Bio Unit 3 Concept Checks

Polar bear somatic cells contain 74 total chromosomes. How many chromosomes would a polar bear sperm cell contain? a. 74 pairs b. 146 total c. 37 pairs d. 74 total e. 37 total

37 total

In 1871, Francis Galton reported experiments in which, in each of multiple generations, he transfused blood from a true-breeding strain of black rabbits into individuals of a true-breeding strain of white rabbits. Nevertheless, he reported, in each generation the kits (babies) of the white rabbits were as white as their parents. In regard to heredity, this experiment demonstrates that: A) characteristics of blood are not hereditary. B) red blood cells (erythrocytes) have no nucleus. C) blood transfusions do not affect hereditary characteristics. D) the recipient's coat color is not affected by blood transfusions. E) None of the other answer options is correct.

C) blood transfusions do not affect hereditary characteristics.

A true breeding black rabbit is crossed with a true breeding white rabbit to produce an F1 generation with 8 individuals. If blending inheritance were true, which of the following would represent the expected phenotype of the F1 generation? a. 0 black rabbits, 0 white rabbits, 16 gray rabbits b. 9 black rabbits, 3 white rabbits, 3 gray rabbits, 1 spotted rabbit c. 16 black rabbits, 0 white rabbits, 0 gray rabbits d. 0 black rabbits, 16 white rabbits, 0 gray rabbits e. 5 black rabbits, 4 white rabbits, 7 gray rabbits

a. 0 black rabbits, 0 white rabbits, 16 gray rabbits

Color blindness is a recessive X-linked trait in humans. In a family where the mother is heterozygous for color blindness and the father is color-blind, the probability of their having a color-blind daughter is: a. 1/2. b. 1/4. c. 1. d. 0. e. 1/16.

a. 1/2.

For most genes on the human X chromosome, what percent of XY males with a mutant allele on the X chromosome will express the mutant phenotype? a. 100% b. 0% c. 50% d. There is insufficient data to predict. e. 25%

a. 100%

Consider two situations. Situation 1: II-1 and II-2 have a son with only color blindness. Situation 2: II-1 and II-2 have a son with only hemophilia. If these two genes are so far apart that they are unlinked, which of the two situations is more likely? a. Both situations are equally likely. b. Situation 1 is more likely. c. Situation 2 is more likely.

a. Both situations are equally likely.

Which of the populations would you expect to have the most genetic diversity within the group? a. a stock of tomato plants that is not true breeding b. the F1 generation of tomato plants from the cross of two different true-breeding stocks c. a true-breeding stock of tomato plants

a. a stock of tomato plants that is not true breeding

Regulatory transcription factors: a. bind to the enhancers and recruit the general transcriptional factors to the promoters. b. recruit Xist RNA to the X chromosome. c. recruit CRP-AMP complex to the promoter. d. bind to promoters and recruit the RNA polymerase complex to the promoters.

a. bind to the enhancers and recruit the general transcriptional factors to the promoters.

What is the function of the mitotic spindle? a. keeping sister chromatids connected b. separating sister chromatids c. dividing cytoplasm between daughter cells d. replicating chromosomes

a. keeping sister chromatids connected

Which gene in the diagram codes for a repressor protein that binds to the operator site when lactose is not present? a. lacI b. lacZ c. both lacZ and lacY d. both lacI and lacO

a. lacI

The frequency of recombination is______for genes that are closer together compared to genes that are further apart in the same chromosome. a. larger b. smaller

a. larger

Assuming that the trait represented by the filled symbols in the pedigree is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree shown suggest? a. recessive b. dominant

a. recessive

Refer to the drawing of mRNA shown. Choose the letter that best fits the description. The 3′ UTR corresponds to: a. region D. b. region B. c. region E. d. region C. e. region A.

a. region D.

Which of Mendel's findings is not applicable when predicting the results of crosses involving genes that are closely linked? a. the law of independent assortment b. the law of segregation c. complete dominance d. all of these choices are correct e. the occurrence of alternate forms (alleles) of genes

a. the law of independent assortment

All of the F1 progeny from the parental cross have a wile-type phenotype. a. true b. false

a. true

A woman is heterozygous for a recessive allele that causes X-linked hemophilia. This recessive allele has a mutation that makes a gene for a blood-clotting factor nonfunctional. Considering the implications of X-inactivation, the level of clotting factor in her blood is likely to be approximately _____ that of a homozygous non-mutant woman. None of the other answer options is correct. a. 1 b. 1/2 c. 3/4 d. 1/4

