Cell Metabolism - GRE Subject Test: Biology
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Which of the following products is not formed during fermentation in humans?
Which of the following products is not formed during fermentation in humans?
When oxygen is not readily available in the blood, cells use fermentation as a means of anaerobic respiration. The process is used to generate NAD+, which can be used as a reactant in glycolysis to produce small amounts of ATP. Glycolysis still occurs in this environment, breaking glucose into pyruvate and producing two ATP per cycle.
Fermentation in humans converts pyruvate to lactate (lactic acid) and NADH to NAD+.
When oxygen is not readily available in the blood, cells use fermentation as a means of anaerobic respiration. The process is used to generate NAD+, which can be used as a reactant in glycolysis to produce small amounts of ATP. Glycolysis still occurs in this environment, breaking glucose into pyruvate and producing two ATP per cycle.
Fermentation in humans converts pyruvate to lactate (lactic acid) and NADH to NAD+.
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What is the primary purpose of fermentation in cells?
What is the primary purpose of fermentation in cells?
Under anaerobic conditions, fermentation follows the process of glycolysis. While glycolysis is responsible for creating ATP, fermentation allows the body to regenerate the NAD+ that is reduced during glycolytic processes. This key step allows glycolysis to continue, and more ATP to be made.
Under anaerobic conditions, fermentation follows the process of glycolysis. While glycolysis is responsible for creating ATP, fermentation allows the body to regenerate the NAD+ that is reduced during glycolytic processes. This key step allows glycolysis to continue, and more ATP to be made.
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What is the purpose of lactic acid and ethanol in the fermentation process?
What is the purpose of lactic acid and ethanol in the fermentation process?
Fermentation is a form of anaerobic respiration where there is no oxygen available as the final electron acceptor to the electron transport chain. As such, pyruvate is reduced, yielding lactic acid and, in the presence of lactate decarboxylase, ethanol. However, the products of fermentation do not undergo the Krebs cycle nor electron transport chain. The purpose of fermentation is to regenerate NAD+ so that glycolysis can continue. The cell does this by transferring the electron from NADH to pyruvate. Fermentation is less efficient per glucose than is aerobic oxidation, generating a fraction of the ATP. Lactic acid and ethanol are actually quite toxic to the cell (in humans they are immediately sent to the liver to be detoxified).
Fermentation is a form of anaerobic respiration where there is no oxygen available as the final electron acceptor to the electron transport chain. As such, pyruvate is reduced, yielding lactic acid and, in the presence of lactate decarboxylase, ethanol. However, the products of fermentation do not undergo the Krebs cycle nor electron transport chain. The purpose of fermentation is to regenerate NAD+ so that glycolysis can continue. The cell does this by transferring the electron from NADH to pyruvate. Fermentation is less efficient per glucose than is aerobic oxidation, generating a fraction of the ATP. Lactic acid and ethanol are actually quite toxic to the cell (in humans they are immediately sent to the liver to be detoxified).
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In anaerobic conditions, pyruvate will undergo fermentation. Which of the following molecules are end products of fermentation?
I. Ethanol
II. Butanol
III. Aspartic acid
IV. Lactic acid
In anaerobic conditions, pyruvate will undergo fermentation. Which of the following molecules are end products of fermentation?
I. Ethanol
II. Butanol
III. Aspartic acid
IV. Lactic acid
Either ethanol or lactic acid can be produced through fermentation depending on the organism. Ethanol fermentation only occurs in bacteria and yeast. Lactic acid fermentation has been found to occur in multiple kingdoms.
Fermentation allows for the regeneration of 
which can allow for glycolysis to continue. Butanol is a four carbon alcohol and aspartic acid is an amino acid found in proteins.
Either ethanol or lactic acid can be produced through fermentation depending on the organism. Ethanol fermentation only occurs in bacteria and yeast. Lactic acid fermentation has been found to occur in multiple kingdoms.
Fermentation allows for the regeneration of
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Where does glycolysis occur in the cell?
Where does glycolysis occur in the cell?
Glycolysis is the first step of aerobic respiration and takes place in the cytosol of the cell. The products of glycolysis (pyruvate and NADH) are transported into the mitochondria to continue the respiration processes. The Krebs cycle takes place in the mitochondrial matrix. The proteins of the electron transport chain are situated in the inner mitochondrial membrane, generating the proton gradient across this membrane by expelling protons into the intermembrane space.
