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1. In Kölreuter’s studies, reciprocal crosses
a. always gave identical results.
2. During what year did Gregor Mendel orally present his genetics project?
3. Mendel’s research was rediscovered in the published studies of
a. de Vries.
4. Which of the following is not a characteristic that makes an organism suitable for genetic studies?
a. A small number of chromosomes
5. Which of the following methods was not used by Mendel in his study of the genetics of the garden pea?
6. A key factor that allowed Mendel to interpret the results of his breeding experiments was that
a. the varieties of peas he used were “true-breeding.”
d. pollination could be controlled
7. If Mendel had performed experiments on cattle rather than on peas, the patterns of inheritance would not have been easily detectable, because cattle
b. have small numbers of offspring.
8. If two strains of true-breeding plants that have different alleles for a certain character are crossed, their progeny are called
b. the F1 generation.
9. Mendel concluded that each pea has two units for each character, and each gamete contains one unit. Mendel’s “unit” is now referred to as a(n)
10. Mendel’s crossing of spherical-seeded pea plants with wrinkled-seeded pea plants resulted in progeny that all had spherical seeds. This indicates that the wrinkled-seed trait is
11. Which statement about the inheritance of color in schmoos is most likely to be correct?
a. Brown is dominant to white.
12.Which statement about the inheritance of footedness in schmoos is most likely to be correct?
e. This cannot be answered without more information.
13. If big feet (B) in schmoos is dominant to small feet (b), the genotype of the big-footed white parent schmoo with respect to the foot gene can
c. only be Bb.
14. If a trait not expressed in the F1 generation reappears in the F2 generation, the inheritance of the trait in question is an example of
b. dominance and recessiveness.
15. The physical appearance of a character is called
b. the phenotype.
16. Different forms of a gene are called
17. Segregation of alleles occurs
a. during gamete formation.
18. Separation of the alleles of a single gene into different gametes is called
19. The site on the chromosome occupied by a gene is called a(n)
20. A particular genetic cross in which the individual in question is crossed with an individual known to be homozygous for a recessive trait is referred to as a
e. test cross.
21. A pea plant with red flowers is test crossed, and one-half of the resulting progeny have red flowers, while the other half has white flowers. Therefore, the genotype of the test-crossed parent was
22. In a _______ cross, genes for two different characters separate.
23. In garden peas, the allele for tall plants is dominant over the allele for short plants. A true-breeding tall plant is crossed with a short plant, and one of their offspring is test crossed. Out of 20 offspring resulting from the test cross, about _______ should be tall.
24. A dihybrid cross
c. results in offspring of lower quality than that of the parents.
25. The genotype of an organism that expresses a dominant trait can be determined by
e. observing the genotype of the progeny.
26. In mice, short hair is dominant to long hair. If a short-haired individual is crossed with a long-haired individual and both long- and short-haired offspring result, one can conclude that
b. the short-haired individual is heterozygous.
In dogs, trait A is caused by dominant alleles; trait B is caused by recessive alleles. A dog that is homozygous for both traits is mated to a dog with trait B. If the two genes are unlinked, which of the following are the expected F1 phenotypic ratios?
28. In cocker spaniels, black color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). If the genes are unlinked and the offspring of BBss and bbss individuals are mated with each other, what fraction of their offspring will be black and spotted?
29. Mendel’s dihybrid crosses
a. resulted in four different phenotypes.
b. produced recombinant phenotypes.
c. led to the formation of the law of independent assortment.
d. involved genes located on separate chromosomes.
30. In Mendel’s experiments, if the allele for tall (T) plants was incompletely dominant over the allele for short (t) plants, what offspring would have resulted from crossing two Tt plants?
a. 1⁄4 tall; 1⁄2 intermediate height; 1⁄4 short
31. One of the major contributions of Mendel to the study of genetics was
a. the use of statistics and probability to analyze data.
32. Despite the law of independent assortment, when two loci are on the same chromosome, the phenotypes of the progeny sometimes do not fit the predicted phenotypes due to
33. Classical albinism results from a recessive allele. Which of the following is the expected ratio for the progeny when a normally pigmented male with an albino father has children with an albino woman?
c. 1⁄2 normal; 1⁄2 albino
90 percent penetrance for producing blue sclera, 60 percent penetrance for fragile bones, and 40 percent penetrance for deafness. If these probabilities of penetrance are independent, _______ percent of individuals with the blue sclera allele will have deafness, blue sclera, and fragile bones.
37. Genetic mutations are
c. inherited changes in DNA.
38. Tall pea plants are crossed to short, and the progeny are medium height. The F1 plants are crossed together, but the progeny observed among the F2 have nine different size classes. This result is best explained by
d. an increased number of phenotypes in multiple alleles.
d. All the progeny would be smooth-seeded and intermediate in height.
40. It has been found that at a certain locus of the human genome, 200 different alleles exist in the population. Each person has at most _______ alleles.
41. Which of the following statements about Mendelian genetics is false?
c. Only two alleles can exist for a given gene.
