Explain the relationship between Earth’s ancient atmosphere and the evolution of some of the first life forms on Earth by selecting the most accurate of the provided descriptions. Use the terms anaerobic and phototrophic correctly, and accurately reflect the effect of cyanobacteria on the atmosphere.
Phototrophic organisms appeared during the first two billion years of Earth’s existence. Anaerobic organisms appeared within one billion years of Earth’s formation. From these organisms evolved the cyanobacteria, which produce oxygen as a by-product of photosynthesis, leading to the oxygenation of the atmosphere.
For the first two billion years of Earth’s existence, the atmosphere had no molecular oxygen. Thus, the first organisms were anaerobic. Cyanobacteria appeared within one billion years of Earth’s formation. From these evolved the phototrophic organisms, which produce oxygen as a by-product of photosynthesis, leading to the oxygenation of the atmosphere.
For the first two billion years of Earth’s existence, the atmosphere had no molecular oxygen. Thus, the first organisms were anaerobic. Phototrophic organisms appeared within one billion years of Earth’s formation. From these organisms evolved the cyanobacteria, which produce oxygen as a by-product of photosynthesis, leading to the oxygenation of the atmosphere.
For the first two billion years of Earth’s existence, the atmosphere had no molecular oxygen. Thus, the first organisms were anaerobic. Within one billion years of Earth's formation, cyanobacteria appeared, which produce oxygen as a by-product of photosynthesis, leading to the oxygenation of the atmosphere. From these organisms evolved phototrophic organisms.
37.
Which of these statements is the best explanation for this?
Extremophiles can be altered genetically in vitro to allow them to live in extreme conditions and this capability of alteration can be used to help humans. For example, some water-resistant prokaryotes have developed DNA repair mechanisms. Also, they could be developed and used in the treatment of human disease.
Extremophiles have specialized adaptations that allow them to live in extreme conditions. These adaptations can be mobilized to help humans. For example, some water-resistant prokaryotes have developed DNA repair mechanisms. Also, they could be developed and used in the treatment of human disease.
Extremophiles can be altered genetically in vitro to allow them to live in extreme conditions and this capability of alteration can be used to help humans. For example, some radiation-resistant prokaryotes have developed DNA repair mechanisms. Also, they could be developed and used in the treatment of human disease.
Extremophiles have specialized adaptations that allow them to live in extreme conditions. These adaptations can be mobilized to help humans. For example, some radiation-resistant prokaryotes have developed DNA repair mechanisms. Also, they could be developed and used in the treatment of human disease.
38.
Given an environmental sample, describe briefly the methods that would best detect the presence of a non-culturable prokaryote in that sample, and amplify the prokaryotic DNA.
Recombinant DNA techniques are used to detect the presence of a non-culturable prokaryote in an environmental sample. Polymerase chain reaction is used to amplify selected portions of prokaryotic DNA.
Molecular biology techniques are used to detect the presence of a non-culturable prokaryote in an environmental sample. Electrophoresis is used to amplify selected portions of prokaryotic DNA.
Molecular biology techniques are used to detect the presence of a non-culturable prokaryote in an environmental sample. Polymerase chain reaction is used to amplify selected portions of prokaryotic DNA.
Recombinant DNA techniques are used to detect the presence of a non-culturable prokaryote in an environmental sample. Electrophoresis is used to amplify selected portions of prokaryotic DNA.
39.
Scientists believe that the first organisms on Earth were extremophiles. Justify this claim with relevant evidence of what scientists know about Earth's early environment.
Earth’s early environment was full of extreme places with high levels of oxygen in the atmosphere, no ozone to shield Earth’s surface from mutagenic radiation, much geologic upheaval, and volcanic activity. Extremophiles are bacteria and archaea that are adapted to grow in extreme environments.
Earth’s early environment was full of extreme places with little oxygen in the atmosphere, no ozone to shield Earth’s surface from mutagenic radiation, much geologic upheaval and volcanic activity. Extremophiles are bacteria and archaea that are adapted to grow in extreme environments.
Earth’s early environment was full of extreme places with little oxygen in the atmosphere and excessive concentrations of ozone that contributed to mutagenic radiation. Extremophiles are phototrophic bacteria and cyanobacteria that are adapted to grow in extreme environments.
For the first two billion years of Earth’s existence, the atmosphere had no molecular oxygen.
40.
Describe a typical prokaryotic cell.
It has a cell wall enclosing cell membrane, cytoplasm, ribosomes and nucleoid region with genetic material. It may have a protective capsule, flagellum, pili and plasmids.
It has a cell wall enclosing cell membrane, cytoplasm, ribosomes and nucleus containing genetic material. It may have a protective capsule, flagellum, pili and plasmids.
It has a cell wall enclosing nuclear membrane, cytoplasm, ribosomes and nucleoid region with genetic material. It may have a protective capsule, flagellum, pili and plasmids.
It has a cell wall enclosing nuclear membrane, cytoplasm, mitochondria, vacuoles and nucleoid region with genetic material. It may have a protective capsule, flagellum, pili and plasmids.
41.
Explain the statement that both Archaea and Bacteria have the same basic structures, but these structures are built from different chemical components.
