Ap Bio unit 2: ch 25 and 26
Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. The table below shows the number of nucleotide differences between the species. Which of the following phylogenetic trees is most consistent with the data?
34215
A scientist is attempting to provide support for the hypothesis that RNA\ was the first genetic material. Which of the following would be a workable alternate hypothesis? A. RNA, like DNA, is a carrier of genetic information and contains the nitrogen bases adenine, guanine, and cytosine. B. RNA can be observed to self-replicate without the assistance of proteins, while DNA always requires protein-based enzymes to replicate. C. RNA exists in both single-stranded and double-stranded configurations; however, it is less stable compared with DNA. D. Transfer RNA\ and ribosomal RNA are products of transcription, but they are not translated as is mRNA.
B
Which of the following statements best justifies the claim that the conditions in at least one of the experiments could generate the molecular building blocks essential for life? A. The carbon dioxide gas and water vapor in experiment 1 could react spontaneously to produce the phospholipids required by the first life-forms. B. The nitrogen gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids. C. The sulfur dioxide gas in experiment 2 could donate the excited electrons required to drive the process of photosynthesis. D. The methane gas in experiment 2 could act as the electron acceptor required to complete the process of cellular respiration
B
A widely accepted hypothesis about the origin of life on Earth is that life arose approximately 3.5 billion years ago as the result of a complex sequence of chemical reactions that took place spontaneously in Earth's atmosphere. Another hypothesis about the origin of life suggests that life began somewhere else in the universe and arrived on Earth by chance. Which of the following questions might scientists ask to most reliably determine if there has ever been life on Mars? A. How far from Earth was Mars 3.5 billion years ago? B. Is there scientific proof that Earth ever had an oxygen-free atmosphere? C. Did Mars have the elements present in its atmosphere to support life? D. Was there oxygen gas on Mars 3.5 billion years ago?
C
Which of the following questions about the origin of life on Earth is most scientifically testable? A. Why were the earliest life-forms created using only twenty amino acids? B. Did life originate to make the universe a better place? C. Was catalytic RNA used by ancient organisms as a stepping stone to acquire protein enzymes? D. Can simple organic molecules form spontaneously in an oxygen-free atmosphere?
D
All of the following were likely present on the primitive Earth during the evolution of self-replicating molecules EXCEPT A. amino acids and nucleotides B. nitrogen C. simple carbohydrates D. freestanding liquid water E. an O2-rich atmosphere
E
Group IV of the cladogram most likely includes which of the following species? A P and S only B Q and T only C R and W only D U and W only
a
The fossils in a layer of rock are significantly different from those in the rock layer directly above it. One hypothesis to explain the difference is that a major extinction event occurred at the point in time represented by the transition between the two rock layers. Which of the following is the best plan for collecting data to use in a test of the hypothesis? A Examining the upper part of the lower rock layer for evidence of a catastrophic event, such as the presence of shocked quartz, iridium, or soot particles B Digging farther into the hillside to look for a section of sedimentary rock that has a third layer below the two layers that were already identified C Comparing the genomes of organisms from different evolutionary lineages to estimate the relative geologic age of the upper rock layer D Searching fossil collections in several museums for examples of the types of features once shared among organisms that are now extinct
a
The phylogenetic trees in Figures 2 and 3 depict two different phylogenies of the same populations of sticklebacks. Which of the following questions will best help determine which tree represents the most accurate phylogeny? A Is the EDA gene as representative of the differences between the populations as the 25 random genes that were examined for Figure 3? B Are the low-plated populations found only in freshwater and the high-plated populations found only in saltwater environments? C Is the common ancestor of the organisms represented in Figure 2 different from the common ancestor of the organisms represented in Figure 3? D Is the expression level of the EDA gene analyzed in Figure 2 significantly greater than the expression levels of the 25 genes analyzed in Figure 3?
a
The validity of the cladogram is best supported by molecular evidence for which of the following changes in the amino acid composition of the beta-hemoglobin protein during the evolution of these species? A Arginine to leucine at position X on the cladogram B Arginine to leucine at position Y on the cladogram C Leucine to arginine at position W on the cladogram D Leucine to arginine at position Z on the cladogram
a
Which organism would the researchers most likely predict to be the most distantly related to eukaryotes? A Organism I B Organism II C Organism III D Organism IV
a
Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence? A All organisms carry out glycolysis in mitochondria. B Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life. C Across the three domains, all organisms depend solely on the process of anaerobic respiration for ATP production. D The presence of glycolysis as an energy-releasing process in all organisms suggests that convergent evolution occurred.
b
In the "RNA world" model for the origin of life, the first protocells (probionts) relied on RNA, not DNA, for information storage and transmission. Which of the following could best be considered evidence in support of the RNA world model? A DNA is more stable than is RNA. B Some RNA molecules in contemporary cells have catalytic function. C RNA is so complex in both structure and function that it must have preceded DNA. D RNA has secondary structure whereas DNA does not.
b
Mitochondria are found in most eukaryotic cells and contain their own DNA and ribosomes that are similar to those typical of many prokaryotic cells. Which of the following statements is justified by these observations? A The mitochondrion is the only location in which eukaryotic cells can synthesize ATP. B An ancestral cell most likely engulfed anaerobic prokaryote in a relationship that proved beneficial for both cells. C Mitochondrial membranes provide abundant surface area for reactions because of the infoldings called cristae. D The mitochondrion plays a role in respiration, but it also stores the cell's extra mRNA.
