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Zorluk: KolayDetermining Control Groups and Baseline Conditions

To investigate how salinity affects the heart rate of *Daphnia magna* (water fleas), a researcher prepared 44 beakers containing different water solutions. Beaker 11 contained pond water with 0%0\% added salt. Beaker 22 contained pond water with 0.5%0.5\% added salt. Beaker 33 contained pond water with 1.0%1.0\% added salt. Beaker 44 contained pond water with 1.5%1.5\% added salt. In each beaker, 1010 *Daphnia magna* were placed, and their average heart rate was recorded after 3030 minutes. Which beaker serves as the control group to establish the baseline heart rate under normal conditions?

  1. A
    Beaker 22, because it contains the lowest non-zero concentration of added salt.
  2. Beaker 11, because it contains pond water with no added salt to establish a comparison standard.Cevap
  3. C
    Beaker 33, because it represents the median concentration of added salt.
  4. D
    Beaker 44, because it contains the highest concentration of added salt to show the maximum effect.

Cevap

Beaker 1, because it contains pond water with no added salt to establish a comparison standard.
The correct answer is the option stating that Beaker 1 serves as the control group because it contains pond water with no added salt. A control group is used to establish a baseline condition under normal, unmanipulated circumstances. Since the experiment is testing the effect of salinity on heart rate, the beaker with 0%0\% added salt represents the natural baseline state of the organisms in their usual habitat, allowing the researcher to compare the effects of added salt in the other groups.

Adım Adım Çözüm

1
Identify the independent variable that is being manipulated in the experiment.
The independent variable is the concentration of added salt (0.5%0.5\%, 1.0%1.0\%, and 1.5%1.5\%).
Determining what is being altered helps isolate the baseline condition.
2
Locate the group where the independent variable is not manipulated (left at its normal, default level).
Beaker 1 has 0%0\% added salt, representing normal pond water conditions.
The control group must represent the baseline condition without the experimental treatment.
3
Select the option that correctly identifies this unmanipulated group as the control.
Beaker 1 is the control group.
This group provides the baseline data to compare against the other groups.

Anahtar Kavram

A control group establishes a baseline for comparison by keeping the independent variable at its normal or zero level.
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Konular

Determining Control Groups and Baseline Conditions

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