Bio 110 Exam 3
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals that are heterozygous for this allele? a) 0.32 b) 0.04 c) 0.16 d) 0.020
a) 0.32
Here are four individual strands of DNA: 1- 5'AATTCCGGCCTAACTT3' 2- 5'AAGTTAGGCCGGAATT3' 3- 5'TTAAGGCCGGATTGAA3' 4- 5'TTCAATCCGGCCTTAA3' Which strands would pair with one another? a) 1 and 2, 3 and 4 b) 1 and 4, 2 and 3 c) 1 and 3, 2 and 4 d) 1 and 3 only
a) 1 and 2, 3 and 4
Below are four DNA sequences. Which pair(s) encodes alleles of the same gene? 1-attcgctaacgca 2-accggcaacattc 3-attccctaactca 4-acccgcatcattc a) 1 and 3, 2 and 4 b) 2 and 3 c) 1 and 3 d) 1 and 2 e) 2 and 4
a) 1 and 3, 2 and 4
The recessive alleles for cinnibar eyes (cn) and vestigial wings (vg) identify two autosomal genes on the third chromosome of Drosophila melanogaster. When females, heterozygous at these two genes (cn+cn vg+vg), were crossed with cinnibar-eyed, vestigial winged males, the following classes and numbers of progeny (n=1000) were obtained: •Wild-type eye color, wild-type wings 42 •Wild-type eye color, vestigial wings 464 •Cinnibar eye color, vestigial wings 38 •Cinnibar eye color, wild-type wings 456 The heterozygous females in this cross produce approximately _____________ gametes with the genotype cn vg. a) 3.8 % b) 4.2 % c) 46.4 % d) 45.6 %
a) 3.8 %
If one parent who has Huntington's disease is heterozygous for the trait and the other parent is not affected, what are the chances of their offspring inheriting the trait? a) 50% b) 100% c) 0 d) 25%
a) 50%
Which of the following statements about mutations is false? a) A knock-out mutation results in a total absence of the mutated protein. b) Addition and deletion mutations disrupt the primary structure of proteins. c) A deletion mutation results in the loss of a base in the DNA sequence. d) An addition mutation results in an added base in the DNA sequence.
a) A knock-out mutation results in a total absence of the mutated protein.
If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred? a) An addition mutation and a deletion mutation. b) An addition mutation c) None. d) A deletion mutation.
a) An addition mutation and a deletion mutation.
You are examining a trait which shows three distinct phenotypes, with the phenotype of heterozygotes expressing both alleles seen in the homozygotes. This is an example of: a) Codominance. b) Complete dominance. c) Incomplete dominance. d) Pleiotrophy.
a) Codominance.
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? a) DNA in both daughter cells would be radioactive. b) One of the daughter cells, but not the other, would have radioactive DNA. c) Neither of the two daughter cells would be radioactive. d) All four bases of the DNA would be radioactive.
a) DNA in both daughter cells would be radioactive.
All of the following are directly required for protein synthesis EXCEPT __________________. a) DNA polymerase b) tRNA c) ribosomes d) RNA polymerase
a) DNA polymerase
Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? a) DNA polymerase can assemble DNA only in the 5' to 3' direction b) DNA polymerase can assemble DNA only in the 3' to 5' direction c) it is more efficient than assembling complete new strands d) only short DNA sequences can extend off the RNA primers e) the replication forks block the formation of longer strands
a) DNA polymerase can assemble DNA only in the 5' to 3' direction
DNA is a self-replicating molecule. What accounts for this important property of DNA? a) Replication is thermodynamically spontaneous and requires no enzymes. b) The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C. c) Its two strands are held together by easily broken covalent bonds.
b) The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C.
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is a) UUA. b) UUU. c) TTT. d) AAA. e) either UAA or TAA, depending on first base wobble.
b) UUU.
Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents? a) XnXn and XnY b) XNXn and XNY c) XNXN and XnY d) XNXN and XNY
b) XNXn and XNY
All female mammals have one active X chromosome per cell instead of two. What causes this? a) activation of the BARR gene on one X chromosome, which then becomes inactive b) activation of the XIST gene on the X chromosome that will become the Barr body c) attachment of methyl (CH3) groups to the X chromosome that will remain active d) crossing over between the XIST gene on one X chromosome and a related gene on an autosome e) inactivation of the XIST gene on the X chromosome derived from the male parent
b) activation of the XIST gene on the X chromosome that will become the Barr body
Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools? a) genetic b) biological c) ecological d) morphological
b) biological
In animals that exhibit the haplo/diploid mode of sex determination, the males are fertile and produce sperm. In these animals sperm are produced _______________. a) via replication of the haploid state to the diploid state, followed by meiosis b) by mitosis (simple cell division) c) by meiosis
b) by mitosis (simple cell division)
Two animals are considered members of different species if they _____. a) live in different habitats b) cannot mate and produce viable, fertile offspring c) are members of different populations d) are geographically isolated e) look different
b) cannot mate and produce viable, fertile offspring
After DNA replication is completed, _____. a) each new DNA double helix consists of two new strands b) each new DNA double helix consists of one old DNA strand and one new DNA strand c) there are four double helices d) each of the four DNA strands consists of some old strand parts and some new strand parts e) one DNA double helix consists of two old strands and one DNA double helix consists of two new strands
b) each new DNA double helix consists of one old DNA strand and one new DNA strand
In the formula for determining a populations genotype frequencies, the "pq" in the term 2pq is necessary because _____. a) the population is doubling in number b) heterozygotes have two alleles c) heterozygotes can come about in two ways d) the population is diploid
b) heterozygotes have two alleles
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 flower color trait in radishes is an example of which of the following? a) sex linkage b) incomplete dominance c) codominance d) a multiple allelic system
b) incomplete dominance
Which of the following damages cells and causes cell aging? a) reducing stress b) inflammation c) exercise d) all of the above
b) inflammation
All of the following take place in the nucleus of a eukaryotic cell except ______________. a) tRNA synthesis b) linkage of an amino acid to its appropriate tRNA molecule c) DNA replication d) mRNA synthesis
b) linkage of an amino acid to its appropriate tRNA molecule
You are studying two new mutations in Drosophila melanogaster. The mutation squiggle produces flies with antennae that are crooked rather than straight. It is inherited as an autosomal recessive. The mutation zebra produces flies that have bodies with black and white stripes. It is inherited as an autosomal dominant. What would be the correct nomenclature for a fly that is heterozygous for both of these mutations ? a) an+ an B+ B b) sq+ sq Ze+ Ze c) sq sq Ze Ze d) an+ an b+ b
b) sq+ sq Ze+ Ze
DNA strands are called antiparallel because of _______________. a) semiconservative replication b) the two strands having opposite polarities c) the alignment of bases required for protein synthesis d) the specific base-pairing rules
b) the two strands having opposite polarities
In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male? a) black females; orange males b) tortoiseshell females; black males c) tortoiseshell females; tortoiseshell males d) orange females; black males
b) tortoiseshell females; black males
The process of DNA replication is semiconservative. This means that a replicated chromosome is composed of: a) two DNA molecules (sister chromatids). One molecule is composed of two newly synthesized strands of DNA, while the template molecule is composed of the two parental (templatE. strands of DNA. b) two DNA molecules (sister chromatids), each with one newly synthesized strand of DNA and one parental (templatE. strand of DNA. c) two DNA molecules (sister chromatids). Each DNA molecule contains segments of both newly synthesized and parental (templatE. DNA randomly mixed throughout the molecule. d) one DNA molecule and one RNA molecule (sister chromatids).
b) two DNA molecules (sister chromatids), each with one newly synthesized strand of DNA and one parental (templatE. strand of DNA.
In water snakes, body color is controlled by two alleles that display incomplete dominance. Snakes with the BB genotype are brown, those with the Bb genotype are gray, and individuals with the bb genotype are green. If a brown snake and a gray snake are crossed, what ratio of phenotypes should be expected in the offspring? a) 1:1, gray:green b) 1:2:1, brown:gray:green c) 1:1, brown:gray d) 1:1:1, brown:gray:green e) 1:1, brown:green
c) 1:1, brown:gray
Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height? a) a combination of complete dominance and environmental factors b) incomplete dominance c) a combination of polygenic inheritance and environmental factors d) a combination of multiple alleles and codominance e) a combination of epistasis and environmental factors
c) a combination of polygenic inheritance and environmental factors
Normally, only female cats have the tortoiseshell phenotype because _____. a) the Y chromosome has a gene blocking orange coloration b) only males can have Barr bodies c) a male inherits only one allele of the X-linked gene controlling hair color d) multiple crossovers on the Y chromosome prevent orange pigment production
c) a male inherits only one allele of the X-linked gene controlling hair color
Normally, only female cats have the tortoiseshell phenotype because a) multiple crossovers on the Y chromosome prevent orange pigment production. b) only males can have Barr bodies. c) a male inherits only one allele of the X-linked gene controlling hair color. d) the males die during embryonic development. e) the Y chromosome has a gene blocking orange coloration.
c) a male inherits only one allele of the X-linked gene controlling hair color.
