Bio 2 - Chapter 4 Test (Spring 2014)

The correct answer is Citric acid cycle. The Krebs cycle is also known as the citric acid cycle because it begins with the formation of citric acid. This cycle is a series of biochemical reactions that occur in the mitochondria of cells and is an essential part of cellular respiration. It plays a crucial role in the production of ATP, the energy currency of the cell. The Krebs cycle involves the breakdown of glucose and the generation of high-energy molecules such as NADH and FADH2, which are used in the electron transport chain to produce ATP.

Photosynthesis is the correct answer because it is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen. This process occurs in the chloroplasts of plant cells and is essential for the plant's survival. Through photosynthesis, plants are able to produce their own food and release oxygen into the atmosphere. Cellular respiration is the opposite process, where glucose is broken down to release energy. The cell cycle and mitosis are unrelated processes involved in cell division and growth.

A producer is an organism that has the ability to make its own source of chemical energy through a process called photosynthesis. This process involves converting sunlight into chemical energy in the form of glucose. Producers, such as plants and some bacteria, play a crucial role in ecosystems as they provide energy to other organisms through the food chain.

The diagram to the right is depicting a mitochondrion, which is an organelle found in eukaryotic cells. The folded inner membrane is a characteristic feature of mitochondria and is known as the cristae. These folds increase the surface area of the inner membrane, allowing for more space for the electron transport chain and ATP synthesis. Therefore, structure A in the diagram is the folded inner membrane of the mitochondrion.

The correct answer is the breakdown of carbon-based molecules into smaller molecules. ATP is produced through cellular respiration, a process in which carbon-based molecules such as glucose are broken down in the presence of oxygen. This breakdown releases energy, which is used to convert ADP (adenosine diphosphate) into ATP (adenosine triphosphate). Therefore, the chemical energy required to produce ATP comes from the breakdown of carbon-based molecules into smaller molecules.

The three-carbon molecule formed by glycolysis is pyruvate. Glycolysis is the first step in cellular respiration, where glucose is broken down into two molecules of pyruvate. This process occurs in the cytoplasm and produces a small amount of ATP and NADH. Pyruvate then enters the mitochondria for further breakdown in the citric acid cycle. Carbon dioxide is produced later in the process during the citric acid cycle and oxidative phosphorylation.

The light-dependent reactions in photosynthesis capture and transfer energy from sunlight. These reactions occur in the thylakoid membranes of chloroplasts and involve the absorption of light by chlorophyll and other pigments. This energy is then used to generate ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy-rich molecules that will be used in the subsequent dark reactions of photosynthesis to build sugars. Therefore, capturing and transferring energy is the primary function of the light-dependent reactions.

Chlorophyll is the correct answer because it is the main light-absorbing pigment found in plant leaves. It is responsible for capturing light energy during photosynthesis and converting it into chemical energy. Chlorophyll molecules are located within the chloroplasts, which are the organelles responsible for photosynthesis. Thylakoids are membrane structures within the chloroplasts where the chlorophyll molecules are embedded. Grana are stacks of thylakoids. While all of these terms are related to the process of photosynthesis, chlorophyll specifically refers to the light-absorbing molecules.

Structure B in the diagram is the mitochondrial matrix. The mitochondrial matrix is the space within the inner membrane of the mitochondria. It contains enzymes that are involved in various metabolic reactions, such as the citric acid cycle. The matrix also houses the mitochondrial DNA and ribosomes, which are necessary for the synthesis of proteins within the mitochondria.

The correct answer is the citric acid cycle. The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that occur in the mitochondrial matrix. It is an important stage in cellular respiration, where acetyl-CoA is oxidized to produce energy-rich molecules such as NADH and FADH2. This cycle plays a crucial role in generating ATP, the main energy currency of the cell.

