Genetics Exam 3

Question 1

1. What is the purpose of a complementation test?

A. to determine whether an organism is homozygous dominant or recessive at a particular locus
B. to determine whether an allele is dominant. or recessive
C. to determine whether lethal alleles are present
D. to determine whether two mutants with the same phenotype have defects in the same gene

Answer 1

D. to determine whether two mutants with the same phenotype have defects in the same gene

Question 2

2. If fewer than 100% of individuals of a dominant genotype express the dominant phenotype, the phenotype is described as having reduced___

A. Expression
B. Pension
C. Penetrance
D. Expressivity

Answer 2

C. Penetrance

Question 3

3. Which structure that forms during meiosis leads directly to the formation of recombinant chromosomes?

A. Microtubule
B. Centromere
C. Sister Chromatid
D. Cross Over

Answer 3

D. Cross over

Question 4

4. In horses, black coat color is dominant over chestnut brown. Suppose a black horse is mated to a chestnut brown and the offspring are twins. One foal is black and the other is chestnut brown. What can you conclude about the genotype of he black parent?

A. The genotype must be homozygous dominant
B. The genotype type must be homozygous recessive
C. The genotype must be heterozygous
D. The genotype cannot be determined from the data

Answer 4

C. The genotype must be heterozygous

Question 5

5. In a cross between parents with the genotypes AaBb and aabb, where A and B loci are unlinked, what percentage of the offspring will have a phenotype that differs from the phenotype of the AaBb and aabb parents.

A. 100%
B. 75%
C. 50%
D. 25%

Answer 5

C. 50%

Question 6

6. In Mendel’s peas purple flower is dominant to white. From which of the following phenotypes can you not infer the genotype completely?

A. purple
B. White
C. True Breeding Purple
D. True Breeding White.

Answer 6

A. purple

Question 7

7. Which of the following is not one of Mendel’s conclusions based on his monohybrid crosses?

A. alleles exist in pairs
B. alleles have different DNA sequences
C. alleles segregate equally into gametes
D. one allele can mask the expression of another allele

Answer 7

B. alleles have different DNA sequences

Question 8

8. What does 10 map units represent?

A. 1% recombination between two genes on the same chromosomes
B. 10% recombination between two genes on some chromosome
C. 1% recombination between two different genes on different chromosomes
D. 10% recombination between two genes on different chromosomes

Answer 8

A. 1% recombination between two genes on the same chromosomes

Question 9

9. What term is used for a block of single-nucleotide polymorphisms (SNPs) that are almost always inherited together?

A. Genome
B. Marker
C. Polymorphism
D. Haplotype

Answer 9

D. Haplotype

Question 10

11. A different version of a gene is

A. allele
B. loci
C. genotype
D. phenotype

Answer 10

A. allele

Question 11

12. Which of the following statements is true

A. The genotype is the physical appearance of a trait
B. Alleles, genes, and loci, are different names for the same thing
C. The phenotype of the dominant allele is never seen in the F1 progeny of a monohybrid cross
D. A test cross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele

Answer 11

D. A test cross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele

Question 12

13. Which of the following factors cannot impact sex development in different organisms?

A. Mitosis
B. Genotype
C. Environment
D. Sex chromosomes

Answer 12

A. Mitosis

Question 13

14. Which of the following leads to gametes receiving incorrect number of chromosomes?

A. Apoptosis
B. Synapsis
C. Heterozygosity
D. Non-disjunction

Answer 13

D. Non-disjunction

Question 14

15. Which of the following is not a common dosage compensation mechanism in organisms

A. X-inactivation
B. Y- over expression
C. X over expression
D. X under expression

Answer 14

B. Y- over expression

Question 15

16. A form of a gene that has a slightly different sequence than other forms of he same gene but encodes the same type of an RNA or protein, is called a(n)

A. complementation group
B. Linkage group
C. Allele
D. trait

Answer 15

C. Allele

Question 16

17. The difference between co-dominance and incomplete dominance?

A. With co-dominance, neither allele produces sufficient protein. With incomplete dominance, both alleles make sufficient protein.
B. With co-dominance, both alleles produce protein. With incomplete dominance, neither allele makes sufficient
C. With co-dominance, the phenotype lies between the phenotypes of the parental extremes. For incomplete dominance, the phenotype of both alleles is seen
D. In co-dominance, the phenotype reflects both alleles. For incomplete dominance, the phenotype lies between the phenotypes of the parental extremes

Answer 16

D. In co-dominance, the phenotype reflects both alleles. For incomplete dominance, the phenotype lies between the phenotypes of the parental extremes

Question 17

18. What are Barr bodies?

A. Highly condensed and inactivated X chromosomes in males
B. Highly condensed and inactivated X chromosomes in females
C. Highly condensed and inactivated SRY gene in males
D. Highly condensed and inactivated SRY gene in females

Answer 17

B. Highly condensed and inactivated X chromosomes in females

Question 18

19. Which of the following can a genome-wide association study do?

A. Identify the dominant and recessive alleles of an individual
B. Identify alleles associated with a trait
C. Identify regions of the genome that influence a trait
D. Identify causative genes underlying a trait.

