Biology - MCAT Biology
Card 0 of 11296
Which of the following is not a tenet of the Cell Theory?
Which of the following is not a tenet of the Cell Theory?
All of the answer choices are tenets of the Cell Theory, except for the one concerning organelles. Not every cells has membrane-bound organelles (e.g. prokaryotic cells).
All of the answer choices are tenets of the Cell Theory, except for the one concerning organelles. Not every cells has membrane-bound organelles (e.g. prokaryotic cells).
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An unknown cell type has been isolated. It is suspected that this cell is prokaryotic. The presence of which of these cell structures would confirm that the cell is prokaryotic?
An unknown cell type has been isolated. It is suspected that this cell is prokaryotic. The presence of which of these cell structures would confirm that the cell is prokaryotic?
Cytoplasm is found in all types of cells. Flagella is found in all cells that are mobile. Spores can be found in bacteria but also fungi. Ribosomes are found in prokaryotic cells albeit smaller in size compared to those in eukaryotic cells.
Cytoplasm is found in all types of cells. Flagella is found in all cells that are mobile. Spores can be found in bacteria but also fungi. Ribosomes are found in prokaryotic cells albeit smaller in size compared to those in eukaryotic cells.
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Which of the following components of an animal cell would NOT also be observed in a bacterial cell?
Which of the following components of an animal cell would NOT also be observed in a bacterial cell?
This question is asking about one of the differences between eukaryotes and prokaryotes. While both eukaryotes and prokaryotes use DNA to encode their genetic information, making "DNA" incorrect, remember that prokaryotes lack membrane-bound organelles. \This makes both "ribosomes" and "phospholipid cell membrane" incorrect, because neither of them are membrane-bound organelles. We are left with "nucleus," which is the correct answer.
This question is asking about one of the differences between eukaryotes and prokaryotes. While both eukaryotes and prokaryotes use DNA to encode their genetic information, making "DNA" incorrect, remember that prokaryotes lack membrane-bound organelles. \This makes both "ribosomes" and "phospholipid cell membrane" incorrect, because neither of them are membrane-bound organelles. We are left with "nucleus," which is the correct answer.
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Which of the following would not be found in a prokaryotic cell?
Which of the following would not be found in a prokaryotic cell?
One of the key differences between prokaryotes and eukaryotes is that prokaryotes have no membrane bound organelles, therefore, prokaryotes would not have mitochondria. Prokaryotes have a plasma membrane for protection, ribosomes for protein production, RNA in the form of mRNA, tRNA, and rRNA, and DNA polymerase to replicate their DNA.
One of the key differences between prokaryotes and eukaryotes is that prokaryotes have no membrane bound organelles, therefore, prokaryotes would not have mitochondria. Prokaryotes have a plasma membrane for protection, ribosomes for protein production, RNA in the form of mRNA, tRNA, and rRNA, and DNA polymerase to replicate their DNA.
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A scientist studying a culture of bacteria finds an organism he hadn't seen before. He thinks it might be some kind of single-celled eukaryote. What observed characteristic would support the scientists prediction?
A scientist studying a culture of bacteria finds an organism he hadn't seen before. He thinks it might be some kind of single-celled eukaryote. What observed characteristic would support the scientists prediction?
The characteristic that defines a eukaryote is the presence of membrane bound organelles, such as the nucleus, mitochondria, Golgi body, and chloroplasts. Both eukaryotes and prokaryotes have ribosomes, DNA and RNA, and and electron trasnsport chain. Bacteria and plants have cell walls but not all eukaryotes do, so it is not a defining characteristic.
The characteristic that defines a eukaryote is the presence of membrane bound organelles, such as the nucleus, mitochondria, Golgi body, and chloroplasts. Both eukaryotes and prokaryotes have ribosomes, DNA and RNA, and and electron trasnsport chain. Bacteria and plants have cell walls but not all eukaryotes do, so it is not a defining characteristic.
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Which of the following is not a characteristic of prokaryotes?
Which of the following is not a characteristic of prokaryotes?
Prokaryotes do not have membrane-bound organelles, such as the nucleus or mitochondria. In fact, endosymbiotic theory suggests that mitochondria evolved from symbiotic prokaryotic relationships. Prokaryotes are often associated with all of the other characteristics listed.