ATP synthase is the correct answer because it is the enzyme located at the end of the electron transport chain. This enzyme plays a crucial role in the production of ATP, the main energy currency of the cell. It uses the energy from the flow of protons across the inner mitochondrial membrane to convert ADP and inorganic phosphate into ATP. ATP synthase acts as a molecular turbine, utilizing the electrochemical gradient generated during electron transport to drive the synthesis of ATP.

Glycolysis is the correct answer because it is the initial step in cellular respiration where glucose is broken down into two molecules of pyruvate. This process occurs in the cytoplasm and does not require oxygen. Photosynthesis, on the other hand, is the process by which plants convert sunlight into energy-rich molecules like glucose. Aerobic respiration and electron transport are subsequent steps in cellular respiration that occur in the presence of oxygen.

Cellular respiration is the correct answer because it is the process by which cells break down sugars, such as glucose, to produce ATP (adenosine triphosphate) in the presence of oxygen. This process occurs in the mitochondria of cells and involves several stages, including glycolysis, the Krebs cycle, and oxidative phosphorylation. Anaerobic respiration, on the other hand, occurs in the absence of oxygen, while photosynthesis is the process by which plants convert sunlight into energy.

Anaerobic respiration, also known as fermentation, is the process that breaks down sugars to produce ATP when oxygen is not present. In this process, glucose is partially broken down through glycolysis to produce a small amount of ATP. Unlike cellular respiration, which requires oxygen, anaerobic respiration does not rely on oxygen as the final electron acceptor. Instead, it uses other molecules, such as pyruvate or acetaldehyde, to complete the breakdown of glucose and produce ATP. Fermentation occurs in various organisms, including bacteria and yeast, and is used in processes such as the production of alcohol and bread.

The Krebs cycle is a series of chemical reactions that occur in the mitochondria of cells, and it is an important part of cellular respiration. During the Krebs cycle, energy-rich molecules such as ATP are produced, along with carbon dioxide as a waste product. Therefore, the correct answer is ATP and carbon dioxide.

Eukaryotes use cellular respiration for their cellular energy needs. Cellular respiration is the process by which cells convert glucose and oxygen into carbon dioxide, water, and ATP (adenosine triphosphate), which is the energy currency of the cell. Eukaryotes, which include organisms such as plants, animals, fungi, and protists, have complex cellular structures and organelles, including mitochondria, where cellular respiration takes place. Prokaryotes, on the other hand, lack mitochondria and perform a different type of respiration called anaerobic respiration or fermentation. Therefore, the correct answer is eukaryotes.

The photosystems transfer energy to the Calvin cycle through ATP and NADPH. This is because during photosynthesis, the photosystems (specifically photosystem II and photosystem I) capture light energy and use it to excite electrons. These excited electrons are then passed through an electron transport chain, which generates ATP and NADPH. The ATP and NADPH are then used in the Calvin cycle, a series of chemical reactions that convert carbon dioxide into glucose. Therefore, the photosystems transfer energy in the form of ATP and NADPH to the Calvin cycle for the production of glucose.

The process of photosynthesis involves chloroplasts, which are organelles in plant cells that contain chlorophyll. Chloroplasts absorb sunlight and convert it into chemical energy in the form of glucose. This chemical energy is then stored in the plant for later use. This explanation aligns with the given correct answer: "Chloroplasts absorb sunlight and store chemical energy."

The ATP molecule is often referred to as the "energy currency" of the cell because it stores and transfers energy. It is responsible for storing the energy obtained from food and releasing it when needed for various cellular processes. ATP acts as a carrier of chemical energy, allowing it to be easily transported and used in different parts of the cell. Therefore, the phrase "stores and transfers energy" accurately describes the function of the ATP molecule.

The main function of the Krebs cycle is to produce molecules that carry high-energy electrons to the electron transport chain. The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria of cells. It plays a crucial role in cellular respiration by breaking down acetyl-CoA, a molecule derived from pyruvate, and producing energy-rich molecules such as NADH and FADH2. These molecules then carry high-energy electrons to the electron transport chain, where they are used to generate ATP, the main energy currency of the cell.