Typical cells in Archaea and Bacteria contain a cell wall, cell membrane, nucleoid region, ribosomes, and often a capsule, flagellum, and pili. However, these are sometimes made from different chemical compounds. Cell walls of Bacteria contain peptidoglycan while Archaea do not. Plasma membrane lipids of Bacteria are fatty acids while those of Archaea are phytanyl groups.
Typical cells in Archaea and Bacteria contain a cell wall, cell membrane, nucleoid region and often a capsule, flagellum, and pili but in some instances different chemical compounds make them. Cell walls of Bacteria contain peptidoglycan while Archaea do not. Bacteria contain 70S ribosomes while Archaea contain 80S ribosomes.
Typical cells in Archaea and Bacteria contain a cell wall, nuclear membranes, nucleoid region and often a capsule, flagellum, and pili but in some instances different chemical compounds make them. Cell walls of Bacteria contain peptidoglycan while Archaea do not. Plasma membrane lipids of bacteria are fatty acids, while the plasma membrane lipids of Archaea are phytanyl groups.
Typical cells in Archaea and Bacteria contain a cell wall, cell membrane, nucleoid region and often a capsule, flagellum, and pili but in some instances different chemical compounds make them. Cell walls of Bacteria contain peptidoglycan while Archaea do not. Plasma membrane lipids of Bacteria are phytanyl groups, while the plasma membrane lipids of Archaea are fatty acids.
42.
Three basic prokaryotic categories are cocci, spirilli, and bacilli. Describe and compare the basic structural features of each category by choosing the most accurate summary.
These three prokaryote groups have similar basic structural features. They typically have cell walls enclosing nuclear membranes, cytoplasm, ribosomes, mitochondria, and a nucleoid region with genetic material. They may have a protective capsule, flagellum, pili, and plasmids.
Cocci and spirilli have similar basic structural features. They typically have cell walls enclosing cell membranes, a flagellum for locomotion, and pili for attachment. Bacilli are rod shaped and contain ribosomes and a nucleoid region with genetic material.
These three prokaryote groups have similar basic structural features. They typically have cell walls enclosing cell membranes, cytoplasm, ribosomes, and a nucleoid region with chromosomes. They may have a protective capsule, flagellum, pili, and plasmids.
Bacilli and spirilli have similar basic structural features. They typically have cell walls enclosing nuclear membranes, a flagellum for locomotion, and pili for attachment. Cocci are spherical and contain ribosomes and a nucleoid region with genetic material.
43.
Which macronutrient do you think is most important? Justify your claim by providing accurate evidence to support it.
Carbon, because it represents 12% of the total dry weight of a typical cell and is a component of all macromolecules.
Oxygen, because it is necessary and is a major component for all macromolecules. It also accounts for 50% of the total composition of a cell.
Carbon, because it is necessary and is a major component for all macromolecules. It also accounts for 50% of the total composition of a cell.
Nitrogen, because it is necessary and is a major component for all macromolecules. It also accounts for 50% of the total composition of a cell.
44.
A bacterium requires only a particular amino acid as an organic nutrient and lives in a completely lightless environment. What mode of nutrition (free energy and carbon) does it use? Justify your response.
Chemoheterotroph, as it must rely on chemical sources of energy living in a lightless environment and a heterotroph if it uses organic compounds for its carbon source.
Chemoorganotroph, as it must rely on chemical sources of energy living in a lightless environment and an organotroph if it uses organic compounds for its carbon source.
Chemolitoautotroph, as it must rely on chemical sources of energy living in a lightless environment and an autotroph if it uses organic compounds for its carbon source.
Chemoheterotroph, as it must rely on chemical sources of energy living in a lightless environment and a heterotroph if it uses organic compounds for its carbon source.
45.
Assuming that you could synthesize all of the nitrogen-containing compounds needed if you had nitrogen, what might you need to include in your diet if you could fix nitrogen like some prokaryotes?
My diet might include fruits or vegetables and water as nitrogen is present in the highest amount in water.
My diet might include fruits or vegetables, water and air as atmospheric nitrogen could be simply absorbed.
My diet might include fruits or vegetables, cheese, meat, water, and air as atmospheric nitrogen could be simply absorbed.
My diet might include cheese or meat, water, and air as atmospheric nitrogen could be simply absorbed.
46.
Which are more important: macronutrients or micronutrients? Which reasoning explains why?
Neither are important, as cells can survive as well as carry out essential functions without either types of nutrients.
Micronutrients, even though they are required in lesser amounts; without them cells cannot survive and carry out functional processes.
Macronutrients, as they are required in larger amounts by cells and thus are more essential than micronutrients.
Neither is more important as both types of nutrients are absolutely necessary for prokaryotic cell structure and function.
47.
(credit: modification of work by Michael W Peck/ResearchGate)
Botulism is a potentially fatal food-borne disease. It is caused by toxins from the bacteria Clostridium botulinum (C. botulinum). This bacteria produces spores, which are difficult to destroy. The graph shows the amount of time a sample needs to be heated based on temperature. Note the time scale is a log scale: Log 1 is 10 minutes, log 2 is 100 minutes and log 3 is 1,000 minutes.