Prokaryotes do not have membrane-bound organelles, such as the nucleus or mitochondria. In fact, endosymbiotic theory suggests that mitochondria evolved from symbiotic prokaryotic relationships. Prokaryotes are often associated with all of the other characteristics listed.
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Which of the following would not help determine whether a cell was eukaryotic or prokaryotic?
Which of the following would not help determine whether a cell was eukaryotic or prokaryotic?
Membrane bound organelles are specific only to eukaryotes. Circular DNA is only present in prokaryotes. Rough endoplasmic reticulum is only present in eukaryotes, as all prokaryotic ribosomes are cytoplasmic. Although prokaryotes have circular DNA, both eukaryotes and prokaryotes have double-stranded DNA.
Membrane bound organelles are specific only to eukaryotes. Circular DNA is only present in prokaryotes. Rough endoplasmic reticulum is only present in eukaryotes, as all prokaryotic ribosomes are cytoplasmic. Although prokaryotes have circular DNA, both eukaryotes and prokaryotes have double-stranded DNA.
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A scientist discovers a new bacteria growing on a plant in his house. He brings it into the lab to study its growth. He grows the new bacteria alongside a known obligate anaerobic bacteria, and sees that after an hour, the new bacteria has not grown as much as the anaerobic bacteria. What classification most likely describes the type of the new bacteria?
A scientist discovers a new bacteria growing on a plant in his house. He brings it into the lab to study its growth. He grows the new bacteria alongside a known obligate anaerobic bacteria, and sees that after an hour, the new bacteria has not grown as much as the anaerobic bacteria. What classification most likely describes the type of the new bacteria?
Since the obligate anaerobe grows well, we know that both bacteria are grown in an anaerobic environment.
A facultative anaerobe can grow in an aerobic or anaerobic environment. It simply grows better when oxygen is present; therefore, we would see slower growth from a facultative anaerobe than an obligate anaerobe when there is no oxygen present. If the bacteria were aerobic, it would not grow at all in the anaerobic environment.
Since the obligate anaerobe grows well, we know that both bacteria are grown in an anaerobic environment.
A facultative anaerobe can grow in an aerobic or anaerobic environment. It simply grows better when oxygen is present; therefore, we would see slower growth from a facultative anaerobe than an obligate anaerobe when there is no oxygen present. If the bacteria were aerobic, it would not grow at all in the anaerobic environment.
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All of the following are characteristics of prokaryotic cells except for __________.
All of the following are characteristics of prokaryotic cells except for __________.
Protists, fungi, plants, and animals are eukaryotic, while bacteria are prokaryotic. The rest of the answer choices are characteristic of prokaryotic cells.
Protists, fungi, plants, and animals are eukaryotic, while bacteria are prokaryotic. The rest of the answer choices are characteristic of prokaryotic cells.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is a key difference between human cells and Neisseria?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is a key difference between human cells and Neisseria?
Prokaryotes like Neisseria do not have mitochondria, while eukaryotic human cells do. In fact, prokaryotes probably gave rise to the first mitochondria via the theory of endosymbiosis.
Prokaryotes like Neisseria do not have mitochondria, while eukaryotic human cells do. In fact, prokaryotes probably gave rise to the first mitochondria via the theory of endosymbiosis.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist is using a Gram stain to investigate Neisseria. If Neisseria is bright pink upon examination after staining, which of the following is likely true?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist is using a Gram stain to investigate Neisseria. If Neisseria is bright pink upon examination after staining, which of the following is likely true?
Bright pink cells under Gram stain are characteristic of Gram negative status. This is associated with an outer lipid membrane and reduced peptidoglycan. The reduction in peptidoglycan is what leads to a failure to retain the Gram stain, which would have colored the cells purple.
Bright pink cells under Gram stain are characteristic of Gram negative status. This is associated with an outer lipid membrane and reduced peptidoglycan. The reduction in peptidoglycan is what leads to a failure to retain the Gram stain, which would have colored the cells purple.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist views his Gram stained Neisseria under a microscope, and finds that they are present in groups of two, each of which is a round cell. In what category of bacteria does Neisseria most likely fall?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist views his Gram stained Neisseria under a microscope, and finds that they are present in groups of two, each of which is a round cell. In what category of bacteria does Neisseria most likely fall?