During photosynthesis, plants use carbon dioxide and water to produce glucose and oxygen. This process occurs in the chloroplasts of plant cells, specifically in the presence of sunlight. Carbon dioxide is absorbed from the atmosphere through tiny pores called stomata, while water is taken up from the roots. Through a series of chemical reactions, the energy from sunlight is used to convert carbon dioxide and water into glucose, a form of sugar that serves as the primary energy source for plants. Oxygen is released as a byproduct and is released into the atmosphere.

Glycolysis is the metabolic pathway that breaks down glucose into pyruvate. It is the first step in cellular respiration and occurs in the cytoplasm of the cell. The cytoplasm is the fluid-filled region between the cell membrane and the nucleus, where many cellular processes take place. Therefore, glycolysis takes place in the cytoplasm.

The end products of glycolysis are pyruvate, NADH, and ATP. Glycolysis is the first step in cellular respiration and occurs in the cytoplasm of cells. During glycolysis, glucose is broken down into two molecules of pyruvate. This process also produces two molecules of NADH, which can be used in the electron transport chain to produce ATP. Additionally, glycolysis directly produces a small amount of ATP through substrate-level phosphorylation. Therefore, the correct answer is pyruvate, NADH, and ATP.

The ultimate source of energy in almost every food chain is the sun. Producers, such as plants, use sunlight to perform photosynthesis and convert it into chemical energy. This energy is then transferred to consumers, which are organisms that eat the producers. Detritivores, on the other hand, obtain their energy from decomposing organic matter. However, this organic matter ultimately originated from the producers, which relied on the sun for their energy. Therefore, the sun is the ultimate source of energy in the food chain.

A molecule of ATP, or adenosine triphosphate, is composed of adenosine, ribose (a sugar molecule), and three phosphate groups. Adenosine is a nucleoside that consists of adenine (a nitrogenous base) and ribose. The three phosphate groups are attached to the ribose molecule. This structure allows ATP to store and release energy in cells, as the high-energy phosphate bonds can be broken to release energy when needed.

The Krebs cycle, also known as the citric acid cycle, provides the electron transport chain in cellular respiration with the energy it needs to function. During the Krebs cycle, acetyl-CoA is oxidized, producing NADH and FADH2, which carry high-energy electrons. These electrons are then transferred to the electron transport chain, where they are used to generate ATP through oxidative phosphorylation. Therefore, the Krebs cycle plays a crucial role in supplying the energy required for the electron transport chain to function properly.

In the light-independent reactions of photosynthesis, carbon dioxide enters the Calvin cycle and sugars are made. This is because during the Calvin cycle, carbon dioxide molecules are combined with molecules called RuBP (ribulose bisphosphate) to form a six-carbon molecule called PGA (phosphoglycerate). PGA is then converted into other molecules, such as glucose, which are used to produce sugars. This process is known as carbon fixation and is essential for the production of organic compounds in plants.

In the light-dependent reactions of photosynthesis, energy from sunlight is captured and converted into chemical energy in the form of ATP and NADPH. This energy is used in the subsequent dark reactions to convert carbon dioxide into sugars through a process called carbon fixation. Therefore, the correct answer is "Energy is captured."

The purpose of the light reactions is to make ATP and NADPH for use in the Calvin cycle. During the light reactions of photosynthesis, light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH. These energy-rich molecules are then used in the Calvin cycle, the second stage of photosynthesis, to fuel the synthesis of glucose and other organic molecules. Therefore, the primary function of the light reactions is to produce ATP and NADPH, which are essential for the production of glucose.

ATP (adenosine triphosphate) is a molecule that is pictured in the diagram. It consists of an adenosine molecule, which is made up of adenine and ribose, and three phosphate groups. ATP is commonly referred to as the "energy currency" of cells, as it is involved in various cellular processes and acts as a source of energy for metabolic reactions.

