Bio Chapter 15 B

61) 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) 1/2 Dd : 1/2 dd; all right coiling B) All Dd; all right coiling C) 1/2 Dd : 1/2 dd; half right and half left coiling D) All Dd; all left coiling E) All Dd; half right and half left coiling

1/2 Dd : 1/2 dd; all right coiling

37) If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis? A) All the gametes will be diploid. B) Half of the gametes will be n + 1, and half will be n — 1. C) 1/4 of the gametes will be n + 1, one will be n — 1, and two will be n. D) There will be three extra gametes. E) Two of the four gametes will be haploid, and two will be diploid.

1/4 of the gametes will be n + 1, one will be n - 1, and two will be n.

44) A phenotypically normal prospective couple seeks genetic counseling because the man knows that he has a translocation of a portion of his chromosome 4 that has been exchanged with a portion of his chromosome 12. Although he is normal because his translocation is balanced, he and his wife want to know the probability that his sperm will be abnormal. What is your prognosis regarding his sperm? A) 1/4 will be normal, 1/4 with the translocation, 1/2 with duplications and deletions. B) All will carry the same translocation as the father. C) None will carry the translocation since abnormal sperm will die. D) His sperm will be sterile and the couple might consider adoption. E) 1/2 will be normal and the rest with the fatherʹs translocation.

1/4 will be normal, 1/4 with the translocation, 1/2 with duplications and deletions.

43) Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual? A) 47, +21 B) 47, XXY C) 47, XXX D) 47, XYY E) 45, X

47, +21

42) 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) 0% B) 25% C) 33% D) 50% E) 75%

75%

57) A gene is considered to be non-Mendelian in its inheritance pattern if it seems to ʺviolateʺ Mendelʹs laws. Which of the following would then NOT be considered non-Mendelian? A) A gene whose expression varies depending on the gender of the transmitting parent B) A gene derived solely from maternal inheritance C) A gene transmitted via the cytoplasm or cytoplasmic structures D) A gene transmitted to males from the maternal line and from fathers to daughters E) A gene transmitted by a virus to egg-producing cells

A gene transmitted to males from the maternal line and from fathers to daughters

46) Women with Turner syndrome have a genotype characterized as which of the following? A) aabb B) Mental retardation and short arms C) A karyotype of 45, X D) A karyotype of 47, XXX E) A deletion of the Y chromosome

A karyotype of 45, X

47) The frequency of Down syndrome in the human population is most closely correlated with which of the following? A) Frequency of new meiosis B) Average of the ages of mother and father C) Age of the mother D) Age of the father E) Exposure of pregnant women to environmental pollutants

Age of the mother

32) Genes D and F could be A) located on different chromosomes. B) located very near to each other on the same chromosome. C) located far from each other on the same chromosome. D) Both A and B E) Both A and C

Both A and C

59) Correns described that the inheritance of variegated color on the leaves of certain plants was determined by the maternal parent only. What phenomenon does this describe? A) Mitochondrial inheritance B) Chloroplast inheritance C) Genomic imprinting D) Infectious inheritance E) Sex-linkage

Chloroplast inheritance

54) In order for chromosomes to undergo inversion or translocation, which of the following is required? A) Point mutation B) Immunological insufficiency C) Advanced maternal age D) Chromosome breakage and rejoining E) Meiosis

Chromosome breakage and rejoining

35) 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) Recombination map D) Cytogenetic map E) Banded map

Cytogenetic map

41) A nonreciprocal crossover causes which of the following products? A) Deletion only B) Duplication only C) Nondisjunction D) Deletion and duplication E) Duplication and nondisjunction

Deletion and duplication

45) Abnormal chromosomes are frequent in malignant tumors. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse? A) An increase in non-disjunction B) Expression of inappropriate gene products C) A decrease in mitotic frequency D) Death of the cancer cells in the tumor E) Sensitivity of the immune system

Expression of inappropriate gene products

55) Which of the following statements describes genomic imprinting? A) It explains cases in which the gender of the parent from whom an allele is inherited affects the expression of that allele. B) It is greatest in females because of the larger maternal contribution of cytoplasm. C) It may explain the transmission of Duchenne muscular dystrophy. D) It involves an irreversible alteration in the DNA sequence of imprinted genes.

