BIO 9C - Enzymes

Fireflies emit light. The production of light by an organism is called bioluminescence. To generate visible light, cells in a firefly’s tail produce thousands of luciferase enzymes. Luciferase binds to a chemical called luciferin. Once bound, the luciferase enzyme speeds up a chemical reaction that combines an oxygen molecule and luciferin to produce oxyluciferin. This reaction requires energy and releases light. Which of the following best describes how the luciferase enzyme speeds up the chemical reaction?

• Luciferase increases the amount of time the light is visible.

• Luciferase decreases the amount of energy required for the reaction to start.

• Luciferase increases the number of sites on luciferin that must bind to oxygen.

• Luciferase decreases the temperature of the environment inside the body of the firefly.

Tags

NGSS.HS-PS1-4

The graphs show the reaction rate for an enzyme across a range of temperatures and pH.

Based on these data, this enzyme functions best as what temperature and pH?

• Temperature of 27oC and a pH of 4

• Temperature of 37oC and a pH of 6

• Temperature of 40oC and a pH of 8

• Temperature of 50oC and a pH of 10

Tags

NGSS.HS-PS1-5

Pepsin and trypsin are two of the digestive enzymes that break down protein. A group of students studied the pH requirements of these enzymes. The graph below shows the results.

The students found that pepsin functions best in an acid environment and trypsin functions best in a neutral environment. Based on their observations, pepsin most likely aids in digestion in which part of the human body?

• Pancreas

• Intestines

• Mouth

• Stomach

Tags

NGSS.MS-LS1-3

NGSS.MS-LS1-7

The diagram represents one way an enzyme can be inhibited.

Which statement explains the effect of an inhibitor on an enzyme?

• A substrate will be able to bond with the enzyme.

• The enzyme will likely be attacked by immune cells.

• The enzyme will be unable to produce more enzymes.

• A substrate will be unable to attach to the enzyme.

People who have Alzheimer’s disease experience an increasing loss of brain function and cognition over time. Alzheimer’s is characterized by a buildup of abnormal protein fragments that damage brain cells. Recently scientists have discovered an enzyme, BACE2, that decreases these abnormal protein fragments in the brain of a person with Alzheimer’s disease. Which statement explains how BACE2 most likely works?

• BACE2 breaks down into smaller pieces that react with the abnormal protein fragments, forming more complex molecules.

• BACE2 speeds up the reaction that breaks down the abnormal protein fragments.

• BACE2 molecules link several abnormal protein fragments together, forming a complete protein.

• BACE2 is a reactant that combines with the abnormal protein fragments.

Tags

NGSS.HS-PS1-2

A student measured the time required for a protein sample to be completely digested in the presence of an enzyme under different pH levels. At which pH is the enzyme most active?

• 7.1

• 6.9

• 6.8

• 7.2

Tags

NGSS.HS-PS1-5

Based on the graph above, at what temperature range is enzyme activity at its greatest?

• 15-25 ºC

• 25-35 ºC

• 35-45 ºC

• 45-55 ºC

A student measured the time required for a protein sample to be completely digested in the presence of an enzyme under different pH levels. At which pH is the enzyme least active?

• 7.1

• 6.9

• 6.8

• 7.2

Which is the MOST valid conclusion based on this graph?

• Enzymes are not affected greatly by temperature.

• Enzymes work most effectively at low temperatures.

• Raising the temperature always makes an enzyme work better.

• Enzyme function decreases after a certain favorable temperature.

Tags

NGSS.HS-PS1-5

An enzyme and substrate are mixed and heated. The graph above shows how the reaction of sucrose, the substrate, varies with temperature. Which of the following best explains the second increase in reaction rate at higher temperatures?

• The higher temperatures reactivate enzymes that had been damaged.

• The higher temperatures cause the substrate to begin to evaporate.

• The higher temperatures lead to more collisions between enzymes.

• The higher temperatures cause the substrate to react on its own.