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Zorluk: OrtaDetermining Control Groups and Baseline Conditions

A botanist conducted an experiment to measure the rate of transpiration in *Arabidopsis thaliana* when exposed to varying concentrations of exogenous abscisic acid (ABA) under constant ambient conditions (22∘C22^\circ\text{C} and 30%30\% relative humidity). Four groups of 15 plants each were treated as follows:

- Group 1: Sprayed with an equal volume of distilled water containing 0 μM0\ \mu\text{M} ABA.
- Group 2: Sprayed with a 10 μM10\ \mu\text{M} ABA solution.
- Group 3: Sprayed with a 50 μM50\ \mu\text{M} ABA solution.
- Group 4: Sprayed with a 100 μM100\ \mu\text{M} ABA solution.

All groups were maintained under identical lighting and temperature conditions, and transpiration rates were recorded 2 hours post-treatment. Which group served as the control group in this experiment, and what was its primary purpose?

  1. Group 1, because it establishes a baseline rate of transpiration in the absence of ABA to isolate the chemical's specific effect.Cevap
  2. B
    Group 4, because it demonstrates the maximum physiological reduction in transpiration achievable under maximum dosage.
  3. C
    Group 2, because it utilizes the minimal active concentration required to initiate stomatal closure.
  4. D
    All four groups simultaneously, because all environmental factors were kept constant across every plant.

Cevap

Group 1 served as the control group because it received zero concentration of the independent variable (0 μM0\ \mu\text{M} ABA), allowing researchers to establish an unmanipulated baseline measurement to evaluate the specific physiological effects of ABA treatment.
Group 1 is the control group because it receives an equal volume of distilled water without any active ABA (0 μM0\ \mu\text{M}). This isolates the effect of ABA from other variables such as leaf wetting or background humidity, establishing an unmanipulated baseline measurement for comparison.

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1
Identify the independent variable tested in the experiment.
The independent variable is the concentration of exogenous abscisic acid (ABA) sprayed onto the plants (0 μM0\ \mu\text{M}, 10 μM10\ \mu\text{M}, 50 μM50\ \mu\text{M}, and 100 μM100\ \mu\text{M}).
Control groups are defined relative to the manipulation of the independent variable.
2
Determine which group receives a zero-level or unmanipulated treatment of the independent variable.
Group 1 receives 0 μM0\ \mu\text{M} ABA (sprayed only with distilled water).
A negative control group provides a baseline measurement by omitting the active chemical factor being tested while holding all procedural steps identical.
3
Select the option that correctly identifies Group 1 and states its purpose.
Group 1 serves as the baseline to compare against the transpiration rates of the ABA-treated groups.
Without Group 1, researchers could not verify whether changes in transpiration resulted specifically from ABA or from procedural factors such as spraying liquid onto the leaves.

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Determining Control Groups and Baseline Conditions
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Determining Control Groups and Baseline Conditions

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