The cells examined from the 2,400 people in this study were from ______. a) hair b) surgically removed tissue c) blood d) skin scrapings
c) blood
A new DNA strand elongates only in the 5' to 3' direction because a) DNA polymerase can only add nucleotides to the free 3' end. b) Okazaki fragments prevent elongation in the 3' to 5' direction. c) replication must progress toward the replication fork. d) the polarity of the DNA molecule prevents addition of nucleotides at the 3' end. e) DNA polymerase begins adding nucleotides at the 5' end of the template.
a) DNA polymerase can only add nucleotides to the free 3' end.
In eukaryotes, transcription takes place in the ______________________________. a) nucleus b) cell membrane c) ribosomes d) cytoplasm
a) nucleus
Pedigrees reveal that a trait shows a dominant pattern of inheritance if that trait generally _______. a) skipped generations b) was lethal c) did not skip generations d) was only inherited by males
c) did not skip generations
A gene that affects the expression of a second gene is an example of __________________. a) pleiotropy b) codominance c) epistasis d) polygenic inheritance e) incomplete dominance
c) epistasis
Macroevolution is _____. a) the same as microevolution, but includes the origin of new species b) defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye c) evolution above the species level d) defined as a change in allele or gene frequency over the course of many generations
c) evolution above the species level
The research showed that individuals who _______ had younger looking cells based on telomere measurements. a) slept at least 8 hours every night b) quit smoking or reduced the number of cigarettes smoked each day c) exercised for an average of 30 minutes per day d) all of the above
c) exercised for an average of 30 minutes per day
In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because _____. a) the population is diploid b) heterozygotes have two alleles c) heterozygotes can come about in two ways d) the population is doubling in number
c) heterozygotes can come about in two ways
Short segments of newly synthesized DNA are joined into a continuous strand by _____. a) DNA polymerase b) helicase c) ligase d) primase e) single-strand binding protein
c) ligase
Lagging strand replication is made possible by the presence of ________________. a) primases b) helicases c) ligases d) RNA polymerase
c) ligases
When genes on a particular chromosome do not assort independently in genetic crosses, the genes are _______________. a) recombinants b) wild type c) linked d) homozygous alleles e) not linked
c) linked
The researchers found that telomeres were ______. a) shorter in smokers who exercised compared to those who did not exercise b) shorter in individuals who ate less and exercised regularly c) longer in individuals who exercised regularly d) longer in nonsmokers who did not exercise compared to those who did exercise
c) longer in individuals who exercised regularly
Males are more often affected by sex-linked traits than females because _____. a) male hormones such as testosterone often alter the effects of mutations on the X chromosome b) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome c) males are hemizygous for the X chromosome d) X chromosomes in males generally have more mutations than X chromosomes in females
c) males are hemizygous for the X chromosome
The genetic code is said to be "redundant" because _____________________________________. a) one anticodon can attach to several amino acids b) there is more than one initiation codon c) one amino acid can have more than one codon d) one codon can signify more than one amino acid
c) one amino acid can have more than one codon
The effects of ______________________ can be almost completely overcome by regulating the diet of the individual from infancy. a) cystic fibrosis b) sickle-cell disease c) phenylketonuria (PKU) d) Huntington's disease
c) phenylketonuria (PKU)
Transfer RNA (tRNA) functions in _________________________________. a) cell division b) DNA replication c) polypeptide elongation d) RNA transcription
c) polypeptide elongation
An old DNA strand is used as a _____ for the assembly of a new DNA strand. a) primer b) complement c) template d) model e) source of nucleotides
c) template
Which one of these processes describes bottleneck effect? a) sudden change in environments that alters gene frequency of a population b) transfer of alleles in and out of a population due to movement of fertile individuals c) alleles transferred to the next generation in portions that differ from previous generation d) chance events that change allele frequency
a) sudden change in environments that alters gene frequency of a population
Sympatric speciation is _____. a) initiated by the appearance of a geographic barrier b) the process by which most animal species have evolved c) the appearance of a new species in the same area as the parent population d) especially important in the evolution of island species e) the emergence of many species from a single ancestor
c) the appearance of a new species in the same area as the parent population
Soon after the island of Hawaii rose above the sea surface (somewhat less than one million years ago), the evolution of life on this new island should have been most strongly influenced by ________. a) sexual selection b) a genetic bottleneck c) the founder effect d) habitat differentiation
c) the founder effect
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes? a) 50% b) 100% c) 75% d) 0% e) 25%
b) 100%
If a male affected by a recessive sex-linked trait reproduces with a female who is homozygous wild type for that trait, what is the chance that any of their offspring will have the trait? a) 50% b) 75% c) 100% d) 0 e) 25%
d) 0
Cinnabar eyes is a sex-linked, recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes? a) 0% b) 25% c) 50% d) 100%
d) 100%
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is a) 5' TCA 3'. b) 3' ACU 5'. c) 3' UGA 5'. d) 3' UCA 5'. e) either UCA or TCA, depending on wobble in the first base.
