test 2 ch. 12 mcat practice test

Which of the following populations would be most likely to demonstrate genetic drift? A) A large population of bacteria is grown over an extended period in a continuous culture system. B) A researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process. C) Someone takes an extended course of antibiotics, leaving a relatively small number of surviving bacteria. D) A researcher performs a Gram stain to separate gram-positive and gram-negative bacteria. He places the gram-positive bacteria in one test tube and the gram-negative bacteria in the other.

A researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process. The bacteria are being selected for specific characteristics. There are important differences between the two groups, so this is not genetic drift.

Why would it be highly advantageous to a cell to form a mutualism with a prokaryote capable of aerobic cellular respiration? A) A prokaryote capable of aerobic cellular respiration is capable of producing organic materials, such as sugars, using light energy. B) Aerobic cellular respiration involves an electron transport chain with oxygen as the terminal electron acceptor. This produces large amounts of ATP as the electron transport chain produces the greatest amount of ATP in cellular respiration. C) A symbiotic prokaryote increases the nutritional diversity of the organism, greatly increasing possible food sources. D) Having a symbiotic prokaryote increases the genetic diversity of the cell.

Aerobic cellular respiration involves an electron transport chain with oxygen as the terminal electron acceptor. This produces large amounts of ATP as the electron transport chain produces the greatest amount of ATP in cellular respiration. It is true that having a symbiotic prokaryote could contribute to genetic diversity. It is thought that eukaryotic cells obtained genes from bacteria and from archaea. However, that is not the most immediate benefit of having this type of symbiotic prokaryote.

It is hypothesized that early photosynthesis was anoxygenic. Think about the role of oxygen in photosynthesis as carried out by green plants, green algae, and cyanobacteria (as opposed to modern organisms that use anoxygenic photosynthesis). What would have been different in anoxygenic photosynthesis (or is different in modern organisms that use anoxygenic photosynthesis)? A) Green plants, green algae, and cyanobacteria split H2O to replace an excited electron in noncyclic photophosphorylation. Oxygen is released into the atmosphere. In anoxygenic photosynthesis, a different molecule (such as H2S) is split and a different product (such as sulfur) is released. B) Anoxygenic organisms do not require light while oxygenic organisms do require light. C) Anoxygenic organisms would have been able to produce only NADPH, not ATP. D) Anoxygenic organisms would not have been able to produce ATP, only NADPH.

Green plants, green algae, and cyanobacteria split H2O to replace an excited electron in noncyclic photophosphorylation. Oxygen is released into the atmosphere. In anoxygenic photosynthesis, a different molecule (such as H2S) is split and a different product (such as sulfur) is released.

Which of the following is NOT evidence that mitochondria originated as independent prokaryotes, as stated by the endosymbiont hypothesis? A) Mitochondria have a membrane that includes peptidoglycan. B) Mitochondria have ribosomes that are the same size as prokaryotic ribosomes. C) Mitochondria have circular DNA that resembles that of prokaryotes. D) Phylogenetic analyses place mitochondrial ribosomal RNA sequences within a bacterial phylum.

Mitochondria have a membrane that includes peptidoglycan. Phylogenetic analyses look at genetic similarities to propose evolutionary relationships. Analyses show that the mitochondrial ribosomal RNA sequence fits within a bacterial phylum.

It is hypothesized that early photosynthesis was anoxygenic. If so, what was the effect of the appearance of organisms using oxygenic photosynthesis? A) The increase in organisms using oxygenic photosynthesis led to a decrease in the diversity of organisms as they outcompeted organisms using anoxygenic photosynthesis. B) Organisms using oxygenic photosynthesis release oxygen into the atmosphere, causing an increase in the oxygen in the atmosphere and allowing for the development of aerobes. C) The increase in oxygen in the atmosphere from organisms using oxygenic photosynthesis caused a great decrease in diversity as obligate aerobes were killed. D) The increase in organisms using oxygenic photosynthesis led to an increased ability to use solar radiation.

Organisms using oxygenic photosynthesis release oxygen into the atmosphere, causing an increase in the oxygen in the atmosphere and allowing for the development of aerobes. Some organisms may have been killed by higher oxygen concentrations, but many organisms using anoxygenic photosynthesis still exist. Other organisms did well in the new environment, so it is not appropriate to simply say that there was a decrease in diversity.

Which of the following best explains the endosymbiont hypothesis? A) Prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of cellular respiration evolved into chloroplasts and the prokaryotes capable of photosynthesis evolved into mitochondria. B) Prokaryotes capable of digestion took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of digestion evolved into lysosomes. C) Prokaryotes capable of cellular respiration began to associate with prokaryotes capable of photosynthesis. They fused together to form eukaryotic cells. D) Prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of cellular respiration evolved into mitochondria and the prokaryotes capable of photosynthesis evolved into chloroplasts.

Prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of cellular respiration evolved into mitochondria and the prokaryotes capable of photosynthesis evolved into chloroplasts.

What is one piece of evidence that supports the RNA world hypothesis? A) RNA is more stable than DNA and therefore more likely to have been able to exist in such a harsh environment. B) RNAs can have catalytic activity. C) There are traces of RNA that have been dated and found to be older than any traces of DNA. D) Early cells relied more heavily on RNA than on DNA.

RNAs can have catalytic activity.

Phylogenetic trees for bacteria are constructed by which of the following? A) examining the amount of horizontal gene transfer; those organisms that exchange the largest amounts of genetic material in this manner are the most closely related B) analyzing molecular similarities and then using computer algorithms or optimality criteria to construct phylogenetic trees showing hypothesized evolutionary relationships C) examining morphological, nutritional, and biochemical similarities to determine which individuals appear to be the most similar D) placing organisms with the most similar characteristics together; these organisms show convergent evolution and therefore belong together in the phylogeny

analyzing molecular similarities and then using computer algorithms or optimality criteria to construct phylogenetic trees showing hypothesized evolutionary relationships Convergent evolution occurs when organisms develop similar characteristics because of similar evolutionary pressures, not because they were inherited from a shared ancestor.

According to the RNA world hypothesis, which of the following was the correct sequence of developments? A) biological building blocks (e.g., amino acids, sugars, and nucleosides), then RNA (including catalytic and self-replicating RNA), then DNA, then protein synthesis, then lipid bilayers surrounding early cellular life B) biological building blocks (e.g., amino acids, sugars, and nucleosides), then lipid bilayers surrounding these building blocks, then RNA (including catalytic and self-replicating RNA), then protein synthesis, then DNA C) biological building blocks (e.g., amino acids, sugars, and nucleosides), then DNA, then RNA (including catalytic and self-replicating RNA), then protein synthesis, then lipid bilayers surrounding early cellular life D) biological building blocks (e.g., amino acids, sugars, and nucleosides), then RNA (including catalytic and self-replicating RNA), then protein synthesis, then DNA, then lipid bilayers surrounding early cellular life

biological building blocks (e.g., amino acids, sugars, and nucleosides), then RNA (including catalytic and self-replicating RNA), then protein synthesis, then DNA, then lipid bilayers surrounding early cellular life

What was the LUCA? A) the type of prokaryote that evolved into a eukaryote B) the last eukaryote before eukaryotes diversified C) the first cellular organism to evolve D) the last organism prior to the divergence of bacteria and archaea

the last organism prior to the divergence of bacteria and archaea