Question

quiz! which of the following graphs best shows the relationship between the reaction rate of an enzyme - catalyzed reaction and substrate concentration? graphs labeled a, b, c, d (a: peak then drop; b: increases then levels off; c: peak then drop; d: linear increase) are shown you are using the free version of this game (with ads). if you want to use the ad - free member version, click the button below. please note: this will open in a new tab/window! please save your progress before proceeding! go to ad - free

Explanation:

In an enzyme - catalyzed reaction, initially, as substrate concentration increases, the reaction rate increases because more substrate molecules can bind to the active sites of the enzymes. However, once all the active sites of the enzymes are occupied (saturation point), further increase in substrate concentration will not increase the reaction rate significantly (the rate plateaus).

• Graph A: Shows a peak and then a decrease, which is not consistent with enzyme - catalyzed reaction kinetics as the rate should not decrease after reaching a certain point.
• Graph B: Shows an increase in rate with increasing substrate concentration until it reaches a plateau (when enzymes are saturated), which matches the expected kinetics of an enzyme - catalyzed reaction.
• Graph C: Shows a peak and then a decrease, which is incorrect for enzyme - catalyzed reactions.
• Graph D: Shows a linear increase, which would be the case if there were no enzyme saturation, but in reality, enzymes have a limited number of active sites, so the rate should plateau.

Answer:

B. The graph with a curve that increases with substrate concentration and then plateaus.