Question 1

The enzyme sucrase increases the rate at which sucrose is broken down into glucose and fructose. Sucrase works by

Accepted Answer

Enzymes lower the activation energy required for a reaction to occur, which increases the rate of the reaction. This is also true for sucrase, which facilitates the breakdown of sucrose into glucose and fructose by lowering the activation energy required for the reaction to occur. Therefore, the best choice is B, lowering the activation energy of the reaction.

Question 2

An active site is

Accepted Answer

The active site is the specific region on the enzyme where the substrate binds and the chemical reaction occurs. It is usually a pocket or a groove on the enzyme's surface that has a specific shape and chemical composition that enables it to selectively bind to a particular substrate or group of substrates.

Question 3

The statement "enzymes are highly specific" means that certain

Accepted Answer

Enzymes are specific in the sense that they catalyze only certain reactions involving specific substrates. This specificity is due to the shape and chemical properties of the enzyme's active site, which only allow certain substrates to bind and react. The specificity of enzymes is an important factor in regulating biochemical pathways and ensuring that the proper reactions occur at the right time and place.

Question 4

In the presence of alcohol dehydrogenase, the rate of reduction of acetaldehyde to ethanol increases as the concentration of acetaldehyde is increased. Eventually, the rate of the reaction reaches a maximum, at which point further increases in the concentration of acetaldehyde have no effect. Why?

Accepted Answer

The reaction rate reaches a maximum because all the enzyme molecules (alcohol dehydrogenase) are saturated with acetaldehyde, meaning they are all bound to substrate molecules, and the enzyme is working at its maximum capacity.

Question 5

The ability of an enzyme to change shape when it binds to its substrate is called

Accepted Answer

The ability of an enzyme to change its shape when it binds to its substrate is called induced fit. This allows the enzyme to better fit and interact with the substrate, leading to increased efficiency in the catalytic reaction.

Question 6

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\to$ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Accepted Answer

The binding of glyceraldehyde 3-phosphate to the enzyme forms an enzyme-substrate complex in which the enzyme catalyzes the conversion of glyceraldehyde 3-phosphate to 1,3-diphosphoglycerate. This option is the best choice as it accurately reflects the process of enzyme-catalyzed reactions where the enzyme and the substrate form a temporary complex to facilitate the reaction.

Question 7

Enzymes of the acid-base catalysis type contain

Accepted Answer

Enzymes with acid-base catalysis contain acidic or basic amino acid side chains (R groups) in their active site which participate in proton transfer reactions during catalysis.

Question 8

In some cases, a substrate-enzyme complex is stabilized by

Accepted Answer

A substrate-enzyme complex can be stabilized by a variety of intermolecular interactions, including hydrogen bonds, covalent bonds, ionic attractions, and hydrophobic interactions. Therefore, choice E, "All of the above," is the best answer.

Question 9

The enzyme glucose oxidase binds the six-carbon sugar glucose and catalyzes its conversion to glucono-1,4-actone. Mannose is also a six-carbon sugar, but glucose oxidase cannot bind mannose. The specificity of glucose oxidase is based on the

Accepted Answer

The specificity of enzymes is determined by the three-dimensional shape and structure of their active sites. Glucose oxidase has an active site that is complementary in shape and charge to glucose, allowing it to bind and catalyze the conversion of glucose to glucono-1,4-actone. However, mannose has a slightly different shape and charge distribution than glucose, preventing it from binding to the active site of glucose oxidase. This specificity allows enzymes to selectively bind and catalyze reactions for specific substrates.

Question 10

The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

Accepted Answer

Even though the hydrolysis of sucrose to glucose and fructose is exergonic, it still requires a certain amount of activation energy to occur. This activation energy is high enough that it cannot be overcome by the small amount of energy available at room temperature, and therefore, no detectable conversion occurs.

Question 11

The presence of a catalyst affects the

Accepted Answer

The answer of The presence of a catalyst affects the
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Question 12

Binding of substrate to the active site of an enzyme is

Accepted Answer

Binding of substrate to the active site of an enzyme is usually a reversible process. This means that the enzyme can release the substrate once the reaction has occurred, freeing up the active site to bind other molecules.

Question 13

Which of the following determines the rate of a reaction?

Accepted Answer

The rate of a reaction is determined by the activation energy, which is the energy barrier that must be overcome for the reaction to occur. A higher activation energy impedes the reaction, while a lower activation energy facilitates it. The other choices represent chemical reactions but do not provide information about the rate of the reaction. The overall change in free energy (E) can provide information about the spontaneity and directionality of a reaction, but not its rate.

Question 14

Trypsin and elastase are both enzymes that catalyze hydrolysis of peptide bonds. But trypsin only cuts next to lysine and elastase only cuts next to alanine. Why?

Accepted Answer

The specificity of trypsin and elastase is due to the shape of their active sites which have different amino acid residues that interact with the substrate. Trypsin has a positively charged pocket which interacts with the negatively charged side chain of lysine, while elastase has a smaller pocket which only accommodates the smaller side chain of alanine.

