Unit 1 Chapter 3 (1st Secondary) Biology
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The following graph shows the effect of altering a factor on the rate of an enzyme controlled reaction. What is shown on the x axis?
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PH
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Temperature
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Substrate concentration
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Enzyme concentration
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This quiz assesses understanding of enzyme activity, focusing on factors like temperature and pH, and their effects on enzymes such as pepsin and trypsin.
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- 2.
The following graph shows the effect of a factor on the activity of two enzymes. What should be shown on the x axis?
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Temperature
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PH
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Substrate concentration
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Enzyme concentration
Correct Answer
A. pHExplanation
The x-axis of the graph should represent the factor that is being tested, which in this case is the effect of a factor on the activity of two enzymes. The graph shows the effect of this factor on the enzymes, so the x-axis should represent the different levels or values of the factor being tested. In this case, the factor being tested is pH, so pH should be shown on the x-axis.Rate this question:
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- 3.
Why does the rate of enzyme activity decrease as it approaches 40O C?
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The enzyme is becoming denatured.
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There is more enzyme present.
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There is more kinetic energy.
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There are more collisions between enzyme and substrate (forming the enzyme-substrate complex.)
Correct Answer
A. The enzyme is becoming denatured.Explanation
As the temperature approaches 40°C, the enzyme starts to denature. Denaturation is the process in which the enzyme loses its shape and function due to the disruption of its weak chemical bonds. The increase in temperature causes the enzyme's active site to change, preventing it from effectively binding with the substrate and catalyzing the reaction. Therefore, the rate of enzyme activity decreases as it approaches 40°C due to denaturation.Rate this question:
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- 4.
The figure below illustrates the enzyme-substrate interaction. What do the labels A, B, C, and D mean?
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A enzyme-substrate complex / B enzyme / C products / D substrate
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A enzyme-substrate complex / B substrate / C enzyme / D products
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A substrate / B enzyme / C enzyme-substrate complex / D products
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A products / B substrate / C enzyme / D enzyme substrate complex
Correct Answer
A. A enzyme-substrate complex / B substrate / C enzyme / D productsExplanation
The labels A, B, C, and D in the figure represent the different components involved in the enzyme-substrate interaction. A represents the enzyme-substrate complex, where the enzyme and substrate are bound together. B represents the substrate, which is the molecule that the enzyme acts upon. C represents the enzyme, which is the protein that catalyzes the chemical reaction. D represents the products, which are the molecules formed as a result of the enzymatic reaction.Rate this question:
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- 5.
In the reaction involving the catalase enzyme and the hydrogen peroxide, the enzyme breaks the reactant into …….
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H2O and O2
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H+ and O2
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H2O2 + H2
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None of the above
Correct Answer
A. H2O and O2Explanation
The catalase enzyme catalyzes the decomposition of hydrogen peroxide (H2O2) into water (H2O) and oxygen gas (O2). This reaction occurs naturally in cells and helps to break down the toxic hydrogen peroxide into harmless water and oxygen.Rate this question:
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- 6.
In the reaction involving the catalase and the hydrogen peroxide, at the beginning time, the …..
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Number of reactant break down decreases
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Number of reactant break down increases
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Reactants break down decreases first then increases
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None of them
Correct Answer
A. Number of reactant break down increasesExplanation
In the reaction involving catalase and hydrogen peroxide, the catalase enzyme helps break down the hydrogen peroxide into water and oxygen. At the beginning of the reaction, there is a high concentration of hydrogen peroxide, and as the reaction progresses, the catalase enzyme breaks down more and more hydrogen peroxide molecules. Therefore, the number of reactant break down increases over time.Rate this question:
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- 7.
Most enzymes work best at a pH of about ……..
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5
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6
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7
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8
Correct Answer
A. 7Explanation
Most enzymes work best at a pH of around 7 because this is the pH at which their active site is most stable and can effectively bind to the substrate. At higher or lower pH levels, the active site may become denatured or the charges on the enzyme and substrate may be disrupted, preventing proper binding and reducing enzyme activity. Therefore, a pH of 7 is optimal for most enzymes to function efficiently.Rate this question:
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- 8.
The pancreatic juice does not contain …….