b. 1/2

Among the exons in a primary RNA transcript, two are subject to alternative splicing. In RNA processing, one or the other or neither or both regions may be excised from the primary transcript as introns. How many different amino acid sequences could this transcript encode? a. 3 b. 4 c. 2 d. 5 e. 1

b. 4

Which of the genotypes would result in true-breeding stock? a. Aa, but not AA or aa b. AA or aa, but not Aa c. AA, Aa, or aa d. AA, but not Aa or aa e. aa, but not Aa or AA

b. AA or aa, but not Aa

Which one of the statements about regulation of translation is correct? a. One of the key variables for influencing efficient translation is the sequence of nucleotides flanking the first GUG codon. b. Regulation of translation does not depend on sequences in the 3′ UTR or the poly(A) tail. c. The translation initiation complex scans for a TAC codon near the 5′ cap. d. Translation initiation complexes recognize and bind to the 5′ cap. e. The 5′ UTR sequence does not affect the efficiency of translation initiation.

d. Translation initiation complexes recognize and bind to the 5′ cap.

In crosses involving linked genes, recombinant offspring result from: a. Mendelian segregation and independent assortment of alleles b. Mendelian segregation c. independent assortment of alleles d. a crossover e. sex-linked inheritance

d. a crossover

Inheritance due to a rare X-linked dominant mutation can be distinguished from inheritance due to a rare autosomal dominant mutation because, in the X-linked case: a. affected mothers do not have affected daughters b. the two possibilities cannot be distinguished c. affected mothers do not have affected sons d. affected fathers do not have affected sons e. affected fathers do not have affected daughters

d. affected fathers do not have affected sons

Histone modification: a. is random and independent of the environment or cell type. b. is fixed; once a histone is modified, it stays that way and the genes with which it is associated are turned on or off permanently. c. can change over time in response to environmental cues, but this has no effect on gene expression. d. can change over time in response to environmental cues, allowing genes to be turned on or off as needed. e. is fixed, but this has no effect on whether genes are expressed.

d. can change over time in response to environmental cues, allowing genes to be turned on or off as needed.

With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb × aa BB) can be described as 9:3:3:1 when A and B are dominant over a and b. To what phenotypes do the "3"s in the ratio refer? a. dominant for the A trait and recessive for the B trait b. recessive for both traits c. dominant for both traits d. dominant for one trait and recessive for the other

d. dominant for one trait and recessive for the other

A human cell with a total of 23 chromosomes is: a. aneuploid. b. diploid. c. polyploid. d. haploid.

d. haploid.

Which of the events occurs during RNA processing? a. the removal of all exons during RNA splicing b. the removal of poly(A) tails from the primary transcript c. the removal of a nucleotide cap to the 5′ end and a poly(A) tail to d. the 3′ end of the newly transcribed RNA e. the addition of a nucleotide cap to the 5′ end and a poly(A) tail to the 3′ of the newly transcribed RNA

e. the addition of a nucleotide cap to the 5′ end and a poly(A) tail to the 3′ of the newly transcribed RNA

In a diploid individual, there are two genes called "A" and "B" on one chromosome. One homolog of that chromosome carries A and B alleles of those genes, and the homologous chromosome carries different forms (alleles) of these same genes, a and b. If there is a single crossover between these two genes involving one pair of non‐sister chromatids during metaphase I of meiosis, the resulting four gametes would be: a. AaBb, AaBb, AaBb, AaBb. b. AB, Ab, aB, ab. c. Ab, Ab, aB, aB. d. AB, AB, ab, ab. e. AB, ab, AB, ab.

b. AB, Ab, aB, ab.

Which individuals are expected to have essentially the same Y chromosome? a. I-1, II-5, III-9 b. II-1, III-1, IV-1 c. II-5, III-8, IV-3 d. I-1, II-7, III-9

b. II-1, III-1, IV-1

Predict what would happen if crossing over between homologous chromosomes occurred as part of mitosis. a. daughter cells would be haploid b. daughter cells would not be genetically identical c. daughter cells would be genetically identical e. there would be no effect, because sister chromatids separate in anaphase

b. daughter cells would not be genetically identical

In meiosis, recombination occurs: a. during both prophases I and II and involves exchange of chromosome fragments between all four chromatids. b. during only prophase I and involves exchange between chromatids of homologous chromosomes. c. during only prophase II and involves exchange of chromosome fragments between sister chromatids. d. during both prophases I and II and involves exchange of chromosome fragments between sister chromatids.

b. during only prophase I and involves exchange between chromatids of homologous chromosomes.