Answer 18

B. Identify alleles associated with a trait

Question 19

20. While doing fieldwork in Madagascar you discover a new dragonfly species with either red or clear wings. You preformed 2 crosses using different sets of red-winged parents with unknown genotypes and collected the following data.
    Cross. Offspring phenotype
21. Red X Red 147 red-winged + 52 clear-winged
22. Red X Red 396 red-winged
    From these results you can conclude:

A. Red is recessive and clear is dominant
B. Clear is recessive and red is dominant
C. There is evidence of epistasis
D. Red and clear are codominant

Answer 19

B. Clear is recessive and red is dominant

Question 20

21. What does a Manhattan show?

A. The inheritance pattern of a particular trait
B. Associations of traits with locations of the chromosomes
C. The genes associated with a particular trait
D. The distribution of phenotypes in a population

Answer 20

B. Associations of traits with locations of the chromosomes

Question 21

22. What is the role of the SRY gene in humans?

A. it initiates the X inactivation process in females
B. It is located on the X chromosome and causes X to pair with the Y chromosome during male meiosis
C. It is located on the Y chromosome and initiates the developmental pathways toward the male phenotype
D. It is located on an autosomal chromosome and represses the expression of autosomal genes in order to balance their expression level with genes on the X chromosome

Answer 21

C. It is located on the Y chromosome and initiates the developmental pathways toward the male phenotype

Question 22

23. Hemophilia in humans is usually caused by a defective factor 8 protein. The factor 8 gene is on the human X chromosome. Which statement about the inheritance of hemophilia is more correct?

A. This condition occurs almost exclusively in males born to a carrier mothers due to Y-linked recessive inheritance
B. This condition occurs almost exclusively in females sired to carrier fathers due to X-linked recessive inheritance
C. this condition almost exclusively occurs in females sired to carrier fathers due to Y-linked recessive inheritance
D. this condition occurs almost exclusively in males born to carrier mothers due to X-linked recessive inheritance

Answer 22

D. this condition occurs almost exclusively in males born to carrier mothers due to X-linked recessive inheritance

Question 23

24. The capital R locust determines flower color in a new plant species. However, Rr plants have pink flowers. What type of inheritance does this demonstrate for flower color in the plants?

A. complete dominance
B. Incomplete dominace
C. Codominance
D. Complementation

Answer 23

B. Incomplete dominace

Question 24

25. In humans, blood types A&B are codominant to each other and each is dominant to type O. What blood type are possible amongst the offspring of a couple whose blood types are AB and A.

A. A, B, AB, and O
B. A, B, and AB only
C. A, B, and O only
D. A and AB only

Answer 24

B. A, B, and AB only

Question 25

26. If two independently isolated mutations with the same phenotype complement each other, each provides the function the other lacks, so they are mutations of _____ genes. A. Different B. Similar C. Identical D. Homologous

Answer 25

A. Different

Question 26

27. A 2015 study found that hot temperatures altered the expression of sex chromosomes in Australia's bearded dragon lizards. The lizards were female in appearance and were capable of laying eggs, despite having the ZZ chromosomes usually associated with male lizards. The is an example of A. The ZZ, ZW sex determination of lizards and birds B. The temperature-dependent sex determination of lizards and reptiles C. When females are the heterogametic sex D. When males are the homogametic sex

Answer 26

B. The temperature-dependent sex determination of lizards and reptiles

Question 27

28. ________ involve mutations at specific nucleotide positions that have at least tow or more variants that are found in at least 1% of the population. A. microarrays B. Single nucleotide polymorphisms or SNPs C. linkage groups D. haplotypes

Answer 27

B. Single nucleotide polymorphisms or SNPs

Question 28

29. ______ results in daughter cells that each contains the complete identical genome of the parent cell A. Meiosis B. Mitosis C. Aneuploidy D. Trisomy

Answer 28

B. Mitosis

Question 29

30. In dogs, short fur is dominant over long fur. A dog with short fur is crossed with a dog with long fur. In a litter of four, all of the puppies have short fur. What is the best conclusion A. the dog with short fur is definitely homozygous B. the dog with short fur is probably homozygous C. the dog with short fur is definitely heterozygous D. the dog with short fur is probably heterozygous

Answer 29

B. The dog with short fur is probably homozygous

Question 30

31. In corn colored seed (C) is dominant to colorless seed (c) and full seed (S) is dominant to shrunken seed (s). A completely heterozygous CcSs plant was testcrossed against a homozygous recessive plant and the following genotypes were inferred. C-S- 4292 ccss 4605 C-ss 86 ccS- 44 A. Are the parental types in Cis or Trans configuration? B. Are the recombinant types in Cis or Trans configuration? C. What is the map distance between the two loci? _____C_________S______

Answer 30

A. Cis B. Trans C. Map distance (in centimorgans, cM) is calculated by: Recombination frequency (RF)=Number of recombinantoffspring/Total number of offspring×100 C–ss = 86 ccS– = 44 Total recombinants = 86 + 44 = 130 Total offspring = 4292 + 4605 + 86 + 44 = 9027 RF=(130/9027)×100≈1.44% Answer C: Map distance = ~1.4 cM

Question 31

33. A. X and Y axis for microarray

Answer 31

A. the x-axis typically represents genes, while the y-axis represents the intensity of expression or the expression ratio of a gene