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Pancreatic amylase
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Lipase
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Pepsin
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Trypsin
Correct Answer
A. PepsinExplanation
The pancreatic juice is a fluid secreted by the pancreas that aids in digestion. It contains enzymes such as pancreatic amylase, lipase, and trypsin, which help break down carbohydrates, fats, and proteins respectively. However, pepsin is not found in pancreatic juice. Pepsin is an enzyme that is produced in the stomach and helps in the digestion of proteins.Rate this question:
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- 9.
The chemical reactions in the living organisms are catalyzed by biological catalysts called ……..
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Hormones
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Enzymes
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Carbohydrates
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Lipids
Correct Answer
A. EnzymesExplanation
Enzymes are biological catalysts that facilitate chemical reactions in living organisms. They speed up the rate of reactions by lowering the activation energy required for the reaction to occur. Enzymes are highly specific and can only catalyze a particular reaction or a group of related reactions. They are essential for various metabolic processes such as digestion, respiration, and synthesis of molecules. Hormones, carbohydrates, and lipids are important components of living organisms but do not directly catalyze chemical reactions.Rate this question:
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- 10.
As the temperature increases from 00 C to the optimal temperature, the reacting molecules gain…….. energy and move faster.
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Less
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More
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No
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None of the above
Correct Answer
A. MoreExplanation
As the temperature increases, the reacting molecules gain more energy and move faster. This is because higher temperatures provide more kinetic energy to the molecules, causing them to vibrate and move at a faster rate.Rate this question:
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- 11.
Enzymes in general start to get damaged with a rise in temperature above …... OC
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40
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80
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Zero
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30
Correct Answer
A. 40Explanation
Enzymes are proteins that catalyze chemical reactions in the body. However, they are sensitive to changes in temperature. As the temperature increases, the enzymes become more and more damaged. At a certain temperature, known as the optimum temperature, enzymes function at their highest efficiency. Above this temperature, the enzymes start to denature and lose their shape, leading to a decrease in their activity. Therefore, the correct answer is 40 degrees Celsius, as it represents the temperature at which enzymes begin to get damaged.Rate this question:
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- 12.
The enzyme sticks to the …… and product is released.
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Enzyme-substrate complex
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Reaction
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Neighboring enzyme
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Substrate
Correct Answer
A. SubstrateExplanation
The correct answer is "Substrate". In an enzymatic reaction, the enzyme binds to the substrate to form an enzyme-substrate complex. This complex allows the enzyme to catalyze the reaction and convert the substrate into a product. Once the reaction is complete, the product is released from the enzyme, allowing it to bind to another substrate molecule and continue the catalytic process. Therefore, the substrate is the molecule to which the enzyme binds and from which the product is eventually released.Rate this question:
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- 13.
Enzymes …..... complex molecules into simpler ones.
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Build up
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Break down
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Accelerate
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Deactivate
Correct Answer
A. Break downExplanation
Enzymes are biological catalysts that speed up chemical reactions in the body. They do this by breaking down complex molecules into simpler ones. This process is known as catabolism. Therefore, the correct answer is "Break down."Rate this question:
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- 14.
Few enzymes …….. complex molecules from simple ones.
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Build up
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Break down
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Inhibit the formation of
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Deactivate
Correct Answer
A. Build upExplanation
Enzymes are biological catalysts that speed up chemical reactions in living organisms. In this context, enzymes are responsible for building up complex molecules from simple ones. They facilitate the synthesis of larger molecules by joining smaller molecules together through chemical reactions. This process is known as anabolic reactions. Therefore, the correct answer is "Build up."Rate this question:
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- 15.
In the graph shown below, what are the terms (A), (B), (C) and (D)?
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(A) reactants/ (B) products/ (C) with enzyme/ (D) without enzyme
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(A) products/ (B) reactants/ (C) with enzyme/ (D) without enzyme
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(A) Products/ (B) reactants/ (C) without enzyme/ (D) with enzyme
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(A) Reactants/ (B) products/ (C) without enzyme/ (D) with enzyme
Correct Answer
A. (A) Reactants/ (B) products/ (C) without enzyme/ (D) with enzymeExplanation
The graph shows the relationship between reactants and products in a chemical reaction, with and without the presence of an enzyme. The x-axis represents time, while the y-axis represents the concentration of reactants and products. The correct answer is (A) Reactants/ (B) products/ (C) without enzyme/ (D) with enzyme because it accurately describes the terms represented by each letter in the graph.Rate this question:
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- 16.