Glycolysis is the first step of aerobic respiration and takes place in the cytosol of the cell. The products of glycolysis (pyruvate and NADH) are transported into the mitochondria to continue the respiration processes. The Krebs cycle takes place in the mitochondrial matrix. The proteins of the electron transport chain are situated in the inner mitochondrial membrane, generating the proton gradient across this membrane by expelling protons into the intermembrane space.
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Which of the following products is not created during glycolysis?
Which of the following products is not created during glycolysis?
Glycolysis is the first step of both aerobic and anaerobic cellular respiration. It results in the formation of two molecules of NADH, ATP, and pyruvate. FADH2 is not produced until the Krebs (citric acid) cycle.
Glycolysis is the first step of both aerobic and anaerobic cellular respiration. It results in the formation of two molecules of NADH, ATP, and pyruvate. FADH2 is not produced until the Krebs (citric acid) cycle.
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What is the net production of ATP in glycolysis?
What is the net production of ATP in glycolysis?
While four ATP are produced during glycolysis, two are also consumed in the process. This results in a net production of two molecules of ATP. Additionally two of the high energy intermediates NADH are produced for each molecule of glucose during glycolysis.
While four ATP are produced during glycolysis, two are also consumed in the process. This results in a net production of two molecules of ATP. Additionally two of the high energy intermediates NADH are produced for each molecule of glucose during glycolysis.
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For each molecule of glucose that enters glycolysis __________ molecules of __________ are produced.
For each molecule of glucose that enters glycolysis __________ molecules of __________ are produced.
For each molecule of glucose entering into glycolysis, there is a resulting two molecules of pyruvate. Glucose is a 6-carbon molecule and pyruvate is a 3-carbon molecule. No carbon is gained or lost in this stage of energy production.
For each molecule of glucose entering into glycolysis, there is a resulting two molecules of pyruvate. Glucose is a 6-carbon molecule and pyruvate is a 3-carbon molecule. No carbon is gained or lost in this stage of energy production.
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Which of the following is not part of the Calvin cycle?
Which of the following is not part of the Calvin cycle?
ATP is produced during the light-dependent reactions of photosynthesis by photosystem II. Carbon dioxide is fixed by combining with RuBP during calvin cycle. NAPDH donates electrons causing it to be oxdized to NADP+.
ATP is produced during the light-dependent reactions of photosynthesis by photosystem II. Carbon dioxide is fixed by combining with RuBP during calvin cycle. NAPDH donates electrons causing it to be oxdized to NADP+.
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Photosynthesis is a __________ process, while cellular respiration is a __________ process.
Photosynthesis is a __________ process, while cellular respiration is a __________ process.
Anabolic processes are those that make complex macromolecules out of simple reagents. Photosynthesis is an anabolic process because it converts carbon dioxide, water, and energy into sugars and oxygen. Catabolic processes break down larger macromolecules into simpler ones which can then be oxidized to produce usable energy. This energy can then be used to drive anabolic processes. Cellular respiration is a catabolic process because it breaks down sugar and oxygen into carbon dioxide, water, and energy. Since photosynthesis requires the net input of energy (sunlight) it is a nonspontaneous reaction. The opposite is true for cellular respiration, however the energy is in the form of ATP, not sunlight.
Anabolic processes are those that make complex macromolecules out of simple reagents. Photosynthesis is an anabolic process because it converts carbon dioxide, water, and energy into sugars and oxygen. Catabolic processes break down larger macromolecules into simpler ones which can then be oxidized to produce usable energy. This energy can then be used to drive anabolic processes. Cellular respiration is a catabolic process because it breaks down sugar and oxygen into carbon dioxide, water, and energy. Since photosynthesis requires the net input of energy (sunlight) it is a nonspontaneous reaction. The opposite is true for cellular respiration, however the energy is in the form of ATP, not sunlight.
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Plants are known as __________ because they derive the chemical energy necessary for life from the sun.
Plants are known as __________ because they derive the chemical energy necessary for life from the sun.
Plants are autotrophs capable of producing complex molecules from the suns energy and other simple substances such as water, carbon dioxide, and minerals. Heterotrophs cannot fix their own carbon and must use organic molecules as their carbon sources. Auxotrophs are organisms that are unable to synthesize a particular compound required for its growth/survival. Lithotrophs use inorganic substrates to obtain their energy (often from dissolved minerals in rocks). Detritivores are a type of heterotroph that feed on dead animal and plant matter, and the waste products of each.
