Adım Adım Çözüm
Anahtar Kavram
Control groups isolate the independent variable to determine baseline measurements and confirm that observed results are due to the experimental manipulation.
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