b
The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow? A Searching horizontal rock layers in any class of rock and try to find those that contain the greatest number of fossils B Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones C Looking in sedimentary layers next to bodies of water in order to find marine fossils of bivalves and trilobites D Using relative dating techniques to determine the geological ages of the fossils found so they can calculate the rate of speciation of early organisms
b
Transposable elements are significant features in the genomes of almost all eukaryotic organisms. The accumulation of these elements in various species can help determine their relatedness. Table 1 indicates the presence (++) or absence (−−) of 5 segments of DNADNA that have been moved by transposition (transposons) in 6 primate species. Which of the following best predicts how phylogenetic relationships might be revised if transposon 1 was not found in chimpanzees? A Bonobos would be more closely related to humans than to chimpanzees. B Chimpanzees would be more closely related to humans than to bonobos. C Orangutans would be more closely related to humans than to chimpanzees. D Chimpanzees would be more closely related to gibbons than to gorillas.
b
Which of the following observations best supports the hypothesis that a large object collided with Earth in a period of time associated with a mass extinction? A A species found only in Australia resembles a species found only in North America. B An analysis of radiation reaching Earth from outer space suggests that water might have existed on distant planets. C A fossil of an extinct species of mammal is found to have morphological characteristics that are similar to those of a living nocturnal mammal. D Iridium, which is common in meteorites but rare on Earth, is found in sedimentary rock that contains the last appearance of many species in the fossil record.
b
By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses? A The molecules essential to life today did not exist at the time Earth was first formed. B The molecules essential to life today could not have been carried to the primordial Earth by a comet or meteorite. C The molecules essential to life today could have formed under early Earth conditions. D The molecules essential to life today were initially self-replicating proteins that were synthesized approximately four billion years ago.
c
The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the model? A Prokaryotes and eukaryotes acquire nutrients from the surrounding environment. B Organelles such as mitochondria and the endoplasmic reticulum have membranes composed of phospholipids. C Mitochondria and some prokaryotes share similar metabolic reactions that produce ATPATP. D Eukaryotes evolved after prokaryotes and have more complex structures.
c
To determine the evolutionary history and relationships among organisms, scientists gather evidence from a wide variety of sources including paleontology, embryology, morphology, behavior, and molecular biology. A phylogenetic tree of vertebrates is shown. Which of the following statements is most consistent with the phylogenetic tree shown? A Birds and turtles evolved their own means of gas exchange independently of the other vertebrates. B Mammals are most closely related to birds because they share a direct common ancestor. C The common ancestor of reptiles, birds, and mammals produced amniotic eggs. D Crocodiles are direct descendents of ray-finned fishes since they live in the same environment.
c
Which of the following provides evidence to best support the researchers' claim? A The organelle has a phospholipid membrane. B The organelle has protein in the membrane. C The organelle has a double membrane. D The organelle has an internal aqueous environment that is similar to the cytosol of the larger cell.
c
A researcher hypothesizes that RNA molecules were present in the most recent common ancestor of all living organisms. Which of the following scientific questions would best test the hypothesis? A Is it possible to produce an RNA polymer in a laboratory setting? B How many distinct functions can a particular RNA molecule perform in a cell? C How many different monomers of RNA are found in a eukaryotic cell? D Do any known organisms function entirely without RNA?
d
The Stanley Miller apparatus demonstrated that organic molecules could assemble spontaneously in an environment lacking free oxygen and containing water, methane, and ammonia in the presence of an abundant energy source, such as an electric discharge. The research was considered supportive of the organic soup hypothesis, which states that the primitive atmosphere provided inorganic precursors from which organic molecules could have been synthesized in the presence of an energy source. Based on subsequent research, the primordial atmosphere was determined to contain less methane and more carbon dioxide. The new data about the composition of the early atmosphere had which of the following effects on origin-of-life hypotheses? A Miller's work was discarded as not relevant to an origin-of-life hypothesis. B Miller's work was used to refute the new hypothesis about the composition of the atmosphere. C The organic soup hypothesis was abandoned as no longer being supportable. D A new organic soup hypothesis was proposed to account for the new data about the atmosphere.
d
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (nontaster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the nontaster allele. The nucleotides present at the three positions are shown in the table below.Which of the following conclusions is supported by the data? A Humans and bonobos belong to the same genus because the nucleotide sequence of the TAS2R38 gene is the same B Chimpanzees are equally related to humans and bonobos because all three groups possess variants of the TAS2R38 gene. C Humans are more closely related to bonobos than to chimpanzees because the branch of the tree with humans is closest to the branch of the tree with bonobos. D Bonobos are more closely related to humans than to gorillas because bonobos and humans share a more recent common ancestor than bonobos and gorillas do.
d
Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells? A The cytoplasm of both eukaryotes and prokaryotes is surrounded by a plasma membrane. B Eukaryotes and prokaryotes both contain ribosomes, but the ribosomes of eukaryotes are more complex in structure than those of prokaryotes. C Eukaryotes exchange segments of internal membranes between the endoplasmic reticulum and Golgi apparatus, but prokaryotes have no such internal membranes. D Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.
d
The table above shows derived characters for selected organisms. Based on the information in the table, which of the following cladograms best represents the evolutionary relationships among the organisms?
fish, amphibians, crocks, birds, mammals
Which of the following phylogenetic trees best illustrates (with the X) the point at which the mutation in the GULO gene most likely occurred during the evolutionary history of these organisms?
x before chimp
Which of the following cladograms provides the simplest and most accurate representation of the data in the table?
ywvzx