43. If the same allele has two or more phenotypic effects, it is said to be
44. The ABO blood groups in humans are determined
by a multiple allelic system in which IA and IB are codominant and are dominant to iO. If an infant born to a type O mother also is type O, possible genotypes for the father are
d. O, A, or B.
45. In the ABO blood type system,
c. A and B are codominant.
46. The genetic disease blue sclera is determined by an autosomal dominant allele. The eyes of individuals with this allele have bluish sclera. These same individuals may also suffer from fragile bones and deafness. This is an example of
47. A mutation at a single locus causes a change in many different characters. This an example of a(n) _______ effect.
48. Epistasis refers to
e. the expression of one gene masking the expression of another.
49. When a given trait is the result of multigene action, one of the genes may mask the expression of one or all other genes. This phenomenon is termed
50. What percent of the progeny do you expect to be albino?
51. What percent of the progeny do you expect to be agouti?
52. What percent of the progeny do you expect to be black?
53. The complete phenotype of an organism is dependent on
54. A dominant allele K is necessary for normal hearing. A dominant allele M on a different locus results in deafness no matter which other alleles are present. If a kkMm individual is crossed with a Kkmm individual, _______ percent of the offspring will be deaf.
55. If Mendel’s crosses between spherical-seeded tall plants and wrinkled-seeded short plants had produced many more than 1⁄16 wrinkled-seeded short plants in the F2 generation, he might have concluded that
a. the spherical seed and tall traits are linked.
56. A linkage group corresponds to
d. a group of genes on the same chromosome.
57. When a dihybrid black, straight-winged fly is crossed to a double-recessive brown, curly-winged fly, the frequency at which black curly-winged and brown straight-winged flies are seen in the progeny is called the _______ frequency.
d. linked and show 20 percent recombination.
59. How many linkage groups are present in a female human?
60. An organism that produces either male gametes or female gametes, but not both, is called
61. It is predictable that half of the human babies born will be male and half will be female because
a. of the segregation of the X and Y chromosomes during male meiosis.
63. How many autosomes do humans have?
b. 22 pairs
64. Sex in humans is determined by
a. a gene called SRY found on the Y chromosome.
65. When reciprocal crosses produce identical results, the trait is
b. not sex-linked.
66. A human male carrying an allele for a trait on the X chromosome is
67. White eyes is a recessive sex-linked trait in fruit flies. If a white-eyed female fruit fly is mated to a red-eyed male, their offspring should be
c. all white-eyed males and all red-eyed females.
68. What percent of their female progeny will show the cleft chin trait?
69. What percent of their male progeny will show the cleft chin trait?
70. Y-linked genes include a gene that produces hairy pinnae (the external ear). A male with hairy pinnae will pass this trait
b. only to his sons.
71. Alleles for genes located on mitochondrial DNA are said to be maternally inherited. What is the reason for this pattern of inheritance?
b. The egg contributes virtually all of the cytoplasmic organelles to the zygote.
72. Which of the following organelles contain(s) DNA?
e. a, b, and c
73. The approximate total number of genes in the human nuclear genome is closest to
74. Humans have _______ genes in their mitochondria.
1. A(n) _______ trait is one that can be passed from one generation to another.
2. A(n) _______ is an observable feature, such as flower color; a(n) _______ is a particular form of a character, such as a white flower.
3. A cross between two parents that differs by a single trait is a(n) _______ cross.
4. When a cross is made and a trait disappears in the F1 generation, only to reappear in the F2, the trait is
5. The totality of all the genes of an organism is known as the organism’s _______.
6. The physical appearance of a character is the _______, whereas the genetic constitution is the _______.
7. A(n) _______ is a portion of DNA that resides at a particular locus or site on a chromosome and encodes a particular function.
8. The region of the chromosome occupied by a gene is called the _______.
9. A cross between two heterozygous parents that differs by two independent traits is a(n) _______ cross.
10. To determine the overall probability of independent events, one should _______ the probabilities of the individual events.
11. To determine the probability of an event that can occur in two or more different ways, one should _______ the individual probabilities.
12. Mendel’s laws of inheritance can be applied to human genetics through the study of _______.
13. One particular allele of a gene may be defined as _______, or standard, because it is present in most individuals and gives rise to an expected trait, or phenotype.
14. The AB phenotype found in individuals with IAIB genotype is an example of _______.
15. When the expression of one gene depends on the expression of another gene, the genes demonstrate _______.
16. The hypothesis that hybrid vigor, or heterosis, results from the superiority of the heterozygote in comparison to either homozygote is known as _______.
17. When many genes contribute to the phenotype, variation is said to be _______.
18. Quantitative variation is the result of the interaction of _______ and _______.
19. Genes at different loci on the same chromosome can separate and recombine to form _______.
20. Geneticists make use of _______ frequencies to create genetic maps that show the arrangement of genes on a chromosome.
21. Recombination is most likely to occur between two loci that are _______.
22. A female that is heterozygous for a recessive sex-linked character is a _______.
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