FL Biology EOC - L.18.11 - Enzymes

Enzymes are proteins that are specific to one type of reaction and speeds up the rate of the reaction. Proteins are a catalyst that lowers the activation energy of reactions inside of cells.

• True

• False

Enzymes are proteins that speed up reaction rates in cells but work more effectively at the correct temperatures, pHs, and concentrations. If the temperature or pH factors are too high or low, enzymes may become ineffective and be destroyed.

• True

• False

The graph shows how enzymes affect reactions in cells. Which statement best summarizes the information shown in the graph?

• Enzymes increase the energy of the reactants.
• Enzymes decrease the energy level of the products.
• Enzyme decrease the activation energy of the reaction.
• Enzymes reverse the direction of the reaction.

Tags

NGSS.HS-PS1-4

At high temperatures enzyme activity declines because of:

• Denaturation
• Decreased Kinetic Motion
• Increased H-Bonding
• Dissociation of Ionic Compounds

Which of the factors does NOT affect enzymatic activity?

• Temperature
• pH
• Concentration
• Color

Tags

NGSS.HS-PS1-5

Based on the graph, what pH does Enzyme C work best at?

• 1.5

• 6

• 8

• 9

Tags

NGSS.HS-PS1-5

Based on the graph, what is the optimal temperature for the enzyme?

• 20

• 40

• 43

• 60

What does an enzyme do for the activation energy?

• It raises it

• It slows it down

• It speeds it up

• It reduces it

As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloride acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach.

Which of the following most likely happens to pepsin as it enters the small intestine?

• It becomes inactive.

• It begins to replicate.

• It's shape changes to engulf large proteins.

• It's activity increases to digest more proteins.

Answer explanation

Enzymes have an ideal pH, at which they best function. Many enzymes cannot function at all outside their ideal pH range. Pepsin functions best in the extreme acid environment of the stomach and will, therefore cease to function in the much higher pH of the small intestine.

In living cells, enzymes act as catalysts, which may reduce the amount of activation energy required for a chemical reaction to occur. In the graphs below, pathway x is a solid line representing the uncatalyzed reaction. The dotted line shows the catalyzed reaction.

Which graph best illustrates the changes in a reaction when the catalyst reduces the amount of energy required?

• 
• 
• 
• 

Answer explanation

A catalyst decreases the activation energy needed for a reaction to occur. This allows the reaction to happen faster.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS1-5