Practice #2 – Flashcards
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Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence?
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genetic drift
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Which statement about variation is true?
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All new alleles are the result of nucleotide variability.
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Which of the following is a true statement concerning genetic variation?
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It must be present in a population before natural selection can act upon the population.
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Hardy-Weinberg equilibrium must occur in populations wherein
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Only two of the responses above are correct.
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In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
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0.80
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Evolution
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can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met.
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Arrange the following from most general (i.e., most inclusive) to most specific (i.e., least inclusive): 1. natural selection 2. microevolution 3. intrasexual selection 4. evolution 5. sexual selection
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4, 2, 1, 5, 3
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Which of the following statements best summarizes evolution as it is viewed today?
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It is the differential survival and reproduction of the most-fit phenotypes.
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You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown. Which population is most likely to be subject to the bottleneck effect?
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population A
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A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2?
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0.42
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9) All of the following are part of a prokaryotic cell except A) DNA. B) a cell wall. C) a plasma membrane. D) ribosomes. E) an endoplasmic reticulum.
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An endoplasmic reticulum
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The evolution of eukaryotic cells most likely involved
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endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria.
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Which organelle or structure is absent in plant cells? A) mitochondria B) Golgi vesicles C) microtubules D) centrosomes E) peroxisomes
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Centrosomes
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In a plant cell, DNA may be found
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in the nucleus, mitochondria, and chloroplasts.
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What do the cell walls of plants and the extracellular matrix of animal cells have in common?
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They have functional connections with the cytoskeleton inside the cell.
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Which of the following is present in a prokaryotic cell? A) mitochondrion B) ribosome C) nuclear envelope D) chloroplast E) ER
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ribosome
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Which cell would be best for studying lyosomes?
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phagocytic white blood cell
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What is the expected phenotypic ratio in the F2 generation from a dihybrid parental cross (AABB x aabb)? Assume the complete dominance and self pollination in the F1 generation.
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9:3:3:1
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The genotype of F1 individual in a trihybrid cross is LlBbJj. Assuming independent assortment of these three genes, what is the probability that F2 offspring from self pollination of the F1 generation will have the following genotype, llBBJj?
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1/32
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What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
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Traits are inherited in discrete units, and are not the results of "blending.
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A 1:2:1 phenotype ratio in the F2 generation of a monohybrid cross is a sign of...
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incomplete dominance.
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Three babies were mixed up in a hospital. After consideration of the data below, which of the following represents the correct baby and parent combinations?
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I-2, II-3, III-1
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Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?
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4
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For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. What was the basis of this thinking?
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Proteins are made of 20 amino acids and DNA is made of 4 nucleotides.
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The human genome is minimally contained in which of the following?
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Every human cell
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Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
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1/2
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In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?
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1/64
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Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?
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3/4
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Most genes have many more than two alleles. However, which of the following is also true? A) At least one allele for a gene always produces a dominant phenotype. B) Most of the alleles will never be found in a live-born organism. C) All of the alleles but one will produce harmful effects if homozygous. D) There may still be only two phenotypes for the trait. E) More than two alleles in a genotype is considered lethal.
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There may still be only two phenotypes for the trait
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The following question refer to the pedigree chart in Figure 14.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. 40) What is the genotype of individual II-5?
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ww
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The following question refer to the pedigree chart in Figure 14.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. 42) What is the probability that individual III-1 is Ww?
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1
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Use the following pedigree (Figure 14.3) for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. 43) What is the genotype of the deceased individual in generation II?
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heterozygous for a gene for colon cancer
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Use the following pedigree (Figure 14.3) for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. 44) In each generation of this family after generation I, the age at diagnosis is significantly lower than would be found in nonfamilial (sporadic) cases of this cancer (~ 63 years). What is the most likely reason?
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Hereditary (or familial) cases of this cancer typically occur at earlier ages than do nonfamilial forms.
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Use the following pedigree (Figure 14.3) for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. 45) From this pedigree, how does this trait seem to be inherited?
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as an autosomal dominant
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Use the following pedigree (Figure 14.3) for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. 46) The affected woman in generation IV is thinking about her future and asks her oncologist (cancer specialist) whether she can know whether any or all of her children will have a high risk of the same cancer. The doctor would be expected to advise which of the following? I. genetic counseling II. prenatal diagnosis when/if she becomes pregnant III. testing to see whether she has the allele IV. testing to see whether her future spouse or partner has the allele
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I and II only
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Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies.
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Epistasis is involved.
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Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. 50) How many genes must be responsible for these coat colors in Labrador retrievers?
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2
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Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. 51) In one type cross of black × black, the results were as follows: 9/16 black 4/16 yellow 3/16 brown The genotype aabb must result in which of the following?
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yellow
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Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. 52) If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F? will be expected to be which of the following?
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purple and long
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Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. 53) In the F? generation of the above cross, which of the following phenotypic ratios would be expected?
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6:3:3:2:1:1
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Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. 54) The flower color trait in radishes is an example of which of the following?
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codominance
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The centromere is a region in which
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chromatids remain attached to one another until anaphase.
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Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
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32
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If there are 20 chromatids in a cell, how many centromeres are there?
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10