d) 3' UCA 5'.
The following is an mRNA sequence: 5'-AAUCCAUUU-3' Which of the following sets of anticodons would associate during translation? 1- 5'-TTAGGTAAA-3' 2- 5'-UUAGGUAAA-3' 3- 5'-AAATGGATT-3' 4- 5'-AAAUGGAUU-3' a) 1 b) 2 c) 3 d) 4
d) 4
If the recombination frequency between P and O is 7.4, and between N and O it is 7.9, what is the likely order of these genes on the chromosome if the distance between N and P is 15.7? a) None of these choices b) N-O-P c) O-P-N d) Either P-O-N or N-O-P e) O-N-P
d) Either P-O-N or N-O-P
Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true? a) His sons will develop Huntington's disease but not his daughters. b) All of his children will develop Huntington's disease. c) His daughters will die of Huntington's disease but not his sons. d) It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease. e) There is not enough information to answer the question.
d) It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? a) It stabilizes the unwound parental DNA. b) It catalyzes the lengthening of telomeres. c) It unwinds the parental double helix. d) It joins Okazaki fragments together. e) It synthesizes RNA nucleotides to make a primer.
d) It joins Okazaki fragments together.
Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)? a) One deletion mutation. b) One addition mutation. c) One addition and two deletion mutations. d) One addition and one deletion mutation.
d) One addition and one deletion mutation.
Which of the following statements is true of linkage? a) The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. b) All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome. c) Crossing over occurs during prophase II of meiosis. d) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. e) Linked genes are found on different chromosomes.
d) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced? a) Recombination did not occur in the cell during meiosis. b) The two genes are linked but on different chromosomes. c) Both of the characters are controlled by more than one gene. d) The two genes are closely linked on the same chromosome.
d) The two genes are closely linked on the same chromosome.
The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-19th century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species? a) No; they still can interbreed. b) Yes; they are reproductively isolated based on habitat. c) Yes; natural selection has affected the frequency of the two different forms. d) Yes; they have completely different coloration.
a) No; they still can interbreed.
Which of the following statements accurately describes the differences between DNA replication in prokaryotes and DNA replication in eukaryotes? a) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. b) Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. c) Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. d) The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes.
a) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.
What name is given to the process in which pre-mRNA is edited into mRNA? a) RNA processing b) gene expression c) polypeptide formation d) transcription e) translation
a) RNA processing
Which of the following is true of an X-linked gene, but not of a Y-linked gene? a) The gene is present in both males and females. b) It does not segregate like other genes. c) Sister chromatids separate during mitosis. d) It is only expressed in female offspring. e) It is expressed in half of the cells of either male or female.
a) The gene is present in both males and females.
A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time? a) The two phenotypes are about equally adaptive under laboratory conditions. b) There has been a high rate of mutation of allele A to allele a. c) There has been sexual selection favoring allele a. d) The genotype AA is lethal.
a) The two phenotypes are about equally adaptive under laboratory conditions.
You are studying two genes that are located on the same chromosome. They are located 55 map units apart. How will the alleles of these genes behave in a dihybrid cross? a) They will appear to segregate independently, as if they are located on different chromosomes. b) Can't say without knowing the recombination frequency. c) They will stay together.
a) They will appear to segregate independently, as if they are located on different chromosomes.
