Question 1

Which of the following best describes the role of an enzyme in a biological reaction?

Accepted Answer

Enzymes lower the activation energy, allowing reactions to proceed more quickly.

Question 2

In the β-Gal Glow™ lab, what is the purpose of using fluorescein in the standard curve?

Accepted Answer

To compare the brightness of fluorescence and estimate the reaction rate.

Question 3

Which equation correctly represents the relationship between enzyme activity and substrate concentration at low substrate levels?

Accepted Answer

$$v = k[E][S]$$

Question 4

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 5

If the temperature of an enzyme-catalyzed reaction is increased beyond the enzyme's optimal range, what is the most likely outcome?

Accepted Answer

The enzyme will denature, causing a decrease in reaction rate.

Question 6

Which of the following best explains why enzymes are specific to their substrates?

Accepted Answer

The three-dimensional shape of the enzyme's active site matches only certain substrates.

Question 7

During the β-Gal Glow™ lab, why does fluorescence only occur when galactose monomers are bound to the fluorescein molecule?

Accepted Answer

The enzyme β-galactosidase releases fluorescein from the substrate, allowing it to fluoresce.

Question 8

Which of the following graphs best represents the effect of increasing substrate concentration on the rate of an enzyme-catalyzed reaction?

Accepted Answer

A curve that rises quickly and then levels off as substrate concentration increases.

Question 9

Which formula describes the Michaelis-Menten relationship between reaction rate ($$v$$), substrate concentration ($$[S]$$), maximum rate ($$V_\max$$), and Michaelis constant ($$K_m$$)?

Accepted Answer

$$v = \frac{V_\max[S]}{K_m + [S]}$$

Question 10

How does a non-competitive inhibitor affect enzyme activity?

Accepted Answer

It binds to a separate site, changing the enzyme's shape and reducing activity.

Question 11

Why do scientists measure the initial reaction rate when studying enzyme kinetics?

Accepted Answer

Because the substrate concentration is highest and product inhibition is minimal.

Question 12

Which of the following statements about pH and enzyme activity is correct?

Accepted Answer

Enzyme activity can decrease if the pH is too high or too low compared to the enzyme's optimum.

Question 13

A student adds more enzyme to a reaction mixture while keeping substrate concentration constant. What is the expected effect on the reaction rate?

Accepted Answer

The reaction rate will increase until the substrate becomes limiting.

Question 14

Which of the following best explains why β-galactosidase can break down lactose but not all glycosidic bonds?

Accepted Answer

The enzyme's active site is specific to the bond between galactose and glucose in lactose.

Question 15

Which of the following is a real-world example of competitive inhibition?

Accepted Answer

A drug binds to an enzyme's active site, preventing the natural substrate from binding.

Question 16

If an enzyme has an optimal temperature of $$37^\circC$$, what will likely happen if the temperature is raised to $$70^\circC$$?

Accepted Answer

The enzyme will denature and lose its catalytic activity.

Question 17

Which of the following best describes the effect of increasing substrate concentration when the enzyme is already saturated?

Accepted Answer

The reaction rate will level off and approach $$V_\max.$$

Question 18

Which of the following is NOT a factor that can affect enzyme activity?

Accepted Answer

Color of the enzyme

Question 19

In the β-Gal Glow™ lab, why is it important to use a standard curve of fluorescein?

Accepted Answer

To compare fluorescence intensity and estimate the rate of enzyme-catalyzed reactions.

Enzyme Function and Laboratory Investigation: β-Gal Glow™

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