In humans salivary amylase enzyme breaks down starch. What is the optimum pH for this reaction?
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7.8 - 8.2
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2.5 - 3
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5.7 - 6
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6.8 - 7.5
Correct Answer
A. 6.8 - 7.5Explanation
Salivary amylase is an enzyme that helps break down starch in the mouth. Enzymes usually have an optimum pH at which they function most effectively. In the case of salivary amylase, the optimum pH range for its activity is 6.8 - 7.5. This means that the enzyme works best and catalyzes the breakdown of starch most efficiently within this pH range. Deviations from this pH range can result in reduced enzyme activity and slower starch digestion.Rate this question:
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- 17.
From the experiment of the action of catalase enzyme on the hydrogen peroxide, the catalase works best at a pH of ….....
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1
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4
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7
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10
Correct Answer
A. 7Explanation
Catalase is an enzyme that helps break down hydrogen peroxide into water and oxygen. Enzymes are sensitive to changes in pH, and their activity can be affected by it. In this experiment, the catalase enzyme works best at a pH of 7. This is because pH 7 is considered neutral, and many enzymes have an optimal pH around this range. At pH 7, the enzyme's active site is in the proper conformation to bind with the hydrogen peroxide substrate and catalyze the reaction efficiently.Rate this question:
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- 18.
Which of the following statements is true about metabolism?
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It only involves the processes that build up the large molecules in the body.
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It only involves the processes that break down the small molecules in the body.
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It only involves the processes that break down the large molecules in the body.
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It involves all of the processes that break down and build up molecules in the body.
Correct Answer
A. It involves all of the processes that break down and build up molecules in the body.Explanation
Metabolism involves all of the processes that break down and build up molecules in the body. This includes both anabolic processes, which build up larger molecules from smaller ones, and catabolic processes, which break down larger molecules into smaller ones. Therefore, the statement that metabolism involves all of the processes that break down and build up molecules in the body is true.Rate this question:
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- 19.
Which is not true about enzymes?
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Enzymes are biological catalysts.
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Enzymes are proteins.
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Enzymes speed up reactions by raising the activation energy required to start the reaction.
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Enzymes are not changed in the reaction.
Correct Answer
A. Enzymes speed up reactions by raising the activation energy required to start the reaction.Explanation
Enzymes actually lower the activation energy required to start a reaction, not raise it. This allows reactions to occur more easily and at a faster rate.Rate this question:
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- 20.
At 0°C, enzyme action …… because the rate of formation of enzyme substrate complex ……... . But raising the temperature, …….. the formation rate. Therefore enzyme action ………. .
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Decreases / increases / speeds up / stops.
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Increases / stops / decreases / speeds up.
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Speeds up / increases / stops / decreases.
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Stops / decreases / speeds up / increases.
Correct Answer
A. Stops / decreases / speeds up / increases.Explanation
At 0°C, enzyme action stops because the rate of formation of enzyme-substrate complex decreases. But raising the temperature speeds up the formation rate. Therefore, enzyme action increases.Rate this question:
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- 21.
Why are amylases, proteases and lipases added to detergents? Because ....
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Amylases break down starch stains / proteases break down protein stains / lipases break down fat and grease stains.
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Amylases break down protein stains / proteases break down starch stains / lipases break down fat and grease stains.
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Amylases break down starch stains / proteases break down fat and grease stains / lipases break down protein stains.
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Amylases break down fat and grease stains / proteases break down protein stains / lipases break down starch stains.
Correct Answer
A. Amylases break down starch stains / proteases break down protein stains / lipases break down fat and grease stains. -
- 22.
Enzyme catalyzing rearrangement of atomic groupings without altering molecular weight or number of atoms is ……
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Ligase
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Isomerase
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Lipase
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Pepsin
Correct Answer
A. IsomeraseExplanation
Isomerases are enzymes that catalyze the rearrangement of atomic groupings within a molecule, resulting in the formation of isomers. Isomers are molecules that have the same molecular formula but different structural arrangements. In this case, the enzyme catalyzes the rearrangement of atomic groupings without altering the molecular weight or number of atoms in the molecule. Ligase, lipase, and pepsin do not perform this specific function, making isomerase the correct answer.Rate this question:
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- 23.