In 1983, a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails. Females have less white in their tails than do males, and display it less often. The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 40-45% white. If this observed trait difference were due to a difference in the original colonizing population, it would most likely be due to ________. a) a founder effect b) gene flow between populations c) a genetic bottleneck d) mutations in the UCSD population
a) a founder effect
An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake? a) a genetic bottleneck b) a founder event c) directional selection d) disruptive selection
a) a genetic bottleneck
In Drosophila, two genes on the fourth chromosome, bent wings (b) and shaven bristles (svn) are completely linked. If a fly with the genotype bb svnsvn is crossed to a fly with the genotype b+b+ svn+svn+, what type(s) of gametes will their offspring produce. a) b+ svn+ and b svn b) b+ svn+, b svn, b+ svn and b svn+ c) b+ svn+ d) b svn
a) b+ svn+ and b svn
Mice with the genotypes BBCc and bbcc are crossed. The alleles for brown coat (b) and no pigment (c) are recessive, and black coat (B) is dominant. What color of mice would NOT be produced by this mating? a) brown b) white c) black
a) brown
Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. These two juniper species are kept separate by _____. a) gametic isolation b) habitat isolation c) behavioral isolation d) temporal isolation
a) gametic isolation
Which of the following is the first step in allopatric speciation? a) geographic isolation b) formation of a reproductive barrier c) genetic drift d) polyploidy e) hybridization
a) geographic isolation
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. What proportion of their sons would be color-blind and of normal height? a) half b) one out of four c) none d) three out of four e) all
a) half
In eukaryotes, DNA replication takes place: a) in the nucleus during interphase. b) in the cytoplasm during mitosis. c) in the nucleus during mitosis. e) in the cytoplasm during interphase.
a) in the nucleus during interphase.
A homozygous tomato plant with red fruit and yellow flowers was crossed with a homozygous tomato plant with golden fruit and white flowers. The F1 all had red fruit and yellow flowers. The F1 were testcrossed by crossing them to homozygous recessive individuals and the following offspring were obtained: Red fruit and yellow flowers-41 Red fruit and white flowers-7 Golden fruit and yellow flowers-8 Golden fruit and white flowers-44 How many map units separate these genes? a) 17.6 b) 15 c) 18.1 d) 17.1
b) 15
What ratio of F1 generation phenotypes would be expected from a test cross of flies differing in two characters (females are heterozygous for both genes, and males are homozygous recessive for both genes) if the two genes assort independently of each other? a) 8:2:2:1 b) 1:1:1:1 c) 9:3:3:1 d) 3:3:1:1 e) 5:5:1:1
b) 1:1:1:1
If both parents are carriers of an recessive inherited trait, what are the chances that their child will express that trait? a) 50% b) 25% c) 0 d) 100%
b) 25%
For the mRNA sequence 3' UAC 5', what is the appropriate tRNA anticodon? a) 3' GTA 5' b) 3' GUA 5' c) 3' AUG 5' d) 3' ATG 5'
b) 3' GUA 5'
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? a) 8 b) 4 c) 2 d) 16
b) 4
________________________ is an example of a recessive inherited trait. a) Huntington's disease b) Cystic fibrosis c) Brachydactyly. d) The AB blood type
b) Cystic fibrosis
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? a) All four bases of the DNA would be radioactive. b) DNA in both daughter cells would be radioactive. c) One of the daughter cells, but not the other, would have radioactive DNA. d) Neither of the two daughter cells would be radioactive. e) Radioactive thymine would pair with nonradioactive guanine.
b) DNA in both daughter cells would be radioactive.
True or false? A codon is a group of three bases that can specify more than one amino acid. a) True b) False
b) False
What is the function of helicase in DNA replication? a) It joins together Okazaki fragments. b) It untwists the double helix and separates the two DNA strands. c) It adds nucleotides to the new strand in the 5' to 3' direction. d) It relieves strain from twisting of the double helix as it is unwound. e) It checks for errors in the newly synthesized DNA strand.
b) It untwists the double helix and separates the two DNA strands
The researchers used strands of DNA located at the ends of chromosomes (called telomeres) to classify the cells they studied. What assumption did they make about telomeres? a) Longer telomeres indicate that the person from whom the cells came does not exercise. b) Longer telomeres indicate younger cells. c) Shorter telomeres indicate younger cells. d) Telomere length is not an accurate indicator of cell age.
b) Longer telomeres indicate younger cells.