After breeding the F1 generation (brother and sister mating), all the F2 female progeny would have the same genotype. a. true b. false

b. false

If you crossed a true-breeding yellow-seed plant (AA) with a heterozygous yellow-seed plant (Aa), offspring: a. genotypes would be 1 Aa: 1 aa b. genotypes would be 1 AA: 1 Aa c. genotypes would be 1 AA: 2 Aa d. phenotypes would be 1/2 yellow-seed plants and 1/2 green-seed plants

b. genotypes would be 1 AA: 1 Aa

With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb × aa BB) can be described as 9:3:3:1 when A and B are dominant over a and b. To what phenotypes do the "9" in the ratio refer? a. dominant for the A trait and recessive for the B trait b. recessive for both traits c. dominant for both traits d. dominant for one trait and recessive for the other

c. dominant for both traits

You are given two populations of true-breeding tomato plants with two simple dominant/recessive traits that sort independently. Using the multiplication rule, how many different phenotypic combinations would you expect to see in the F2 generation? In what phenotypic ratio? a. two; 3:1 b. three; 9:6:1 c. four; 9:3:3:1

c. four; 9:3:3:1

Humans with hypohidrotic ectodermal dysplasia have defects in the formation and function of their sweat glands. Males with the condition have reduced ability to sweat over their entire body. Females with the condition lose the ability to sweat only in patches of skin. Where must the gene that encodes this trait be located? a. in an autosome b. in the Y chromosome c. in the X chromosome

c. in the X chromosome

A loss of function mutation in which labeled sequence in the diagram would likely result in continuous production of the enzymes from the lac operon? a. lacZ b. both lacZ and lacY c. lacI d. lacY

c. lacI

Which of the processes would result in gametes that violate Mendel's principle of segregation? a. dominance b. independent assortment c. nondisjunction d. epistasis

c. nondisjunction

Considering an X-linked dominant trait, if an unaffected woman and an affected man decide to have children, which of the following statements is TRUE about the possibilities for their children? a. their sons are expected to be heterozygous for the gene b. their daughters are not expected to show the dominant trait c. all their children, whether male or female, are expected to show the dominant trait d. all of their sons are expected to show the dominant trait e. their daughters are expected be heterozygous for the gene

e. their daughters are expected be heterozygous for the gene

You are given two populations of true-breeding tomato plants with two simple dominant/recessive traits that sort independently. Using the multiplication rule, how many of the F2 progeny would you expect to have recessive phenotype for both traits? a. 9/16 b. 6/16 c. 3/16 d. 1/16

d. 1/16

Suppose that, in humans, ability to roll the tongue (R) is dominant to being unable to roll (r), and having freckles (F) is dominant to having no freckles (f). If a woman heterozygous for both traits married a man with no freckles who couldn't roll his tongue, what is the probability that they would have a freckled, tongue-rolling child? a. 3/16 b. 3/4 c. 1/16 d. 1/4 e. 9/16

d. 1/4

In a cell undergoing meiosis, when a single crossover occurs between two genes of interest, the result is: a. 4 chromosomes: all recombinant b. 4 chromosomes: 3 nonrecombinant and 1 recombinant c. 4 chromosomes: all nonrecombinant d. 4 chromosomes: 2 nonrecombinant and 2 recombinant e. 4 chromosomes: 1 nonrecombinant and 3 recombinant

d. 4 chromosomes: 2 nonrecombinant and 2 recombinant

In human cells, at the end of mitosis and after cytokinesis, how many chromosomes have moved into each daughter cell? a. 22 b. 92 c. 23 d. 46

d. 46

During meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell. false true

false

Proteins produced from the Xist RNA transcripts coats the X chromosome to inactivate it. true false

false

diploid or haploid: bacterium

haploid

diploid or haploid: egg cell

haploid

diploid or haploid: sperm

haploid

What must be true of individual I‑2? a. She is a carrier of both mutations, carrying one mutation in each of her two homologous chromosomes. b. She is a carrier of both mutations, carrying both mutations in the same chromosome. c. She is a carrier of the hemophilia mutation. d. She is a carrier of the color‑blindness mutation.

d. She is a carrier of the color‑blindness mutation.