Which treatment would effectively kill the spores and be safe?
Heating for 120 minutes at 70 °C.
Heating for 100 minutes at 75 °C.
Heating for 300 minutes at 85°C.
Heating for 30 minutes at 90°C.
48.
Have foodborne illnesses related to biofilms changed over time? Explain.
Yes, better sterilization and canning procedures have reduced the incidence of botulism. Most cases of foodborne illness now are related to small-scale food production.
No, better sterilization and canning procedures have reduced the incidence of botulism. Most cases of foodborne illness now are related to small-scale food production.
No, better sterilization and canning procedures have increased the incidence of botulism. Most cases of foodborne illnesses now are related to large-scale food production.
Yes, better sterilization and canning procedures have reduced the incidence of botulism. Most cases of foodborne illnesses now are related to large-scale food production.
(credit: modification of work by Michael W Peck/ResearchGate)
Botulism is a potentially fatal food-borne disease. It is caused by toxins from the bacteria Clostridium botulinum (C. botulinum). This bacteria produces spores, which are difficult to destroy. The graph shows how heating affects C. botulinum spores. The spores are heated to 75°C and kept at that temperature.
Make a claim based on this graph.
Heating to 75°C kill C. botulinum spores almost instantly.
Keeping the spores at 75°C for 10 minutes kills most of the spores.
For most spores to die, the 75°C temperature must be kept for more than two hours.
Heating to 75°C has very little effect on C. botulinum spores.
50.
What was the Plague of Athens? Compare the summaries below and select the one that best describes this disease and correctly identifies related current impacts.
The Plague of Athens was a disease believed caused by Yersinia pestis that killed one-quarter of Athenian troops in 430 BC. The bacterium causes between 10 and 15 million cases of typhoid fever today, resulting in over 10,000 deaths annually.
The Plague of Athens was a disease believed caused by Salmonella entericaserovar typhi that killed one-quarter of Athenian troops in 430 BC. The bacterium causes between 5 and 10 million cases of typhoid fever today, resulting in over 20,000 deaths annually.
The Plague of Athens was a disease believed caused by Yersinia pestis that killed one-quarter of Athenian troops in 430 BC. The bacterium causes between 16 and 33 million cases of typhoid fever today, resulting in over 200,000 deaths annually.
The Plague of Athens was a disease believed caused by Salmonella entericaserovar typhi that killed one-quarter of Athenian troops in 430 BC. The bacterium causes between 16 and 33 million cases of typhoid fever today, resulting in over 200,000 deaths annually.
51.
Identify three beneficial results of symbiotic nitrogen fixation.
Plants benefit from an endless supply of nitrogen; soils benefit from being naturally fertilized; and bacteria benefit from using potassium from plants.
Plants benefit from a limited supply of nitrogen; soils benefit from being naturally fertilized, and bacteria benefit from using photosynthates from plants.
Plants benefit from an endless supply of carbon; soils benefit from being naturally fertilized; and bacteria benefit from using photosynthates from plants.
Plants benefit from an endless supply of nitrogen; soils benefit from being naturally fertilized; and bacteria benefit from using photosynthates from plants.
52.
(credit: modification of work by Samir S. Radwan, et al./Scientific Reports, under CC BY 4.0 license)
The image shows the results of a research that studied various bacteria for their ability to remove mercury, cadmium and lead from an environment over time.
Make a claim about removal of mercury by these bacteria?
All the bacteria shown here can remove mercury from the environment.
The bacteria that remove the mercury complete the process in 3-4 days.
The bacteria that remove the mercury complete the process in 7-8 days.
Only a few bacteria shown here can remove the mercury from the environment.
Consider the images from the Exxon Valdez oil spill in Alaska in 1989. Make a case on what the success of bioremediation of oil spills depends.
Success depends on the presence of only aromatic and highly branched hydrocarbon chain compounds, and the temperature.
Success depends on the presence of less nonvolatile and more aromatic and highly branched hydrocarbon chain compounds, and the temperature.
Success depends on the type of oil compounds, the presence of naturally-occurring oil-solubilizing prokaryotes in the ocean, and the type of water body.
Success depends on the type of oil compounds, the presence of naturally-occurring oil-solubilizing prokaryotes in the ocean, and the temperature.
54.
Why is the relationship between sustainable agriculture and nitrogen fixers called a symbiotic relationship?
Due to agrobacterium which are nitrogen fixers, plants benefit from an endless supply of nitrogen; soils benefit from being naturally fertilized and bacteria benefit from using photosynthates from plants.
Due to rhizobia, which are nitrogen fixers, plants benefit from an endless supply of nitrogen; soils benefit from being naturally fertilized and bacteria benefit from using photosynthates from plants.
Due to rhizobia, which are nitrogen fixers, plants benefit from an endless supply of nitrogen; soils benefit from being naturally fertilized and bacteria benefit from using potassium from plants.
Due to rhizobia, which are nitrogen fixers, plants benefit from a limited supply of nitrogen; soils benefit from being naturally fertilized and bacteria benefit from using potassium from plants.
