Unit 1 Chapter 3 (1st Secondary) Biology

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.

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.

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.

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.

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.

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."

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."

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.

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.

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.

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).

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.

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.

The x-axis on the graph shows the factor that is being altered, and the effect of this alteration on the rate of an enzyme controlled reaction is being measured. The correct answer is "Temperature" because the graph is showing how changing the temperature affects the rate of the reaction.

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.

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.

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".

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.

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.

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.

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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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The X-axis represents the acidity degree, while the Y-axis represents the enzyme action.

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.

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.

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.

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.

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.

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.

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.

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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.

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.

Enzymes and reactant molecules form a temporary association because enzymes catalyze reactions by binding to the reactant molecules, forming an enzyme-substrate complex. This association is temporary because once the reaction is complete, the enzyme releases the product and can bind to another substrate molecule. This allows the enzyme to be reused and participate in multiple reactions.