Because of X-inactivation, female mammals are all mosaics for genes on the X chromosomes; that is, different cell lineages within the body may express the genes of one or the other parental X chromosome. true false

true

In humans, fruit flies, and many other organisms, most of the genes on the X chromosome are not found on the Y chromosome. true false

true

In mammals this dosage compensation is the result of X-inactivation in females. true false

true

In the mammalian developing female (XX) embryo, a random inactivation of either the maternally derived X chromosome or the paternally derived X chromosome results in all the cells from subsequent cell divisions expressing only genes on the active X chromosome. true false

true

Modification of bases in mRNA transcripts can change the mRNA sequence and thus the characteristics of the protein for which it codes. true false

true

The model of clustering genes into operons is commonly found in both prokaryotes and eukaryotes. true false

true

Transcriptional regulation in eukaryotic cells requires the coordinated action of many proteins that interact with one another and with DNA sequences near the gene. true false

true

If one of the traits Mendel studied was encoded by a single gene with three alleles that produced different phenotypes, what would he have observed if he crossed all possible pairs of the three true-breeding lines in the F1 and F2 generations? A) In each of the crosses, he would have observed two phenotypes in the F1 generation. B) Only a single phenotype would have been observed in the F1 generation because only one allele can be dominant. C) No evidence would exist for the law of segregation. D) No true-breeding plants would have been produced in the F2. E) None of the answer options is correct.

E) None of the answer options is correct.

Genes a and b are located close together in the same chromosome. Allele A for long wings is completely dominant to allele a for short wings. Allele B for light body color is completely dominant to allele b for dark body color. A female fly is heterozygous for both genes such that alleles A and b are present in one homolog, whereas alleles a and B are present in the other homolog. If she is crossed with a male fly that is homozygous recessive for both genes, then the majority of their progeny would: a. have long wings and a light body or short wings and a dark body b. have short wings and a light body or long wings and a dark body c. have long wings and a light body or long wings and a dark body d. have short wings and a light body or long wings and a light body e. look just like their mother.

b. have short wings and a light body or long wings and a dark body

Which phrase describes a sister chromatid? a. the second copy of a homologous chromosome b. one member of a replicated chromosome c. the second, noncoding strand of double‑stranded DNA d. mRNA that is being copied and still in complex with DNA

b. one member of a replicated chromosome

Modification of histone tails is one mechanism of: a. X-inactivation. b. post-translational modification. c. None of the other answer options is correct. d. RNA processing. e. RNA editing.

b. post-translational modification.

Nondisjunction results in gametes that violate which principle? a. independent assortment b. segregation c. dominance

b. segregation

Which of the choices has the most similarity in nucleotide sequence? a. the X and the Y chromosomes b. sister chromatids c. homologous chromosomes d. non‑sister chromatids e. nonhomologous chromosomes

b. sister chromatids

A homologous chromosome pair is best described as 2 chromosomes that have: a. identical sequences of nucleotides. b. the same genes in the same order but possibly with different alleles of some of the genes. c. the same alleles of the same genes in the same order. d. different alleles of the same genes arranged in a different order. e. different genes arranged in a different order with potentially different alleles of some of the genes.

b. the same genes in the same order but possibly with different alleles of some of the genes.

Color blindness is a recessive X-linked trait in humans. In a family where the mother is color-blind and the father is normal, the probability of their having a color-blind son is: a. 1/2. b. 1/4. c. 1. d. 0. e. 1/16.

c. 1.

You are given two true-breeding groups of gerbils. The gerbils in the first group have black coat color and curly tails; the gerbils in the second group have yellow coat color and straight tails. When you produce an F1 generation, you see only gerbils with black coat color and curly tails. When you produce an F2 generation, you see some gerbils with black coat color (75 percent) and some gerbils with yellow coat color (25 percent). You also see some of the gerbils have straight tails (25 percent) and others (75 percent) have curly tails. If the single alleles responsible for coat color and tail appearance sort independently, how many of the black gerbils in this generation are expected to have straight tails? a. 100% b. 75% c. 25% d. 0%

c. 25%

For the partial diploid genotype shown here, (I+ P+ Oc Z+/ I- P- O+ Z-) determine whether functional B-galactosidase is synthesized in the absence and the presence of lactose. a. B-galactosidase is not produced whether lactose is present or absent b. B-galactosidase is produced when lactose is present but not produced when lactose is absent c. B-galactosidase is produced whether lactose is present or absent d. B-galactosidase is not produced when lactose is present but is produced when lactose is absent

c. B-galactosidase is produced whether lactose is present or absent

A mutation is found that prevents transcription of the HOX3A gene, which is known to be in chromosome 12. Genetic mapping of the mutation suggests that it is located in chromosome 11. Which of the answer choices could make these two observations possible? a. The mutation changes the DNA sequence of an enhancer of the HOX3A gene. b. The mutation prevents ribosome binding by altering sequences of the HOX3A mRNA. c. The mutation affects a transcription factor that binds to HOX3A gene sequences. d. The mutation increases transcription of an miRNA that has sequence homology to the HOX3A gene.

c. The mutation affects a transcription factor that binds to HOX3A gene sequences.

