An investigator conducted an experiment to evaluate how different concentrations of a newl… — ACT

An investigator conducted an experiment to evaluate how different concentrations of a newly synthesized chemical compound, Compound Y, affect the rate of starch hydrolysis by the enzyme amylase. The experiment was conducted at $37^\circ\text{C}$ and a neutral pH of $7.0$ . Four trials were prepared with the compositions shown in the table below:

Trial	Starch Solution (mL)	Amylase Solution (mL)	Compound Y Solution (mL)	Distilled Water (mL)
1	$5.0$	$1.0$	$0.0$	$1.0$
2	$5.0$	$1.0$	$1.0$ ( $0.1\text{ M}$ )	$0.0$
3	$5.0$	$1.0$	$1.0$ ( $0.5\text{ M}$ )	$0.0$
4	$5.0$	$0.0$	$0.0$	$2.0$

The rate of starch hydrolysis was determined for each trial by measuring the concentration of maltose produced after $10\text{ minutes}$ .

To determine the effect of Compound Y on amylase activity, the investigator compared the rate of starch hydrolysis in the trials containing Compound Y to the rate in a control group that established the baseline activity of amylase alone. Which trial served as this control group?

Trial 1Answer
B
Trial 2
C
Trial 4
D
Trial 3

Answer

Trial 1

The correct answer is Trial 1. To isolate the effect of Compound Y on the enzyme amylase, the control group must contain the active enzyme and the substrate (starch) under identical physical conditions (temperature and pH) but without any Compound Y. Trial 1 meets these criteria by substituting the Compound Y solution with distilled water to keep the total volume constant.

Step-by-Step Solution

Identify the goal of the experiment and the variable being tested.

The experiment investigates the effect of Compound Y on the rate of starch hydrolysis by the enzyme amylase. The independent variable is the concentration of Compound Y.

Understanding the variable being tested is essential to identifying the appropriate control that isolates this variable.

Determine the baseline conditions required to isolate the effect of Compound Y.

To see how Compound Y affects the enzyme's rate of reaction, we need to compare it to a reaction mixture containing both the enzyme (amylase) and its substrate (starch) but lacking Compound Y.

A control group must keep all other variables constant while omitting the independent variable of interest.

Analyze the compositions of the trials to find the matching setup.

Trial 1 has both starch and amylase, but

0.0\text{ mL}

of Compound Y (replaced by distilled water to maintain a constant volume). Trial 4 has no amylase at all, meaning it cannot show the baseline activity of the enzyme. Therefore, Trial 1 is the correct control group.

This isolates the presence of Compound Y as the single variable differing between the baseline and the active experimental groups.

Key Concept

A control group or baseline condition provides a standard of comparison to isolate the effect of the independent variable, maintaining all other experimental conditions constant while excluding the variable under study.

Estimated Time:1m 30s

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