Round bacterial cells are considered cocci. In this case, with two cells, it would be classified specifically as a diploccocus.
Round bacterial cells are considered cocci. In this case, with two cells, it would be classified specifically as a diploccocus.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The same scientist continues to explore Neisseria under a microscope, and makes a surprising finding for a bacterium. He wonders if the sample was mislabeled. Which of the following is likely to surprise this scientist if it were found in a sample that was labeled Neisseria?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The same scientist continues to explore Neisseria under a microscope, and makes a surprising finding for a bacterium. He wonders if the sample was mislabeled. Which of the following is likely to surprise this scientist if it were found in a sample that was labeled Neisseria?
Prokaryotes like Neisseria do not have mebrane bound organelles, including nuclei. Their DNA is stored in the cytosol without the benefit of extensive sequestration.
Prokaryotes like Neisseria do not have mebrane bound organelles, including nuclei. Their DNA is stored in the cytosol without the benefit of extensive sequestration.
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Unlike eukaryotes, prokaryotes have no membrane-bound organelles. How, then, are prokaryotes able to generate energy?
Unlike eukaryotes, prokaryotes have no membrane-bound organelles. How, then, are prokaryotes able to generate energy?
This question has several components for understanding what it is asking, and what the answer is. The first clue is the use of the word "energy," which is often code for ATP in biology. In eukaryotes, ATP is generated in the mitochondria through a long multi-step process, in which a proton gradient is established to produce ATP from glucose metabolism in the presence of oxygen. Note that even autotrophs require mitochondria in conjunction with chloroplasts; photosynthesis does not negate the necessity of an ion gradient for ATP synthesis.
Prokaryotes do not have mitochondria, but do generate ATP to carry out many biomolecular functions. Because there are no membrane-bound organelles, in order to complete bacterial metabolism prokaryotes must generate a proton gradient between the intra- and extra-cellular spaces, generally between the plasma membrane and the cell wall. This allows an electron transport chain to function along the cell membrane, using the proton gradient between the membrane and the bacterial cell wall to generate ATP.
This question has several components for understanding what it is asking, and what the answer is. The first clue is the use of the word "energy," which is often code for ATP in biology. In eukaryotes, ATP is generated in the mitochondria through a long multi-step process, in which a proton gradient is established to produce ATP from glucose metabolism in the presence of oxygen. Note that even autotrophs require mitochondria in conjunction with chloroplasts; photosynthesis does not negate the necessity of an ion gradient for ATP synthesis.
Prokaryotes do not have mitochondria, but do generate ATP to carry out many biomolecular functions. Because there are no membrane-bound organelles, in order to complete bacterial metabolism prokaryotes must generate a proton gradient between the intra- and extra-cellular spaces, generally between the plasma membrane and the cell wall. This allows an electron transport chain to function along the cell membrane, using the proton gradient between the membrane and the bacterial cell wall to generate ATP.
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Eukaryotes can share which of the following structures with prokaryotes?
Eukaryotes can share which of the following structures with prokaryotes?
The chief difference between prokaryotic and eukaryotic cells is the presence of membrane-bound organelles. Mitochondria and Golgi bodies are examples of such organelles, and are only found in eukaryotes. Nucleoids are only found in prokaryotes, while eukaryotes use membrane-bound nuclei.
Cell walls can be found in either prokaryotes or eukaryotes. Many prokaryotic bacteria use cell walls as protection from the external environment, while eukaryotic plants cells use cell walls to help maintain rigidity and prevent water loss.
The chief difference between prokaryotic and eukaryotic cells is the presence of membrane-bound organelles. Mitochondria and Golgi bodies are examples of such organelles, and are only found in eukaryotes. Nucleoids are only found in prokaryotes, while eukaryotes use membrane-bound nuclei.
Cell walls can be found in either prokaryotes or eukaryotes. Many prokaryotic bacteria use cell walls as protection from the external environment, while eukaryotic plants cells use cell walls to help maintain rigidity and prevent water loss.
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Which of the following cell types does not have a cell wall?
Which of the following cell types does not have a cell wall?
No animal cells will have cell walls. Trichocytes are specialized to be hard and resilient, but do not have cell walls.
Fungi, plants, and bacteria do use cell walls. The distinction between gram positive and gram negative bacteria refers to the composition of the cell wall only; both positive and negative bacteria have a cell wall present.