The structure labeled D in the diagram is the granum. A granum is a stack of thylakoid membranes found in chloroplasts. These thylakoid membranes contain chlorophyll, which is responsible for capturing light energy during photosynthesis. The granum plays a crucial role in the light-dependent reactions of photosynthesis by providing a large surface area for the absorption of light and facilitating the movement of electrons.

All cells use chemical energy because it is the primary form of energy that powers cellular processes. Chemical energy is derived from the breakdown of molecules such as glucose through cellular respiration, which produces adenosine triphosphate (ATP) as a usable energy source. This energy is then used for various cellular activities like metabolism, growth, and reproduction. While some cells, like plant cells, can also use solar energy through photosynthesis to convert it into chemical energy, not all cells have the ability to do so. Therefore, the statement that all cells use chemical energy is true.

The part labeled B in the diagram is ribose. Ribose is a type of sugar molecule that is a component of RNA (ribonucleic acid). It is a pentose sugar, meaning it has five carbon atoms. Ribose plays a crucial role in the structure and function of RNA, as it forms the backbone of the RNA molecule and helps in the synthesis of proteins.

In the electron transport chain, the energy generated from the Krebs cycle is used to pump hydrogen ions across the inner mitochondrial membrane. This creates a concentration gradient, with a higher concentration of hydrogen ions on one side of the membrane. This gradient is later used by the ATP synthase enzyme to produce ATP, which is the cell's main energy source. Therefore, the correct answer is "across the inner mitochondrial membrane."

The light-independent reactions of photosynthesis, also known as the Calvin cycle, are responsible for converting carbon dioxide into glucose. These reactions occur in the stroma of the chloroplasts and do not require light energy directly. Carbon dioxide is the primary source of carbon atoms for building glucose molecules during this process. Oxygen is produced as a byproduct of photosynthesis but is not directly involved in the light-independent reactions. Water is required for the light-dependent reactions, which produce ATP and NADPH that are used in the Calvin cycle. Cellulose, while an important component of plant cell walls, is not directly involved in the light-independent reactions.

The electron transport chain in photosynthesis is a series of proteins located in the thylakoid membrane. This chain is responsible for transferring electrons from water to NADP+ during the light-dependent reactions of photosynthesis. The proteins in the chain play a crucial role in the generation of ATP and the production of NADPH, which are both essential for the Calvin cycle and the overall process of photosynthesis.

The structure labeled C in the diagram is the stroma. The stroma is the fluid-filled region within the chloroplasts where various metabolic reactions occur, including the Calvin cycle of photosynthesis. It surrounds the thylakoid membranes, which are responsible for capturing light energy and converting it into chemical energy. The stroma also contains enzymes and other molecules necessary for photosynthesis. Chlorophyll, granum, and thylakoid membranes are all components within the chloroplast, but they are not specifically labeled as structure C in the diagram.

The hydrogen ions for the photosystems of the light-dependent reactions come from water. In the process of photosynthesis, water molecules are split into hydrogen ions, electrons, and oxygen. The hydrogen ions are then used in the photosystems to generate energy, while the oxygen is released as a byproduct. This process, known as photolysis, provides the necessary source of hydrogen ions for the photosystems to produce ATP and NADPH, which are essential for the synthesis of sugars during the light-dependent reactions.

The part labeled C in the diagram is phosphate. This is because phosphate is a component of ATP (adenosine triphosphate), which is a molecule that stores and releases energy in cells. Phosphate groups are essential for the function of ATP, as they are responsible for transferring energy between molecules in cellular processes.

Electrons provide the energy to operate the protein pumps in the electron transport chain. As electrons are passed along the chain, energy is released and used to pump hydrogen ions across the mitochondrial membrane, creating a concentration gradient. This gradient is then used by ATP synthase to produce ATP, which is the energy currency of the cell. Oxygen is the final electron acceptor in the chain, and carbon dioxide is not directly involved in providing energy for the protein pumps.