“Lock and key theory” is related with …....
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Digestion of carbohydrates in the intestine.
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Absorption of carbohydrates from intestine.
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Absorption of proteins to the blood.
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Diffusion of water to inside plant cells.
Correct Answer
A. Digestion of carbohydrates in the intestine.Explanation
The lock and key theory is related to the digestion of carbohydrates in the intestine. This theory suggests that enzymes, which act as the "keys," have specific shapes that fit into the "locks" of specific substrates. In the case of carbohydrate digestion, enzymes such as amylase break down complex carbohydrates into smaller molecules that can be absorbed and utilized by the body. This process of breaking down carbohydrates into simpler forms is essential for their digestion and absorption in the intestine.Rate this question:
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- 24.
An experiment was carried out to know the effect of the acidity degree and the enzyme action; the results were recorded on the figure below. What are the X-axis and the Y-axis represent?
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A
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B
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C
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D
Correct Answer
A. AExplanation
The X-axis represents the acidity degree, while the Y-axis represents the enzyme action.Rate this question:
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- 25.
The enzyme in the diagram has had its active site irreversibly changed. What scientific term describes this change?
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Deformation
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Decomposition
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Denaturation
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Deposition
Correct Answer
A. DenaturationExplanation
Denaturation is the correct term to describe the irreversible change in the active site of an enzyme. Denaturation occurs when the protein structure of the enzyme is disrupted, leading to the loss of its normal shape and function. This can be caused by factors such as high temperature, extreme pH levels, or exposure to certain chemicals.Rate this question:
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- 26.
With reference to enzymes, what does “denatured” mean?
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The enzyme’s active site has been irreversibly changed.
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The enzyme has been killed.
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The enzyme has been used as much as it can be and must be replaced.
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The enzyme has been damaged and subsequently works more slowly.
Correct Answer
A. The enzyme’s active site has been irreversibly changed.Explanation
Denaturation of an enzyme refers to the irreversible alteration of its active site, which is the specific region where substrates bind and reactions occur. This change can be caused by factors such as high temperature, extreme pH, or exposure to certain chemicals. When the active site is denatured, the enzyme loses its ability to catalyze reactions effectively or at all. This is different from being killed or used up, as denaturation refers specifically to the structural change in the active site.Rate this question:
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- 27.
In some metabolic reactions, large molecules are broken down into smaller ones. What biological reaction breaks down glucose in cells to release energy?
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Mitosis
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Respiration
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Osmosis
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Photosynthesis
Correct Answer
A. RespirationExplanation
Respiration is the biological reaction that breaks down glucose in cells to release energy. During respiration, glucose is broken down in a series of chemical reactions, ultimately producing ATP (adenosine triphosphate), which is the main energy currency of cells. This process occurs in the mitochondria of cells and is essential for providing energy for various cellular activities. Mitosis is the process of cell division, osmosis is the movement of water across a semipermeable membrane, and photosynthesis is the process by which plants convert sunlight into energy.Rate this question:
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- 28.
What monomer subunits join together to form starch in a metabolic reaction?
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Sucrose
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Glucose
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Glycogen
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Cellulose
Correct Answer
A. GlucoseExplanation
Glucose monomer subunits join together to form starch in a metabolic reaction. Starch is a polysaccharide that serves as a storage form of energy in plants. Glucose molecules link together through glycosidic bonds to form long chains of starch. This allows plants to store excess glucose for later use when energy is needed. Sucrose, glycogen, and cellulose are also polysaccharides, but they are not the monomer subunits that form starch.Rate this question:
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- 29.
Fill in the blank: The reactant that an enzyme will bind to, due to its complementary shape, is a/an …………..
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Active site
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Protein
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Catalyst
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Substrate
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Product
Correct Answer
A. SubstrateExplanation
Enzymes are proteins that act as catalysts in biochemical reactions. They have a specific region called the active site where they bind to a molecule called the substrate. The active site and the substrate have complementary shapes, allowing them to fit together like a lock and key. This binding of the substrate to the active site facilitates the reaction, allowing the enzyme to catalyze the conversion of the substrate into a product. Therefore, the correct answer is substrate.Rate this question:
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- 30.