Imagine that a rancher has a herd of cattle with brown hides and short horns. All of his cattle are also relatively short in stature. If all of these traits were "true breeding," what could you say about the progeny of these cattle? a. Since the cattle are "true-breeding," the progeny of this herd will all be sterile. b. The progeny of these cattle will have short horns, but a variety of hide colors and heights.It is impossible to determine the traits of such progeny―they will likely demonstrate different hide colors, horn lengths, and heights. c. The progeny of these cattle will be short in stature and have brown hides and short horns. d. The progeny of these cattle will have brown, black, white, and spotted hides.

c. The progeny of these cattle will be short in stature and have brown hides and short horns.

If an XY male carries a mutation on his X chromosome, ______ will receive the mutant X. a. all of his sons b. all his sons and daughters c. all of his daughters d. half his sons and half his daughters

c. all of his daughters

If you crossed two heterozygous yellow-seed pea plants (genotypes Aa), the relative frequency of: a. homozygous yellow-seed plants (genotype AA) would be 1/4 b. the a allele in each parent's gametes would be 1/2 c. all of these choices are correct d. the A allele in each parent's gametes would be 1/2 e. green-seed plants (genotype aa) would be 1/4

c. all of these choices are correct

In the lac operon diagrammed, which coding sequence(s) code for the enzymes required to effectively use lactose as a source of energy? a. lacI b. both lacI and lacO c. both lacZ and lacY d. lacZ e. lacY

c. both lacZ and lacY

Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of a large cell. Predict what is different about the cell cycle in a muscle cell. a. the G1 and G2 phases are extended b. S phase happens twice c. cytokinesis does not occur d. M phase is inhibited

c. cytokinesis does not occur

The frequency of recombination during meiosis is a function of: a. the distance between the genes: the closer the genes are, the more frequent the recombination between them b. the alleles of the gene: recombination happens less frequently between recessive alleles c. the distance between genes: the farther apart the genes are, the more frequent the recombination between them d. whether or not the genes are sex-linked: genes in X chromosomes recombine much more frequently than do genes in the autosomes e. whether or not the genes are sex-linked: genes in Y chromosomes recombine much more frequently than do genes in the autosomes

c. the distance between genes: the farther apart the genes are, the more frequent the recombination between them

Which of the outcomes represents the expected genotypes of an F1 generation consisting of 16 individuals from a cross of a true-breeding black (BB) rabbit and a true-breeding white (bb) rabbit? a. 16 BB, 0 bb, 0 Bb b. 4 BB, 4 bb, 8 Bb c. 8 BB, 8 bb, 0 Bb d. 0 BB, 0 bb, 16 Bb

d. 0 BB, 0 bb, 16 Bb

If you tracked an individual X chromosome from a male to his first generation offspring, then to his second generation offspring, what pattern would you see? a. his X chromosome would be found only in his daughters and grandaughters b. his X chromosome would be found only in his sons, then in both his grandaughters and grandsons c. his X chromosome would be found only in his daughters and grandsons d. his X chromosome would be found only in his daughters, then in both his granddaighters and grandsons e. his X chromosome would be found only in his sons and grandsons

d. his X chromosome would be found only in his daughters, then in both his granddaighters and grandsons

Genes that are located in the same chromosome and are close together: a. are always located on autosomes b. are usually clustered on the Y chromosome c. are never located on the X chromosome d. may not assort independently from each other e. always segregate from one another during division

d. may not assort independently from each other

diploid or haploid: apple tree cell

diploid

diploid or haploid: skin cell

diploid

If these genes are far enough apart to undergo independent assortment, and II‑1 and II‑2 have another son, what is the probability that the child will be affected with color blindness alone, hemophilia alone, or both traits together? a. None of the other answer options is correct. b. 1/2 c. 3/8 d. 5/8 e. 3/4

e. 3/4

Recall that in Mendel's work, mating between yellow, wrinkled, seed-producing plants and plants that produced smooth green seeds resulted in a ratio of 9:3:3:1 for progeny phenotypes. This observed ratio can be explained by: a. the principle of independent assortment b. the addition rule c. incomplete dominance d. the multiplication rule e. both the multiplication rule and the principle of independent assortment

e. both the multiplication rule and the principle of independent assortment

A normal female who carries a recessive X-linked allele for hemophilia will pass it on to: a. all of her daughters. b. half of her daughters. c. half of her sons. d. all of her sons. e. half of both her sons and daughters.

e. half of both her sons and daughters.