It explains cases in which the gender of the parent from whom an allele is inherited

53) At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype? A) Early prophase B) Late telophase C) Anaphase D) Late anaphase or early telophase E) Late prophase or metaphase

Late prophase or metaphase

58) Genomic imprinting is generally due to the addition of methyl (-CH3) groups to C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true? A) Methylation of C is permanent in a gene. B) Genes required for early development stages must not be imprinted. C) Methylation of this kind must occur more in males than in females. D) Methylation must be reversible in ovarian and testicular cells. E) The imprints are transmitted only to gamete-producing cells.

Methylation must be reversible in ovarian and testicular cells.

60) Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore in which body systems would you expect most mitochondrial gene mutations to be exhibited? A) The immune system and the blood B) Excretory and respiratory systems C) The skin and senses D) Nervous and muscular systems E) Circulation

Nervous and muscular systems

50) 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) People in Latin or South America B) The Inuit and other peoples in very cold habitats C) People living in equatorial areas of the world D) Very small population groups E) No groups have such higher frequency

No groups have such higher frequency

49) What is the source of the extra chromosome 21 in an individual with Down syndrome? A) Nondisjunction in the mother only B) Nondisjunction in the father only C) Duplication of the chromosome D) Nondisjunction or translocation in either parent E) It is impossible to detect with current technology

Nondisjunction or translocation in either parent

51) 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 somatic cell production. D) One member of the couple underwent nondisjunction in gamete production.

One member of the couple underwent nondisjunction in gamete production.

33) The frequency of crossing over between any two linked genes will be which of the following? A) Higher if they are recessive B) Dependent on how many alleles there are C) Determined by their relative dominance D) The same as if they were not linked E) Proportional to the distance between them

Proportional to the distance between them

48) An inversion in a human chromosome often results in no demonstrable phenotypic effect in the individual. What else may occur? A) There may be deletions later in life. B) Some abnormal gametes may be formed. C) There is an increased frequency of mutation. D) All inverted chromosomes are deleted. E) The individual is more likely to get cancer.

Some abnormal gametes may be formed.

34) Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons? A) The frequency of crossing over varies along the length of the chromosome. B) The relationship between recombination frequency and map units is different in every individual. C) Physical distances between genes change during the course of the cell cycle. D) The gene order on the chromosomes is slightly different in every individual. E) Linkage map distances are identical between males and females.

The frequency of crossing over varies along the length of the chromosome.

40) One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called? A) Deletion B) Disjunction C) Inversion D) Translocation E) Duplication

Translocation

52) 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) Watson and Crickʹs structure of DNA was not done until 1953. B) Chromosomes were piled up on top of one another in the nucleus. C) Chromosomes were not distinguishable during interphase. D) A method had not yet been devised to halt mitosis at metaphase.

Watson and Crickʹs structure of DNA was not done until 1953.

36) If a human interphase nucleus contains three Barr bodies, it can be assumed that the person A) has hemophilia. B) is a male. C) has four X chromosomes. D) has Turner syndrome. E) has Down syndrome.

has four X chromosomes.

56) The pedigree in Figure 15.4 shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely A) mitochondrial. B) autosomal recessive. C) sex-linked dominant. D) sex-linked recessive. E) autosomal dominant.

mitochondrial

38) If a pair of homologous chromosomes fails to separate during anaphase of meiosis I, what will be the chromosome number of the four resulting gametes with respect to the normal haploid number (n)? A) n + 1; n + 1; n - 1; n - 1 B) n + 1; n - 1; n; n C) n + 1; n - 1; n - 1; n - 1 D) n + 1; n + 1; n; n E) n - 1; n - 1; n; n

n + 1; n + 1; n - 1; n - 1

39) A cell that has 2n + 1 chromosomes is A) trisomic. B) monosomic. C) euploid. D) polyploid. E) triploid.

trisomic