GENETICS EXAM 1 UH LIN/DAANE

1.) Which of the following indicates the correct order of these events?

A) Metaphase - Prometaphase - Prophase - Anaphase - Telophase

B) Prophase - Prometaphase - Metaphase - Anaphase - Telophase

C) Telophase - Prometaphase - Prophase - Metaphase - Anaphase

D) Anaphase - Telophase - Prophase - Prometaphase - Metaphase

B) Prophase - Prometaphase - Metaphase - Anaphase - Telophase

2.) In a dihybrid cross using Mendelian inheritance, if both parents are heterozygous for both traits, what will be the phenotypic ratio of their offspring?

A) 3:1

B) 9:3:3:1

C) 1:1

D) 1:2:1

B) 9:3:3:1

3.) A testcross is always performed between the individual that is heterozygous for the genes to be mapped and an individual who is ____________.

A) heterozygous for the genes

B) lacking the genes

C) homozygous dominant for the genes

D) homozygous recessive for the genes

D) homozygous recessive for the genes

4.) Crossing over is more likely to occur between genes that are __________ on a chromosome

A) close together

B) far apart

B) far apart

5.) You are working with fruit flies, but you forgot to write down the parents of your cross. You count the progeny, and find you have 40 red-eyed males, 80 red-eyed females, and 40 white-eyed males. White eyes (w) are recessive to red (w+). Assuming that all genotypes from this cross should have equal survival rates, what are the genotypes of the parent flies?

A) X^w+ Y and X^w+ X^w

B) X^w+ Y and X^w X^w

C) X^w Y and X^w+ X^w

D) X^w Y and X^w+ X^w+x

A) X^w+ Y and X^w+ X^w

6.) The pedigree below shows the inheritance pattern of a rare genetic disorder that is inherited in an X-linked dominant manner through one family. The filled in circles and squares show affected individuals. What is the probability of individual III-2 being born male and affected?

A) 1/4

B) 1/2

C) 1/3

D) 0

D) 0

7.) What is the probability that an offspring will have an ssRR genotype from a cross of two SsRr individuals?

A) 6.25%

B) 25%

C) 3.12%

D) 12.5%

A) 6.25%

8.) Wild-type Drosophila have red eyes, but it is possible to isolate mutants that have different eye colors. The chart below summarizes the results of crosses between pure-breeding flies with different eye colors

+ = wildtype phenotype (= red eyes)

- = non-wildtype phenotype

Based on the chart, how many eye-color mutants have mutations in the SAME gene as the Garnet mutant? (Assume that all mutant alleles are recessive.)

A) 2

B) 3

C) 0

D) 6

C) 0

9.) The physical structure that is formed when two chromatids cross over is called a(n) _______.

A) chiasma

B) karyotype

C) bivalent

D) synaptonemal complex

A) chiasma

10.) In a chi-square test to determine if two genes are linked or assorting independently, what is the default (null) hypothesis that is tested?

A) The genes are assorting independently.

B) The distance between the genes is very small.

C) The genes are located on the sex chromosomes.

D) The genes are linked to one another.

E) No crossing over occurs.

A) The genes are assorting independently.

11.) The genetic composition of an individual is called its _____________

A) none of these choices are correct

B) genotype

C) phenotype

D) dominance

E) hybrid

B) genotype

12.) Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (The * indicates the centromere.)

before A B C D * E F G H

after A B C D * E F E F G H

A) Inversion

B) Deletion

C) Translocation

D) Duplication

D) Duplication

13.) Two genes that are located on the same chromosome are said to be _________

A) physically linked

B) parental-like

C) nonparental-like

D) recombinant

A) physically linked

14.) You are studying a diploid organism that has 14 pairs of chromosomes. How many chromatids will a gamete from this organism have?

A) 7

B) 28

C) 56

D) 14

E) 112

D) 14

15.) Chromosomal deletions and duplications are frequently the result of __________.