The graph provided shows the reaction profile of a biological reaction. Which letter indicates the activation energy?
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X
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Y
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Z
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W
Correct Answer
A. XExplanation
The activation energy is the energy required for a reaction to occur. In the given graph, the letter X represents the highest point on the reaction profile, which indicates the activation energy. This is because the reactants need to overcome this energy barrier in order to proceed to the products.Rate this question:
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- 31.
Which of the following statements correctly links enzymes, substrates, and active sites?
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The enzyme’s active site is constantly changing to have a complementary shape to a range of substrates.
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The substrate has an active site that has a complementary shape to a range of enzymes.
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The substrate has an active site that has an identical shape to a specific enzyme.
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The enzyme has an active site that has an identical shape to a range of substrates.
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The enzyme has an active site that has a complementary shape to a specific substrate.
Correct Answer
A. The enzyme has an active site that has a complementary shape to a specific substrate.Explanation
The correct answer is "The enzyme has an active site that has a complementary shape to a specific substrate." This statement accurately describes the relationship between enzymes, substrates, and active sites. Enzymes are proteins that catalyze chemical reactions by binding to specific substrates at their active sites. The active site of an enzyme is specifically shaped to fit and bind with a particular substrate, like a lock and key. This complementary shape allows the enzyme to interact with the substrate and facilitate the reaction.Rate this question:
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- 32.
The enzyme differs from the chemical catalyst in that the enzyme ……….
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Does not decompose in the reaction
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Increases the rate of reaction
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Has an organic chemical structure
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Decreases heat of activation of the reaction
Correct Answer
A. Has an organic chemical structureExplanation
Enzymes are biological catalysts that are made up of organic molecules, specifically proteins. Unlike chemical catalysts, which can be inorganic compounds, enzymes have a complex organic chemical structure. This organic structure allows enzymes to interact with specific substrates and speed up chemical reactions without being consumed or decomposed in the process. Therefore, the correct answer is that enzymes have an organic chemical structure.Rate this question:
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- 33.
Which of the following graphs represents the metabolism in a baby?
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A
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B
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C
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None
Correct Answer
A. BExplanation
Graph B represents the metabolism in a baby. The graph shows a steady increase in metabolism over time, which is typical for a growing baby. The other graphs do not show this consistent upward trend, making them less likely to represent the metabolism in a baby.Rate this question:
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- 34.
Without digestive enzymes, animals would not be able to break down food molecules quickly enough to provide themselves with the energy and nutrients they need to survive. Which of the following would most likely happen in the absence of digestive enzymes in an animal’s body?
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The rate of digestion reactions would increase extremely.
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The digestion reactions would proceed but at an extremely lower rate.
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The digestion reactions would stop completely.
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The rate of digestion reactions would remain the same.
Correct Answer
A. The digestion reactions would proceed but at an extremely lower rate.Explanation
Digestive enzymes play a crucial role in breaking down food molecules into smaller, absorbable units. Without these enzymes, the digestion reactions would still occur, but at a much slower pace. This is because the enzymes are responsible for speeding up the chemical reactions involved in digestion. Without them, the process would be significantly slowed down, resulting in a much lower rate of digestion reactions.Rate this question:
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- 35.
Which of the following reaction is catalyzed by Lipase?
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Breaking of bonds
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Formation of bonds
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Intramolecular rearrangement of bonds
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Transfer of group from one molecule to another
Correct Answer
A. Breaking of bondsExplanation
Lipase is an enzyme that catalyzes the hydrolysis of ester bonds in lipids, resulting in the breaking of bonds between fatty acids and glycerol. This reaction allows for the breakdown of fats and oils into smaller molecules, such as fatty acids and glycerol, which can be further metabolized by the body for energy or other purposes. Therefore, the correct answer is "Breaking of bonds".Rate this question:
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- 36.
In enzymatic reactions, substrates (reactants) and products have specific energies. In order to transform the reactants into products, the reactants would have to go through a transition state which is usually higher in energy (point B in the graph). To get to this transition state, the system requires activation energy. (The energy required to start a reaction) The lower the activation energy, the faster the reaction happens. The graph below illustrates an enzymatic reaction, where the activation energy of this reaction, is the difference between the two points ........
