Exam Chapter 15 Chromosomal Basis for Inheritance AP Biology Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? A) Other female-specific factors influence eye color in flies. B) Other male-specific factors influence eye color in flies. C) The gene involved is on an autosome. D) The gene involved is on the X chromosome. E) The gene involved is on the Y chromosome. 2) Morgan and his colleagues worked out a set of symbols to represent fly genotypes. Which of the following are representative? A) AaBb AaBb B) 46, XY or 46, XX C) +2 +3 D) vg+vgse+se vgvgsese 1) 2) 3) A man with Klinefelter syndrome (47, XXY) is expected to have any of the following EXCEPT 3) A) female body characteristics. B) possible breast enlargement. C) increased testosterone. D) lower sperm count. E) long limbs. 4) A woman is found to have 47 chromosomes, including 3 X chromosomes. Which of the following describes her expected phenotype? A) Normal female B) Sterile female C) Masculine characteristics such as facial hair D) Enlarged genital structures E) Excessive emotional instability 4) 5) Males are more often affected by sex-linked traits than females because 5) A) males are hemizygous for the X chromosome. B) X chromosomes in males generally have more mutations than X chromosomes in females. C) female hormones such as estrogen often compensate for the effects of mutations on the X. D) mutations on the Y chromosome often worsen the effects of X-linked mutations. E) male hormones such as testosterone often alter the effects of mutations on the X chromosome. 6) What is the chromosomal system for determining sex in mammals? 6) A) X-0 B) X-X C) Z-W D) X-Y E) Haploid-diploid 1
7) What is the chromosomal system for sex determination in birds? 7) A) X-X B) X-Y C) X-0 D) Haploid-diploid E) Z-W 8) What is the chromosomal system of sex determination in most species of ants and bees? 8) A) X-0 B) Z-W C) Haploid-diploid D) X-X E) X-Y 9) SRY is best described in which of the following ways? 9) A) A gene present on the X chromosome that triggers female development B) An autosomal gene that is required for the expression of genes on the Y chromosome C) Required for development, and males or females lacking the gene do not survive past early childhood D) An autosomal gene that is required for the expression of genes on the X chromosome E) A gene region present on the Y chromosome that triggers male development 10) 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) Tortoiseshell females; tortoiseshell males B) Tortoiseshell females; black males C) Orange females; orange males D) Black females; orange males E) Orange females; black males 11) 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) XcXc and XCY B) XCXc and XCY C) XCXC and XCY D) XCXC and XcY E) XcXc and XcY 10) 11) 12) Calico cats are female because 12) A) a male inherits only one of the two X-linked genes controlling hair color. B) the Y chromosome has a gene blocking orange coloration. C) multiple crossovers on the Y chromosome prevent orange pigment production. D) the males die during embryonic development. E) only females can have Barr bodies. 2
13) In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female? A) 4:3 male to female B) 2:1 male to female C) 3:1 male to female D) 1:2 male to female E) 1:1 male to female 13) Refer to the following information to answer the questions below. A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was six 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. 14) How many of their daughters might be expected to be color-blind dwarfs? 14) A) One out of four B) Three out of four C) None D) All E) Half 15) What proportion of their sons would be color-blind and of normal height? 15) A) All B) Three out of four C) One out of four D) None E) Half 16) They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes? A) 0.25 B) 1.00 C) 0.75 D) 0.50 E) 0 16) 17) A Barr body is normally found in the nucleus of which kind of human cell? 17) A) Somatic cells of a male only B) Unfertilized egg cells only C) Both male and female somatic cells D) Sperm cells only E) Somatic cells of a female only 18) Sex determination in mammals is due to the SRY region of the Y chromosome. An abnormality could allow which of the following to have a male phenotype? A) Translocation of SRY to an autosome of a 46, XX individual B) A person with one normal and one shortened (deleted) X C) Turner syndrome, 45, X D) Down syndrome, 46, XX E) A person with too many X chromosomes 18) 3
19) How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced? A) The two genes are linked. B) Both of the characters are controlled by more than one gene. C) Recombination did not occur in the cell during meiosis. D) The testcross was improperly performed. E) The two genes are linked but on different chromosomes. 19) 20) New combinations of linked genes are due to which of the following? 20) A) Crossing over B) Independent assortment C) Mixing of sperm and egg D) Nondisjunction E) Deletions 21) What does a frequency of recombination of 50% indicate? 21) A) Independent assortment is hindered. B) The genes are located on sex chromosomes. C) All of the offspring have combinations of traits that match one of the two parents. D) Abnormal meiosis has occurred. E) The two genes are likely to be located on different chromosomes. 