No animal cells will have cell walls. Trichocytes are specialized to be hard and resilient, but do not have cell walls.
Fungi, plants, and bacteria do use cell walls. The distinction between gram positive and gram negative bacteria refers to the composition of the cell wall only; both positive and negative bacteria have a cell wall present.
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Which of the following organelles is not bound by a membrane?
Which of the following organelles is not bound by a membrane?
Ribosomes are not membrane-bound organelles. All of the other organelles are membrane-bound, and are thus only found in eukaryotes. Ribosomes, which are the site of protein synthesis, are found in both prokaryotes and eukaryotes.
Ribosomes are not membrane-bound organelles. All of the other organelles are membrane-bound, and are thus only found in eukaryotes. Ribosomes, which are the site of protein synthesis, are found in both prokaryotes and eukaryotes.
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Prokaryotes that can utilize oxygen if available, but do not require it, are called __________.
Prokaryotes that can utilize oxygen if available, but do not require it, are called __________.
Facultative anaerobes are adaptive prokaryotes that can survive in either aerobic or anaerobic environments. These organisms are capable of both cellular respiration, through use of the electron transport chain along the cell membrane, and fermentation. They will adopt the more efficient process (cellular respiration) when oxygen is present, but can easily switch between one metabolism and the other.
Obligate anaerobes cannot produce energy in the presence of oxygen, and obligate aerobes cannot produce energy in the absence of oxygen.
Facultative anaerobes are adaptive prokaryotes that can survive in either aerobic or anaerobic environments. These organisms are capable of both cellular respiration, through use of the electron transport chain along the cell membrane, and fermentation. They will adopt the more efficient process (cellular respiration) when oxygen is present, but can easily switch between one metabolism and the other.
Obligate anaerobes cannot produce energy in the presence of oxygen, and obligate aerobes cannot produce energy in the absence of oxygen.
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Which of the following will not survive in the presence of oxygen?
Which of the following will not survive in the presence of oxygen?
Obligate anaerobes are incapable of producing energy in the presence of oxygen, and can only metabolize compounds via fermentation and anaerobic respiration. Oxygen acts as a toxin to obligate anaerobes.
In contrast, obligate aerobes are only capable of aerobic cellular respiration and cannot survive in the absence of oxygen. Facultative anaerobes are capable of multiple respiration mechanisms and can continue to generate energy in a fluctuating atmosphere, in either the presence or absence of oxygen.
Obligate anaerobes are incapable of producing energy in the presence of oxygen, and can only metabolize compounds via fermentation and anaerobic respiration. Oxygen acts as a toxin to obligate anaerobes.
In contrast, obligate aerobes are only capable of aerobic cellular respiration and cannot survive in the absence of oxygen. Facultative anaerobes are capable of multiple respiration mechanisms and can continue to generate energy in a fluctuating atmosphere, in either the presence or absence of oxygen.
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A researcher observes an unknown bacterium under the microscope. His results reveal that the bacterium is gram positive and has a spherical shape. Which of the following is a possible identity of this bacterium?
A researcher observes an unknown bacterium under the microscope. His results reveal that the bacterium is gram positive and has a spherical shape. Which of the following is a possible identity of this bacterium?
Recall that the shape of a bacteria classifies the bacteria as either a bacillus, coccus, or spirilla. Bacillus bacteria are rod-shaped, coccus bacteria are spherically shaped, and spirilla bacteria twist into a spiral. Since the researcher observes a spherical shape, the bacteria must be a coccus.
Bacteria classified as coccus often contain the word ‘coccus’ in their names. Of the three bacteria listed, only the Staphylococcus aureus contains the word ‘coccus’ in its name. This means that it is a coccus and, therefore, is a possible identity of this bacteria.
Recall that the shape of a bacteria classifies the bacteria as either a bacillus, coccus, or spirilla. Bacillus bacteria are rod-shaped, coccus bacteria are spherically shaped, and spirilla bacteria twist into a spiral. Since the researcher observes a spherical shape, the bacteria must be a coccus.
Bacteria classified as coccus often contain the word ‘coccus’ in their names. Of the three bacteria listed, only the Staphylococcus aureus contains the word ‘coccus’ in its name. This means that it is a coccus and, therefore, is a possible identity of this bacteria.
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