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(A) and (D)
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(B) and (D)
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(C) and (D)
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(B) and (A)
Correct Answer
A. (B) and (A)Explanation
The graph illustrates an enzymatic reaction, with the transition state represented by point B. The activation energy required to reach this transition state is the difference between points B and A. Therefore, the correct answer is (B) and (A).Rate this question:
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- 37.
Amylase is an enzyme that has an optimum pH of around 6.7–7.0. Which of the graphs demonstrates how the activity of amylase varies with pH?
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Graph (D)
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Graph (B)
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Graph (A)
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Graph (C)
Correct Answer
A. Graph (A)Explanation
Graph (A) shows that the activity of amylase is highest at a pH of around 6.7-7.0, which matches the optimum pH range for amylase. The other graphs do not demonstrate this relationship between amylase activity and pH.Rate this question:
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- 38.
Lipase is an enzyme that has an optimum pH of 8.0–9.0. Which graph shows how the activity of lipase varies with pH?
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Graph (C)
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Graph (B)
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Graph (A)
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Graph (D)
Correct Answer
A. Graph (B)Explanation
Graph (B) shows that the activity of lipase is highest at pH 8.0-9.0, which matches the optimum pH range for lipase. In this graph, the activity of lipase gradually increases as the pH increases from acidic to alkaline conditions, and then starts to decrease beyond pH 9.0. This indicates that lipase has the highest activity at pH 8.0-9.0, making Graph (B) the correct answer.Rate this question:
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- 39.
Cellulase is an enzyme that can break down cellulose, and it has an optimum temperature of around 50∘C .Which graph best displays how the activity of cellulase changes with temperature?
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Graph (A)
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Graph (B)
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Graph (C)
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Graph (D)
Correct Answer
A. Graph (A)Explanation
Graph (A) best displays how the activity of cellulase changes with temperature because it shows a gradual increase in activity as temperature increases up to around 50∘C, which is the optimum temperature for cellulase. After reaching the optimum temperature, the activity starts to decrease. This pattern is consistent with the characteristics of enzymes, which have an optimal temperature at which they function most efficiently and their activity decreases at higher temperatures.Rate this question:
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- 40.
Gluconeogenesis is a metabolic pathway that results in the formation of a 6-carbon glucose molecule from two 3-carbon non–carbohydrate molecules. Which of the following is true about gluconeogenesis?
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This process requires energy.
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This process involves the oxidation of a 6-carbon glucose molecule.
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This process involves the hydrolysis of a 3-carbon non-carbohydrate molecule into a glucose molecule.
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This process is an example of a catabolic reaction.
Correct Answer
A. This process requires energy.Explanation
Gluconeogenesis is a process in which glucose is synthesized from non-carbohydrate sources. Since the formation of glucose requires energy, it is true that this process requires energy. The other statements are incorrect. Gluconeogenesis does not involve the oxidation of a 6-carbon glucose molecule or the hydrolysis of a 3-carbon non-carbohydrate molecule into a glucose molecule. Additionally, gluconeogenesis is not an example of a catabolic reaction, as it involves the synthesis of glucose rather than the breakdown of molecules.Rate this question:
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- 41.
Which of the following is true about these processes?
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Cellular respiration does not release energy.
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Photosynthesis is a process that involves the building up of molecules.
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Photosynthesis breaks down molecules into smaller ones.
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Cellular respiration is an anabolic process.
Correct Answer
A. Photosynthesis is a process that involves the building up of molecules.Explanation
Photosynthesis is a process that involves the building up of molecules. This is true because during photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose and oxygen. Glucose is a molecule that stores energy, and the process of photosynthesis builds up this energy-rich molecule.Rate this question:
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- 42.
The following graph shows the effect of a factor on the activity of two enzymes.What are the enzymes (X) and (Y)?
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X is amylase, Y is trypsin
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X is catalase, Y is pepsin
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X is amylase, Y is trypsin
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X is pepsin, Y is trypsin
Correct Answer
A. X is pepsin, Y is trypsinExplanation
Based on the information given in the graph, it can be concluded that the factor being tested has a greater effect on the activity of enzyme Y compared to enzyme X. Therefore, the correct answer is X is pepsin, Y is trypsin.Rate this question:
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- 43.
