USABO Practice Exam 2024 - Questions with Verified Answers

USABO Practice Exam 2024 - Questions with Verified Answers What enzyme does HIV use to convert RNA to DNA? Reverse Transcriptase The promoter region of a prokaryotic gene is located ______ to the gene and is the bindin ...

USABO Practice Exam 2024 - Questions with Verified Answers What enzyme does HIV use to convert RNA to DNA? Reverse Transcriptase The promoter region of a prokaryotic gene is located ______ to the gene and is the binding site for ______. 5'...RNA polymerase Which of the following is TRUE of prokaryotes? I. Simultaneous transcription and translation II. Presence of intron sequences III. Circular DNA I and III only Integral transmembrane proteins are proteins imbedded in the cell membrane. Which of the following amino acids would you MOST expect to find in the transmembrane region of such proteins? Tryptophan When the base composition of DNA from bacterium Mycobacterium tuberculosis was determined, 18% of the bases were found to be adenine. What is the G + C content in M. tuberculosis? 64% The frequency of individuals affected with an autosomally recessive inherited disorder is 1 in 4. Assuming that the population affected by this disease is in Hardy-Weinberg equilibrium, what is the proportion of carrier individuals in this population? 50% The velocity of action potential conduction across a nerve axon is increased by the presence of the myelin sheath. In the peripheral nervous system, what cell myelinates the axon? schwann cell The cell bodies of afferent (sensory) nerves involved in somatic reflexes are located in the Dorsal root ganglion Rods and cones are associated with _____ and _____ vision, respectively. Light/dark...color Populations that are likely to be living at a density near the limit of their resources, are characterized as K-selected In many types of cancer, the function of the p53 gene is lost. Wild-type p53 is MOST likely to be a tumor suppressor What glycolytic product is shuttled to the mitochondria in aerobic respiration? Pyruvate During human development, which process leads to the formation of three germ layers? Gastrulation Telomerase is responsible for _____ the size of telomeres, and its function is often ____ in carcinogenesis. maintaining ... increased Which of the following is NOT a mode of natural selection? sexual selection Protostomes have _____ and _____ types of cleavage. spiral ... determinate Which of the following is NOT a characteristic of all chordates? Vertebrae In cardiac muscle, calcium ions can move freely between adjacent cells through which of the following? gap junctions Unlike most polypeptide hormones, steroid hormones are unique in that they Diffuse across cell membranes In superoxide dismutase 1, an enzyme implicated in amyotrophic lateral sclerosis (Lou Gehrig's disease), a copper ion is bound to the active site and is important for enzyme activity. In this enzyme, copper most likely functions as a(n) Cofactor The order of normal blood flow through the human heart is right atrium, right ventricle, lungs, left atrium, left ventricle, body Allopatric speciation refers to species formed after which type of separation: Geographic Which two functional groups are always found in amino acids? Carboxyl and amine Movement of ions across the membrane from higher to lower concentrations through a channel protein is an example of Facilitated diffusion Which group of plants has vascular tissue but does not produce seeds? I. Mosses II. Ferns III. Gymnosperms Which of the following is true for transport in xylem? Movement through xylem depends mainly on transpiration Predation is considered a _________ interaction, while Mutualism is considered a ___________ interaction. +/-, +/+ Which of the following organisms is INCORRECTLY paired with its trophic level? Beetle - secondary consumer Which of the following is an example of habituation? Hydra initially contract when gently touched, but soon stop responding. Suppose gene "C" is the gene for color. Its dominant allele has the effect of allowing the production of fur color while its recessive allele interrupts color production. At another locus, there exists another gene that influences color, at which black (B) is dominant to brown (b). What is the relationship between these genes called? Epistatic During migrations, some birds use which of the following as reference frameworks? I. The sun II. Constellations III. Earth's magnetic field I, II, and III Generally, there are more species per square kilometer in which of the following types of ecosystem? Coral reef RUBP is used and PGA is formed in: dark reaction (Calvin cycle) of photosynthesis Which is TRUE of the dark reaction (Calvin cycle) of photosynthesis? It uses carbon dioxide In the fern life cycle, the dominant generation is the: diploid sporophyte Assume a person is placed on cortisol medication, a glucocorticoid. How would you expect the rates of ACTH and CRF hormone production to change in the person? ACTH production would decrease, CRF production would increase Carbon particles were injected into the blood of mice. In which of the following places would you most likely find the particles? In monocytes of the spleen Kidneys provide osmoregulation for the body. Consumption of which nutrient creates the greatest need for osmoregulation? Protein During translation in prokaryotes, the ribosome binds to: the Shine-Dalgarno sequence The quaternary structure of a protein is determined by: interactions between amino acids of different polypeptide chains. Which of the following is not a function of the parasympathetic division of the nervous system? Stimulation of the adrenal medulla You place a growing seedling in an east-facing window. On which side of the plant will active auxin accumulate? West side Which of the following is NOT a characteristic of all mammalian species? Placenta Suppose the lac repressor of E. coli is mutated so that it never binds to the operator. Which of the following is true? The result depends on the concentration of glucose You examine a leaf cross-section under a microscope and find many loosely packed cells. These cells have many chloroplasts and relatively thin cell walls. These cells are: Parenchyma For the biomass pyramid shown below, choose the correct statement. secondary consumer primary consumer producer Producers reproduce quickly but are also consumed at a rapid rate Which of the following would be most likely to increase competition among the members of the vole population in a given area? An increase in the reproduction rate of voles Tobacco mosaic virus has RNA rather than DNA as its genetic material. If the RNA genome from a tobacco mosaic virus is mixed with proteins from a human rhinovirus, the result is a mixed virus. If that virus could infect a cell and reproduce, what would you expect the resulting viruses to be like? Tobacco Mosaic Virus An amphipathic molecule is a molecule that is characterized by: A hydrophilic end and a hydrophobic end The function of a molecular chaperone is to bind to specific structures on the polypeptide in order to assist the folding of a protein into its correct three dimensional shape. Ethidium Bromide is used in electrophoresis of DNA fragments because it: makes the fragments visible under UV light. The species Homo sapiens first appeared in which geologic epoch? Pleistocene Which of the following marine communities would be LEAST affected by a volcanic eruption or meteor impact that injected enough debris into the atmosphere to reduce sunlight by 50% for two years? Deep sea vent community A unique feature of fertilization in angiosperms is that: it is a double fusion event; one sperm fertilizes the egg, the other sperm combines with the polar or fusion nucleus. Which statement describing plant structure is appropriate? Sclerenchyma cells provide support for the plant body The Hardy-Weinberg equilibrium principle assumes all of the following statements EXCEPT: for a given trait the frequency of dominant alleles is greater than that of recessive alleles. Professor Jones is running an experiment with his graduate students in his physiology lab. One group of students drinks a liter of water, another group drinks a liter of coffee, and a third group drinks a liter of concentrated salt solution. The volume of urine produced by all individuals in the three groups is measured over a period of several hours. At the end of the monitoring period, which group will have produced the greatest volume of urine and which group the least? Those who drank coffee will produce the most urine, while those who drank the salt solution will produce the least