Plants are autotrophs capable of producing complex molecules from the suns energy and other simple substances such as water, carbon dioxide, and minerals. Heterotrophs cannot fix their own carbon and must use organic molecules as their carbon sources. Auxotrophs are organisms that are unable to synthesize a particular compound required for its growth/survival. Lithotrophs use inorganic substrates to obtain their energy (often from dissolved minerals in rocks). Detritivores are a type of heterotroph that feed on dead animal and plant matter, and the waste products of each.
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Plants undergo which of the following processes:
I. Photosynthesis
II. Cellular respiration
III. Lactic acid metabolism
Plants undergo which of the following processes:
I. Photosynthesis
II. Cellular respiration
III. Lactic acid metabolism
Plants undergo both photosynthesis and cellular respiration. Glucose is made during photosynthesis and then this glucose is used to generate ATP in cellular respiration. This ATP can then be used to drive the complex anabolic processes of plants. Lactic acid metabolism commonly occurs in muscle tissue under anaerobic conditions but is not found to occur in plants.
Plants undergo both photosynthesis and cellular respiration. Glucose is made during photosynthesis and then this glucose is used to generate ATP in cellular respiration. This ATP can then be used to drive the complex anabolic processes of plants. Lactic acid metabolism commonly occurs in muscle tissue under anaerobic conditions but is not found to occur in plants.
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Which of the following are photosynthetic inputs?
I. 
II. 
III. 
IV. Light
Which of the following are photosynthetic inputs?
I.
II.
III.
IV. Light
Carbon dioxide, water, and light are the photosynthetic inputs. Oxygen gas is an output product of photosynthesis, not an input.
In the light reactions of photosynthesis the energetic intermediates NADPH and ATP are generated through chlorophyll pigments excited by sunlight. These then provide the energy and reducing power necessary for the generation of glucose in the Calvin cycle.
Carbon dioxide, water, and light are the photosynthetic inputs. Oxygen gas is an output product of photosynthesis, not an input.
In the light reactions of photosynthesis the energetic intermediates NADPH and ATP are generated through chlorophyll pigments excited by sunlight. These then provide the energy and reducing power necessary for the generation of glucose in the Calvin cycle.
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Which of the following are photosynthetic outputs?
I. 
II. 
III. 
IV. Sugar
Which of the following are photosynthetic outputs?
I.
II.
III.
IV. Sugar
is the molecular formula for a monosaccharide (sugar). This sugar can then be used in cellular respiration to create chemical energy to drive the various anabolic processes of the plant. The oxygen that is produced through photosynthesis provides the oxygen that we breathe in order to undergo our own cellular respiration. Water is an input of photosynthesis.
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Chlorophyll absorbs many different wavelengths of visible light, but __________ light is absorbed the least.
Chlorophyll absorbs many different wavelengths of visible light, but __________ light is absorbed the least.
Chlorophyll is green because it absorbs all wavelengths of visible light except it reflects, not absorbs green. This green light reflected and is therefore the color that we perceive. The wavelengths of red and blue light work well to excited the two different photosystems involved in photophosphorylation. While ultraviolet light is found on the electromagnetic spectrum, it is not considered to be visible light. Ultraviolet light is more energetic and has a shorter wavelength than that of visible light.
Chlorophyll is green because it absorbs all wavelengths of visible light except it reflects, not absorbs green. This green light reflected and is therefore the color that we perceive. The wavelengths of red and blue light work well to excited the two different photosystems involved in photophosphorylation. While ultraviolet light is found on the electromagnetic spectrum, it is not considered to be visible light. Ultraviolet light is more energetic and has a shorter wavelength than that of visible light.
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Where in the chloroplast is the pH the lowest?
Where in the chloroplast is the pH the lowest?
The pH is lowest in the thylakoid lumen. During photophosphorylation, protons are pumped into the thylakoid lumen from the stroma. The more protons found in the thylakoid space results in its lower pH. This lumen can have a pH of as low as 4. Protons then move down there concentration gradient out into the stroma in a process that produces ATP.
The stroma of the chloroplast has a pH of approximately 8, while the pH of the cytosol is closer to 7.