Question 15

The enzyme $\alpha$-amylase increases the rate at which starch is broken down into smaller oligosaccharides by _______ of the reaction.

Accepted Answer

Enzymes such as amylase lower the activation energy required for a reaction to occur, thus increasing the rate of the reaction. The other choices listed do not accurately describe the role of enzymes in catalyzing reactions.

Question 16

Which of the following is an enzyme?

Accepted Answer

Catalase is an enzyme which catalyzes the breakdown of hydrogen peroxide into water and oxygen. Manganese dioxide is a compound, hemoglobin is a protein, and malathion is an insecticide.

Question 17

Which of the following statements about enzymes is true?

Accepted Answer

All of the statements are true. Enzymes are proteins with a specific amino acid sequence and they exhibit high specificity in their catalytic activity. Enzymes lower the energy barrier by providing an alternative reaction pathway, which enables the reaction to occur at a faster rate.

Question 18

Enzymes catalyze a reaction by _______ the substrates.

Accepted Answer

Enzymes can catalyze a reaction by orienting substrates in the correct position for a reaction to occur, inducing strain in the substrate to break chemical bonds, and adding chemical groups or charges to the substrate to increase its reactivity. Therefore, all of the options are correct.

Question 19

The molecules that are acted on by an enzyme are called

Accepted Answer

The term "substrates" refers to the molecules that are acted on by an enzyme.

Question 20

The catalysis mechanism used by lysozyme to break down bacterial cell walls is

Accepted Answer

Lysozyme uses induced strain catalysis to break down bacterial cell walls. This mechanism involves the enzyme distorting the substrate's shape to make its bonds easier to break.

Quiz 8: Energy, Enzymes, and Metabolism

The enzyme sucrase increases the rate at which sucrose is broken down into glucose and fructose. Sucrase works by

An active site is

The statement "enzymes are highly specific" means that certain

In the presence of alcohol dehydrogenase, the rate of reduction of acetaldehyde to ethanol increases as the concentration of acetaldehyde is increased. Eventually, the rate of the reaction reaches a maximum, at which point further increases in the concentration of acetaldehyde have no effect. Why?

The ability of an enzyme to change shape when it binds to its substrate is called

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\to$ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Enzymes of the acid-base catalysis type contain

In some cases, a substrate-enzyme complex is stabilized by

The enzyme glucose oxidase binds the six-carbon sugar glucose and catalyzes its conversion to glucono-1,4-actone. Mannose is also a six-carbon sugar, but glucose oxidase cannot bind mannose. The specificity of glucose oxidase is based on the

The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

The presence of a catalyst affects the

Binding of substrate to the active site of an enzyme is

Which of the following determines the rate of a reaction?

Trypsin and elastase are both enzymes that catalyze hydrolysis of peptide bonds. But trypsin only cuts next to lysine and elastase only cuts next to alanine. Why?

The enzyme $\alpha$ -amylase increases the rate at which starch is broken down into smaller oligosaccharides by _______ of the reaction.

Which of the following is an enzyme?

Which of the following statements about enzymes is true?

Enzymes catalyze a reaction by _______ the substrates.

The molecules that are acted on by an enzyme are called

The catalysis mechanism used by lysozyme to break down bacterial cell walls is

Quiz 8: Energy, Enzymes, and Metabolism

The enzyme sucrase increases the rate at which sucrose is broken down into glucose and fructose. Sucrase works by

An active site is

The statement "enzymes are highly specific" means that certain

In the presence of alcohol dehydrogenase, the rate of reduction of acetaldehyde to ethanol increases as the concentration of acetaldehyde is increased. Eventually, the rate of the reaction reaches a maximum, at which point further increases in the concentration of acetaldehyde have no effect. Why?

The ability of an enzyme to change shape when it binds to its substrate is called

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate →\to→ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Enzymes of the acid-base catalysis type contain

In some cases, a substrate-enzyme complex is stabilized by

The enzyme glucose oxidase binds the six-carbon sugar glucose and catalyzes its conversion to glucono-1,4-actone. Mannose is also a six-carbon sugar, but glucose oxidase cannot bind mannose. The specificity of glucose oxidase is based on the

The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

The presence of a catalyst affects the

Binding of substrate to the active site of an enzyme is

Which of the following determines the rate of a reaction?

Trypsin and elastase are both enzymes that catalyze hydrolysis of peptide bonds. But trypsin only cuts next to lysine and elastase only cuts next to alanine. Why?

The enzyme α\alphaα -amylase increases the rate at which starch is broken down into smaller oligosaccharides by _______ of the reaction.

Which of the following is an enzyme?

Which of the following statements about enzymes is true?

Enzymes catalyze a reaction by _______ the substrates.

The molecules that are acted on by an enzyme are called

The catalysis mechanism used by lysozyme to break down bacterial cell walls is

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\to$ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

The enzyme $\alpha$ -amylase increases the rate at which starch is broken down into smaller oligosaccharides by _______ of the reaction.