22) A 0.1% frequency of recombination is observed 22) A) only on genetic maps of viral chromosomes. B) only in sex chromosomes. C) on unlinked chromosomes. D) in genes located very close to one another on the same chromosome. E) in any two genes on different chromosomes. 23) The following is a map of four genes on a chromosome: 23) Figure 15.1 Between which two genes would you expect the highest frequency of recombination? A) E and G B) A and G C) W and E D) A and W E) A and E 24) What is the reason that linked genes are inherited together? 24) A) Alleles are paired together during meiosis. B) Genes align that way during metaphase I of meiosis. C) They are located close together on the same chromosome. D) Chromosomes are unbreakable. E) The number of genes in a cell is greater than the number of chromosomes. 4
D, F, and J are three genes in Drosophila. The recombination frequencies for two of the three genes are shown in Figure 15.3. Figure 15.3 25) Genes D and F could be 25) A) located far from each other on the same chromosome. B) located very near to each other on the same chromosome. C) located on different chromosomes. D) Both A and B E) Both A and C 26) The frequency of crossing over between any two linked genes will be which of the following? 26) A) Higher if they are recessive B) Proportional to the distance between them C) The same as if they were not linked D) Dependent on how many alleles there are E) Determined by their relative dominance 27) Which of the following is a map of a chromosome that includes the positions of genes relative to visible chromosomal features, such as stained bands? A) Linkage map B) Physical map C) Cytogenetic map D) Banded map E) Recombination map 27) 28) If a human interphase nucleus contains three Barr bodies, it can be assumed that the person 28) A) is a male. B) has four X chromosomes. C) has Turner syndrome. D) has Down syndrome. E) has hemophilia. 29) A cell that has 2n + 1 chromosomes is 29) A) trisomic. B) triploid. C) polyploid. D) monosomic. E) euploid. 5
30) One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called? A) Duplication B) Disjunction C) Translocation D) Deletion E) Inversion 31) In humans, male-pattern baldness is controlled by an autosomal gene that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald? A) 50% B) 0% C) 75% D) 25% E) 33% 32) Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual? A) 47, XXX B) 47, +21 C) 45, X D) 47, XXY E) 47, XYY 30) 31) 32) 33) Women with Turner syndrome have a genotype characterized as which of the following? 33) A) A karyotype of 47, XXX B) aabb C) A deletion of the Y chromosome D) Mental retardation and short arms E) A karyotype of 45, X 34) The frequency of Down syndrome in the human population is most closely correlated with which of the following? A) Age of the father B) Average of the ages of mother and father C) Exposure of pregnant women to environmental pollutants D) Frequency of new meiosis E) Age of the mother 34) 35) What is the source of the extra chromosome 21 in an individual with Down syndrome? 35) A) Duplication of the chromosome B) It is impossible to detect with current technology C) Nondisjunction in the father only D) Nondisjunction in the mother only E) Nondisjunction or translocation in either parent 36) Down syndrome has a frequency in the U.S. population of ~ 1/700 live births. In which of the following groups would you expect this to be significantly higher? A) The Inuit and other peoples in very cold habitats B) Very small population groups C) People in Latin or South America D) People living in equatorial areas of the world E) No groups have such higher frequency 36) 6
37) A couple has a child with Down syndrome when the mother is 39 years old at the time of delivery. Which is the most probable cause? A) The woman inherited this tendency from her parents. B) One member of the couple carried a translocation. C) One member of the couple underwent nondisjunction in gamete production. D) One member of the couple underwent nondisjunction in somatic cell production. 38) In 1956 Tijo and Levan first successfully counted human chromosomes. The reason it would have taken so many years to have done so would have included all but which of the following? A) Chromosomes were not distinguishable during interphase. B) Chromosomes were piled up on top of one another in the nucleus. C) A method had not yet been devised to halt mitosis at metaphase. D) Watson and Crick's structure of DNA was not done until 1953. 39) In order for chromosomes to undergo inversion or translocation, which of the following is required? A) Immunological insufficiency B) Point mutation C) Advanced maternal age D) Chromosome breakage and rejoining E) Meiosis 40) A certain kind of snail can have a right-handed direction of shell coiling (D) or left handed coiling (d). If direction of coiling is due to a protein deposited by the mother in the egg cytoplasm, then a Dd egg-producing snail and a dd sperm-producing snail will have offspring of which genotype(s) and phenotype(s)? A) All Dd; all right coiling B) 1/2 Dd : 1/2 dd; all right coiling C) All Dd; half right and half left coiling D) All Dd; all left coiling E) 1/2 Dd : 1/2 dd; half right and half left coiling 37) 38) 39) 40) 7