The pH is lowest in the thylakoid lumen. During photophosphorylation, protons are pumped into the thylakoid lumen from the stroma. The more protons found in the thylakoid space results in its lower pH. This lumen can have a pH of as low as 4. Protons then move down there concentration gradient out into the stroma in a process that produces ATP.
The stroma of the chloroplast has a pH of approximately 8, while the pH of the cytosol is closer to 7.
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In the Calvin cycle, carbon is reduced to ultimately form glucose. Where does this carbon come from?
In the Calvin cycle, carbon is reduced to ultimately form glucose. Where does this carbon come from?
The carbon fixed in the Calvin cycle comes from the air in the form of 
. This carbon is reduced through the usage of NADPH and ATP, produced in the light reactions of photosynthesis, in order to make glucose.
The soil provides valuable water and mineral nutrients for the plant. The sun provides the energy necessary to drive photosynthesis. And pure water contains only hydrogen and oxygen. Lithotrophs utilize inorganic carbon, usually from rocks.
The carbon fixed in the Calvin cycle comes from the air in the form of
The soil provides valuable water and mineral nutrients for the plant. The sun provides the energy necessary to drive photosynthesis. And pure water contains only hydrogen and oxygen. Lithotrophs utilize inorganic carbon, usually from rocks.
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Plants such as corn are capable of C4 respiration. In order to undergo C4 respiration, which additional enzyme must the plant utilize?
Plants such as corn are capable of C4 respiration. In order to undergo C4 respiration, which additional enzyme must the plant utilize?
Plants that undergo C4 respiration must also utilize the enzyme PEP carboxylase. This enzyme allows for carbon dioxide to be fixed to PEP to produce oxaloacetate. C4 respiration allows for lower levels of photorespiration, which can cause a decrease in photosynthetic efficiency.
Rubisco is the enzyme that adds carbon dioxide to ribulose bisphosphate to produce two molecules of 3-phosphoglycerate. Alkaline phosphatase is an enzyme that hydrolyzes phosphates from a variety of substrates under alkaline conditions. Kinases are enzyme which add phosphate groups to specific targets, such as fructose-1-phosphate.
Plants that undergo C4 respiration must also utilize the enzyme PEP carboxylase. This enzyme allows for carbon dioxide to be fixed to PEP to produce oxaloacetate. C4 respiration allows for lower levels of photorespiration, which can cause a decrease in photosynthetic efficiency.
Rubisco is the enzyme that adds carbon dioxide to ribulose bisphosphate to produce two molecules of 3-phosphoglycerate. Alkaline phosphatase is an enzyme that hydrolyzes phosphates from a variety of substrates under alkaline conditions. Kinases are enzyme which add phosphate groups to specific targets, such as fructose-1-phosphate.
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CAM (crassulacean acid metabolism) plants undergo __________ photosynthesis and keep their stomata __________ during the day.
CAM (crassulacean acid metabolism) plants undergo __________ photosynthesis and keep their stomata __________ during the day.
CAM plants utilize C4 photosynthesis and keep their stomata closed during the day. By using the enzyme PEP carboxylase, CAM plants are able to store up enough fixed carbon during the night in order to keep their stomata closed during the day. The closure of the stomata prevents the loss of water from the plant. This is especially important in hot, dry climates.
CAM plants utilize C4 photosynthesis and keep their stomata closed during the day. By using the enzyme PEP carboxylase, CAM plants are able to store up enough fixed carbon during the night in order to keep their stomata closed during the day. The closure of the stomata prevents the loss of water from the plant. This is especially important in hot, dry climates.
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In humans, __________ is the primary form for storing excess glucose and it is commonly found in __________ cells.
In humans, __________ is the primary form for storing excess glucose and it is commonly found in __________ cells.
Glycogen is the common form for storing glucose in animal cells, while starch is the common form for storing glucose in plant cells. These saccharides are very similar, but glycogen is more easily digestable due to its structure. Liver and muscle cells are the primary storage places for glycogen. Adipose cells are primarily known for the storage of fats.
Glycogen is the common form for storing glucose in animal cells, while starch is the common form for storing glucose in plant cells. These saccharides are very similar, but glycogen is more easily digestable due to its structure. Liver and muscle cells are the primary storage places for glycogen. Adipose cells are primarily known for the storage of fats.
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