A group of students designed experiments to study yeast fermentation under various conditions. During their planning, they identified several procedural issues. Match each experimental procedure to the primary source of error or confounding variable it introduces.
- Testing the fermentation rate of different sugars using different brands of yeast for each sugar type.Introducing biological variability by not using a single, uniform source of the organism.
- Measuring the volume of carbon dioxide gas produced using a beaker with markings instead of a graduated cylinder with markings.Using a measurement tool with low precision to record the dependent variable.
- Placing the yeast mixture in direct sunlight for Trial 1 but in a dark drawer for Trial 2 when testing the effect of temperature.Failing to control external environmental conditions (light and radiant heat) across trials.
Cevap
Testing the fermentation rate with different brands of yeast matches introducing biological variability; measuring gas volume using a beaker matches using a measurement tool with low precision; and placing trials in different light conditions matches failing to control external environmental conditions.
The correct pairings connect each experimental flaw to its specific category of error: varying the yeast source introduces biological variability; using a beaker instead of a graduated cylinder limits measurement precision; and varying light exposure fails to control external environmental conditions.
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Anahtar Kavram
Identifying sources of error and confounding variables in an experimental design.