__________ is an example of a character that is controlled by more than one gene (a quantitative character) and demonstrates a continuum of phenotypes. a) Pleiotropy b) Polygenic inheritance c) Epistasis d) Codominance e) Incomplete dominance
b) Polygenic inheritance
Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize the amino acid phenylalanine. This amino acid is not naturally produced by humans. Therefore, the most efficient and effective treatment is which of the following? a) Feed them the substrate that can be metabolized into this amino acid. b) Regulate the diet of the affected persons to severely limit the uptake of the amino acid. c) Transfuse the patients with blood from unaffected donors. d) Feed the patients the missing enzymes in a regular cycle, such as twice per week. e) Feed the patients an excess of the missing product.
b) Regulate the diet of the affected persons to severely limit the uptake of the amino acid.
What is meant by the description "antiparallel" regarding the strands that make up DNA? a) One strand is positively charged and the other is negatively charged. b) The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. c) The twisting nature of DNA creates nonparallel strands. d) One strand contains only purines and the other contains only pyrimidines. e) Base pairings create unequal spacing between the two DNA strands.
b) The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
Of the following statements, which is/are usually true if the genes for two different characters are linked? a) The alleles for each character won't segregate. b) The genes are on the same chromosome and do not assort independently. c) The alleles for the linked genes assort independently from one another. d) A proportional number of parental phenotypes and recombinant phenotypes are represented among offspring. e) All of the above
b) The genes are on the same chromosome and do not assort independently.
Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during DNA replication? a) The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. b) The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. c) The leading strand is synthesized at twice the rate of the lagging strand. d) The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.
b) The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
In humans, what determines the sex of offspring and why? a) The male determines sex because the sperm can fertilize either a female egg or a male egg. b) The male gamete determines sex because each male gamete can contribute either an X or a Y chromosome. c) The chromosome contribution from both parents determines sex because the offspring uses all the parents' chromosomes. d) The female gamete determines sex because only the female gametes can have one of two functional sex chromosomes. e) The female gamete determines sex because only the female gamete provides cytoplasm to the zygote.
b) The male gamete determines sex because each male gamete can contribute either an X or a Y chromosome.
The gene controlling ear color in an organism known as a gizmo has two alleles that exhibit incomplete dominance: CR, which codes for red ears; and CY, which codes for yellow ears. Individuals that are homozygous for the CR allele have red ears, whereas the heterozygous genotype produces orange ears. Those that are homozygous for the CY allele have yellow ears. If two individuals with orange ears are crossed, what ratio of phenotypes should be expected in the offspring? a) 9:3:1, red:yellow:orange ears b) 3:1, red:yellow ears c) 1:2:1, red:orange:yellow ears d) 1:2:1, red:yellow:orange ears e) 1:3, red:yellow ears
c) 1:2:1, red:orange:yellow ears
The following is a strand of mRNA: 5'AUUCGGCAUUCC 3' Which of the following DNA strands is its template? 1- 5'TAAGCCGTAAGG 3' 2- 5'GGAAUGCCGAAU 3' 3- 5'GGAATGCCGAAT 3' 4- 5'AUUCGGCAUUCC 3' a) 1 b) 2 c) 3 d) 4
c) 3
A DNA sequence reads 3' AGGCTTA 5'. Therefore, the complementary DNA strand must read _______________.' a) 3' AGGCTTA 5' b) 3' TCCGAAT 5' c) 3' TAAGCCT 5' d) 3' UAAGCCU 5'
c) 3' TAAGCCT 5'
The following enzymes are involved in DNA replication on the lagging strand: 1-ligase 2-primase 3-helicase 4-polymerase In order for normal DNA replication to occur, these enzymes must work in the following order: a) 2,3,4,1 b) 4,2,1,3 c) 3,2,4,1 d) 1,2,3,4
c) 3,2,4,1
At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence? a) 3' G C C T A G G 5' b) 5' A C G T T A G G 3' c) 5' A C G U U A G G 3' d) 5' G C C U A G G 3' e) 5' G C C T A G G 3'
c) 5' A C G U U A G G 3'
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following? a) All organisms have experienced convergent evolution. b) Different organisms have different numbers of different types of amino acids. c) A gene from an organism can theoretically be expressed by any other organism. d) DNA was the first genetic material. e) The same codons in different organisms translate into the different amino acids.
c) A gene from an organism can theoretically be expressed by any other organism.
