Mastering Biology Chp. 24 HW

25 July 2022
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question
Which statement about endotoxins is true?
answer
Endotoxins are released only when bacteria die and their cell walls break down. Endotoxins, which are released only when bacteria die and their cell walls break down, are a component of the outer membrane of gram-negative bacteria.
question
Bioremediation is _____.
answer
the use of organisms to remove pollutants from the environment The use of organisms to remove pollutants from the environment is the general definition of the term bioremediation.
question
Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are __________.
answer
chemoautotrophs They use inorganic molecules (in redox reactions) for energy and carbon dioxide for carbon.
question
__________ include prokaryotic autotrophs that float near the surface of water and are the basis of the food chain.
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Phytoplankton These photosynthetic organisms serve as the basis of the food chain.
question
The prokaryotic organisms most likely found living in salt ponds are _____.
answer
halophiles These archaea live in salty environments, such as the Dead Sea.
question
Which of the following processes contributes to genetic recombination in prokaryotes?
answer
Transduction In transduction, bacteriophages carry bacterial genes from one host cell to another, producing a recombinant bacterial genome. Read about the other processes that contribute to genetic recombination in prokaryotes.
question
Genes for the resistance of antibiotics are often located __________.
answer
on plasmids Genes for the resistance of antibiotics are often located on plasmids.
question
Identify the thylakoid membrane of the cyanobacterium shown here.
Identify the thylakoid membrane of the cyanobacterium shown here.
answer
The thylakoid membrane of the cyanobacterium is an infolded plasma membrane. Although prokaryotic cells lack the complex compartmentalization of eukaryotic cells, some prokaryotic cells do have specialized foldings of the plasma membrane, which perform metabolic functions. For example, photosynthetic prokaryotes called cyanobacteria have thylakoid membranes similar to those in the chloroplasts of photosynthetic eukaryotes. Read about the internal and genomic organization of prokaryotes.
question
Which statement is true about obligate anaerobes?
answer
They are poisoned by O2. Some obligate anaerobes live exclusively by fermentation; others extract chemical energy by anaerobic respiration, in which substances other than O2 accept electrons at the "downhill" end of electron transport chains. Oxygen is toxic to them.
question
Which statement about natural selection on early Earth is correct?
answer
Natural selection could act on a population of proto-cells on early Earth, selecting for those that were stable and had self-replicating, catalytic RNA that allowed them to grow and divide to produce similar daughter proto-cells.