A) non-homologous chromosomes exchanging pieces

B) the use of colchicine

C) failure to separate chromosomes during anaphase

D) abnormal crossover events

D) abnormal crossover events

16.) A heterozygote possesses a phenotype that is intermediate between the homozygous dominant and homozygous recessive phenotypes. This is most likely an example of ________.

A) lethal alleles

B) incomplete dominance

C) sex-influenced inheritance

D) gene dosage

B) incomplete dominance

17.) Which of the following is not an example of euploidy?

A) Diploid

B) Triploid

C) Polyploid

D) Aneuploid

E) Tetraploid

D) Aneuploid

18.) Two pea plants that are heterozygous for the dominant tall gene and the dominant purple flower gene are mated. The cross resulted in 9866 progeny, of which 5550 were tall with purple flowers. What are the expected ratios of the other phenotypic classes?

A) 5550 short/white flower, 5550 tall/white flower, 5550 short/purple flower

B) 1850 short/white flower, 616 tall/white flower, 1850 short/purple flower

C) 1850 short/white flower, 1850 tall/white flower, 1850 short/purple flower

D) 616 short/white flower, 1850 tall/white flower, 1850 short/purple flower

D) 616 short/white flower, 1850 tall/white flower, 1850 short/purple flower

19.) You are a researcher examining the expression pattern of a wobbly fly phenotype. You have flies that fly straight and those having a wobble flight. When you cross a straight flying strain with a strain showing a wobble flight, all the F1 flies fly straight. In the F2 generation, you get 762 straight flying flies and 238 wobbly flies. Your null hypothesis is that one gene controls flight patterns and that straight is dominant to wobbly. Use chi square analysis to test your hypothesis. What is your chi square number? Do you reject or accept the null hypothesis? Use the table listed below to help answer the question.

A) Chi square = 0.768; reject

B) Chi square = 0.768; accept

C) Chi square = 0.192; reject

D) Chi square = 0.192; accept

B) Chi square = 0.768; accept

20.) You are studying a new species of plant similar to Mendel's pea plants. You are specifically interested in two genes that are located on two different chromosomes. In this plant, the gene for height has two alleles, T (tall) and t (short). The gene for leaf color has two alleles P (purple) and p (pink). What meiotic products do you expect from diploid cells that are homozygous for the tall allele and heterozygous for the leaf color alleles?

A) An equal number of TP and Tp gametes

B) An equal number of TP and tp gametes

C) 2 TP gametes for every 1 Tp gamete

D) An equal number of Tp, tP, tp, and TP gametes

A) An equal number of TP and Tp gametes

21.) An individual carries the allele for polydactyly, a dominant trait, but is phenotypically normal. This is an example of __________.

A) gene dosage

B) codominance

C) incomplete penetrance

D) simple Mendelian inheritance

E) incomplete dominance

C) incomplete penetrance

22.) If this pedigree shows a dominant disorder caused by the dominant A allele, what are the genotypes of the parents in this pedigree?

A) aa and AA

B) Aa and Aa

C) aa and Aa

D) aa and aa

C) aa and Aa

23.) In a mapping experiment with three linked genes, which phenotype should occur most often in the F2 offspring?

A) Phenotypes of individuals with single crossover events.

B) Parental phenotypes.

C) Phenotypes of individuals with double crossover events.

D) All of the phenotypes should occur equally in the F2 generation.

B) Parental phenotypes.

24.) An individual with type A blood and an individual with type B blood mate and have offspring. What blood type is not possible in their offspring?

A) Type O blood

B) Type AB blood

C) All blood types are possible

D) Type B blood E) Type A blood

C) All blood types are possible

25.) In peas, the round allele (R) is dominant to the wrinkled allele (r). A plant with roundpeas is crossed to a plant with wrinkled peas, and half of the resulting plants have round peas. What are the most likely genotypes of the parents in this cross?

A) RR × rr

B) RR × Rr

C) Rr × rr

D) Rr × Rr

E) rr × rr

C) Rr × rr

26.) The production of wild-type offspring from a cross between parents that both display the same recessive phenotype illustrates the genetic phenomenon of _______.