A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative. Which of the following is a possible phenotype for the father? a) O negative b) A negative c) B positive d) AB negative
c) B positive
Which of the following mutations would likely be most dangerous to a cell? a) Substitution of one nucleotide for another b) Deletion of three nucleotides c) Deletion of one nucleotide
c) Deletion of one nucleotide
If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred? a) Both addition and deletion. b) None. c) Deletion. d) Addition.
c) Deletion.
Pull out a piece of paper and pencil because this question will take some thought. First, work out the predicted offspring of a mating between a white-eyed female and a red-eyed male Drosophila. Next, work out the predicted offspring of a heterozygous red-eyed female and a white-eyed male. What is the result of both crosses? a) In the first case, all females will have white eyes and all males red eyes. In the second case, this is reversed. b) In the first case, all males will have white eyes. In the second case, this will be reversed. c) In the first case, all females will have red eyes and all males will have white eyes. In the second case, there will be equal numbers of white and red eyes. d) In both cases, the result is the same. e) In the first case, there will be equal numbers of white and red eyes. In the second case, only females will have red eyes.
c) In the first case, all females will have red eyes and all males will have white eyes. In the second case, there will be equal numbers of white and red eyes.
What is the function of the release factor during translation in eukaryotes? a) It supplies a source of energy for termination of translation. b) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. c) It binds to the stop codon in the A site in place of a tRNA. d) It releases the ribosome from the ER to allow polypeptides into the cytosol.
c) It binds to the stop codon in the A site in place of a tRNA.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? a) It synthesizes RNA nucleotides to make a primer. b) It stabilizes the unwound parental DNA. c) It joins Okazaki fragments together. d) It unwinds the parental double helix.
c) It joins Okazaki fragments together.
You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits? a) Both red and white are pleiotropic. b) Pink is dominant, and red and white are recessive. c) Red shows incomplete dominance over white. d) Red is completely dominant.
c) Red shows incomplete dominance over white.
Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility and death, usually from coronary artery disease, at an average age of approximately 13. Patients, who look very old even as children, do not live to reproduce. Which of the following represents the most likely assumption? a) Successive generations of a family will continue to have more and more cases over time. b) Each patient will have had at least one affected family member in a previous generation. c) The disorder may be due to mutation in a single protein-coding gene. d) All cases must occur in relatives; therefore, there must be only one mutant allele. e) The disease is autosomal dominant.
c) The disorder may be due to mutation in a single protein-coding gene.
Which of the following statements about independent assortment and segregation is correct? a) The law of segregation is accounted for by anaphase of mitosis. b) The law of segregation requires describing two or more genes relative to one another. c) The law of independent assortment requires describing two or more genes relative to one another. d) The law of independent assortment is accounted for by observations of prophase I.
c) The law of independent assortment requires describing two or more genes relative to one another.
If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein? a) One. b) Three. c) Two. d) None.
c) Two.
In a dihybrid cross of a female who is heterozygous for body color (yb+ yb) and cut wings (cw+ cw) with a yellow-bodied, cut-winged male (yb yb cw cw), the following classes and numbers of progeny (out of 1000) were obtained: •Wild type body color, wild type wings 248 •Wild type body color, cut wings 252 •Yellow body, cut wings 247 •Yellow body color, wild type wings 253 Which of the following conclusions can you make about the genes for body color and cut wings? a) These two genes are 25 map units apart. b) These two genes are 50 map units apart. c) These two genes are located on different chromosomes. d) These two genes could either be 50 or more map units apart or could be on different chromosomes.
d) These two genes could either be 50 or more map units apart or could be on different chromosomes.
What is the reason that closely linked genes are typically inherited together? a) Alleles are paired together during meiosis. b) The number of genes in a cell is greater than the number of chromosomes. c) Genes align that way during metaphase I of meiosis. d) They are located close together on the same chromosome.
d) They are located close together on the same chromosome.