During intense exercise, the body may not be able to supply enough oxygen to the muscles for aerobic respiration. As a result, the muscles switch to anaerobic respiration, which produces lactic acid as a byproduct. The accumulation of lactic acid in the muscles leads to a burning sensation, known as muscle fatigue or "burning feeling." Therefore, lactic acid is the end product of fermentation that causes the burning feeling in working muscles.

ATP (adenosine triphosphate) is a molecule that stores and provides energy for cellular processes. When ATP is transformed into ADP (adenosine diphosphate), a phosphate group is removed from ATP, resulting in the release of energy. This process is known as hydrolysis, where water is used to break the bond between the phosphate groups. The removal of a phosphate group from ATP allows the energy stored in the molecule to be utilized by the cell for various metabolic reactions.

Fermentation allows glycolysis to continue making a small amount of ATP. During fermentation, when oxygen is not available, glycolysis is able to continue by using an alternative pathway to produce ATP. This process is important in situations where there is a lack of oxygen, such as during intense exercise or in certain microorganisms. By allowing glycolysis to continue, fermentation helps to provide a limited but necessary energy source for the cell.

Cellular respiration is the process by which cells convert energy from the chemical bonds of carbon-based molecules, such as glucose, into usable energy in the form of ATP. Oxygen is required for this process to occur, and it is used to break down the carbon-based molecules and release energy. The correct answer accurately describes this process, stating that carbon-based molecules from food and oxygen are used to make ATP.

The mitochondrion is the correct answer because it is the organelle responsible for converting molecules from the food we eat into usable energy. This process, known as cellular respiration, occurs within the mitochondria's inner membrane, where glucose and oxygen are broken down to produce ATP, the cell's main source of energy. The Golgi apparatus is involved in processing and packaging proteins, the chloroplast is responsible for photosynthesis in plant cells, and the lysosome is involved in cellular waste disposal.

Oxygen acts as the final electron acceptor at the end of the electron transport chain in cellular respiration. During the process of cellular respiration, electrons are transferred from molecules such as glucose to carrier molecules in the electron transport chain. These carrier molecules pass the electrons down the chain, releasing energy in the process. Oxygen is the final acceptor of these electrons, combining with hydrogen ions to form water. This allows the electron transport chain to continue functioning and produce ATP, the energy currency of the cell.

The Calvin cycle is not a stage of cellular respiration. It is a series of biochemical reactions that occur in the chloroplasts of plants during photosynthesis. The Calvin cycle is responsible for converting carbon dioxide into glucose, which is used as a source of energy for the plant. Cellular respiration, on the other hand, is the process by which cells break down glucose to produce ATP, the energy currency of the cell. Therefore, the Calvin cycle is not a stage of cellular respiration.

The diagram to the right shows a structure labeled E, which is the thylakoid membranes. Thylakoid membranes are found in chloroplasts and are responsible for the light-dependent reactions of photosynthesis. They contain chlorophyll and other pigments that capture light energy and convert it into chemical energy. The thylakoid membranes are arranged in stacks called grana, which are not labeled in the diagram. Therefore, the correct answer is thylakoid membranes.

ATP (adenosine triphosphate) is a molecule that stores and releases energy for cellular processes. It consists of three phosphate groups. When one of these phosphate groups is removed, ATP is converted into ADP (adenosine diphosphate), and energy is released. This process is known as hydrolysis, where a water molecule is used to break the bond between the phosphate groups. Therefore, the correct answer is "has a phosphate group removed."

Chemosynthesis is a process where organisms use chemical compounds as a source of energy to produce food. Unlike photosynthesis that uses sunlight, chemosynthesis occurs in environments where sunlight is not available, such as deep-sea hydrothermal vents or caves. Organisms in these environments rely on the energy obtained from the oxidation of inorganic compounds, such as hydrogen sulfide or methane, to synthesize organic molecules. Therefore, chemical compounds are the correct answer as they serve as the source of energy for chemosynthesis.