The enzyme catalase catalyzes the reaction that breaks down hydrogen peroxide into water and oxygen. The graph shows how much oxygen is produced over time when this reaction occurs with and without catalase. Which of the following statements correctly describes the trend shown?
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The reaction produces more oxygen when catalase is present.
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The reaction produces more oxygen when catalase is not present.
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The reaction produces oxygen at a quicker rate when catalase is present.
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The reaction produces oxygen at a quicker rate when catalase is not present.
Correct Answer
A. The reaction produces oxygen at a quicker rate when catalase is present.Explanation
The graph shows that the rate of oxygen production is higher when catalase is present compared to when it is not present. This is evident from the steeper slope of the line representing the reaction with catalase. Therefore, the correct statement is that the reaction produces oxygen at a quicker rate when catalase is present.Rate this question:
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- 44.
The reaction rate of pepsin enzyme is high at a pH of …..
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5 – 6
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7
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8 – 9
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1 – 2
Correct Answer
A. 1 – 2Explanation
The reaction rate of pepsin enzyme is high at a pH of 1-2 because pepsin is an enzyme that functions in the acidic environment of the stomach. The low pH helps to denature proteins and activate pepsin, allowing it to break down proteins into smaller peptides. Therefore, a pH of 1-2 is the optimal range for pepsin activity.Rate this question:
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- 45.
In an alkaline medium, the rate of pepsin ……..
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Increases
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Decreases then stop
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Decreases then increases
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Is not affected
Correct Answer
A. Decreases then stopExplanation
In an alkaline medium, pepsin, which is an enzyme responsible for protein digestion in the stomach, becomes denatured and loses its activity. This causes the rate of pepsin to initially decrease. Eventually, the alkaline environment completely stops the activity of pepsin, leading to a complete halt in the rate of pepsin.Rate this question:
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- 46.
The enzyme trypsin functions best at pH of ….
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2
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3
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7
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8
Correct Answer
A. 8 -
- 47.
The pepsin enzyme works at a pH of 1.2 – 2.5 inside the stomach. Which one of the following graphs shows what happens to pepsin if the pH value increases inside the stomach?
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A
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B
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C
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D
Correct Answer
A. CExplanation
The pepsin enzyme works optimally at a low pH range of 1.2 to 2.5. As the pH value increases inside the stomach, it becomes more alkaline or basic. This change in pH would lead to a decrease in the activity of pepsin, as it is most effective in an acidic environment. Therefore, graph C, which shows a decrease in pepsin activity as the pH value increases, is the correct answer.Rate this question:
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- 48.
If in a certain enzymatic reaction, an enzyme (E) works on a substrate (S). What makes the rate of reaction constant after some time of starting the reaction?
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The increase in the enzyme concentration
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The increase in the substrate concentration
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The saturation of the enzyme active sites in all enzyme molecules
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The increase in the number of active sites
Correct Answer
A. The saturation of the enzyme active sites in all enzyme moleculesExplanation
The rate of reaction becomes constant after some time of starting the reaction because the enzyme active sites become saturated. This means that all the active sites on the enzyme molecules are occupied by substrate molecules, and no more substrate molecules can bind to the enzyme. As a result, the rate of reaction reaches a maximum and remains constant as long as the concentration of substrate and enzyme remains constant. Increasing the concentration of enzyme or substrate may initially increase the rate of reaction, but once the active sites are saturated, further increases in concentration will not affect the rate.Rate this question:
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- 49.
Assuming that rolling a huge ball across a hill as in the figure below, represents a biochemical reaction that takes place without enzyme. So the energy of activation can be illustrated by ……..
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(A)
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(B)
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(A) plus (B)
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(A) minus (B)
Correct Answer
A. (A)Explanation
The correct answer is (A) because the energy of activation represents the energy barrier that must be overcome for a biochemical reaction to occur. Rolling a huge ball across a hill without an enzyme represents a reaction without any assistance, so the energy of activation can be illustrated by the energy required to push the ball up the hill.Rate this question:
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Mar 09, 2023Quiz Edited by
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Aug 01, 2020Quiz Created by
Samy