A) gene dosage

B) a spontaneous mutation

C) complementation

D) incomplete penetrance

E) simple recessive allele

C) complementation

27.) In Drosophila, the genes reduced (rd) bristles and withered (whd) wing are both found on chromosome 2. You have isolated a new recessive mutation in Drosophila that results in corrugated (corr) veins. χ2-analysis has revealed that corr is linked to the genes rd and whd on Chr. 2. You perform a three-point cross to determine the relative order of the three genes. Two pure-breeding mutant lines were crossed to produce an F1 female that is normal in appearance for all three traits. The phenotypes of 1000 progeny resulting from a testcross of an F1 female are summarized below.

380 withered, reduced

385 corrugated

44 withered, corrugated

41 reduced

7 withered

8 corrugated, reduced

65 wildtype

70 withered, corrugated, reduced

Which gene is in the middle?

A) corr

B) whd

C) rd

C) rd

28.) A karyotype is a(n) _____.

A) organelle of eukaryotic cells.

B) organized representation of the chromosomes within a cell.

C) stage of prophase I in meiosis.

D) protein complex bound to the centromere of an individual chromosome.

E) division of the cytoplasmic material following mitosis.

B) organized representation of the chromosomes within a cell.

29.) You have performed the following three point test cross in maize with the sugary (su), lazy (lz), and glossy (gl) genes. You want to infer the order and distance between genes. (Note: alleles in lower case are recessive; order alleles are written is not necessarily their order on the chromosome.)Which of the following maps is accurate for this trihybrid cross (numbers indicate map units):

A) Su1 0.7, Gl 0.8, Lz

B) Lz 14.7, Su 23.6, Gl

C) Su 14.7, Gl 23.6, Lz

D) Gl 10.7, Lz 14.7, Su

E) Lz 10.7, Su 14.7, Gl

E) Lz 10.7, Su 14.7, Gl

30.) In a dihybrid cross of two heterozygous individuals, you expect a 9:3:3:1 phenotypic ratio in the offspring, but observe a ratio of 9:7. What is the most likely explanation?

A) Epistatic interaction of the two genes

B) Simple Mendelian inheritance

C) Codominance

D) It is a sex-limited trait

E) Incomplete penetrance

A) Epistatic interaction of the two genes

31.) Meiosis differs from mitosis in that:

A) mitosis results in two daughter cells whereas meiosis results in four.

B) daughter cells resulting from meiosis has half the number of chromosomes.

C) daughter cells resulting from mitosis are genetically identical.

D) Two from A, B and C.

E) All of A, B and C

E) All of A, B and C

32.) The Law of Independent Assortment states that __________.

A) two different genes will NOT randomly assort their alleles during the formation of haploid cells

B) two different alleles will randomly assort during the formation of haploid cells

C) two different genes will randomly assort their alleles during the formation of diploid cells

D) two different genes will randomly assort their alleles during the formation of haploid cells

D) two different genes will randomly assort their alleles during the formation of haploid cells

33.) What is the most likely mode of transmission for the following trait? Assume the trait is rare in the population.

A) Autosomal dominant

B) Autosomal recessive

C) X-linked dominant

D) X-linked recessive

D) X-linked recessive

34.) The common goldfish Carassius auratus has 100 chromosomes and is tetraploid. The goldfish therefore has __________ sets of chromosomes containing __________ chromosomes each

A) 1; 100

B) 4; 100

C) 4; 25

D) 2; 50

C) 4; 25

35.) How does haploinsufficiency explain dominance of an allele that codes for a non-functional protein over an allele that codes for a functional protein?

A) A single functional copy of the gene produces sufficient gene product for normal biological function

B) A single functional copy of the gene produces insufficient gene product for normal biological function

C) The null allele produces a product that does not interfere with proper function of the normal allele product

D) The null allele rapidly mutates to reacquire normal functionality

B) A single functional copy of the gene produces insufficient gene product for normal biological function