SRY is best described as _____. a) an autosomal gene that is required for the expression of genes on the X chromosome b) an autosomal gene that is required for the expression of genes on the Y chromosome c) a gene present on the X chromosome that triggers female development d) a gene region present on the Y chromosome that triggers male development
d) a gene region present on the Y chromosome that triggers male development
Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms? a) temporal isolation b) behavioral isolation c) gametic isolation d) habitat isolation
d) habitat isolation
In Drosophila, one gene affects the formation of anterior body parts and another gene affects the formation of posterior body parts. These "polarity genes" are designated bcd and nos. A fly designated bcd+/bcd nos+/nos+ would be _________________. a) heterozygous for both of these dominant mutant alleles b) homozygous for both genes c) heterozygous for both genes d) homozyogous for one gene and heterozygous for the other e) heterozygous for both of these recessive mutant alleles
d) homozyogous for one gene and heterozygous for the other
You are working for a fly geneticist who sends you to a produce market to find new mutations. You rummage through the dumpsters and capture 100 flies. You note that 100% of the flies have red eyes and 90% have long body bristles (10% have short body bristles). Based on these results, you can conclude that __________________. a) red eyes are dominant and short body bristles are recessive b) short body bristles and long body bristles are located on different chromosomes c) red eyes and short body bristles are located on different chromosomes d) in this produce market, red eyes and long bristles are wild-type traits e) red eyes and long body bristles are inherited in a dominant manner
d) in this produce market, red eyes and long bristles are wild-type traits
An individual that is heterozygous for an allele and that exhibits a phenotype intermediate between that of the two homozygous alternatives is an example of _____. a) polygenic inheritance b) pleiotropy c) codominance d) incomplete dominance e) epistasis
d) incomplete dominance
A mutation in the DNA sequence of a gene that codes for a protein: a) is always harmful to the organism, impairing the function of the protein. b) cannot be repaired. c) is a very common occurrence, happening in about one out of every 100 nucleotides. d) is only heritable if it occurs in a gamete producing cell.
d) is only heritable if it occurs in a gamete producing cell.
RNA processing converts the RNA transcript into _____. a) a protein b) DNA c) a eukaryotic cell d) mRNA e) a polypeptide
d) mRNA
Research indicates that the best estimate of your age is from ______. a) the number of days you've lived b) the number of minutes you exercise every week c) your body mass index (BMI) d) markers in your cells
d) markers in your cells
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their daughters might be expected to be color-blind dwarfs? a) all b) half c) three out of four d) none e) one out of four
d) none
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? a) red × roan b) red × white c) white × roan d) roan × roan
d) roan × roan
Which of the following types of molecules help to hold the DNA strands apart while they are being replicated? a) primase b) ligase c) DNA polymerase d) single-strand DNA binding proteins
d) single-strand DNA binding proteins
The leading and the lagging strands differ in that a) the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. b) the leading strand is synthesized at twice the rate of the lagging strand. c) the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. d) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
d) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA? a) RNA processing b) gene expression c) polypeptide formation d) transcription e) translation
d) transcription
How do the events of meiosis I promote the production of new combinations of alleles? a) via both independent assortment and crossing over between sister chromatids b) via independent assortment alone c) via crossing over between homologous chromosomes only d) via both crossing over between homologous chromosomes and independent assortment e) via crossing over between sister chromatids only
d) via both crossing over between homologous chromosomes and independent assortment
What possible blood types could offspring have if their two parents have the blood types A and AB, respectively? a) AB only b) A, B, AB, and O c) A and O only d) A and B only e) A, B, and AB only
e) A, B, and AB only
Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition? a) Only if a woman is XXX could she have this condition. b) Women can never have this condition. c) One-fourth of the daughters of an affected father and a carrier mother could have this condition. d) One-half of the daughters of an affected man would have this condition. e) Very rarely: it is rare that an affected male would mate with a carrier female.
e) Very rarely: it is rare that an affected male would mate with a carrier female.
Polypeptides are assembled from _____. a) hexoses b) glycerol c) nucleotides d) proteins e) amino acids
e) amino acids
What is the most important factor that holds a gene pool of a species together and prevents speciation? a) behavioral isolation b) hybridization c) prezygotic barriers d) sexual selection e) gene flow
e) gene flow
In general, the frequency with which crossing over occurs between two linked genes depends on what? a) whether the genes are dominant or recessive b) the phase of meiosis in which the crossing over occurs c) whether the genes are on the X or some other chromosome d) the characters the genes code for e) how far apart they are on the chromosome
e) how far apart they are on the chromosome
The action of helicase creates _____. a) DNA fragments and replication forks b) primers and replication bubbles c) DNA fragments and replication bubbles d) primers and DNA fragments e) replication forks and replication bubbles
e) replication forks and replication bubbles
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein? a) RNA processing b) gene expression c) polypeptide formation d) transcription e) translation
e) translation