KS practice #5 of 14 Enzymes

The diagram models how a poison bonds to the active site of an enzyme. Which function is the enzyme most likely unable to perform because of the attachment of the poison molecule?

• the release of stored chemical energy

• the donation of electrons to the substrate

• the supply of activation energy for a reaction

• the catalysis of the reaction with the substrate

The graph shows how the activity of an enzyme changes at different temperatures. Which statement best describes what happens to the enzyme when the temperature of the reaction increases to 63°C?

• The enzyme is used up and the reaction stops.

• The enzyme begins to decrease the rate of the reaction.

• The enzyme continues to increase the rate of the reaction.

• The enzyme changes shape and can no longer speed up the reaction.

Carbonic anhydrase is an enzyme involved in the reaction of carbon dioxide with water form a molecule that dissolves well in the liquid part of blood. How does carbonic anhydrase affect this reaction?

• by making the reaction reversible

• by changing chemical products of the reaction

• by increasing the time needed for the reaction to occur

• by decreasing the amount of energy needed to complete the reaction

Tags

NGSS.HS-PS1-4

Which graph best shows how enzyme activity changes as the temperature is adjusted above and below the enzyme’s optimum temperature?

• graph A

• graph B

• graph C

• graph D

The enzyme pepsin is found in the stomach. Which medicine is most likely to directly interfere with pepsin’s function?

• a medicine that affects pH

• a medicine that prevents clotting

• a medicine that blocks neural impulses

• a medicine that lowers cholesterol levels

Which action must occur for an enzyme to catalyze a chemical reaction?

• A competitive inhibitor must first bind to an active site.

• A substrate must bind to an active site of the enzyme.

• A substrate must bind to an allosteric site of the enzyme.

• A noncompetitive inhibitor must first bind to an active site.

Lipase is an enzyme that breaks down lipids in the digestive system of humans. It functions best at a pH range of 4.0 to 5.0. When a person takes an antacid tablet to relieve heart burn, the antacid increases the pH to around 7 in certain areas of the digestive system. Which initial effect would most likely be caused by a change in pH?

• More lipids would be digested.

• Fewer lipids would be digested.

• The production of lipase molecules would increase.

• The production of lipase molecules would decrease.

Which statement best describes a relationship between enzymes and a simple biological reaction?

• Enzymes will increase the amount of substrate formed during a biological reaction.

• Enzymes will decrease the amount of substrate formed during a biological reaction.

• A reaction rate can be increased when the specific enzyme for a biological reaction is present.

• A reaction rate can be decreased when multiple enzymes for a biological reaction are present

Microbes in the digestive system break down food, which allows nutrients to be absorbed by the body’s cells. How will these body cells most likely be affected if an individual suffers from a high fever?

• The body cells will swell because an increase in temperature promotes greater water absorption.

• The body cells will stop absorbing nutrients because the heat melts the lipid bilayer of the plasma membrane.

• The body cells will shrivel because the heat eliminates the chemical gradients on either side of the plasma membrane.

• The body cells will bring in fewer nutrient molecules because the transport proteins lose their proper shape due to the high temperature.

Tags

NGSS.HS-LS1-3

Each cell in the human body contains thousands of different enzymes responsible for regulating reactions within the cell. Which statement explains why a single enzyme is unable to regulate a variety of reactions?

• The binding of a product and an enzyme is specific.

• The binding of a substrate and an enzyme is specific.

• The enzyme is consumed by the products of the reactions.

• The enzyme is consumed by the substrates of the reactions