CFA: Enzymes

Salivary amylase is an enzyme in the human body that digests carbohydrates from food.  When food mixed with saliva enters the stomach, the action of salivary amylase slows dramatically.  Which causes salivary amylase enzyme to stop digesting food?

• The pH of the stomach is lower than in the mouth.

• The concentration of food decreases in the stomach.

• The temperature of the food increases in the stomach.

• The food is mixed more in the mouth than in the stomach

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What does letter Z represent in this image?

• enzyme

• enzyme-product complex

• substrate

• enzyme-substrate complex

• product(s )

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How does the addition of heat affect the ability of an enzyme to help the sugar molecules form a bond?

• Heat allows the sugar molecules to bond more quickly.

• Heat provides places on the enzyme for other molecules to bond

• Heat changes the enzyme so that the sugar molecules can no longer bond

• Heat changes the chemical composition of the sugar molecules so they no longer need the enzyme

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Humans can use starch as an energy source but are unable to use cellulose for energy.  Which of the following best explains the difference in how these molecules are processed in the body?

• Humans can chew starch but cannot chew cellulose

• Humans dissolve starch in blood plasma but cannot dissolve cellulose

• Humans make an enzyme to digest starch but cannot absorb cellulose

• Human muscle cells can absorb starch but cannot absorb cellulose

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Which of the following are characteristics of an enzyme?

• Binds with any type of substrate

• Is reusable

• Is a catalyst for a biochemical reaction

• Increases activation energy

• Is affected by temperature and pH

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Which statement describes how a change in pH affects the activity of an enzyme?

• It alters the shape of the enzyme

• It alters the density of the enzyme

• It alters the solubility of the enzyme

• It alters the concentration of the enzyme

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The graph shows the activity of an enzyme that causes spoiling and discoloration of a fruit at different temperatures.

What temperature will prevent spoiling and discoloration of the fruit?

• 90 degrees

• 80 degrees

• 60 degrees

• 40 degrees

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Trypsin is an enzyme that catalyzes protein digestion in the small intestine.

Based on the two graphs, what is the best temperature and pH for trypsin activity?

• 37 degrees, pH of 8

• 37 degrees, pH of 10

• 59 degrees, pH of 8

• 59 degrees, pH of 10

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The graph shows the activity of an enzyme with respect to change in temperature.

Which point on the graph indicates that the enzyme is least effective in converting a substance into a product?

• P

• Q

• R

• S

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Hydrogen peroxide naturally breaks down into oxygen and water over time.  When exposed to the enzyme catalase, hydrogen peroxide (H₂O₂) is rapidly converted into oxygen and water.

1What feature of catalase most likely is responsible for the change in the rate of conversion of hydrogen peroxide into water and oxygen?

• Catalase speeds up the conversion of H₂O_2, water & oxygen by decreasing the reaction’s activation energy.

• Catalase bonds permanently with the reactants causing H₂O₂ to rapidly break down by increasing the activation energy.

• Catalase has a flexible structure that allows it to bind and convert any small hydrogen containing compound into water and oxygen.

• Catalase remains intact, so small amounts of it convert large amounts of hydrogen peroxide into water & oxygen immediately.

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